WO2012013360A1 - Implantable electrode device, in particular for sensing an intracardiac electrogram - Google Patents

Implantable electrode device, in particular for sensing an intracardiac electrogram Download PDF

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Publication number
WO2012013360A1
WO2012013360A1 PCT/EP2011/003849 EP2011003849W WO2012013360A1 WO 2012013360 A1 WO2012013360 A1 WO 2012013360A1 EP 2011003849 W EP2011003849 W EP 2011003849W WO 2012013360 A1 WO2012013360 A1 WO 2012013360A1
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WO
WIPO (PCT)
Prior art keywords
electrode device
energy
resonant circuit
electrode
characteristic
Prior art date
Application number
PCT/EP2011/003849
Other languages
French (fr)
Inventor
Erhard Kisker
Original Assignee
Md Start Sa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/EP2010/005703 external-priority patent/WO2012013212A1/en
Application filed by Md Start Sa filed Critical Md Start Sa
Publication of WO2012013360A1 publication Critical patent/WO2012013360A1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/375Constructional arrangements, e.g. casings
    • A61N1/3756Casings with electrodes thereon, e.g. leadless stimulators
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/07Endoradiosondes
    • A61B5/076Permanent implantations
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/24Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25Bioelectric electrodes therefor
    • A61B5/279Bioelectric electrodes therefor specially adapted for particular uses
    • A61B5/28Bioelectric electrodes therefor specially adapted for particular uses for electrocardiography [ECG]
    • A61B5/283Invasive
    • A61B5/287Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/37205Microstimulators, e.g. implantable through a cannula
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02Operational features
    • A61B2560/0204Operational features of power management
    • A61B2560/0214Operational features of power management of power generation or supply
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/04Constructional details of apparatus
    • A61B2560/0462Apparatus with built-in sensors
    • A61B2560/0468Built-in electrodes
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/0002Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
    • A61B5/0031Implanted circuitry
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/68Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/686Permanently implanted devices, e.g. pacemakers, other stimulators, biochips
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/37211Means for communicating with stimulators
    • A61N1/37217Means for communicating with stimulators characterised by the communication link, e.g. acoustic or tactile
    • A61N1/37223Circuits for electromagnetic coupling
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/372Arrangements in connection with the implantation of stimulators
    • A61N1/378Electrical supply
    • A61N1/3787Electrical supply from an external energy source

Definitions

  • Implantable Electrode Device in Particular for Sensing an
  • the present invention relates to an arrangement with an implantable electrode device or to a method, in particular for capturing an intracardiac electrogram and/or for cardiac pacing and/or for optimizing coupling to the electrode device.
  • the focus is primarily on sensing an intracardiac electrogram and/or on delivering an electrical impulse for stimulat- ing a heart.
  • the present invention is not restricted to this particular solution, but in general can be applied to sensing other signals, in particular biopotentials like ECG, EEG, ERG, EMG, and EOG or the like.
  • the signal may correspond to, e.g., a glucose concentration, a phonocardiography signal or a blood pressure.
  • the electrical impulse for instance, can be applied to the brain, different regions of a body or to nerves as well.
  • the invention can be applied to different fields of technology as well.
  • the electrode device according to the present invention can be applied to an, in particular hermetically sealed, vessel or pipe, e.g. for performing electrolysis or electroanalysis inside in a wireless manner.
  • Electrocardiography is a method using electrical signals caused by or during the heartbeat. These electrical signals, corresponding to the activity of the heart, can be used for detecting abnormal rhythms of the heart that may be caused by damages of its conductive tissue. Typically, more than two electrodes are placed on the skin of a human to measure potentials or a voltage corresponding to the electrical activity of the heart. A more direct and precise way to sense a signal corresponding to the electrical activity of the heart makes use of an implanted electrode close to the signal source, i.e. the heart itself, for sensing a so- called intracardiac electrogram.
  • a system for monitoring and analyzing biosignals is known from EP 1 815 784 Al.
  • Cable-less transducers are used for measurement of e.g. electrocardiograms.
  • the transducers can be placed on or implanted under human skin.
  • the transducers make use of a battery as an energy supply for measuring signals by an elec- trode or sensor. If the transducers are implanted, changing the battery is prob- lematic.
  • using a battery leads to a size that is not small enough for an application around or inside a heart, e.g., for sensing intracardiac electrograms.
  • An implantable pacemaker comprising a programmable sensing circuit for sensing a signal which allows for approximating a surface electrocardiogram is disclosed in US 2008/0051672 Al .
  • a medical device is implanted in the area of a shoulder and comprises a telemetry module for sending measured data.
  • Pacing electrodes are connected to the medical device using wires or cables, wherein the pacing electrodes can be used for estimating an intracardiac signal as well. Nevertheless, these wires or cables are problematic or disadvantageous, because they run over a length of about 30 cm in the blood circulation system and can thereby cause undesirable or even fatal physical reactions. Furthermore, the risk of failure as a result of the mechanical stressing during body movements is high. In addition, the electrodes can be dislocated by movements of the patient due to the wires or cables.
  • US 5,713,939 Al relates to a data communication system for control of transcutanous energy transmission to an implantable electrode device, wherein a transmitting coil of an external device and receiving coil of an associated implantable receiver are inductively coupled for energy transfer.
  • the receiving coil is connected to a rectifier input.
  • the rectifier output is permanently connected to a smoothing capacitor and switchable connected to a rechargeable battery.
  • the battery is disconnected from the rectifier, which can be detected by the external device by load analysis.
  • the implantable device permanently rectifies energy provided to the receiving coil since the smoothing capacitor forms a short or low impedance for alternating signals.
  • the load of the coil is reduced. This changed load is used for signaling a battery status.
  • the permanent connection of the rectifier to the coil still causes losses if an alternating current is provided to or by the coil, either by additional parasitic effects of the rectifier or particularly since a smoothing capacitor is provided at the rectifier output consuming energy. Smoothing can be obtained only if the capacitor forms a short or low impedance for alternating currents. Thus, the rectifier still consumes energy from the receiving coil.
  • US 2009/0024180 Al discloses a stimulation system comprising an implantable electrode device.
  • the electrode device is supplied with energy and controlled in an exclusively wireless manner via a time-variable magnetic field generated by an implanted control device.
  • This electrode device is small enough for a placement close to or inside a heart, since energy is transmitted in a wireless manner instead of using a battery. Nevertheless, this electrode device is part of a stimula- tion system and configured for delivery of an electrical impulse only. Thus, it is not suitable for sensing purposes.
  • Sensing a signal as well as delivering an electrical impulse via electrodes of an implanted electrode device demands for proper contact to the surrounding area, in particular tissue, e.g. of a heart.
  • this electrode contacts can be subject of a change or failure, in particular if scar tissue is formed or different physical or physiological reactions occur.
  • sufficient wireless coupling should be ensured, if a wireless transmission is used.
  • Object of the present invention is to provide an arrangement with at least one implantable electrode device or a method, wherein an electrode contact and/or wireless coupling can be characterized, verified and/or optimized.
  • an arrangement in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device.
  • the electrode device comprises at least one electrode for sensing a signal from the surrounding area, preferably a tissue, in particular of a heart, and/or for delivering an electrical impulse to it.
  • the electrode device further comprises a resonance means associated to the electrodes for forming a resonant circuit with the surrounding area via the electrode.
  • the arrangement further comprises a means for determining a characteristic of the resonant circuit preferably indicating the electrical contact of the electrode to the surrounding area, an electrical characteristic of the surrounding area, an electrical resistance across at least two electrodes, and/or a distance, coupling or respective change between the electrode device and the means.
  • a resonance means of the electrode device can be used to form a resonant circuit with the surrounding area via at least one electrode, wherein a characteris- tic of the resonant circuit indicating the electrical contact of the electrode to the surrounding area, an electrical characteristic of the surrounding area and/or the electrical resistance across at least two electrodes is determined.
  • the resonant circuit of the electrode device preferably is supplied with energy, in particular by wire, cable, wireless and/or by means of an energy butter of the electrode device, particularly preferably in an exclusively wireless manner by means of a time-varying magnetic field.
  • Providing energy to the resonant circuit can cause an oscillation of the resonant circuit, in particular an oscillating current.
  • a characteristic of the resonant circuit, in particular the frequency and/or decaying behavior of this oscillation, a corresponding value or signal preferably is used as an indicator of the electrical contact of the electrodes to the surrounding area.
  • the contact can be characterized and/or verified by analyzing the oscillation.
  • energy stored and/or remaining in the resonant circuit preferably causes an oscillation, in particular oscillating current in the resonant circuit, at the natural resonance frequency of the resonant circuit and/or damped depending on the losses of the resonant circuit, both preferably depending on the contact of at least one electrode with the surrounding area.
  • oscillations of the resonant circuit preferably after stopping energy transfer to the electrode device, are referred to as "post-ringing".
  • the electrode device preferably is adapted to partially return energy, a signal, in particular a time-varying magnetic field indicating the characteristic of the reso- nant circuit, in particular wherein the transceiver of the electrode device, in response to reception of energy, automatically generates a time-varying magnetic field corresponding to the characteristic of the resonant circuit.
  • Energy transmitted to the electrode device can at least partially be returned by the electrode de- vice, wherein the returned energy preferably indicates the characteristic of the resonant circuit, in particular in a wireless manner by means of a time-varying magnetic field.
  • the post-ringing, a corresponding signal or a corresponding time-varying mag- netic field preferably comprises information regarding the characteristic of the resonant circuit. Analyzing the post-ringing is particularly preferred for determining the characteristic of the resonant circuit and/or for determining, analyzing and/or verifying the contact of the at least one of the electrodes of the electrode device to the surrounding area, in particular tissue. Further, if the post-ringing is transmitted in a wireless manner, its information and, in particular a reception power level, can be used for determining a distance or corresponding value.
  • magnetic field preferably covers electro-magnetic fields or waves.
  • fields, waves or the like with any kind of magnetic component can be a “magnetic field” in the sense of the present invention as well.
  • the time-varying magnetic field according to the present invention can comprise components generated by different sources, in particular by different parts of the arrangement and/or system, e.g. the electrode device and/or the control unit.
  • the time-varying magnetic field in the sense of the present invention can be generated by the electrode device, in particular if sending the signal and/or the characteristic of the resonant circuit is intended.
  • the time-varying magnetic field H alternatively or additionally can be generated externally if energy transfer to the electrode device and/or delivery of an electrical impulse is intended.
  • the time- varying magnetic field H thus, can be composed by different sources, in particular if energy and signal transfer are performed at the same time.
  • the time-varying magnetic field preferably reaches at least one electrode device and, preferably, the analysis means, the control device, the receiver and/or the control unit. More preferably, the magnetic field reaches each of the electrode devices, the analysis means and/or the control unit.
  • the characteristic of the resonant circuit can be measured directly, in particular by a means for determining placed inside the electrode device and, alternatively or additionally, via a cable connection or the like.
  • the characteristic of the resonant circuit is determined indirectly and/or externally in a wireless manner, in particular by means of a time-varying magnetic field.
  • the characteristic of the resonant circuit indicating the electrical contact of the electrodes to the surrounding area is determined externally, in particular by means of the time-varying magnetic field. This can be performed with less effort, in particular without additional means or only a few minor modifications of the electrode device itself.
  • the characteristic of the reso- nant circuit in particular losses, a damping and/or decay behavior and/or a resonance frequency of in the resonant circuit, a corresponding oscillating current and/or a corresponding time-varying magnetic field is or are used for determining, in particular remote determining in a wireless manner, the electrical contact of the electrodes to the surrounding area and/or the electrical resistance across the electrodes.
  • an electrical behavior of the contact between the electrodes and the surrounding area and/or an electrical characteristic of the surrounding area is or are used to modify the losses and/or resonance frequency of the resonant circuit.
  • the resonant circuit is formed with the surrounding area, wherein the surrounding area preferably forms part of it.
  • the losses, the resonant frequency and/or a corresponding oscillating current and/or time-varying magnetic field H of the resonant circuit can be used for verifying and/or characterizing the contact between the electrodes and the surrounding area, in particular a contact resistance and/or capacitance.
  • the characteristic of this resonant circuit in particular a resonance frequency and/or losses, preferably represented by a damping factor or quality factor of the resonant circuit, depends on the characteristic of the electrical contact between the electrode of the elec- trode device and the surrounding area, in particular tissue, e.g., of a heart.
  • This characteristic can be used for characterizing, analyzing and/or verifying the contact of the at least one electrode of the electrode device to the surrounding area. If a contact malfunction occurs, this malfunction indicated by a variation in a characteristic of a contact and/or of the resonant circuit can be detected. An au- tomatic handling and/or a notification can be provided based on this detection.
  • an electrical resistance across the electrodes and/or of the surrounding area can be determined.
  • a capacitance generated by the contact of the electrode of the electrode device to the surrounding area or other indicators for a contact failure or a proper contact can be determined.
  • at least two electrodes of the electrode device are associated, in particular connected, to the resonance means, forming the resonant circuit or part of it.
  • the electrode device can send the characteristic of the resonant circuit and/or the signal, preferably in a wireless manner by means of the time-varying magnetic field.
  • the electrode device can be supplied with energy exclusively in a wireless man- ner by means of the time-varying magnetic field.
  • the resonance means can be supplied with energy in a wireless manner by means of the time- varying magnetic field, preferably inducing oscillating currents in the resonant circuit.
  • the oscillating currents in the resonant circuit can be used to generate a corresponding time-varying magnetic field.
  • a short pulse of a time-varying magnetic field is applied to the electrode device inducing a current to a transceiver of the electrode device.
  • the arrangement preferably comprises an analysis means, the analysis means be- ing adapted for receiving the signal, the characteristic of the resonant circuit and/or energy sent, in particular returned, by the electrode device comprising corresponding information.
  • the signal and/or energy preferably is sent by the electrode device and/or received by the analysis means via the time-varying magnetic field, respectively.
  • the analysis means can be adapted to verify and/or characterize the contact of at least one electrode of the electrode device to the surrounding area, in particular by analyzing the energy and/or signal sent by the electrode device, and/or returned as response of energy transfer to the resonant circuit by the electrode de- vice.
  • the analysis means can be adapted for determining a strength of the time-varying magnetic field and/or a distance, in particular a relative distance for the electrode device and/or distance change, a coupling factor and/or a corresponding value.
  • the analysis means preferably is adapted to identify a dysfunction, in particular of a heart, and/or an electrical characteristic of the surrounding area, in particular of the tissue and/or of a sample in production technology, by analyzing the signal.
  • a control unit can comprise the analysis means.
  • the control unit can comprise a control device which is adapted for transmitting energy to the at least one im- plantable electrode device in a wireless manner by means of the time-varying magnetic field. Alternatively or additionally, control signals can be transmitted.
  • the control unit can comprise a receiver which is adapted for receiving the energy, in particular comprising information about the characteristic of the resonant circuit and/or the signal from, in particular returned by, the at least one electrode device, preferably exclusively in a wireless manner by means of the time- varying magnetic field, and/or using a transmit coil and/or a receive coil, and/or a magnetic field sensor, in particular a magnetometer, of the control unit, in particular of the receiver.
  • the analysis means can form part of the receiver.
  • a further aspect of the present invention relates to an arrangement comprising the electrode device with a resonant circuit comprising the resonance means, wherein the resonance means is configured for generating a time-varying magnetic field corresponding to an oscillation of the resonant circuit.
  • the arrangement further comprises (an analysis) means placed separately remote from the electrode device, wherein the (analysis) means is configured for determining a strength of the time-varying magnetic field corresponding to the oscillation of the resonant circuit, preferably for determining and/or approximating a relative position and/or orientation of the (analysis) means to the electrode device and/or change thereof, in particular with optimized coupling to each other.
  • a coupling between an implantable electrode device and a analysis means remote there from can be optimized, wherein energy is provided to the electrode device causing a resonant circuit of the electrode device to oscillate and to transmit energy corresponding to this oscillation to the analysis means in a wireless manner.
  • the analysis means receives the energy corresponding to the oscillation and determines its power level at the position of the analysis means or a corresponding value.
  • the method comprises changing a relative position and/or orientation of the electrode device and the analysis means to each other, repeating the steps of providing energy to the electrode device and determining the power level, comparing the power levels and, in particular, interpreting the relative position and/or orientation corresponding to the higher one of the power levels as to providing the higher coupling of the electrode device and the analysis means to each other.
  • a receive power level and/or a characteristic of a resonant circuit of an implantable electrode device, received from the electrode device in a wireless manner in response to providing energy to the electrode device causing an oscillation which generates a corresponding power transmission by the electrode device can be used.
  • a further aspect of the present invention which can be realized independently as well, relates to the arrangement with at least one implantable electrode device, wherein the electrode device comprises a rectifier for rectifying energy supplied to the electrode device.
  • the electrode device comprises a switch opening if it is desired to send a signal and/or to determine a characteristic of a resonant circuit, in particular formed with the surrounding area of the electrode device, such that the energy of the signal and/or the resonant circuit is or are not consumed by the rectifier.
  • An advantage of using a switch for disconnecting the rectifier resides in the fact that energy which is provided to or stored by the transceiver is not consumed by the rectifier. This allows using the transceiver for sending purposes without major losses. Further, a decay behavior of the post ringing, which depends on losses of the resonant circuit, can be reduced. Thus, more oscillation periods are available for analyzing the post ringing. Providing a different means for sending can be omitted, which leads to a smaller and cheaper electrode device. The transceiver, hence, can be used both for sending and receiving.
  • the switch preferably connects the transceiver to the rectifier or to the electrode alternatively.
  • the most advantageous working modes are connecting the rectifier and disconnecting the electrodes form the transceiver for receiving energy and/or connecting the electrodes and disconnecting the rectifier for forming the resonant circuit.
  • the switch can comprise or be formed by a changeover switch. Alternatively or additionally, one or more single switches can be provided. This allows for disconnecting the electrode as well as the rectifier, e.g., for sending a signal provided directly or amplified to the transceiver.
  • the switches preferably are semiconductor switches, e.g. MOSFETs. Semiconductor switches are small, easy to control and consume a low amount of power.
  • the rectifier does not consume energy pref- erably even if hardly any or a negligible amount of energy reaches the rectifier, since leakage or crosstalk might remain even if not intended.
  • energy provided to the rectifier while not i.e.
  • the transceiver preferably is configured for generating a time-varying magnetic field.
  • the at least one switch preferably is configured for disconnecting the transceiver from the rectifier, and/or for connecting the transceiver to a surrounding area via at least one electrode. This allows for sending a signal or energy with the transceiver in a wireless manner, i.e., without a cable or lead.
  • the switch preferably opens, in particular disconnecting the transceiver from the rectifier, if it is desired to send a signal and/or to determine a characteristic of a resonant circuit, such that the energy of the signal and/or of the resonant circuit is or are not consumed by the rectifier.
  • Disconnecting the transceiver disables power consumption by the rectifier, which reduces signal losses and enables active sending with the transceiver, i.e. actively generating a time-varying magnetic field, e.g., by providing a current to the transceiver.
  • the transceiver forms a resonant circuit with a surrounding area of the electrode device when connected to the at least one electrode by the switch.
  • the switch further preferably disconnects the rectifier for forming the resonant circuit with a surrounding area and/or for sending a signal sensed from the surrounding area.
  • the transceiver For forming the resonant circuit, the transceiver should be influenced by the surrounding area, such that an analysis of the surrounding area or of a contact thereto is possible. If, however, energy should be received, a direct connection to the surrounding area might cause losses.
  • An advantage of providing the switch be- tween the transceiver and the electrode resides in the fact that both the efficiency when receiving energy and the resonant circuit with a characteristic depending on the contact to or the electrical characteristic of the surrounding are can be achieved.
  • the switch can connect the transceiver to the at least one electrode of the electrode device for sending the signal.
  • the sensed signal can be directly provided to the transceiver, when a associated receiver is sufficiently sensitive.
  • the switch preferably connects the transceiver to the rectifier of the electrode device for rectifying received energy. This allows energy to be rectified and to be used, e.g., for to be buffered, for generating an electrical impulse or for sending. Further, the switch preferably disconnects the transceiver from the at least one electrode of the electrode device for rectifying received energy and/or for determining a coupling to the electrode device. Thus, a current through the surrounding area and corresponding losses can be avoided while no influence of the surrounding area, a contact thereto or direct delivery of an electrical impulse is needed.
  • the switch preferably can connect the transceiver to at least one electrode of the electrode device for forming the resonant circuit with the surrounding area and disconnects the rectifier, such that the energy of the resonant circuit (RC) is not consumed by the rectifier, in particular simultaneously, for determining and/or sending the characteristic of the resonant circuit.
  • RC resonant circuit
  • the switch is realized by or forms part of the rectifier.
  • switches in particular semiconductor switches, for forming the rectifier is advantageous compared to diodes since losses due to the threshold of the diodes can be avoided. Further, these switches can be used for disconnecting and/or disabling the rectifier, such that it does not consume energy form or provided to the transceiver.
  • the electrode device can comprise the rectifier for rectifying energy supplied to the electrode device, preferably from outside and/or in a wireless manner.
  • the rectifier in particular comprises semiconductor switches, preferably in a H-bridge configuration.
  • the rectifier in a H-bridge configuration or other full-wave rectifiers have a higher efficiency than half-wave rectifiers.
  • rectifiers comprising semiconductor switches are much more efficient compared to com- mon diode-type rectifiers.
  • using a rectifier with semiconductor switches and/or in a H-bridge configuration is particularly advantageous for the field of wireless applications the electrode device is typically used for.
  • the rectifier with semiconductor switches in a H-Bridge configuration allows for deactivating the rectifier by opening each switch.
  • This particular mode according to the present invention allows for improving sending capabilities and/or detectability of the characteristic of the resonant circuit.
  • a rectifier with semiconductor switches in other configurations can be used as well.
  • the rectifier has a rectifying mode which is well known in the art for normal operation and a sending mode, wherein the rectifier disconnects its input and/or provides an invariable connection between its input and output.
  • each switch of the rectifier that connects the input is opened or disconnected in the sending mode.
  • the rectifier does not consume or does only to a min- er extend consume energy.
  • the rectifier In the rectifying mode of the rectifier, energy received by the electrode device is rectified by the rectifier such that the electrode device can be supplied with energy and/or information.
  • the transceiver associated with or connected to the rectifier can be used for sending the sensed signal and/or for determining the characteristic of the resonant circuit. This in particular is supported since signal energy and/or energy stored in the resonant circuit is or are not consumed by the rectifier.
  • the rectifier preferably does not consume the energy of a signal that is to be sent via the transceiver and/or the energy of or stored in the resonant circuit, e.g., if the post-ringing is to be analyzed.
  • the sending performance and/or the ability of analyzing the post-ringing can be improved and/or the transceiver can be used for receiving energy and for sending purposes and/or providing separate transceivers in the electrode device can be omitted.
  • the rectifier can be decoupled and/or disconnected such that the energy of the signal and/or stored in the resonant circuit is or are not consumed by the rectifier. This can be obtained by opening a switch, in particular for disconnecting the rectifier.
  • a further aspect of the present invention which can be realized independently as well, relates to the arrangement with at least one implantable electrode device, wherein, the electrode device comprises a switch connecting one node of a transceiver of the electrode device directly to one of the electrodes of the electrode device.
  • a further aspect of the present invention which can be realized independently as well, relates to a method for characterizing a contact of electrodes of an implantable electrode device to a surrounding area and/or for sending a signal with the implantable electrode device, wherein a switch is used to connect one node of a transceiver of the electrode device directly to one of the electrodes. This allows for an increased influence of the contacts of the electrodes to the surrounding area and/or for directly sending the sensed signal by the electrode device.
  • Connecting one node of the transceiver directly to one of the electrodes using a switch advantageously allows for increasing the influence of the contact between the electrodes and the surrounding area on the characteristic of the resonant circuit. This allows for a more exact and/or reliable characterization, analysis and/or verification of the contact. Further, sensing a signal from the surrounding area can be improved, e.g., by reducing signal energy losses. Disconnecting, e.g. by opening the switch, can prevent energy losses via the electrodes if receiving and rectifying is intended.
  • Energy is preferably transmitted to the electrode device in an alternating manner, in particular by means of an alternating time-varying magnetic field and/or an alternating current.
  • the rectifier of the electrode device preferably consumes and/or transforms the energy provided to the electrode device, in particular by rectifying this energy for supplying the electrode device.
  • a switch For characterizing a contact of electrodes of an implantable electrode device to a surrounding area and/or for sending a signal with the implantable electrode device, a switch preferably is opened if it is desired to send a signal and/or to determine a characteristic of the resonant circuit such that the energy of the signal or of the resonant circuit is not consumed by a rectifier for rectifying energy supplied to the electrode device.
  • the switch of the electrode device can be opened, in particular if it is desired to send a signal and/or to determine a characteristic of the resonant circuit, such that the energy of the signal or the energy stored in or of the resonant circuit is not consumed by a rectifier for rectifying energy supplied to the electrode device.
  • the implantable electrode device preferably comprises at least two electrodes for sensing the signal from the surrounding area and/or for delivering the electrical impulse.
  • the signal preferably can be an intracardiac potential or voltage, a (bio-) potential as an ECG signal, an EEG signal, an EMG signal or the like.
  • the implantable electrode device can comprise a sensor, preferably with electrodes, for sensing the signal, in particular corresponding to a glucose value, blood pressure or the like.
  • the signal optionally can comprise or correspond to the characteristic of the resonant circuit or can correspond to it.
  • the signal can correspond to the oscillating current of the resonant circuit, which can be sensed from the resonant circuit by directly electrically connecting or indirectly coupling, e.g. of the resonant circuit to the analysis means and/or the transceiver.
  • the characteristic of the resonant circuit optionally can comprise the signal, in particular if the signal acts on the resonant circuit via at least one electrode of the electrode device.
  • the energy, characteristic and/or signals sent and/or received by the electrode device and/or the control unit can be transmitted acoustically, visually, mechanically, hydraulically, electrically and/or pneumatically.
  • the energy, characteristic and/or signal is sent and/or transmitted via the time- varying magnetic field.
  • the implantable electrode device can be adapted for sending the characteristic of the resonant circuit and/or the sensed signal, preferably in a wireless manner by means of a time-varying magnetic field.
  • the electrode device can comprise a transceiver, in particular a coil and/or an antenna, that can form part of the resonant circuit and/or the resonance means.
  • the transceiver does not need to comprise any active part.
  • the electrode device can be suppliable with energy exclusively in a wireless manner by means of the time-varying magnetic field. Energy can be transferred to the electrode device, in particular to the transceiver of the electrode device, via the time-varying magnetic field, preferably providing the resonant circuit with energy and/or causing an oscillation of the resonant circuit.
  • the electrode device preferably is adapted for generating electrical impulses and/or for delivering electrical impulses via the electrodes.
  • the electrode device can have a double functionality. It is possible, that the electrode device can sense a signal, in particular corresponding to the electrical activity of a heart, and, at the same time or intermittingly, the electrode device can be used or configured for a pacemaker or defibrillator functionality, i.e. for delivering the electrical impulse. As a synergetic effect, the signal sensed by the electrode device can be used for triggering the stimulation or pacemaker functionality, i.e. for delivering the electrical impulse. Therefore, it is preferred that the electrode device senses the signal and receives a control signal synchronized to the sensed signal for triggering generation or delivery of the electrical impulse.
  • the implantable electrode device preferably is an at least basically passive de- vice, wherein the energy needed for operation is provided by the signal to be sensed itself and/or the power needed for operation is supplied by means of the time-varying magnetic field.
  • the electrode device preferably exclusively delivers less energy by means of generating the time-varying magnetic field and/or by delivering electrical impulses than the amount of energy received by means of the time-varying magnetic field and/or the sensed signal.
  • the electrode device preferably is configured to be supplied with energy exclusively by the intrinsic energy of the sensed signal and/or in a wireless manner by means of the time-varying magnetic field.
  • the signal sensed by the electrode device and/or the characteristic of the resonant circuit can be transmitted in a wireless manner, and the power can be supplied by means of the time-varying magnetic field or the signal itself.
  • the power can be supplied by means of the time-varying magnetic field or the signal itself.
  • no wire, cable, lead or the like is needed and, hence, the reliability can be improved significantly.
  • no battery is needed within the electrode device. This is particularly advantageous for achieving a small form factor, because the size for a portable and/or wireless sensing device is strictly limited to larger form factors if a battery is needed.
  • the electrode device preferably comprises the transceiver for sending the signal in a wireless manner, preferably a coil and/or an antenna, which can form part of the resonant circuit.
  • the resonance means preferably comprises or is formed by the transceiver, in particular a coil and/or an antenna.
  • the transceiver is adapted for sending the characteristic of the resonant circuit and/or the signal in a wireless manner by means of the time- varying magnetic field and/or wherein the transceiver is configured to be supplied with energy exclusively in a wireless manner by means of the time-varying magnetic field.
  • the transceiver preferably emits energy, in particular the signal and/or energy corresponding to the oscillation of the resonant circuit, in particular exclusively by generating a corresponding time-varying magnetic field.
  • the transceiver of the electrode device preferably acts as or is part of the resonance means, which preferably is associated to the electrode of the electrode device and forms the resonant circuit with the surrounding area.
  • At least one electrode is connected to the transceiver of the electrode device, in particular via an amplifier for amplifying the sensed signal and/or the characteristics of the resonant circuit.
  • the transceiver can be configured for generating the time-varying magnetic field corresponding to the signal and/or to the characteristic of the resonant circuit. Signals sensed inside or close to a heart are much stronger and, hence, more reliable and robust than voltages or potentials that can be detected via the skin of a body. Nevertheless, amplification can be advantageous for a good signal-to-noise ratio if the signal is transmitted and/or received.
  • Different, independent transceivers can be used for supplying the electrode device with energy, sending the signal and/or transmitting the characteristic of the resonant circuit or a corresponding value.
  • An energy buffer can be used in the electrode device and is preferably connected to the output of the rectifier.
  • the energy buffer can smooth the power, e.g. the internal voltage.
  • the energy buffer typically is a capacitor, in particular with a ca- pacity for a few seconds or minutes of sending the signal in order to keep the form factor as small as possible.
  • the electrode device can comprise a supervisory component that preferably is adapted for controlling at least one switch and may comprise a timer for a delayed controlling, i.e. switching the switch. Switches in the rectifier can be used either for directing the signal or for directing energy flow inside the electrode device.
  • the supervisory component preferably can deactivate the rectifier if analyzing the characteristic of the resonant circuit and/or if sending the sensed signal is or are desired.
  • the supervisory component can be adapted for activating and/or deactivating the normal operation and/or the sending mode of the rectifier.
  • the supervisory component can be supplied by the rectifier and/or by the energy buffer.
  • the supervisory component can be or comprise a controller, microcontroller or the like. It can be adapted for receiving and/or decoding information, in particular sent via the time-varying magnetic field. Alternatively or additionally, the supervisory component can be adapted for preprocessing or coding information to be sent by the electrode device, in particular in- formation corresponding to the sensed signal or the sensed signal and/or the characteristic of the resonant circuit.
  • the arrangement or system can comprise the electrode device and, in addition, a receiver, in particular a control unit with a receiver, adapted for receiving the signal and/or characteristic of the resonant circuit transmitted via the time- varying magnetic field.
  • such an arrangement or system can comprise at least one electrode device inside or close to the heart as well as a receiver for receiving the signal sensed by the electrode device.
  • the receiver can be placed inside or outside the body and, preferably, comprises a transmit coil and/or a receive coil and/or a magnetic field sensor, in particular a magnetometer, for receiving the signal and/or the characteristic of the resonant circuit.
  • Using the transmit coil can be advantageous as such a coil can be used for both supply- ing the electrode device with energy and receiving the signal.
  • a receive coil can be much more sensitive to the signal and is cheaper than the magnetic field sensor.
  • the magnetic field sensor or magnetometer is preferred with respect to its high sensitivity.
  • a control device can be a further part of the control unit, arrangement and/or system.
  • this control device is configured for transmitting energy to the electrode device and/or for controlling the electrode device in a wireless manner by means of the time-varying magnetic field.
  • the receiver and/or the control device can be implanted as well and/or can form a joint constructional unit, and/or forming the control unit.
  • the control unit does not need to comprise both the receiver and the control device. These can be realized and/or used separately as well.
  • An implantable control device and/or receiver enables a short distance to the electrode device leading to a good control unit signal quality and low losses for wireless energy transmission.
  • the control unit in particular the receiver and/or the control device, can comprise a, preferably rechargeable, battery that may be rechargeable by an inductive coupling method.
  • a transportable system can be provided, wherein a lead- less, wireless and/or cableless electrode device can be used for sensing a signal close to its source and the other component(s) can be used for controlling and/or supplying with energy.
  • control unit can comprise the receiver and the control device can be realized separately.
  • One or both of them can be implanted or not, in particular at different locations.
  • the receiver and the control device are forming a joint constructional unit.
  • An electrical signal in particular an (intracardiac) ECG and/or an EMG signal, can be automatically sensed from a surrounding tissue by an implanted electrode device and/or an electrical signal corresponding to the characteristic of the resonant circuit is generated, wherein the signal is converted into a corresponding time-varying magnetic field, wherein the signal is transmitted to the receiver in a wireless manner, and wherein the signal is converted into an electrical signal by the receiver.
  • the control device triggers the electrode device in a wireless manner by means of the time-varying magnetic field for generating and/or delivering the electric impulse.
  • the triggering is synchronized by or to the signal and/or the characteristic of the resonant circuit.
  • the electrode device can be supplied with energy by the control device in a wireless manner by means of the time-varying magnetic filed.
  • the implanted electrode device is used in particular for sensing a signal corresponding to the electrical heart activity and/or for pacing, in particular for a pacemaker or defibrillator functionality.
  • the electrode device can generally sense any type of, preferably electrical, signals, e.g., signals caused by the brain, muscles and nerves as well as electrochemical processes or the like.
  • the electrode device further can be used implemented inaccessibly, e.g. for detecting a signal corresponding to the characteristics of a liquid flowing through an inaccessible pipe, vessel or the like.
  • the signal to be sensed e.g., can be a characteristic of a sample, in particular an electrical or electrochemical characteristic.
  • the electrical impulse can be used for obtaining electrical or electrochemical reactions as well.
  • the inventive method typically is a full-automatic process, wherein a signal and/or the characteristic of the resonant circuit is or are automatically sensed, transmitted, analyzed and/or used for controlling, i.e. for triggering the generation and/or delivery of a pacing electrical impulse.
  • No human and in particular no healthcare professional or the like is needed either for configuring the method or for performing it.
  • the methods of the present invention are not restricted to a human or animal body. Rather, the methods can be applied in production, chemistry and further fields of technology as well.
  • a signal from the surrounding area is sensed by a preferably implantable electrode device, which can be placed inside a reaction vessel, a pipe or the like and/or can be used for electrolysis, electroa- nalysis or the like.
  • a signal can be sensed from the surrounding area (tissue) can correspond to a characteristic of the resonant circuit is generated by the electrode device, e.g., by sensing oscillations of the resonant circuit.
  • the signal and/or characteristic can be converted into a corresponding time- varying magnetic field, and the signal and/or characteristic is or are transmitted to a receiver in a wireless manner, which converts the signal and/or characteristic back into an electrical signal.
  • the characteristic of the resonant circuit can be transmitted electrically.
  • the electrical im- pulse can comprise the characteristic of the resonant circuit or a corresponding voltage, current or the like, which can be used for transmitting the characteristic of the resonant circuit, in particular to the analysis means.
  • the electrode device is controlled in a wireless manner by means of the time- varying magnetic field for generating and/or delivering an electrical impulse, in particular for electrolysis, electroanalysis or the like.
  • the electrode device is triggered, wherein the triggering is synchronized by or to the signal and/or to the characteristic of the resonant circuit of the electrode device.
  • the electrode device can be supplied with energy in a wireless manner by means of the time-varying magnetic field.
  • the inventive arrangement and/or method can provide characterizing, analyzing and/or verifying the contact of the electrode of the electrode device and, thus, allows for a failsafe electrode device.
  • the stimulation efficiency can be improved by delivering electrical impulses close to the target.
  • the inventive method further can provide advantages regarding the reliability of sensed signals as these can be covered close to its source. Converting the signal, characteristic and/or energy to a corresponding time-varying magnetic filed allows for the advantageous wireless transmission and/or for omitting wire connections.
  • a wireless control of the electrode device and/or wireless energy supply of the electrode device enables a robust assembly. Thus, the error probability can be reduced by omitting wire connections.
  • the implantable electrode device can be supplied with energy controlled depending on at least one parameter corresponding to a distance and/or coupling factor to the electrode device.
  • Multiple electrode devices can be supplied with energy controlled depending on at least one individual parameter corresponding to the respective distance and/or coupling factor.
  • individual transmission characteristics in particular frequencies and/or polarities preferably of time-varying magnetic filed, are used for separately supplying the electrode devices.
  • Supplying one or more electrode devices can be controlled as follows. First, energy is sent towards the electrode device, preferably by means of the time- varying magnetic field. The sent energy preferably is at least partially received by the electrode device causing the electrode device to return energy, in particu- lar comprising a signal, oscillation of the resonant circuit, postringing, information of the amount or density of received energy, modulation or the like. The returned energy preferably is received, in particular by the receiver, and a receive power level of the received energy or a corresponding value is determined. The amount of energy to be sent towards the electrode device, preferably by the con- trol device, is controlled with or depending on the receive power level or the corresponding value.
  • multiple electrode devices are individually provided with energy, wherein the amount and/or density of the energy sent towards the respective electrode device depends on the coupling and/or distance of the respective electrode device, preferably to the associated control device. Since dif- ferent electrode devices will have different positions in a body, distances from the control device or receiver, and/or different coupling factors occur, which can be considered for individually sourcing the respective electrode devices.
  • an arrangement can be used for delivering an electrical impulse and contact verification only.
  • an arrangement can be used for sensing and contact verification only.
  • an arrangement can be used for contact characterization and/or verification and, preferably, for controlling mentioned or further means based thereon.
  • the characteristic of the resonant circuit can be used for placing and/or arrangement of the compo- nents of the arrangement alternatively or additionally to characterizing contracts of the electrode to the surrounding area, sensing the signal and/or delivering the electrical impulse.
  • Fig. 1 is a schematic view of a proposed electrode device
  • Fig. 2 is a schematic view of a proposed electrode device according to a second embodiment
  • Fig. 3 is a schematic diagram of a magnetization curve of a transceiver of the electrode device according to the present invention.
  • Fig. 4 is a schematic sectional view of a core element of a transceiver according to the present invention.
  • Fig. 5 is a schematic view of a rectifier circuit according to the present invention
  • Fig. 6 is a schematic view rectifier circuit according to the present invention according to second embodiment of the present invention
  • Fig. 7A-7C is a timing diagram of a supervisory component according to the present invention.
  • Fig. 8 is a schematic view of an amplifier according to the present invention.
  • Fig. 9 is a schematic view of an arrangement according to the present invention.
  • Fig. 10 is a schematic view of a control unit according to the present invention.
  • Fig. 11 is a schematic diagram of the time profile of a magnetic field and an induced voltage
  • Fig. 12 is a schematic block diagram of an arrangement according to a further embodiment of the present invention.
  • Fig. 13 is a schematic view of an arrangement according to the present invention with a further embodiment of a proposed electrode device.
  • Fig. 1 is a schematical sectional view of a proposed implantable electrode device 1 which can be used for sensing a signal S, in particular an intracardiac electro- gram, and/or for delivering an electrical impulse P.
  • the electrode device 1 can be used for sensing and/or monitoring bio-potentials and/or bio-signals, in particular for ECG, EEG, ERG, EMG and EUG as well as for detecting glucose concentration, blood pressure or phonocardiography signals, wherein the electrodes can be part of a sensor.
  • the electrode device 1 preferably can be used for stimulation purposes like pacing and/or defibrillating as well.
  • the electrode device 1 can be used for other purposes and at other locations, in particular in the human or animal body.
  • the electrode device 1 preferably comprises at least two electrodes 2. It can be constructed without a battery or the like.
  • the electrode device 1 comprises a preferably implantable, waterproof, hermetical sealed, insulated and/or insulating housing 3, wherein the housing 3 preferably incorporates components of the electrode device 1, and the electrodes 2 are preferably inte- grated in the housing 3, or attached thereon.
  • the electrode device 1 can be very compact and in particular configured substantially rod-shaped or cylindrical.
  • the length of the electrode device 1 is less than 3 cm, preferably less than 2 cm, in particular less than 1,5 cm.
  • the diameter is preferably at most 1 cm, preferably less than 8 mm, in particular 5 mm or less.
  • a retaining device can be attached to the electrode device 1, preferably an anchor or a screw which allows the electrode device 1 to be anchored in the heart muscle. According to a further embodiment shown in Fig.
  • a multiplicity of linked elements E are used to form a preferably elongated electrode device 1, in particular of a length greater than 10 cm, preferably greater than 12 cm, in particular greater than 15 cm and/or smaller than 25 cm, preferably smaller than 22 cm, in particular smaller than 18 cm, and/or of a diameter smaller than 5 mm, preferably smaller than 4 mm, in particular smaller than 3 mm and/or greater than 0,5 mm, preferably greater than 1 mm, in particular greater than 1,5 mm.
  • This shape advantageously supports delivery of an electrical impulse P across a heart, e.g., for defibrillation.
  • At least one, two or all of the elements E can be adapted to store energy and/or to be supplied with energy by means of the time-varying magnetic field H.
  • elements E can be added and/or removed, e.g., by removing cap 49, removing (cutting away) one or more elements E and closing the electrode device 1, in particular by fixing cap 49 at electrode device 1 or a preferably flexible housing.
  • the size, in particular the length, of electrode device 1 can be adapted in each individual case.
  • the electrode device 1 in Fig. 2 can comprise one or more of the components of the embodiment shown in and discussed referring to Fig. 1 and 13, in particular forming an electronic module 50. Alternatively or additionally, one or more of the components can be part of the elements E as well.
  • the electrode device 1 preferably comprises at least a transceiver 4 and the electrodes 2, wherein a transceiver 4 and, preferably, an amplifier 6, a rectifier 7, a supervisory component 15 and/or a pulse forming device 16, are preferably placed inside the housing. At least one, preferably more than one, electrode 2, are preferably integrated in the electrically installed housing 3 or attached thereon. Thus, it is possible to achieve a compact electrode device 1 comprising an at least basically smooth surface.
  • the electrodes 2 are allocated on opposite sides. However, the electrodes 2 can also be arranged, for example, circumferential, at one and or at the other end of the electrode device 1 or the housing 3.
  • the time-varying magnetic field H in the sense of the present invention is preferably generated by the electrode device 1 while sending, e.g. the signal S and/or the characteristic of the resonant circuit RC by the electrode device 1 is intended.
  • the time-varying magnetic field H can be generated externally and/or remote of the electrode device 1 if energy transfer to the electrode device 1 and/or delivery of an electrical impulse P is intended.
  • the time-varying magnetic field H can be composed by different sources, in particular if energy transfer to the electrode device 1 and transfer of the signal S and/or of the characteristic of the resonant circuit is or are performed at the same time.
  • "time-varying magnetic field H" can have different sources which are not individually named.
  • the term "magnetic field H" in the sense of the present invention incorporates any field or wave comprising a magnetic component, e.g. electromagnetic waves or the like.
  • the electrode device 1 preferably comprises means for sensing and sending the signal S and/or the characteristic of the resonant circuit RC, the rectifier 7 for rectifying energy received by the transceiver 4, a delay means for generating a delay between reception of the energy and generation of the electrical impulse P, and/or a protection means to prevent or block generation and/or delivery of electrical impulses P when delivery is not intended.
  • the electrode device 1 can also be implemented by other structural elements having a corresponding function.
  • the electrode device 1 preferably comprises transceiver 4 for receiving and/or sending purposes.
  • the transceiver 4 can be provided with energy in a wireless manner, in particular by the time-varying magnetic field H.
  • a current is induced in the transceiver 4, in particular coil 21, by the time-varying magnetic field H.
  • the transceiver 4 may comprise an antenna and/or is adapted for receiving energy from electromagnetic waves or the like.
  • the transceiver 4 can be used for sending purposes, preferably by generating the time-varying magnetic field H, in particular corresponding to a current through transceiver 4.
  • the transceiver 4 can comprise a coil 21, a coil core 20 and/or core elements 22, in particular made of a soft magnetic material or ultrasoft magnetic material, for example in the form of wires or strips (cf. Fig. 4).
  • a soft magnetic material or ultrasoft magnetic material for example in the form of wires or strips (cf. Fig. 4).
  • Such a material has a very low coactive field strength which corresponds to the minimum field strength HI and in particular is less than 0.1 mT.
  • the saturation field strengths of the material are less than about 0.01 to 3 mT.
  • the coil core 20 preferably consists of nonmagnetic or completely or partially of said soft magnetic or ultrasoft magnetic material or a combination of various such magnetic materials.
  • the transceiver 4 comprises a coil 21 preferably having a high number of turns, preferably at least 100 turns, in particular at least 1,000 turns, particularly preferably 2,000 turns or more.
  • the coil 21 has substantially 3,000 turns or more.
  • the coil inside diameter is preferably 1 to 3 mm
  • the coil outside diameter is preferably 2 to 6 mm
  • the coil length is preferably 10 to 30 mm.
  • ferrites or ferromagnetic metal powder and/or compound materials, in particular laminated structures can be used as core materials or soft magnetic materials. An advantage is that as a result of the poor electrical conductivity, these materials only exhibit low eddy current losses.
  • the proposed transceiver 4 can permit the generation of relatively strong electrical impulses P, currents or voltages, in particular an electrical impulse P having a voltage of preferably at least 100 mV, in particular at least 1 V and a time duration of substantially 0.1 ms or more, in particular if stimulation function is intended.
  • this relatively strong and relatively long-lived electrical impulse P can also be achieved with the soft magnetic core material.
  • a magnetic resetting pulse as with the Wiegand wires or the like can be used. However, a combination with other magnetic materials or structures is possible.
  • the transceiver 4 can be configured such that a pulse-like induction voltage (preferably electrical impulse P or corresponding thereto) is generated, in particular for stimulation, when a minimum field strength HI of the, e.g., external magnetic field H acting on the electrode device 1 or transceiver 4 is exceeded (cf. Fig. 3 and 11).
  • the transceiver 4 can have an optional coil core 20 which exhibits an abrupt change in the magnetization, i.e. bitable magnetic properties, when the minimum field strength HI is exceeded. This abrupt change in magnetization or magnetic polarization results in the desired pulse-like induction voltage in the associated coil 21.
  • a reed relay or switch 14 and/or switch 13 in series with at least one electrode 2 can be used for generation and/or delivery of the electrical impulse P.
  • the switches 13 and/or 14 can be formed by and/or comprise semiconductor devices, in particular semiconductor switches.
  • the coil core 20 is preferably constructed of at least one core element 22, preferably of a plurality of core elements 22 (cf. Fig. 4).
  • the individual core elements 22 preferably have a diameter of about 50 to 500 ⁇ , in particular substantially 100 ⁇ and/or a length of 5 to 20 mm, in particular substantially 15 mm.
  • the core elements 22 and/or the coil core 20 is or are particularly preferably so- called Wiegand wires as described in US 3,820,090 and/or supplied by HID Corp., 333 St. Street, North, Heaven, CT 06473, USA under the trade name "Wiegand Effect Sensors” or so-called impulse wires as supplied by Tyco Electronics AMP GmbH, Siemenstrasse 13, 67336 Speyer, Germany.
  • Wiegand wires the soft and hard magnetic layers or core elements 22 are formed of the same material, the different magnetic properties being achieved in particular by mechanical reforming.
  • voltage pulses having a steep edge can be produced with relatively slow field changes of the time-varying magnetic field H.
  • a defined mechanical prestress/pretorsion of a soft-magnetic constituent which can be set using manufacturing parameters (selection of material, tempering and annealing treatments) preferably is used to achieve a defined Barkhausen effect in a magnetic reversal.
  • voltage pulses having a steep edge can be produced.
  • the hard-magnetic constituent and soft magnetic constituent can mechanically support one another.
  • the hard-magnetic constituent can be demagnetized in an activated condition.
  • the soft magnetic constituent preferably has a coercivity field strength which is below the field strength of the time-varying magnetic field H in the examination zone.
  • the hard-magnetic constituent preferably has a coercivity field strength which is higher than the field strength of the alternating field in the examination zone.
  • the hard-magnetic constituent can be demagnetized in an activated condition.
  • the soft magnetic constituent can have coercivity field strength which is below the field strength of the alternating field in the examination zone.
  • the core 20 comprises the soft magnetic constituent and a hard-magnetic constituent which preferably concentrically surrounds the core so that the two constituents can be drawn together and thus formed as a unit. If the core of has a rectangular cross section, the exterior portion can be connected to the core by rolling the hard-magnetic constituent onto the core, preferably at both sides and/or by annealing.
  • core 20 can comprise mixed materials with soft magnetic and hard-magnetic constitutes and/or a corresponding one-compound material.
  • the core 20 can comprise material, in particular amorphous or mixed material, preferably forming a strip.
  • a wire having a hard-magnetic constituent and a soft magnetic constituent can be used.
  • the hard-magnetic constituent can form the outer core elements 22 and soft magnetic constituent can form the inner core element 22.
  • core 20 is formed by the core elements 22 as a composite elongated member and/or strip.
  • the hard-magnetic constituent can be disposed at an exterior of an elongated member, and the soft magnetic constituent can be disposed in an interior of an elongated member.
  • the composite member can also be formed of a wire consisting of the soft magnetic constituent disposed inside a tube consisting of the hard-magnetic constituent.
  • a foil, strip, loop and/or ring including the soft magnetic constituent and hard-magnetic constituent formed into a composite elongated member can be used as core 20.
  • the core 20 can be used without a coil for generating magnetic field pulses.
  • transceiver 4, in particular coil 21, is associated with core 20, in particular such that the high field changes can be used for generating electrical impulse P.
  • core 20 can be realized using ferrit or different material with high magnetic permeability and/or with low electrical conductivity, which can help prevent eddy currents.
  • transceiver 4 for the electrode device 1, in particular at least one for receiving energy and one for sending purposes.
  • These transceivers 4 may comprise different coils, in particular coils of a different number of turns.
  • the transceiver 4 for receiving energy and/or for verifying the contact of the electrodes 2 to the surrounding area can comprise at least 500 turns, preferably at least 1.000 turns, in particular 2.000 turns or more.
  • a transceiver 4 for sending purposes can com- prise a lower number of turns, for example more than 5, preferably more than 50 turns and/or less than 500 turns, preferably less than 200 turns. If different transceivers 4 are used, it is particularly preferred to realize them using a joint core or a coil, wherein the sending part can be contacted using a center tap. Thus, advantages regarding consumption of space can be obtained.
  • the electrical impulse P for stimulation can be a current delivered by the electrode 2, a voltage at the electrode 3 and/or across at least two electrodes 2.
  • the electrical impulse P can be generated by providing energy to the electrode 2 directly, using a switch and/or other means.
  • a switch 13 preferably connects and/or disconnects the output of rectifier 7 and/or buffer 9 to or from an electrode 2 and/or a pulse forming device 16 of the electrode device 1.
  • Closing switch 13 can allow for generating at least one electrical impulse P and/or for delivering electrical impulses P via the electrodes 2. This is particularly preferred if the electrode device 1 is used for stimulation, e.g. pacing.
  • the electrode device 1 is configured such that an electrical impulse P is only generated and delivered when a (first) minimum field strength of the magnetic field HI is exceeded. Furthermore, this or another pulse generation or triggering is preferably only made possible after respective previous activation.
  • the impulse generation and triggering preferably takes place as a result of the external magnetic field H acting on the transceiver 4 being varied in time so that when a first minimum magnetic field strength HI is exceeded (cf. Fig. 3).
  • an abrupt change in the magnetization of the core elements 22 or the coil 21 takes place as shown in the schematic magnetization curve according to Fig. 11.
  • this abrupt change in the magnetization results in a pulse-shaped induction voltage (electrical impulse P in Fig. 11) in the allocated coil 21 of the electrode device 1.
  • This first minimum field strength HI is therefore a switching threshold.
  • a delay means, switch 14, in particular a reed relay, and/or a protection means may be activated or controlled by the first minimum magnetic field strength HI .
  • the induced voltage pulses can have an amplitude of up to about 5 V and are about 5 to 100 ⁇ long.
  • the optional pulse forming device 16 is preferably used that can realize a smoothing filter function, a low pass filter function and/or just an inductivity.
  • the induced voltage pulse can thus in particular be stretched in time.
  • a longer pulse duration can also be achieved by bundling a plurality of core elements 22 in the coil 21, in particu- lar so that the pulse forming device 11 can be completely omitted. If the core 20 and/or core elements 22 are used, rectifier 7 and/or energy storing device 9 might not be needed.
  • the magnitude of the minimum field strength HI depends on various factors, in particular the manufacturing conditions of the core elements 22 if used.
  • the minimum field strength HI is preferably between 0.5 and 20 mT, in particular between 1 to 10 mT and is quite particularly preferably about 2 mT, in particular when impulse wires or Wiegand wires are used. These values are already substantially above the values for magnetic fields usually permissible in public so that any triggering of an electrical impulse P by interference fields usually expected is eliminated.
  • the minimum field strength HI can be higher than 0.01 mT, preferably higher than 0.05 mT and/or when bistable strips are used. This enables operation even if the time-varying magnetic field H is generated in further away, e.g. more than 2 cm, preferably more than 3 cm, in particular more than 4 cm.
  • a transceiver 4 with optional individual core elements 22 or coil core 20 having bistable magnetic properties in particular in the preferred structure of layers having alternately soft and hard magnetic properties (Fig. 4)
  • asymmetrical behavior is achieved on running through the magnetization curve or hysteresis.
  • the polarity of the coil core 20 is (completely) reversed by the external magnetic field H having the opposite direction when the second minimum field strength H2 is exceeded, as can be deduced from the magnetization curve in Fig. 11.
  • the external magnetic field H in particular generated by a control device 28, is used both for controlling (triggering) the generation and de- livery of an electrical impulse P by the electrode device 1 and also for supplying the electrode device 1 with the energy necessary for generating the electrical impulse P.
  • the magnetic field H is preferably also used for said activation of the electrode device 1 for in order to enable generation of the next electri- cal impulse. However, this can be also be effected in another manner or by another signal.
  • the external magnetic field H preferably runs at least substantially parallel to the longitudinal direction of the coil core 20 or the core elements 22.
  • Figure 11 shows schematically a preferred time profile VI of the external magnetic field H acting on the electrode device 1 and the corresponding time profile V2 of the voltage U induced in the electrode device 1 or its transceiver 4.
  • a profile preferably is used for the stimulation functionality.
  • the magnetic field H is preferably generated intermittently and/or as an alternating field.
  • the magnetic field H preferably has a switch-on ratio of less than 0.5, in particular less than 0.25, particularly preferably substantially 0.1 or less.
  • the field strength of the magnetic field H preferably has a substantially ramp- shaped or sawtooth-shaped time profile, at least during the switch-on times as indicated in Fig. 11.
  • the magnetic field H can be alternately generated with an opposite field direc- tion for alternate generation of an electrical impulse P and activation of the electrode device 1 before generation of the next electrical impulse P.
  • the activation preferably takes place only shortly before generating the next electrical impulse P, as indicated in Fig. 11.
  • the frequency of the magnetic field H in one example is only a few Hz, in particular less than 3 Hz and corresponds in particular to the desired frequency of the electrical impulses P to be generated.
  • the magnetic field H can comprise much higher frequencies, e.g. of a few Hz or in the kHz range, in particular for controlling and/or transmitting of energy.
  • the fre- quency of only a few Hz may be used and/or part of the magnetic field H for triggering purposes and/or if a direct generation of the electrical impulse P is intended.
  • the electrode device 1 can provide a high-energy mode and a low-energy mode, wherein the energy delivered by the electrode device 1 for each stimulation by delivering an electrical impulse P via the electrodes 2 in the high-energy mode is higher than the energy delivered for each stimulation in the low-energy mode, preferably at least 50 or 100 times, in particular 200 times.
  • defibrillation and cardiac pacing can be supported simultaneously and/or by one electrode device 1.
  • the high-energy electrical impulse P can be generated when the electrode device 1 is supplied with energy or controlled by means of time-varying magnetic field H of a first transmission characteristic, in particular a first frequency and/or polarity.
  • a low-energy electrical impulse P can be generated by electrode device 1 independently when the stimulation device is supplied with energy or controlled by means of the time-varying magnetic field H of a different second transmission characteristic, in particular a different second frequency and/or polarity of time- varying magnetic field H.
  • different modes can be controlled, activated and/or synchronized.
  • the signal S preferably is sensed across two or more electrodes 2, preferably is amplified by amplifier 6, and/or converted to a corresponding time-varying magnetic field H by means of one ore more transceivers 4.
  • the characteristic of the resonant circuit RC can be amplified and/or con- verted.
  • the electrodes 2 preferably are configured for sensing the signal S from and/or delivering the electrical impulse P to the surrounding area 5, in particular a surrounding tissue, sample, conducting liquid or the like.
  • the surrounding area 5 preferably is a tissue of as a heart.
  • the elec- trode device 1 can be implanted into or close to the heart, wherein the heart forms the surrounding area 5 of the electrode device 1.
  • the signal S can be an electrical potential, a voltage and/or a current, in particu- lar for controlling or related to the heartbeat, that can be sensed by the electrodes 2.
  • the signal S can be sensed e.g. by measuring a voltage across two or more electrodes 2.
  • the electrode device 1 can comprise more than two electrodes 2 as well.
  • the signal S to be sensed preferably is a ECG signal S or corresponds to it. Nevertheless, the signal S can be another electrical body signal S, e.g. related to muscles, alternatively or additionally. Further, signal S can be related to a sample or an analysis result, in particular of an electroanaly- sis.
  • the signal S further can correspond to a characteristic of a resonant circuit RC of the electrode device 1.
  • the characteristic of the resonant circuit can be sent using the signal S.
  • the resonant circuit RC preferably is formed at least with a resonance means RM and/or the surrounding area 5 of the implantable electrode device 1 via the electrodes 2.
  • the characteristic can be used for characterizing and/or verifying the contact of the electrodes 2 with the surrounding area 5, and/or for optimizing a relative position and/or orientation of the electrode device 1 to a remote analysis means 48, which will be described later in further detail, e.g., referring to Fig. 13.
  • the signal S and/or the characteristic of the resonant circuit can be transmitted using different forms of energy transfer, e.g. acoustic, ultrasonic, visual, light, mechanical, pneumatical, hydraulical, electrical, or further different energy transfer methods.
  • the signal S, the characteristic of the resonant circuit and/or corresponding energy is transferred using time-varying magnetic field H.
  • details of the sending process apply mutatis mutandis to sending a characteristic of the resonant circuit RC.
  • Amplifying signal S and/ or the characteristic of the resonant circuit can be rea- sonable for sending this signal S. Therefore, an amplifier 6 can be provided.
  • the signal S can be led to the input of amplifier 6, in particular via a closed switch 10 preferably connecting at least one electrode 2 to the amplifier 6.
  • the preferably amplified signal S in the following can drive the transceiver 4 for generating the time-varying magnetic field H, preferably corresponding to signal S, that can be used for sending, i.e., for transmitting the information sensed by the electrodes 2.
  • the transceiver 4 preferably is formed by or comprises one or more coils 21 for generating time-variable magnetic filed H. Additionally or alternatively, the transceiver 4 comprises or is formed by an antenna or the like.
  • the amplifier 6 preferably is connected or connectable to at least one electrode 2 at its input and/or its output to the transceiver 4.
  • the amplifier 6 can be realized as shown in Fig. 8.
  • a push-pull output stage of amplifier 8 can comprise MOSFETs M5 and M6, wherein, preferably, MOSFET M5 is of the n-channel type and/or MOSFET M6 is of the p-channel type.
  • the gates of MOSFETS M5 and M6 preferably are controlled by the signal S sensed via electrodes 2 or a corresponding value, voltage, current or the like.
  • the amplified signal S preferably is delivered at the node connected to the drains of MOSFETS M5 and M6 and/or to transceiver 4.
  • an oscillating current of resonant circuit RC can be amplified, mutatis mutandis, in particular if different transceivers 4, in particular coils 29, 46, are used to form the resonant circuit RC and for sending. Nevertheless, other solutions are possible.
  • electrode device 1 is passive in the meaning of receiving more energy, in particular by means of time-varying magnetic field H, than delivering, in particular by means of sending the signal S, the characteristic of the resonant circuit R and/or delivering electrical impulses P.
  • the electrode device 1 can be supplied with energy by means of time-varying magnetic filed H generated outside the electrode device 1 inducing a current into the transceiver 4, in particular if the transceiver 4 comprises a coil 21 as depicted in Fig. 1.
  • Sending the signal S can be performed using the intrinsic energy of the sensed signal S, in particular if the optional amplifier 6 is omitted. It is preferred that energy is transmitted to the electrode device 1 in a wireless manner by means of the time-varying magnetic filed H for energy supply, in particular if an amplifier 6 is used.
  • the electrode device is supplied using the intrinsic energy of signal S from the surrounding area 5, accumulated over some time, preferably by rectifying and/or buffering it, in particular over more than 500 ms, more than Is or more than 2 s, and/or less than 10 s, in particular less than 5 s.
  • the electrode device 1 preferably comprises an energy buffer 9, in particular a capacitor.
  • the energy buffer 9 can be connected to the output of rectifier 7.
  • the rectified energy delivered by rectifier 7 can be smoothed by energy buffer 9.
  • the energy buffer 9 is no battery, accumulator or the like.
  • it is an energy storing device which is at least basically based on physical effects, preferably including supercaps, TaN capacitors or the like. Nevertheless, other solutions can be possible.
  • the energy buffer 9 can have a maximum capacity for generation and/or delivery of five electrical impulses P or less, preferably for two, in particular for one electrical impulse P and/or for transmitting the signal S and/or the characteristic of the resonant circuit RC less than 60 sec, preferably less than 5 sec, in particular 3 sec. or less.
  • the energy buffer 9 can have a capacity of less than 500 ⁇ , preferably less than 300 ⁇ , in particular less than 200 ⁇ .
  • a current induced into the transceiver 4 by the time-varying magnetic field H can be rectified by rectifier 7 and stored in energy buffer 9, preferably resulting in a rising voltage across the energy buffer 9.
  • This voltage can be used for gener- ating electrical impulse P and/or for supplying, e.g., the amplifier 6.
  • the energy stored in the energy buffer 9 can be used for supplying a supervisory component 15.
  • Rectifier Energy received by transceiver 4 preferably can be transmitted to the rectifier 7.
  • the transceiver 4 and the rectifier 7 are electrically connected.
  • the rectifier 7 preferably is adapted to transform energy from a time-varying or alternating nature to a substantially continuous one. In particular, an alternating current or voltage can be rectified.
  • Diodes in a bridge configuration can be used for rectifying.
  • the rectifier 7 for commutation preferably comprises semiconductor switches 8 A to 8D with a control port instead or additionally to (intrinsic) diodes.
  • These switches 8A to 8D can have a threshold voltage in the area of a zero-crossing, particularly in contrast to diodes having a threshold voltage of about 0.4 to 0.8 V.
  • the semiconductor switches 8A to 8D, in particular MOSFETs or the like, of the rectifier 7 have a threshold voltage of about zero and/or are biased at about threshold.
  • the threshold voltages and/or a biasing offsets from threshold are less than ⁇ 200 mV, in particular less than ⁇ 100 mV or ⁇ 50 mV.
  • a voltage drop across the devices forming the rectifier 7 can be minimized and/or avoided.
  • the rectifier 7 with semiconductor switches 8A to 8D can allow for reduced power losses and/or more efficient rectifying.
  • semiconductor switch 8B preferably a n-channel-MOSFET
  • semiconductor switch 8C preferably a p-channel-MOSFET
  • Semiconductor switches 8 A and 8D are non-conducting or having a high resistance and/or impedance as long as the potential of node Kl is higher than the potential of node K2.
  • semiconductor switches 8A and 8D are conducting and semiconductor switches 8B and 8C having a high resistance behavior.
  • node K3 preferably is always connected to the one of the nodes Kl and K2 with the higher potential and node K4 always is connected to the one of the notes Kl and K2 with the lower potential leading to the rectifying behavior.
  • the control ports or steering ports, in particular gates, of the semiconductor switches 8A to 8D can be connected and/or contacted via inductive elements I as shown in Fig. 6.
  • semiconductor switches 8A to 8D comprise an intrinsic capacitive behavior at their control ports that can be compensated for using the inductive elements I.
  • Zener diodes Z may be used to prevent over-voltage at the control ports of semiconductor switches 8A to 8D.
  • resistors R can be provided at the control ports of semiconductor switches 8A to 8D. This enables independent control of each of the semiconductor switches 8A to 8D, in particular by control- ling the potentials at nodes K5 to K8.
  • semiconductor switches 8A to 8D can be opened such that the rectifier 7 is deactivated and/or does not consume energy from transceiver 4.
  • the electrode device 1 provides two different work modes or functions, a first one for sending the signal S sensed and/or the characteristic of the resonant circuit RC, and a second one for generation and/or delivery of the electrical impulse P for stimulation purposes.
  • the supervisory component 15 and/or electrode device For sending the signal S and/or for sending and/or determining the characteristic of the resonant circuit RC, the supervisory component 15 and/or electrode device
  • I can connect the amplifier 6 to the electrode 2, e.g., by closing switch 10, disconnecting the rectifier 7, e.g. by opening switch 11, and/or bridging the rectifier 7 and/or connecting transceiver 4 to one electrode 2, in particular by closing switch 12.
  • rectifier 7 comprises semiconductor switches 8A to 8D (cf. Fig. 5 and 6)
  • switch 11 and/or switch 12 can be omitted and their function can be realized using switches 8A to 8D.
  • Opening switch 11 can correspond to opening switches 8A and 8C.
  • Closing switch 12 can correspond to closing switch 8B.
  • Switch 8D should be opened as well in order to prevent a short across energy buffer 9.
  • switches 8 A to 8D preferably are controlled independently from each other and/or by the supervisory component 15. This in the following is discussed in further detail.
  • switches 8 A to 8D preferably are controlled independently from each other and/or by the supervisory component 15. This in the following is discussed in further detail.
  • switches 8 A to 8D preferably are controlled independently from each other
  • I I and 12 can be realized together by using a changeover switch, in particular al- ternatively connecting the transceiver 4 to the rectifier 7 or to the electrode 2.
  • the energy supplied in a wireless manner can preferably be rectified by a rectifier 7, in particular comprising semiconductor switches 8A to 8D.
  • a switch 11 can be opened such that the signal S is not rectified by rectifier 7 in order to improve the sending performance of the transceiver 4.
  • a further switch 12 may be used to connect one node of the transceiver 4 directly to one of the electrodes 2 and/or to close the current circuit if a two-way rectifier 7 is used, that would possibly block the sending process.
  • switches 11 and/or 12 can be omitted if a rectifier 7 with semiconductor switches is used.
  • Opening or closing switches 8A and 8C can replace opening or closing switch 11. Opening or closing switch 8B can replace opening or closing switch 12. Thus, switch 11 and/or 12 can be omitted and their function can be realized using switches 8A to 8D.
  • optional resistors R can be added to rectifier 7.
  • Resulting nodes K5, K6, K7 and K8 can be used for deactivating rectifier 7.
  • a high potential can be chosen for nodes K5 and K7
  • a low potential can be chosen for nodes K6 and K8, such that semiconductor switches 8 A, 8B, 8C and 8D are continuously in their high-ohmic state (open).
  • Different solutions may exist for permanently opening each of the semiconductor switches of rectifier 7 for deactivating it.
  • the energy can be stored in the energy buffer 9, in particular a capacitor.
  • the energy buffer 9 preferably is connected to the rectifier 7, in particular to nodes K3 and K4.
  • the energy buffer 9 is adapted for storing the energy needed for five electrical impulses P or less, in particular for generating only one single electrical impulse.
  • the energy buffer 9 can be very small, in particular much smaller than a storing device as a battery or the like.
  • Electrode device 1 preferably comprises rectifier 7 for rectifying energy supplied to the electrode device 1 and a means for deactivating and/or disconnecting the rectifier, preferably enabling the transceiver 4 to be used for sending purposes as well.
  • switch 11 opens if it is desired to send a signal S and/or to determine or send the characteristic of the resonant circuit RC, preferably such that the energy of the signal S and/or of the resonant circuit RC is or are not consumed by the rectifier 7.
  • transceiver 4 in particular coil 21, is used for receiving energy in order to supply electrode device 1 with energy
  • rectifier 7 it is preferred to use rectifier 7 to rectify this energy.
  • the rectified energy can be stored in energy storing means 9, and can be used for providing an electrical impulse P or different further purposes already discussed above.
  • rectifier 7 preferably is adapted to consume and/or transform as much energy as possible.
  • rectifier 7 provides a low input impedance, e.g., less than 10 ⁇ . If transceiver 4, in particular coil 21, is to be used for sending signal S and/or for forming resonant circuit RC, this behavior of rectifier 7 can be disadvantageous.
  • one or more optional switches 11 can be used to disconnect rectifier 7, in particular such that rectifier 7 does not consume energy of signal S and/or energy of resonant circuit RC.
  • an active rectifier 7, in particular comprising MOSFETS 8A to 8D can be used, in particular as discussed referring to Fig. 5 and 6 and 13.
  • a means is provided to open each of switches 8A to 8D, in particular such that rectifier 7 achieves a high input impedance of preferably several kQ, and/or such that rectifier 7 does not consume energy anymore. This allows for reducing energy losses while sending signal S and/or determining the characteristic of the resonant circuit RC is intended.
  • Supervisory Component 15 is provided to open each of switches 8A to 8D, in particular such that rectifier 7 achieves a high input impedance of preferably several kQ, and/or such that rectifier 7 does not consume energy anymore.
  • the supervisory component 15 can be adapted for processing and/or coding the signal S sensed by the electrode device 1 and/or the characteristic of the resonant circuit RC.
  • the signal S sensed by the electrode device 1 information corresponding to the signal S, to an internal status of the electrode device 1 or of the supervisory component 15, and/or information corresponding to the characteristic of the resonant circuit RC can be coded by the supervisory component 15 and the coded signal S, information and/or the characteristic of the reso- nant circuit RC can be sent by the electrode device 1. This can enable a reduced error probability and/or power consumption.
  • the supervisory component 15 can be adapted for processing and/or decoding information, in particular commands received via the time-varying magnetic field H. Hence, it is possible to control the electrode device 1 in an easy and reliable way.
  • the electrode device 1 can be synchronized or particular information can be requested this way. It is possible to address or control a particular one among several electrode devices 1, in particular by controlling or addressing and/or selecting one supervisory component 15.
  • the supervisory component 15 can be adapted for controlling one or more of the switches 10 to 14, preferably using separate leads and/or a bus system as shown in the example. In particular, the supervisory component 15 controls switch 13 for different possible purposes.
  • the time or time span and/or other control schemes, timings, variables or the like can be preset within the supervisory component 15 and/or can be controlled by the signal S and/or by commands from outside, in particular via time-varying magnetic field H of a particular shape or comprising a modulation, coding or the like.
  • the supervisory component 15 and/or the electrode device 1 can be adapted for closing the switch 13 only if switch 10 is open, in particular disconnecting the amplifier 6 or different sending means, in order to prevent damaging the input of amplifier 6 during delivery of an electrical impulse P.
  • the supervisory component 15 and/or the electrode device 1 can be adapted for opening switch 11 if it is desired to send a signal S such that the energy of the signal S is not consumed by rectifier 7.
  • Switch 11 preferably connects the trans- DC and the rectifier 7 of the electrode device 1, in particular such that energy received can be rectified and stored and/or used for generating an electrical impulse P.
  • the supervisory component 15 and/or the electrode device 1 is adapted for closing switch 12 while sending the signal S is intended. Additionally or alternatively, the supervisory component 15 can be adapted for controlling switches inside the rectifier 7 or for controlling further switches, biasing net- works or the like not shown in Fig. 1, in particular inside the amplifier 6 or a pulse forming device 16.
  • a supervisory component 15 with a low power consumption, in particular in the nW regime.
  • Fig. 7A to 7C show typical timing diagrams of the supervisory component 15.
  • VCC can correspond to the rectified voltage delivered by the rectifier 7.
  • the voltage delivered by rectifier 7 is smoothed by energy buffer 9.
  • Fig. 7A shows an example for the rectified voltage and/or for a voltage associated with the energy buffer 9, which in the following will be called process voltage.
  • the process voltage rises up, in particular exceeding the pinch off voltage V TH of the supervisory component 15, i.e. its minimum operation voltage.
  • Fig. 7B and 7C are showing an inverted and a non-inverted reset signal, respec- tively.
  • the supervisory component 15 can be configured such that the reset signal shown in Fig. 7B keeps low although the process voltage exceeds the pinch of voltage V TH leading to an active reset.
  • the non-inverted reset signal has a high level, leading to an active reset, too.
  • the reset for the supervisory component 15 keeps ac- tive.
  • the non-inverted reset signal switches to high and/or the inverted reset signal switches to low such that the supervisory component 15 starts working.
  • the electrode device 1, in particular supervisory component 15, preferably comprises or is implemented as at least one controller, microcontroller, processor, any other preferably programmable circuit or the like.
  • a microcontroller with a low power consumption and/or a sleep mode for energy saving purposes can be used, in particular an Atmel AT tiny 10 or any controller of the tiny series provided by Atmel Cooperation, 2325 Orchard Parkway, San Jose, Ca 95131.
  • the supervisory component 15 can be programmed in advance and/or by signals transmitted via the time- varying magnetic field H.
  • the supervisory component 15 can comprise a decoding means for decoding a signal provided by the time varying magnetic field H and, preferably received by electrode device 1.
  • the magnetic field H may comprise modulated information that can be demodulated by the supervisory component 15 and/or the rectifier 7, in particular an amplitude modulation that automatically can be demodulated by rectifier 7.
  • This information can be used for programming and/or controlling the supervisory component 15.
  • the pulse forming device 16 preferably is connected to the rectifier 7 and/or energy buffer 9 at its input, and/or to the electrode 2 at its output.
  • the pulse forming device 16 preferably is configured for smoothing the electrical impulse P, e.g., by limiting the slew rate.
  • the pulse forming device 16 can be realized as a filter, a low pass filter or the like.
  • the pulse forming device 16 comprises a capacitor 18 preferably parallel to the electrodes 2 and/or a resistor 19, in particular connecting the input of the pulse forming device 16 to the capacitor 18.
  • an inductive element in particular a coil, can also be used for pulse forming.
  • the pulse forming device 16 can be used for forming or reforming a pulse-like (induction) voltage which is generated or de- livered by transceiver 4 and/or energy buffer 9.
  • the reformed electrical impulse P can then be delivered for stimulation via the connected electrodes 2.
  • the electrode device 1 optionally can comprise an analysis means 48 for analyzing a signal S, which preferably can be sensed via the electrode 2 and/or for detecting, characterizing or analyzing a characteristic of a resonant circuit RC, which will be described later in further detail.
  • the analysis means 48 can be part of the amplifier 6 or placed in front of its input.
  • the analysis means 48 can be configured for detecting peaks and/or patterns in the signal S, e.g., a P-wave, R-wave and/or S-wave of an electrical activity of a heart. Alternatively or additionally, the analysis means 48 can be used or adapted for characterizing the resonant circuit RC, in particular a resonance frequency and/or losses.
  • the signal S, analyzed signal S and/or characteristic and/or a result of this analysis can be sent, in particular by means and/or of a time-varying magnetic field H.
  • the supervisory component 15 can be adapted for controlling the analysis means 48, in particular in a pre-defined manner or by means of the time- varying magnetic field H.
  • the supervisory component 15 and/or semiconductor switch 13 can provide or act as a means for generating a delay between reception of the energy and the generating of at least one of the electrical impulses P. If energy is received and preferably rectified, the supervisory component 15 or a different means may control the semiconductor switch 13 to get into or keep the high resistance state (open) directly. Afterwards, the energy delivered to the electrode device 1 can be stored in the energy buffer 9 for a particular time span, in particular greater than 1 ms, preferably 10 ms and/or less than 500 ms, preferably less than 300 ms.
  • the semiconductor switch 13 can be switched into its low resistance state, in particular by the supervisory component 15 and/or if a threshold is passed by the voltage across or the energy stored in energy buffer 9 and/or if the magnetic field strength passes a minimum field strength (e.g. HI), and the electrical impulse P can be generated and/or delivered.
  • a threshold is passed by the voltage across or the energy stored in energy buffer 9 and/or if the magnetic field strength passes a minimum field strength (e.g. HI)
  • a minimum field strength e.g. HI
  • Switch 13 can be normally open (disconnected) and can be closed, preferably af- ter the energy buffer 9 has been charged, after a particular time span and/or at a particular time.
  • the switch 13 can be closed by the supervisory component 15 and/or for delivery of the electrical impulse P.
  • the supervisory component 15 and/or switch 13 can act as a delay means for delaying delivery of the electrical impulse P.
  • the electrode device 1, in particular the supervisory component 15, preferably comprises a timer for delaying controlling one ore more of the switches 11 to 14.
  • Switch 14 can be provided that does not need to be controllable by supervisory component 15.
  • Switch 14 preferably is adapted to connect and/or disconnect the pulse forming device 16 and/or one or more of the electrodes 2, preferably to the rectifier 7 and/or buffer 9. It is preferred that switch 14 can be controlled from outside and/or directly e.g. using the magnetic field H.
  • switch 14 is a reed switch that can be closed using at least a magnetic field of a particular, minimum field strength e.g. minimum field strength HI (cf. Fig. 3).
  • the mini- mum field strength HI preferably is higher than the field strength of the time- varying magnetic field H used for energy transmission to the electrode device 1.
  • generation and/or delivery of the electrical impulse P can be controlled independently from transmitting energy to the electrode device 1 using switch 14. Protection Means
  • a protection means preferably is adapted to prevent generation and/or to block delivery of electrical impulses P for time span greater than 0.5 ms, preferably greater than 1.0 ms and/or less than 100 ms, preferably less than 20 ms, in par- ticular 10 ms or less, in particular after an electrical impulse P has been finished.
  • generation and/or delivery of an electrical impulse P can be prevented or blocked during a short time span that has been found to be sufficient for preventing unwanted electrical impulses P that may occur due to a disturbance event, and at the same time a generation of a following electrical impulse P is not af- fected.
  • the switch 13 is basically closed (conducting) and an electrical impulse P can be delivered as soon as a sufficient amount of energy is available. After generation and/or delivery of the electrical impulse P is finished, switch 13 can be opened to prevent any further delivery of an electrical impulse P that might be not intended.
  • the supervisory component 15 together with switch 13 can form a protection means for protecting against unwanted delivery of electrical impulses P, e.g., due to any failures or disturbances with effects on the transceiver 4.
  • the electrode device 1 preferably comprises the protection means, in particular realized by supervisory component 15 and/or (semiconductor) switch 13 as already mentioned.
  • the semiconductor switch 13 preferably connects the rectifier 7 and/or the storing element 9 to at least one of the electrodes 2.
  • the semiconductor switch 13 can be provided in series with at least one of the electrodes 2.
  • generating an electrical impulse P and/or delivery of the electrical impulse P can be blocked by semiconductor switch 13.
  • the semiconductor switch 13 has a high resistance state for blocking generation and/or delivery of electrical impulses P as well as a low resistance state for generating an electrical impulse P or for enabling its generation. The state in particular is controlled by the supervisory component 15.
  • a first electrical impulse P is generated and/or delivered.
  • the semiconductor switch 13 is conducting, i.e. closed, and/or the supervisory component 15 generates a corresponding signal that leads to a conducting semiconductor switch 13.
  • the supervisory component 15 After delivery of the first electrical impulse P, the supervisory component 15 generates a signal controlling the semiconductor switch 13 such that it changes from a low resistance state (closed) to a high resistance state (open) for blocking generation and/or delivery of further electrical impulses P.
  • the supervisory component 15 holds this state for a particular time span.
  • the supervisory component 15 can change the control signal in order to switch the (semiconductor) switch 13 into a low resistance state. With switch 13 in low-resistance state, the next electrical impulse P can be generated and/or delivered.
  • arrangement A comprising at least one electrode device 1 and, preferably, an analysis means 48, is described with reference to Fig. 9 depicting a schematical sectional view of a body 41.
  • the electrode device 1 preferably is surrounded by surrounding area 5, in particular implanted in the heart or the heart muscle of a patient, who is shown in Fig. 9 only schematically and in part.
  • the electrode device 1 can be implanted, for example, as described in US 5,411,535 A.
  • the electrode device 1 in arrangement A preferably can be placed close to or insight the heart, since the signal S advantageously is much stronger sensed close to the source than externally, e.g., on the skin.
  • a system preferably comprises at least one electrode device 1 and a control unit 31, the control unit 31 comprising a receiver 24 and, preferably, comprising analysis means 48 and/or control device 28.
  • the analysis means 48 can be realized separately, inside electrode device 1 or in other combinations as well.
  • the proposed arrangement A is configured or works as a capturing system for an intracardiac electrogram and/or as a cardiac pacemaker and/or defibrillator.
  • the arrangement A can, additionally or alternatively, operate for capturing human body signals and/or bio-potentials e.g. ECG signals, EEG signals, ERG signals, EMG signals, EOG signals and/or signals corresponding to a glu- cose concentration, a blood pressure and/or acoustic signals for phono cardiography or the like.
  • the arrangement A can work as a stimulation system, as a defibrillator or can be used for other purposes and at other locations, in particular in the human or animal body. Referring to the introductory part, arrangement A and/or system can be used in different fields of technology as well.
  • Receiver 24 can work as a stimulation system, as a defibrillator or can be used for other purposes and at other locations, in particular in the human or animal body.
  • the receiver 24 preferably is adapted for receiving information, preferably by means of time-varying magnetic field H and/or from the electrode device 1.
  • a receiving means, in particular a coil 29, can be assigned to receiver 24.
  • the time- varying magnetic field H can be converted to a current by coil 29. This current can be received, amplified and/or analyzed by means of receiver 24.
  • the receiver 24 can comprise an input amplifier 33, preferably a low-noise amplifier. This input amplifier 33 can be used amplification of a signal received via coil 29.
  • receiver 24 can comprise one or more internal magnetic field sensors 27 and/or external magnetic field sensors 30, in particular magnetometers, for receiving and/or detecting the time-varying magnetic field H from the electrode device 1, an information provided by the time-varying magnetic field H, and/or the signal S, and/or the characteristic of the resonant circuit RC.
  • Magnetic field sensors 27, 30 can provide a higher input sensitivity than coil 29. Thus, using magnetic field sensors 27, 30 for receiving signal S and/or the characteristic of the resonant circuit RC can be improved.
  • the electrode device 1 is preferably supplied with energy by the control device
  • control device 28 preferably is adapted for providing energy and/or control signals to the electrode device 1, preferably by means of the time-varying magnetic field H.
  • control device 28 can provide energy or signals to a transmitter, in particular coil 29, for generating the time-varying magnetic field H.
  • Control device 28 preferably generates an amplified a power-signal, for example a sawtooth signal, a sign wave or the like. This power-signal is provided to coil
  • control de- vice 28 can comprise means for generating specific power-signal shapes as peaks, modulation, coding or the like for controlling the electrode device 1.
  • a power amplifier 34 can be provided by control device 28.
  • power amplifier 34 provides energy to coil 26 in order to allow for generating sufficiently strong time-varying magnetic fields H for supplying electrode device 1.
  • Control device 28 preferably generates an amplified power-signal, for example a sawtooth signal, a sine wave or the like.
  • the power signal in particular a current, switched current or the like, can be provided to coil 29 for generating a corresponding magnetic field H.
  • the power signal and/or the corresponding time- varying magnetic field H can have specific shapes, in particular peaks, modulation, coding or the like, preferably for controlling, triggering and/or synchronizing one or more electrode devices 1.
  • the power-signal and/or the result of the analyses of signal S and/or the characteristic of the resonant circuit RC can be used by the control device 28, and the control device 28 may generate a specific time-varying magnetic field H, of a special shape, minimum field strength, coding or the like, in particular by coil 29.
  • a strong sine wave can be used for transferring energy; information, in particular in form of peaks and/or modulation, can be superposed to the power-signal primarily used for energy transfer.
  • the control device 28 fur- ther can be controllable or synchronable, preferably to a bioelectrical activity of heart 5, in particular to the signal S and/or the characteristic of the resonant circuit RC sent by the electrode device 1.
  • the control device 28 can control the electrode device 1 to send a sensed signal S and/or the characteristic of the resonant circuit RC.
  • the control device 28 can be configured such that the magnetic field H for controlling electrode device 1 and/or for supplying it with energy is generated intermittently.
  • the control device 28 is configured such that the magnetic field H has a switch-on ratio of less than 0.5, in particular less than 0.25, par- ticularly preferably substantially 0.1 or less.
  • the electrode device 1 can also be used independently of the receiver 24 and/or the control unit 28.
  • the electrode device 1 can be supplied with energy and/or controlled by another device, optionally even by a nuclear spin tomograph or the like, with suitable matching.
  • further possible uses are obtained which go substantially beyond the possible uses of conventional sensing and/or stimulation systems.
  • the arrangement A preferably comprises the, in particular implantable, control unit 31, preferably comprising at least one of the receiver 24 and the control device 28 and, preferably, the implantable electrode device 1 separate there from.
  • the receiver 24 and/or control device 28 can be realized independently of control unit 31 and/or from each other as well, in particular with separate housings and/or placed at different locations.
  • Fig. 10 shows a schematical view of control unit 31 comprising receiver 24 and control device 28.
  • the receiver 24 and control device 28 are assigned to a common transceiver, in particular coil 29, for receiving and/or generating the time-varying magnetic field H.
  • the transceiver of receiver 24 and/or control device 28 preferably is part of control unit 31 as well.
  • the control unit 31, the receiver 24 and/or the control device 28 preferably comprises an energy storage device, preferably battery 32, in particular a rechargeable battery.
  • the receiver 24, the control device 28 and the coil 29 can form control unit 31 with a common and/or implantable case.
  • Battery 32 preferably can be charged in an inductive manner, in particular via coil 29. Independent and/or shared coils can be used for receiving energy, receiving signal S and/or the characteristic of resonant circuit, sending energy and/or sending control signals.
  • Fig. 10 shows the receiver 24 preferably comprising an input amplifier 33, preferably a low noise amplifier.
  • the control unit 31, and/or the control device 28, preferably comprises a power amplifier 34.
  • the control unit 31, receiver 24 and/or control device 28 are preferably arranged in a flexible housing in particular for implanting it directly above the heart near the thoracic wall. To achieve this flexibility, the control unit 31 can be embedded in a silicon cushion.
  • the control unit 31, in particular receiver 24 and/or control device 28, can be implanted as present-day cardiac pacemakers. However, it is not absolutely essential to implant the receiver 24 and/or the control device 28. In principle, each of them can also be used separately and/or in the non-implanted state, that is, as an external device for receiving a signal S and/or the characteristic of the reso- nant circuit RC from the electrode device 1 and/or for controlling and/or supplying with energy of the electrode device 1.
  • the coil 29 can optionally be provided with a ferromagnetic, soft-magnetic or ul- trasoft magnetic core or a half-sided cladding or another shoe or conducting ele- ment to concentrate the magnetic flux.
  • the coil 29 can comprise antenna-like elements or the transceiver of receiver 24 and/or control device 28 can comprise an antenna.
  • Coil 29 preferably comprises a sending portion or coil 25 and/or a receiving por- tion or coil 26.
  • the sending coil 25 can comprise a lower number or turns than the receiving coil 26.
  • coil 26 is assigned to receiver 24 and/or coil 25 is assigned to the control unit 28.
  • coil 29 can comprise a tap that can divide the number of windings of coil 29 asymmetrically, such that only a few turns are used for sending purposes and more or all turns are used for receiving purposes.
  • a magnetic field sensor 30 can be used for receiving or detecting magnetic field H.
  • the receiver can comprise the magnetic field sensor 30 as well as the coil 26 or 29.
  • the magnetic field sensor 30 can be a sensor of the fluxgate type or the like.
  • the receiver 24 can preferably receive or take up the time-varying magnetic field H from electrode device 1, preferably comprising or corresponding to the signal S, and/or the characteristic of the resonant circuit RC, and/or the required heart information, via a separate receiving coil (not shown) and/or magnetic filed sen- sor 30, and/or via the (common) coil 29, in particular so that the generation of electrical impulses P by the electrode device 1 can be controlled using signal S and/or the characteristic of the resonant circuit RC.
  • a separate receiving coil not shown
  • magnetic filed sen- sor 30 and/or via the (common) coil 29, in particular so that the generation of electrical impulses P by the electrode device 1 can be controlled using signal S and/or the characteristic of the resonant circuit RC.
  • additional electrodes or sensors can also be connected directly to the control device 28 or the receiver 24.
  • Control unit 31 can be adapted to verify or characterize the contact of the electrodes 2 of the electrode device 1 to the surrounding area 5 by receiving energy from the electrode device 1 comprising information or corresponding to the characteristic of the resonant circuit RC, and by analyzing the energy. Alterna- tively or additionally, control unit 31 further is adapted to identify a malfunction, in particular of a heart, by analyzing the signal S.
  • Control unit 31 preferably further is adapted for transmitting energy to the at least one implantable electrode device 1 in a wireless manner by means of the time-varying magnetic field H.
  • Control unit 31 further can be adapted for receiving energy from, in particular returned by, the at least one electrode device 1 exclusively in a wireless manner by means of time-varying magnetic field H, in particular using transmit coil 25, re- ceive coil 26, and/or a magnetic field sensor 27, 30, in particular a magnetometer.
  • An preferably electrical signal S in particular an intracardiac ECG, EEG and/or EMG signal, is preferably automatically sensed from the surrounding area 5 (tissue) by the implantable and/or implanted electrode device 1.
  • the electrode device 1 converts the signal S into a corresponding time-varying magnetic field H as already described in detail.
  • This signal S is transmitted to the receiver 24 in a wireless manner and the receiver 24, in particular the associated coil 26 and/or 29, preferably converts the signal S into an electrical signal S.
  • the receiver 24 can receive and, preferably, analyze the signal S, the characteristic of the resonant circuit, and/or the time varying magnetic field H sent by electrode device 1.
  • the signal S is received by means of coil 29 and/or by means of the magnetic field sensor 30 and/or internal magnetic field sensor 27.
  • the incoming signal S, characteristic of the resonant circuit RC and/or a corresponding signal, current or voltage can be amplified and/or analyzed.
  • a data output and/or a display for delivery of the signal S, the analyzed signal S or the like can be provided (not shown). It is particularly preferred that specific values or timings corresponding to the electrical activity of the heart 5 can be analyzed and, preferably, provided to the control device 28.
  • control device 28 can trigger the electrode device 1 in a wireless manner by means of the time-varying magnetic field H for generating and/or delivering at least one electrical impulse P.
  • the triggering is synchronized by or to the signal S and/or the characteristic of the resonant circuit RC sent by the electrode device 1.
  • the received signal S and/or the characteristic of the resonant circuit RC preferably is converted to an electrical signal S by the receiver 2 and/or coil 29 and/or magnetic field sensor 27, 30.
  • the incoming signal S is analyzed, in particular with analysis means 48 and/or compared to a predefined value or range and an action is initiated by reaching or passing it.
  • the arrangement A comprises different electrode devices 1 placed in some distance, in particular in a distance greater than 1 cm, preferably greater than 2 cm and/or less than 20 cm, preferably less than 15 cm. It is particularly preferred that at least one of the electrode devices 1 comprises a delay means for generating a delay between reception of the energy and the generation of at least one of the electrical impulses as already explained in detail.
  • different electrode devices 1 can generate electrical impulses P with a delay between a first electrical impulse P generated by the first electrode device 1 and a second electrical impulse P generated by the second electrode device 1 which preferably comprises the delay means in this example.
  • different electrode devices 1 can be controlled, triggered and/or activated to deliver electrical impulses P, to sense signal S and/or to transmit the characteristic of the resonant circuit RC independently, in particular by means of time-varying magnetic field H of different transmission characteristics, in particular different frequencies and/or polarities.
  • a common, additive stimulation can be adapted to the natural behavior of an object to be stimulated.
  • the heart can be stimulated and/or sensed at a first position and, after a short delay, at a second position, preferably according to its typical or natural activation and/or stimulation.
  • the second electrode device 1 may comprise a reed relay as delay means that can block the delivery and/or generation of the electrical impulse for the particular time span until a minimum field strength for triggering is exceeded (delay means / protection means).
  • all electrode devices 1 or at least one less than the number of electrode devices 1 actually used comprise delay means, in particular (micro-) reed relays 14.
  • different electrode devices 1 can be triggered independently, in particular if, as preferred, the different reed relays of different electrode devices 3 comprising different thresholds, i.e. different minimum magnetic field strengths for triggering.
  • different frequencies or polarities of the time-varying magnetic field H can be used for addressing, selecting and/or controlling different electrode devices 1.
  • a plurality of electrode devices 1 can be used which, in particular, can be controlled and/or supplied with energy by a common control device 28.
  • the wireless electrode device 1 can be implanted in more suitable regions for sensing and/or stimulation, in particular, of the heart muscle, than is possible with wire-bound electrodes.
  • a plurality of electrode devices 1 can be implanted at different locations whereby improved sensing and/or stimulation and, in particular, better cardiac dynamics can be achieved.
  • the electrode devices 1 can then be implanted at different locations, for example.
  • the delay means can be used for synchronizing the electrode device 1 additionally or alternatively.
  • Figure 12 shows another embodiment of the proposed arrangement A comprising the control device 28, the electrode device 1 and an external charging device 35 in a schematic diagram similar to a block diagram.
  • Charging of implanted receiver 24, control unit 31 and/or analysis means 48 can be carried out mutatis mutandis.
  • a plurality of short magnetic field pulses can be generated as a sequence by the control device 28 during the switch-on time of the magnetic field H, i.e. during the switch-on phases.
  • the coil core 21 always changes its magnetization far below the saturation state.
  • a minimum energy consumption can be achieved.
  • bipolar magnetic field pulses are preferably generated by means of a power amplifier, in particular a bridge of switching transistors Ml to M4 (e.g. MOSFETS, also in complementary design) or other switching semiconductor components.
  • a control and the energy storage device or battery 32 of the control device 2 are also indicated in Fig. 12.
  • the control can, for example, comprise one or two signal generators V3 and V4.
  • separating electronics 38 such as a switch or the like can be provided, in particular for deactivating control device 28 by disconnecting battery 32.
  • the control device 28 or its coil 29 is preferably configured such that the control device 28 or its battery 32 can be inductively charged in the implanted state, in particular via the coil 29 or a different receiving means.
  • the charging device 35 can be equipped with a suitable coil 39 and a corresponding power supply, in particular an alternating current supply 40.
  • verifying and/or characterizing the contact of at least one electrode 2 of the electrode device 1 to the surrounding area as well as a method for optimized positioning is described referring to the embodiment shown in Fig. 13, showing an arrangement A, in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device 1.
  • any of the components discussed referring to the preceding embodiments, in particular of Fig. 1 and 2, can be used in the present em- bodiment, and vice versa.
  • the supervisory component 15, switch 10, switch 13, switch 14, amplifier 6 and/or core 20 can be applied to the embodiment of Fig. 13 as well.
  • Additional resonance means RM, switches 11 and/or 12 as well as capacitors 45 and/or 47 can be applied to the embodiment of Fig. 1 or Fig. 2 as well.
  • Electrode device 1 of Fig. 13 can be adapted or perform for any of the preceding aspects and/or the same reference numerals are used for same parts or parts of the same type and the same or similar features, advantages or properties can be achieved even without a repeated description.
  • Resonance Means RM Resonance Means
  • the electrode device 1 of Fig. 13 comprises a resonance means RM preferably associated to the electrodes 2 for forming a resonant circuit RC with the sur- rounding area 5 via the electrodes 2.
  • the resonance means RM preferably comprises transceiver 4 of the electrode device 1, in particular coil 21.
  • transceiver 4 further comprises intrinsic capacities, e.g., inter-winding capacities 44, additional capacitor 45, and/or losses, e.g., due to the finite conductivity of coil 21.
  • the resonance means RM can be formed by or with transceiver 4.
  • additional elements, in particular the additional capacitor 45 can be part of the resonance means RM.
  • coil 21 is used as resonance means RM or part of it and as transceiver 4 for sending the characteristic of the resonant circuit RC, the signal S, a corresponding value and/or for receiving energy by means of time-varying magnetic field H.
  • resonance means RM can be realized separately, in particular by means of a separate coil 46 and/or capacitor 47, preferably connected to the electrodes 2.
  • a separate transceiver for receiving energy and/or for sending signal S and/or the characteristic of the resonant circuit can be provided.
  • the resonance means RM particularly preferably can be connected to the electrodes 2 such that the resonant circuit RC with the surrounding area 5 can be realized. It can be sufficient to realize this resonant circuit RC on demand and/or from time to time only.
  • switches 12 can be provided for connecting the resonance means RM directly or indirectly to the electrodes 2 and, preferably, via the electrodes 2 to the surrounding area 5.
  • the surrounding area 5 is at least substantially electrically conducting and/or in contact to at least two different of the electrodes 2.
  • the electrodes 2 are preferably connected via the surrounding area 5, in particular wherein the surrounding area 5 provides a more or less resistive behavior.
  • the surrounding area 5 connecting the electrodes 2 provides a resistance of more than 10 ⁇ , preferably more than 100 ⁇ , in particular more than 1.000 ⁇ , and/or less than 100 kQ, preferably less than 10 kQ, across the elec- trodes 2 unless no failure occurs.
  • the resistance provided by the surrounding area 5 preferably forms part of resonant circuit RC and, in particular, affects a characteristic of the resonant RC, in particular losses, a damping factor and/or a resonance frequency of the resonant circuit RC. If the properties of the electrical contact between the electrodes 2 and the surrounding area 5 varies, this has an influence on the characteristics of the resonant circuit RC.
  • monitoring the characteristic of the resonant circuit RC can be used for verifying proper contact of the electrodes 2 to the surrounding area 5 and/or to detect changes in the contact properties which can act as an indicator of malfunction, aging, or a different failure. Further, the electrical characteristics of the surrounding area 5 can be determined.
  • the resonance means RM of the electrode device 1 is used to form the resonant circuit RC with the surrounding area 5 via at least two electrodes 2, preferably wherein the characteris- tic of the resonant circuit RC indicates the electrical contact of the electrodes 2 to the surrounding area 5, and/or the electrical resistance across the electrodes 2.
  • the resonant circuit RC can comprise at least one coil 29, 46 and an associated capacitor, in particular a self-capacity 44 of coil 29, 46, stray capacities due to leads, and/or an optional capacitor 45, 47.
  • the resonance means RM is directly or indirectly connected to the electrodes 2, in particular such that the contact of the electrodes 2 with the surrounding area 5 has an influence on the characteristic of the resonant circuit RC.
  • One or more switches 12 can be used to directly connect resonance means RM to one or more of the electrodes 2.
  • Resonance means RM permanently can be connected to rectifier 7.
  • rectifier 7 is controlled differently than discussed referring to Fig. 5 and 6.
  • switches 8A and 8D can be continuously open and/or switches 8B and 8C are continuously closed connecting node Kl to node K4 and node K2 to K3, or vice versa.
  • This is an example for using rectifier 7 for directly connecting resonance means RM to energy buffer 9.
  • energy buffer 9 can become part of resonant circuit RC.
  • Energy buffer 9 can be used to replace optional capacitor 45 leading to a cheaper and less complex solution. Further, energy buffer 9 and/or rectifier 7 can connect resonance means RM to the electrodes 2, preferably realizing the resonant circuit RC with the surrounding area 5. Optionally, parts of energy buffer 9 can be deactivated in order to achieve a sufficiently high resonance frequency of resonant circuit RC. Further, the resonance frequency can be controlled thereby.
  • a separate resonance means RM for forming reso- nant circuit RC and/or determining the characteristic of the resonant circuit RC can be realized using coil 46 and/or capacitor 47.
  • coil 46 and capacitor 47 are forming a resonant circuit RC with the surrounding area 5.
  • Coil 46 and/or capacitor 47 can be configured such that a resonance frequency of corresponding resonant circuit RC results, which is different to that the transceiver 4 is sensitive or selective to for supplying electrode device 1 with energy and/or to send signal S.
  • determining the characteristic of the resonant circuit RC and either supplying the electrode device 1 with energy or sending signal S can be activated separately by choosing different transmission characteristics, preferably frequencies and/or polarities, in particular by generating and/or providing the electrode device with time-varying magnetic field H of different frequencies and/or polarities.
  • the resonant circuit RC preferably is provided with energy such that an electrical oscillation of the resonant circuit RC is caused.
  • Energy can be provided internal- ly, in particular by energy buffer 9, or externally using a wire connection.
  • energy can be provided to the resonance means RM by means of the time-varying magnetic field H for energizing the resonant circuit RC.
  • the electrode device 1, in particular the resonance means RM is provided with energy exclusively in a wireless manner by means of time-varying magnetic field H.
  • time-varying magnetic field H is provided to transceiver 4, in particular coil 21 and/or coil 46, inducing a current to resonance means RM.
  • This current energizes the resonant circuit RC, preferably causing a decrying oscillation.
  • the frequency and/or decay behavior or a corresponding value can be used for determining or as the characteristic of the reso- nant circuit RC.
  • Energizing the resonant circuit RC preferably results in oscillation, in particular in an oscillating current, which preferably keeps oscillating after providing energy has been stopped. In particular, this oscillation decays after stopping the ener- gy transfer to the electrode device 1 depending on and/or indicating losses of the resonant circuit RC.
  • the oscillating current preferably generates a corresponding time-varying magnetic field H after energy transfer has been stopped, in particular by the oscillating current flowing through the transceiver 4, e.g. coil 21 and/or coil 42. Since the oscillating current, in particular causing the corresponding os- cillating or alternating time-varying magnetic field H, preferably remains and/or is detected after stopping the energy transfer, this is referred to as "post-ringing".
  • Sourcing the electrode device 1 can cover providing energy to the resonant circuit RC. This allows for analyzing the characteristic of the resonant circuit with- out an additional sourcing procedure and/or after energy transfer for sourcing the electrode device 1 and/or for generating the electrical impulse P has been stopped. Alternatively or additionally, energy can be provided separately the resonant circuit RC, with a different transmission characteristic, and/or by the electrode device 1, its energy storing means 9 or the like.
  • the characteristic of the resonant circuit RC can be analyzed and/or stored inside electrode device 1 or can be transmitted using a wire connection.
  • the characteristic of the resonant circuit RC is sent in a wireless manner by means of time-varying magnetic field H.
  • energizing resonant circuit RC causes an oscillating current through resonance means RM, in particu- lar through coil 21 and/or coil 46, generating a time-varying magnetic field H corresponding to this current.
  • the energized resonant circuit RC leads to generation of time-varying magnetic field H corresponding to the characteristic of the resonant circuit RC.
  • the contact of the electrodes 2 with the surrounding area influences the characteristic of the resonant circuit RC.
  • the characteristic of the resonant circuit RC can be determined, indicating the electrical contact of the electrodes 2 to the surrounding area 5 and/or the electrical characteristic of the surrounding area 5, in particular the resistance across the electrodes 2.
  • the characteristic of the resonant circuit RC can be determined by observing, in particular receiving, the post ringing, corresponding current and/or time-varying magnetic field H which preferably automatically results after energy has been provided to the resonant circuit RC.
  • the contact of the electrodes 2 with the surrounding area optionally can, but does not need to influence the characteristic of the resonant circuit RC.
  • the post ringing, corresponding current and/or time-varying magnetic field H which, preferably automatically, results after energy has been provided to the resonant circuit RC can be used for determining a distance, coupling factor or respective change, in particular for optimized placement, which will be discussed later in further detail.
  • coil 21 and/or coil 46 can be used for sending the charac- teristic of the resonant circuit RC and/or the post ringing.
  • an antenna or different type of transceiver 4 can be used as well.
  • the resonance means RM comprises or is formed by transceiver 4, in particular a coil 21, 46 and/or an antenna, preferably wherein the trans- ceiver 4 is adapted for sending the characteristic of the resonant circuit RC and/or signal S in a wireless manner by means of the time-varying magnetic field H and/or wherein the transceiver 4 is configured to be supplied with energy exclusively in a wireless manner by means of the time-varying magnetic field H.
  • a resonance frequency of resonant circuit RC can be influenced and/or controlled by modifying the inductivity of coil 29, 46 and/or of the associated capacity.
  • the resonant circuit RC preferably is configured to have a resonance frequency of more than 10 Hz, preferably more than 100 Hz, in particular more than 1.000 Hz, and/or less than 1000 MHz, preferably less than 10 MHz.
  • the resonant circuit RC has a resonance frequency inside of one of the ISM-bands as defined by ITU-R, RR Nos. 5.138 and 5.150, in particular from 6.765 to 6.795 MHz, from 13.553 to 13.567 MHz, from 26,975 to 27,283 MHz, from 40.66 to 40.7 MHz, from 433.05 to 434.79 MHz, 902 to 928 MHz, and/or 2,4 to 2,56 Hz.
  • a first transceiver 4, in particular coil 21 can be used for providing the electrode device 1 with energy for delivery of electrical impulse P, and a second transceiver 4, in particular coil 46, can be used for sending signal S and/or for forming the resonant circuit RC, preferably, with the surrounding area 5 via the electrodes 2.
  • a second transceiver 4, in particular coil 46 can be used for sending signal S and/or for forming the resonant circuit RC, preferably, with the surrounding area 5 via the electrodes 2.
  • This in particular allows coil 21 to be optimized for receiving energy and/or coil 46 for transmitting signal S and/or the characteristic of the resonant circuit RC, in particular the post-ringing signal.
  • arrangement A preferably comprises at least one analysis means 48, the analysis means 48 being preferably adapted for receiving the sig- nal S and/or for receiving energy of, in particular returned by, the electrode device 1.
  • the returned energy preferably comprises or corresponds to the characteristic of the resonant circuit RC.
  • the energy transmitted from the electrode device 1 and received by the analysis means 48 can be transmitted wired, by means of sound, light, electricity, pressure or the like and, particularly preferably, by time- varying magnetic field H and/or the magnetic component of a electromagnetic field, which preferably is used in detection.
  • the transceiver 4 of the electrode device in response to the reception of energy, automatically generates the time-varying magnetic field H corre- sponding to the characteristic of the resonant circuit RC, in particular using a current oscillating in the resonant circuit RC.
  • This in particular can achieved by forming the resonant circuit RC with the transceiver 4.
  • a value corresponding to the decay behavior or differ- ent characteristic of the resonant circuit RC is determined by analysis means 48 and, preferably, is compared to a specific, predefined and/or previous value or range.
  • a threshold is passed, an error can be detected by analysis means 48 and, preferably, this error is signaled by analysis means 48 and/or an information for handling is provided, in particular wherein this information is used for adapting energy transfer to electrode device 1. Alternatively or additionally, this information can be used for increasing or decreasing the strength of electrical impulse P delivered by electrode device 1.
  • Analysis means 48 alternatively or additionally can detect the frequency of the signal provided to it, in particular the frequency of the post-ringing and/or a resonance frequency of resonant circuit RC.
  • the resonance frequency preferably depends on the amount of damping caused by the surrounding area 5 and/or the contact between the electrodes 2 and the surrounding area 5. Even though this dependency might not be that strong compared to a quality factor or damping factor of resonant circuit RC, this characteristic of resonant circuit RC provides the advantage that the absolute value does not depend on a coupling factor and/or distance between electrode device 1 and analysis means 48, receiver 24, control device 28, and/or control unit 31.
  • detecting a variation in frequency preferably is used for an indication of the electrical contact of the electrodes 2 to the surrounding area 5, an electrical characteristic of the surrounding area 5 and/or of the electrical resistance across the electrodes 2.
  • the absolute frequency and/or a frequency shift can be used for verifying the contact of the electrodes 2 with the surrounding area 5.
  • the absolute frequency e.g., can be used for comparison to a predefined value or range.
  • the relative value does not demand for a prede- fined value, but needs previous result for comparison, which preferably is controlled to correspond to an acceptable contact by external means.
  • Analysis means 48 can determine a decay behavior and/or a frequency shift.
  • two independent indicators can be used for detecting a problem and/or error. These indicators can be used for verifying the electrical contact of the electrodes 2 with the surrounding area 5 as well as for determining and/or verifying and/or achieving a proper coupling of electrode device 1 to analysis means 48 and/or receiver 24 and/or control device 28 and/or control unit 31. Both the frequency and the decay behavior can be analyzed and/or combined for a better or more reliable result.
  • the characteristic of resonant circuit RC is provided by resonance means RM of electrode device 1 via time-varying electromagnetic field H which is received by control unit 31 and provided to analysis means 48.
  • analysis means 48 can comprise a receiving means, in particular a coil and/or magnetic field sensor, for receiving the characteristic of resonant circuit RC via time-varying magnetic field H.
  • a signal corresponding to post-ringing of resonant circuit RC preferably is provided to analysis means 48.
  • the post-ringing preferably comprises a decay behavior and/or a frequency of resonant circuit RC forming characteristics of resonant circuits RC. However, different characteristics may exist.
  • Analysis means 48 preferably is adapted for determining the decay behavior, in particular by measuring a corresponding decay of an amplitude of a signal provided to analysis means 48 corresponding to the characteristic of resonant circuit RC. This can be used for determining a damping factor, quality factor or the like.
  • Analysis means can deduce a behavior of the electrical contact of the electrodes 2 to the surrounding area 5, an electrical characteristic of the surrounding area 5, and/or the electrical resistance across the electrodes 2. Further, analysis means 48 preferably verifies a proper contact and/or determines and/or signals any failure or problem, in particular if identifying that the contact resistance is increased.
  • a short magnetic field pulse can be generated, preferably time-varying magnetic field H activated over a time span, preferably of more than 1 ⁇ 8, in particular more than 1 ms, and/or less than 1 s, arrives at the electrode device 1, energizing and preferably causing oscillations in the resonant circuit RC.
  • the oscillations caused by energizing the resonance means RM and/or resonant circuit RC continue after energizing has been stopped, in particular after the time-varying magnetic field H providing energy to electrode device 1 has been deactivated, and is damped due to losses of the resonant circuit RC.
  • a capacitive behavior and/or the resistance across the electrodes 2 caused by the surrounding area 5 preferably have an impact on these losses or further characteristics of the resonant circuit RC.
  • the oscillations can be detected directly at the resonant circuit RC, in particular at coil 29 and/or coil 46. More preferably, a separate receiver, in particular coil 29 and/or magnetic field sensor 27, 30 can be used. By monitoring and/or analyzing a signal corresponding to the oscillation, a status of the electrode device 1 can be determined.
  • the arrangement A can comprise analysis means 48 for analyzing the characteristic of resonant circuit RC.
  • Analysis means 48 can be part of electrode device 1 and/or realized separately, in particular implanted as well.
  • Electrode device 1 can comprise one or more analysis means 48, in particular as depicted in Fig. 13 using dashed lines.
  • the analysis means 48 in Fig. 13 preferably is coupled to resonant circuit RC.
  • analysis means 48 forms part of control unit 31 (cf. Fig. 9 and 10). Analysis means 48 can be realized and/or placed separately as well, which is depicted in Fig. 9 using dashed lines.
  • receiver 24 can comprise analysis means 48.
  • Receiver 24 and/or analysis means 48 preferably is or are adapted to be deac- tivated when the control device 28 transmits energy to the electrode device 1 for protecting their input against overvoltage, in particular for protecting amplifier 33.
  • the input of receiver 24 can be protected by connecting Zener diodes, by disconnecting using a switch, semiconductor switch or the like, preferably for disconnecting the transceiver, in particular coil 29, from the input of receiver 24 and/or analysis means 48.
  • analysis means 48 is realized externally, in particular forming part of control unit 31, a characteristic of the resonant circuit RC can be provided to analysis means 48 using a wire connection. However, providing the characteristic of resonant circuit RC via the time-varying magnetic field H is preferred.
  • the analysis means 48 can be adapted to receiving the characteristic of the resonant circuit RC in a wireless manner, in particular by means of time-varying magnetic field H.
  • the analysis means 48 can be configured for determining a characteristic of the resonant circuit RC indicating the electrical contact of the electrodes 2 to the surrounding area 5 and/or the electrical characteristic of the surrounding area 5, in particular an electrical resistance across the electrodes 2. Analysis means 48, additionally or alternatively, can be used for analyzing sensed signal S as described above.
  • the resonance means RM of electrode device 1 can be used for forming the resonant circuit RC with the surrounding area 5 via the electrodes 2, wherein the resonance means RM simultaneously can be used for supplying the electrode device 1 and/or for generating an electrical impulse P, preferably for stimulation purposes.
  • a permanent connection of the resonance means RM to the electrodes 2 can be provided, resonant circuit RC is formed with the surrounding area 5 via the electrodes 2 and, thus, each of the additional components of electrode device 1 discussed previously are optional.
  • a varying decay behavior is detected.
  • a reduced damping factor can be determined if the decay of the post ringing is reduced, or vice versa.
  • a reduced damping factor can be interpreted as to be caused by an increased contact resistance. This can be handled and/or signaled, in particular as soon as a threshold is reached and/or a range is passed.
  • a frequency shift is detected.
  • an increased frequency is associated with a reduced contact ca- pacitance and/or a decreased frequency is associated with an increased contact capacitance.
  • an increased frequency is associated with reduced losses of the resonant circuit and/or an increased contact resistance and/or a decreased frequency is associated with increased losses of the resonant circuit and/or a decreased contact resistance. This can be handled and/or sig- naled, in particular as soon as a threshold is reached and/or a range is passed.
  • a frequency shift as well as a variation in decay is detected and both of them can be used for more reliably determining a characteristic or problem of the contact, for instance by perform- ing a cross-check for checking plausibility of the detection results.
  • the a characteristic of the contact can be deducted by each of them and the results can be cross-checked, combined and/or an average can be formed for achieving an increased reliability and/or accuracy.
  • An increased contact resistance can be associated with a problem.
  • a reduced damping factor and an increased fre- quency occurring simultaneously can be associated with a more reliable indication for a problem.
  • a problem can be detected with higher thresholds for one of the damping factor and the frequency and/or with lower thresholds for each of them for occurring simultaneously.
  • a problem can be handled and/or signaled, in particular as soon as a threshold is reached and/or a range is passed.
  • Electrode device 1 can be sourced with energy adaptively, preferably depending on the characteristic of the resonant circuit RC. Alternatively or additionally, the electrode device 1 can adapt and/or can be informed to adapt the amount of ener- gy to be delivered for generating electrical impulse P. In particular, a preset value, parameter or the like is determined with the characteristic of the resonant circuit for compensating for a variation of the contact characteristic of the contact between the electrode device 1 and the surrounding area 5.
  • the contact information and/or the characteristic of the resonant circuit RC can be used for adaptively controlling the amount of energy applied to the electrode device 1.
  • the energy provided to the electrode device 1, in particular for delivering electrical impulse P, and/or the energy provided by means of the electrical impulse P can be adapted or increased, which can compensate for possible influences on the stimulation efficiency of electrode device 1.
  • This adaption method can be supported by control unit 31 and/or analysis means 48 which preferably receives the characteristic of the resonant circuit RC from the electrode device 1 and adapts the amount of energy provided to the electrode device 1 and/or the amount of energy provided with one electrical impulse P considering the characteristic of resonant circuit RC.
  • the absolute strength of the signal in particular the strength or amplitude of the time-varying magnetic field H received by analysis means 48 from the electrode device 1 , can be used as an indication for coupling or a coupling factor and, thus, for a placement, direction and/or distance of analysis means 48 and electrode device 1 to each other.
  • a coupling problem can be determined. Further, coupling can be optimized by modifying positions, in particular relative positions, of parts of arrangement A.
  • analysis means 48 and/or control unit 31 can be moved and/or rotated. Afterwards, the strength of time- varying magnetic field H provided by electrode device 1 can be estimated once more by analysis means 48. If the strength of the incoming signal and/or time-varying magnetic field H is increased, the movement can be stopped and/or repeated. If the strength of the signal and/or time-varying magnetic field H is decreased, the modification of arrangement A can be undone and/or a different movement can be chosen.
  • the coupling of a transceiver of the analysis means 48, in particular coil 29, to the transceiver 4 of the electrode device 1 is determined and/or optimized.
  • the transceiver of or associated with the analysis means 48 is considered to form a constructional unit with further components of the analysis means 48, thus, the position of the analysis means 48 corresponds to the position of its transceiver.
  • the transceiver 4 of the electrode device 1 preferably is part of a constructional unit formed by the electrode device 1 and, thus, the position of its transceiver 4 corresponds to the position of the electrode device 1.
  • these are relevant for determining the coupling and further preferably are considered to form the position of the associated electrode device 1 and/or analysis means 48.
  • repeated determination of the characteristics of the resonant circuit RC in particular of a resonance frequency, decay behavior, quality factor and/or of an absolute value of the strength and/or amplitude of a signal and/or time-varying magnetic field H corresponding to the characteristic of resonant circuit RC, can be used either for characterizing and/or verifying contact of the electrodes 2 with the surrounding area 5 and/or for optimizing coupling of the electrode device 1 with receiver 24, control device 28, control unit 31, and/or analysis means 48.
  • transceiver 4 of electrode device 1, in particular coil 21, is used to form resonant circuit RC.
  • one or more additional capacitors 44, and/or configuring rectifier 7 to having a continuous connection to energy buffer 9 or parts of energy buffer 9 can be used for forming resonant circuit RC with or without involving electrodes 2 and/or the surrounding area 5.
  • the characteristics of resonant circuit RC can be well known in advance, in particular prior to implanting electrode device 1.
  • control unit 31, receiver 24 or a corresponding trans-ordinatever, in particular coil 29, coil 26, and/or coil 25 energy can be provided to electrode device 1 and resulting post-ringing provided by the inventive resonant circuit RC can be analyzed.
  • Electrode device 1 Repeatedly energizing resonant circuit RC and analyzing the resulting post- ringing, in particular the strength of time-varying magnetic field H detected after deactivation of energy transfer to electrode device 1, can be used for iterative optimizing coupling, orientation, and/or positioning of components of arrangement A.
  • coupling can be optimized with only minor or even not any modification of electrode device 1 by providing an analysis means 48 that is capable of interpretation of post-ringing or a corresponding signal, preferably comparing a strength of time-varying magnetic field H received or of a corresponding signal, comparing it to a reference value, which can be a value of a recent measurement, and/or indicating whether the coupling is increased, decreased, and/or sufficient considering a predefined value or range.
  • the coupling, the distance, the characteristic of the resonant circuit RC, the characteristic of the contact of the electrode(s) 2 and/or further results provided the analysis means 48 can be signaled to (external) means, e.g., gauge, display, indicator or the like for placement.
  • (external) means e.g., gauge, display, indicator or the like for placement.
  • the analysis means 48, control unit 31, receiver 24 and/or control device 28 is to be implanted or placed at the body as well, the coupling or distance can be presented.
  • a placement and/or orientation of any of the aforementioned components can be controlled and/or verified by the inventive method mutatis mutandis.
  • Resonance means RM and/or resonant circuits RC of different electrode devices preferably can be selected using different frequencies and/or polarities of the time-varying magnetic field H. If more than electrode device 1 is available in ar- rangement A, resonance means RM of different resonance frequencies can be used for different ones of the electrode devices 1. Preferably, the resonance means RM and/or corresponding resonant circuits RC receive energy at the individual resonance frequency much more efficiently than at different frequencies. Thus, a selective energy transfer to resonance means RM of different ones of electrode devices 1 can be provided. Thus, the contact of the electrodes 2 of different ones of the electrode devices 1 can be analyzed and/or verified independently.
  • control unit 31 is adapted to generate the time- varying magnetic field H with different transmission characteristics at least essentially corresponding to characteristics of resonance means RM and/or resonant circuits RC of different ones of the electrode devices 1.
  • the control unit 31 can induce post-ringing in different ones of the electrode devices 1 selectively.
  • resonance means RM and/or resonant circuits RC of different ones of the electrode devices 1 are configured to provide different resonance frequencies, which preferably leads to post-ringing at least basically at those frequencies. This allows for characterizing and/or verifying contacts of electrodes 2 and/or determining an electrical characteristic of surrounding areas 5 of different ones of the electrode devices 1 simultaneously, in particular by observing and/or determining the decay behavior of the post-ringing at those different frequencies.
  • the electrode device 1 can comprise at least two independent transceivers 4, in particular coil 21 and coil 46. Further, it is preferred that these transceivers 4 are selective to time-varying magnetic field H of different transmission characteristics, in particular frequencies or polarities. This allows for selective activating sensing signal S and/or delivering electrical impulse P on the one hand, and sourcing resonant circuit RC on the other hand, in particular for verifying the contact of electrodes 2 with the surrounding area 5. Further, optional switches 11 and/or optional switches 12 can be omitted if separate transceivers 4 are used for sending signal S and/or the characteristic of the resonant circuit RC and/or for receiving energy.
  • One aspect of the present invention relates to an arrangement A, in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one, preferably two, implantable electrode devices 1, the electrode device 1 providing a resonance means RM preferably adapted for receiving energy by means of the time-varying magnetic field H.
  • the resonance means preferably forms part of resonant circuit RC configured to oscillate if provided with energy.
  • the oscillation in particular after stopping or as soon as energy transmission to the electrode device has been stopped, preferably is used for generating a time-varying magnetic field H, in particular electromagnetic field, corresponding to characteristics of resonant circuit RC.
  • the arrangement A preferably further provides analysis means 48 adapted for receiving the time-varying magnetic field H, in particular electromagnetic field, caused by the oscillation of the resonant circuit RC.
  • the magnetic field H and/or a magnetic part of the electromagnetic field can be detected by the induction voltage in a detecting coil or by means of a sensitive magnetic field detector.
  • the magnetic field H can be used for determining an absolute strength of this time-varying magnetic field and/or a corresponding value at the receiving position.
  • magnetic field H can be used for determining a characteristic of the resonant circuit RC, in particular for verifying a status of the electrode device, which does not absolutely necessary must comprise an external electrode for some aspects of the present invention.
  • analysis means 48 is used to receive and determine the characteristic of the resonant circuit RC, wherein the resonant circuit RC is formed by resonance means RM configured for receiving energy and for transmitting time- varying magnetic field H.
  • the resonance means RM forms a resonant circuit RC inside the implantable electrode device 1 or part of it, for determining a relative position, distance, and/or orientation of the means 48 to the electrode device 1.
  • the relative position, distance, and/or orientation of the means 48 to the electrode device 1 is used for iteratively modifying positions and/or orientations of means 48 and electrode device 1 to each other for optimizing a coupling between means 48 and electrode device 1.
  • energy is provided to electrode device 1 by means of time-varying magnetic field H, a different component of time-varying magnetic field H and/or time-varying magnetic field H at a different time is generated by electrode device 1 using the ener- gy provided to it.
  • the time-varying magnetic field H is generated by means of a resonant circuit RC of electrode device 1 is used for determining the distance between the electrode device 1 and an analysis means 48 by determining the absolute strength of the time-varying magnetic field H generated by the electrode device 1 at the position of the analysis means 48.
  • a further aspect relates to, in particular repeatedly, modifying the position and/or orientation of the analysis means 48 to the electrode device 1 and observing a strength variation of the time-varying magnetic field H provided by the resonance means RM of electrode device 1, in particular for placement, implanting and/or assuring proper coupling during lifetime.
  • the energy transmission to the electrode device 1 is stopped avoiding disturbance by the energy transmitting means, in particular control device 28 and/or the transceiver or coil associated therewith.
  • a filter in particular a low pass or bandpass filter and/or a means for limiting a rise time, can be provided, which preferably is associated with, in particular connected to, the transceiver of the control device 28, the analysis means 48 and/or the receiver 24. This allows for omitting disturbance and/or disruption of the postringing form the electrode device 1.
  • sending energy can be stopped avoiding a postringing on the sender site.
  • a current of the transceiver or coil of the control device 28 is stopped in a zero-crossing and/or if the current reaches zero.
  • generation of harmonics or ringing can be avoided. This avoids disturb- ance of receiving the post-ringing form the electrode device 1, in particular of the corresponding time-varying magnetic field H. This simplifies and/or enhances the analysis of the characteristic of resonant circuit RC.
  • the postringing signal preferably is sent out by the electrode device 1, in particu- lar transceiver 4.
  • the postringing signal preferably is detected by the receiver 24, the analysis means 48, the control unit 31 or different detection means.
  • the postringing of the electrode device 1 preferably is recorded and/or fitted with a damped sinusoidal, preferably by means of a microcontroller, in particular embedded in receiver 24, the analysis means 48, the control unit 31, a separate transmitter unit and/or in a separate housing.
  • This fitting can be used for obtaining, in particular both and/or separately, the resonance frequency and the damping factor, wherein the damping factor preferably is sensitive to and/or influenced by the real part of the impedance of the surrounding area 5, in particular impedance of the surrounding area 5 and/or tissue impedance.
  • the amount of energy to be transmitted to the electrode device 1 is controlled depending on a coupling of to the electrode device 1 and/or a distance to the electrode device 1.
  • the time span for transmitting energy to the electrode device 1 and/or the strength or amplitude of the time- varying magnetic field H used for transmitting energy to the electrode device 1 can be controlled depending on the distance and/or a coupling factor.
  • a strength, amplitude or corresponding value of the time-varying magnetic field H generated by the electrode device 1, preferably corresponding to the postring- ing and/or oscillating current of the resonant circuit RC, can be used for determining a coupling factor and/or distance, in particular relative distance.
  • the receiver 24 detects the strength, the amplitude and/or the corresponding value, which can be used to determine and/or control the energy transfer to the electrode device 1.
  • the coupling factor, distance or corresponding value preferably is used to adapt the amount and/or density of energy delivered to supply the electrode device 1.
  • the control device 28 can use coupling factor, distance or corresponding value, a change or variation rate thereof for generating the time-varying magnetic field H for supplying the electrode device 1 depending thereon.
  • the time- varying magnetic field H can be generated, in particular by control device 28, which is stronger (higher density) and/or generated over a longer time span (longer duration) if the distance increases and/or the coupling factor to the electrode device 1 decreases.
  • the time- vary ing magnetic field H can be generated, in particular by control device 28, which is weaken (lower density) and/or generated over a shorter time span (shorter duration) if the distance decreases and/or the coupling factor increases.
  • the energy received by the electrode device 1 can be kept at least substantially constant, in particular with a variation less than 50 %, 30 % or 10 %, even if the coupling and/or distance to the electrode device 1, in particular of the electrode device 1 to the receiver 24, control device 28 and/or the transceiver or coil associated therewith, varies.
  • the postringing is used to determine the distance, coupling or corresponding value.
  • switching of a bistable or soft magnetic element, strip, Wiegand wire or the like can be received remote of the electrode device 1 for determining the distance or coupling factor.
  • an amplitude of a change in magnetic field strength and/or corresponding time-varying magnetic filed H is analyzed for determining the distance, coupling factor and/or corresponding value.
  • the distance or coupling factor or corresponding value can be determined by analyz- ing the electrical impulse P, in particular a strength or amplitude thereof reaching receiver 24 or a different receiving means, which preferably comprises at least one electrode in contact with the surrounding area 5.
  • a voltage or current amplitude can be used for determining the distance, coupling factor and/or corresponding value. Further different solutions may exist.
  • the position of the electrode device 1 in its implanted state and/or an optimum position for the receiver 24 and/or control device 28 can be determined.
  • the control device 28 and/or the receiver 24 can be moved, e.g. line- by-line, linear scanning, rotating, iterative or the like.
  • the electrode device 1 preferably is provided with energy multiple times, preferably in time and/or location intervals.
  • the post ringing can be detected remote of the electrode device 1, preferably at the location from which the electrode device 1 is sourced.
  • the locations of the receiver 24, control device 28 or corresponding transceiver or coils do not need to be identical. In particular, only one of them needs to be moved. If the receiver 24 is moved, the energy received by the receiver 24 varies depending on the distance and/or coupling factor. If the control device 28 is moved, the energy transmitted by the electrode device 1 may vary. If both of them are moved, in particular in a similar manner, the variation will be stronger and, thus, can be detected more easily and/or accurately.
  • the amount or amplitude of the received energy can be used for determining the distance, the coupling factor or corresponding value, which in the following can be used to control the energy provided to the time-varying magnetic field H for supplying the electrode device 1 with energy and/or for keeping constant the amount and/or density of energy provided to the electrode device 1.
  • the distance, coupling factor, position of the electrode device 1 and/or the relative position of the electrode device 1 to the receiver 24 and/or control device 28 preferably is or are determined by receiving and analyzing the time-varying magnetic field H.
  • different transmission methods can be used as well.
  • a sound or ultrasound signal, an electrical signal, an electromagnet- ic wave, an electrostatic field or the like can be provided by the electrode device 1 for determining the distance, coupling factor, position, a corresponding value and/or for sending a signal corresponding to the postringing or a different signal.
  • the electrode device 1 is provided with energy and transmits energy corresponding to the postringing, wherein the energy transmission to and/or from the electrode device 1 can be carried out using the time- varying magnetic field H, a sound, ultrasound, electrical field, electromagnetic wave, light, each wireless or wired, wherein each transmission to and from the electrode device can be carried out either with the same or different transmission methods and/or media.

Abstract

An arrangement with an implantable electrode device is proposed, in particular for sensing an intracardiac electrogram and/or for cardiac pacing, the electrode device comprising a resonance means associated with the electrode for forming a resonant circuit with the surrounding area via electrodes. A characteristic of this resonant circuit is used for verifying the electrical contact of the electrode to the surrounding area.

Description

Implantable Electrode Device, in Particular for Sensing an
Intracardiac Electrogram
The present invention relates to an arrangement with an implantable electrode device or to a method, in particular for capturing an intracardiac electrogram and/or for cardiac pacing and/or for optimizing coupling to the electrode device.
In the following description of the invention, the focus is primarily on sensing an intracardiac electrogram and/or on delivering an electrical impulse for stimulat- ing a heart. However, the present invention is not restricted to this particular solution, but in general can be applied to sensing other signals, in particular biopotentials like ECG, EEG, ERG, EMG, and EOG or the like. Furthermore, the signal may correspond to, e.g., a glucose concentration, a phonocardiography signal or a blood pressure. The electrical impulse, for instance, can be applied to the brain, different regions of a body or to nerves as well. In addition, the invention can be applied to different fields of technology as well. For example, the electrode device according to the present invention can be applied to an, in particular hermetically sealed, vessel or pipe, e.g. for performing electrolysis or electroanalysis inside in a wireless manner.
Electrocardiography (ECG) is a method using electrical signals caused by or during the heartbeat. These electrical signals, corresponding to the activity of the heart, can be used for detecting abnormal rhythms of the heart that may be caused by damages of its conductive tissue. Typically, more than two electrodes are placed on the skin of a human to measure potentials or a voltage corresponding to the electrical activity of the heart. A more direct and precise way to sense a signal corresponding to the electrical activity of the heart makes use of an implanted electrode close to the signal source, i.e. the heart itself, for sensing a so- called intracardiac electrogram.
A system for monitoring and analyzing biosignals is known from EP 1 815 784 Al. Cable-less transducers are used for measurement of e.g. electrocardiograms. The transducers can be placed on or implanted under human skin. The transducers make use of a battery as an energy supply for measuring signals by an elec- trode or sensor. If the transducers are implanted, changing the battery is prob- lematic. Furthermore, using a battery leads to a size that is not small enough for an application around or inside a heart, e.g., for sensing intracardiac electrograms.
An implantable pacemaker comprising a programmable sensing circuit for sensing a signal which allows for approximating a surface electrocardiogram is disclosed in US 2008/0051672 Al . A medical device is implanted in the area of a shoulder and comprises a telemetry module for sending measured data. Pacing electrodes are connected to the medical device using wires or cables, wherein the pacing electrodes can be used for estimating an intracardiac signal as well. Nevertheless, these wires or cables are problematic or disadvantageous, because they run over a length of about 30 cm in the blood circulation system and can thereby cause undesirable or even fatal physical reactions. Furthermore, the risk of failure as a result of the mechanical stressing during body movements is high. In addition, the electrodes can be dislocated by movements of the patient due to the wires or cables.
US 5,713,939 Al relates to a data communication system for control of transcutanous energy transmission to an implantable electrode device, wherein a transmitting coil of an external device and receiving coil of an associated implantable receiver are inductively coupled for energy transfer. The receiving coil is connected to a rectifier input. The rectifier output is permanently connected to a smoothing capacitor and switchable connected to a rechargeable battery. For terminating a charging procedure, the battery is disconnected from the rectifier, which can be detected by the external device by load analysis. The implantable device permanently rectifies energy provided to the receiving coil since the smoothing capacitor forms a short or low impedance for alternating signals.
When the switch disconnects the rechargeable battery, the load of the coil is reduced. This changed load is used for signaling a battery status. However, the permanent connection of the rectifier to the coil still causes losses if an alternating current is provided to or by the coil, either by additional parasitic effects of the rectifier or particularly since a smoothing capacitor is provided at the rectifier output consuming energy. Smoothing can be obtained only if the capacitor forms a short or low impedance for alternating currents. Thus, the rectifier still consumes energy from the receiving coil.
US 2009/0024180 Al discloses a stimulation system comprising an implantable electrode device. The electrode device is supplied with energy and controlled in an exclusively wireless manner via a time-variable magnetic field generated by an implanted control device. This electrode device is small enough for a placement close to or inside a heart, since energy is transmitted in a wireless manner instead of using a battery. Nevertheless, this electrode device is part of a stimula- tion system and configured for delivery of an electrical impulse only. Thus, it is not suitable for sensing purposes.
Sensing a signal as well as delivering an electrical impulse via electrodes of an implanted electrode device demands for proper contact to the surrounding area, in particular tissue, e.g. of a heart. However, this electrode contacts can be subject of a change or failure, in particular if scar tissue is formed or different physical or physiological reactions occur. Further, sufficient wireless coupling should be ensured, if a wireless transmission is used. Object of the present invention is to provide an arrangement with at least one implantable electrode device or a method, wherein an electrode contact and/or wireless coupling can be characterized, verified and/or optimized.
The above object is achieved by an arrangement according to claim 1 or 8, by a method according to claim 30, 32, 37 or 54 or by an use according to claim 45 or 48. Advantageous embodiments are subject of the subclaims.
According to a first aspect of the present invention, an arrangement is provided, in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device. The electrode device comprises at least one electrode for sensing a signal from the surrounding area, preferably a tissue, in particular of a heart, and/or for delivering an electrical impulse to it. The electrode device further comprises a resonance means associated to the electrodes for forming a resonant circuit with the surrounding area via the electrode. The arrangement further comprises a means for determining a characteristic of the resonant circuit preferably indicating the electrical contact of the electrode to the surrounding area, an electrical characteristic of the surrounding area, an electrical resistance across at least two electrodes, and/or a distance, coupling or respective change between the electrode device and the means.
For characterizing a contact of electrodes of an implantable electrode device to a surrounding area and/or for sending a signal with the implantable electrode device,, a resonance means of the electrode device can be used to form a resonant circuit with the surrounding area via at least one electrode, wherein a characteris- tic of the resonant circuit indicating the electrical contact of the electrode to the surrounding area, an electrical characteristic of the surrounding area and/or the electrical resistance across at least two electrodes is determined.
The resonant circuit of the electrode device preferably is supplied with energy, in particular by wire, cable, wireless and/or by means of an energy butter of the electrode device, particularly preferably in an exclusively wireless manner by means of a time-varying magnetic field. Providing energy to the resonant circuit can cause an oscillation of the resonant circuit, in particular an oscillating current. A characteristic of the resonant circuit, in particular the frequency and/or decaying behavior of this oscillation, a corresponding value or signal preferably is used as an indicator of the electrical contact of the electrodes to the surrounding area. Thus, the contact can be characterized and/or verified by analyzing the oscillation. As soon as the energy transfer to the electrode device is stopped, energy stored and/or remaining in the resonant circuit preferably causes an oscillation, in particular oscillating current in the resonant circuit, at the natural resonance frequency of the resonant circuit and/or damped depending on the losses of the resonant circuit, both preferably depending on the contact of at least one electrode with the surrounding area. In the following, oscillations of the resonant circuit, preferably after stopping energy transfer to the electrode device, are referred to as "post-ringing".
The electrode device preferably is adapted to partially return energy, a signal, in particular a time-varying magnetic field indicating the characteristic of the reso- nant circuit, in particular wherein the transceiver of the electrode device, in response to reception of energy, automatically generates a time-varying magnetic field corresponding to the characteristic of the resonant circuit. Energy transmitted to the electrode device can at least partially be returned by the electrode de- vice, wherein the returned energy preferably indicates the characteristic of the resonant circuit, in particular in a wireless manner by means of a time-varying magnetic field.
The post-ringing, a corresponding signal or a corresponding time-varying mag- netic field preferably comprises information regarding the characteristic of the resonant circuit. Analyzing the post-ringing is particularly preferred for determining the characteristic of the resonant circuit and/or for determining, analyzing and/or verifying the contact of the at least one of the electrodes of the electrode device to the surrounding area, in particular tissue. Further, if the post-ringing is transmitted in a wireless manner, its information and, in particular a reception power level, can be used for determining a distance or corresponding value.
In the sense of the present invention, the term "magnetic field" preferably covers electro-magnetic fields or waves. Hence, fields, waves or the like with any kind of magnetic component can be a "magnetic field" in the sense of the present invention as well.
The time-varying magnetic field according to the present invention can comprise components generated by different sources, in particular by different parts of the arrangement and/or system, e.g. the electrode device and/or the control unit. The time-varying magnetic field in the sense of the present invention can be generated by the electrode device, in particular if sending the signal and/or the characteristic of the resonant circuit is intended. The time-varying magnetic field H alternatively or additionally can be generated externally if energy transfer to the electrode device and/or delivery of an electrical impulse is intended. The time- varying magnetic field H, thus, can be composed by different sources, in particular if energy and signal transfer are performed at the same time.
The time-varying magnetic field preferably reaches at least one electrode device and, preferably, the analysis means, the control device, the receiver and/or the control unit. More preferably, the magnetic field reaches each of the electrode devices, the analysis means and/or the control unit.
The characteristic of the resonant circuit can be measured directly, in particular by a means for determining placed inside the electrode device and, alternatively or additionally, via a cable connection or the like. Particularly preferably, the characteristic of the resonant circuit is determined indirectly and/or externally in a wireless manner, in particular by means of a time-varying magnetic field. Preferably, the characteristic of the resonant circuit indicating the electrical contact of the electrodes to the surrounding area is determined externally, in particular by means of the time-varying magnetic field. This can be performed with less effort, in particular without additional means or only a few minor modifications of the electrode device itself. The size of the implantable electrode device can be minimized and the reliability can be improved due to the reduced complexity. Transmitting information corresponding to the characteristic of the resonant circuit via time- varying magnetic field allows for analyzing, characterizing and/or verifying the electrical contacts externally.
According to one aspect of the present invention, the characteristic of the reso- nant circuit, in particular losses, a damping and/or decay behavior and/or a resonance frequency of in the resonant circuit, a corresponding oscillating current and/or a corresponding time-varying magnetic field is or are used for determining, in particular remote determining in a wireless manner, the electrical contact of the electrodes to the surrounding area and/or the electrical resistance across the electrodes. Preferably, an electrical behavior of the contact between the electrodes and the surrounding area and/or an electrical characteristic of the surrounding area is or are used to modify the losses and/or resonance frequency of the resonant circuit. Thus, the resonant circuit is formed with the surrounding area, wherein the surrounding area preferably forms part of it.
The losses, the resonant frequency and/or a corresponding oscillating current and/or time-varying magnetic field H of the resonant circuit can be used for verifying and/or characterizing the contact between the electrodes and the surrounding area, in particular a contact resistance and/or capacitance. By forming the resonant circuit with the surrounding area, the characteristic of this resonant circuit, in particular a resonance frequency and/or losses, preferably represented by a damping factor or quality factor of the resonant circuit, depends on the characteristic of the electrical contact between the electrode of the elec- trode device and the surrounding area, in particular tissue, e.g., of a heart. This characteristic can be used for characterizing, analyzing and/or verifying the contact of the at least one electrode of the electrode device to the surrounding area. If a contact malfunction occurs, this malfunction indicated by a variation in a characteristic of a contact and/or of the resonant circuit can be detected. An au- tomatic handling and/or a notification can be provided based on this detection.
In particular, an electrical resistance across the electrodes and/or of the surrounding area can be determined. Alternatively or additionally, a capacitance generated by the contact of the electrode of the electrode device to the surrounding area or other indicators for a contact failure or a proper contact can be determined. Preferably, at least two electrodes of the electrode device are associated, in particular connected, to the resonance means, forming the resonant circuit or part of it. The electrode device can send the characteristic of the resonant circuit and/or the signal, preferably in a wireless manner by means of the time-varying magnetic field.
The electrode device can be supplied with energy exclusively in a wireless man- ner by means of the time-varying magnetic field. In particular, the resonance means can be supplied with energy in a wireless manner by means of the time- varying magnetic field, preferably inducing oscillating currents in the resonant circuit. The oscillating currents in the resonant circuit can be used to generate a corresponding time-varying magnetic field. A short pulse of a time-varying magnetic field is applied to the electrode device inducing a current to a transceiver of the electrode device. By this measure, energy can be transmitted to the electrode device, in particular to the resonant circuit.
The arrangement preferably comprises an analysis means, the analysis means be- ing adapted for receiving the signal, the characteristic of the resonant circuit and/or energy sent, in particular returned, by the electrode device comprising corresponding information. The signal and/or energy preferably is sent by the electrode device and/or received by the analysis means via the time-varying magnetic field, respectively.
The analysis means can be adapted to verify and/or characterize the contact of at least one electrode of the electrode device to the surrounding area, in particular by analyzing the energy and/or signal sent by the electrode device, and/or returned as response of energy transfer to the resonant circuit by the electrode de- vice. Alternatively or additionally, the analysis means can be adapted for determining a strength of the time-varying magnetic field and/or a distance, in particular a relative distance for the electrode device and/or distance change, a coupling factor and/or a corresponding value. The analysis means preferably is adapted to identify a dysfunction, in particular of a heart, and/or an electrical characteristic of the surrounding area, in particular of the tissue and/or of a sample in production technology, by analyzing the signal.
A control unit can comprise the analysis means. The control unit can comprise a control device which is adapted for transmitting energy to the at least one im- plantable electrode device in a wireless manner by means of the time-varying magnetic field. Alternatively or additionally, control signals can be transmitted.
The control unit can comprise a receiver which is adapted for receiving the energy, in particular comprising information about the characteristic of the resonant circuit and/or the signal from, in particular returned by, the at least one electrode device, preferably exclusively in a wireless manner by means of the time- varying magnetic field, and/or using a transmit coil and/or a receive coil, and/or a magnetic field sensor, in particular a magnetometer, of the control unit, in particular of the receiver. The analysis means can form part of the receiver.
A further aspect of the present invention, that can be realized independently as well, relates to an arrangement comprising the electrode device with a resonant circuit comprising the resonance means, wherein the resonance means is configured for generating a time-varying magnetic field corresponding to an oscillation of the resonant circuit. The arrangement further comprises (an analysis) means placed separately remote from the electrode device, wherein the (analysis) means is configured for determining a strength of the time-varying magnetic field corresponding to the oscillation of the resonant circuit, preferably for determining and/or approximating a relative position and/or orientation of the (analysis) means to the electrode device and/or change thereof, in particular with optimized coupling to each other.
In particular, a coupling between an implantable electrode device and a analysis means remote there from can be optimized, wherein energy is provided to the electrode device causing a resonant circuit of the electrode device to oscillate and to transmit energy corresponding to this oscillation to the analysis means in a wireless manner. Preferably, the analysis means receives the energy corresponding to the oscillation and determines its power level at the position of the analysis means or a corresponding value. Further preferably, the method comprises changing a relative position and/or orientation of the electrode device and the analysis means to each other, repeating the steps of providing energy to the electrode device and determining the power level, comparing the power levels and, in particular, interpreting the relative position and/or orientation corresponding to the higher one of the power levels as to providing the higher coupling of the electrode device and the analysis means to each other.
For optimizing a coupling to the electrode device and/or for characterizing a contact of at least one electrode of the electrode device to its surrounding area, a receive power level and/or a characteristic of a resonant circuit of an implantable electrode device, received from the electrode device in a wireless manner in response to providing energy to the electrode device causing an oscillation which generates a corresponding power transmission by the electrode device, can be used. A further aspect of the present invention, which can be realized independently as well, relates to the arrangement with at least one implantable electrode device, wherein the electrode device comprises a rectifier for rectifying energy supplied to the electrode device. The electrode device comprises a switch opening if it is desired to send a signal and/or to determine a characteristic of a resonant circuit, in particular formed with the surrounding area of the electrode device, such that the energy of the signal and/or the resonant circuit is or are not consumed by the rectifier.
An advantage of using a switch for disconnecting the rectifier resides in the fact that energy which is provided to or stored by the transceiver is not consumed by the rectifier. This allows using the transceiver for sending purposes without major losses. Further, a decay behavior of the post ringing, which depends on losses of the resonant circuit, can be reduced. Thus, more oscillation periods are available for analyzing the post ringing. Providing a different means for sending can be omitted, which leads to a smaller and cheaper electrode device. The transceiver, hence, can be used both for sending and receiving.
The switch preferably connects the transceiver to the rectifier or to the electrode alternatively. The most advantageous working modes are connecting the rectifier and disconnecting the electrodes form the transceiver for receiving energy and/or connecting the electrodes and disconnecting the rectifier for forming the resonant circuit. Thus, the switch can comprise or be formed by a changeover switch. Alternatively or additionally, one or more single switches can be provided. This allows for disconnecting the electrode as well as the rectifier, e.g., for sending a signal provided directly or amplified to the transceiver. The switches preferably are semiconductor switches, e.g. MOSFETs. Semiconductor switches are small, easy to control and consume a low amount of power.
In the sense of the present invention, the rectifier does not consume energy pref- erably even if hardly any or a negligible amount of energy reaches the rectifier, since leakage or crosstalk might remain even if not intended. Preferably, energy provided to the rectifier while not, i.e. to a negligible extend, consuming energy is at least than 5, 10 or 20 times, preferably at least 50 times, in particular at least 100 times lower than the energy received if the switch connects the rectifer, and/or the energy provided to the rectifier is less than 1 μΐ, preferably less than 500 nJ, in particular less than 200 nJ or 100 nJ, and/or the power provided to the rectifier is less than 1 mW, preferably less than 500 W, in particular less than 200, 100 or \ μ . The transceiver preferably is configured for generating a time-varying magnetic field. The at least one switch preferably is configured for disconnecting the transceiver from the rectifier, and/or for connecting the transceiver to a surrounding area via at least one electrode. This allows for sending a signal or energy with the transceiver in a wireless manner, i.e., without a cable or lead.
The switch preferably opens, in particular disconnecting the transceiver from the rectifier, if it is desired to send a signal and/or to determine a characteristic of a resonant circuit, such that the energy of the signal and/or of the resonant circuit is or are not consumed by the rectifier. Disconnecting the transceiver disables power consumption by the rectifier, which reduces signal losses and enables active sending with the transceiver, i.e. actively generating a time-varying magnetic field, e.g., by providing a current to the transceiver. According to one aspect, the transceiver forms a resonant circuit with a surrounding area of the electrode device when connected to the at least one electrode by the switch. The switch further preferably disconnects the rectifier for forming the resonant circuit with a surrounding area and/or for sending a signal sensed from the surrounding area.
For forming the resonant circuit, the transceiver should be influenced by the surrounding area, such that an analysis of the surrounding area or of a contact thereto is possible. If, however, energy should be received, a direct connection to the surrounding area might cause losses. An advantage of providing the switch be- tween the transceiver and the electrode resides in the fact that both the efficiency when receiving energy and the resonant circuit with a characteristic depending on the contact to or the electrical characteristic of the surrounding are can be achieved. Further, the switch can connect the transceiver to the at least one electrode of the electrode device for sending the signal. In particular, the sensed signal can be directly provided to the transceiver, when a associated receiver is sufficiently sensitive. This allows for reducing the complexity of the electrode device since no amplifier is needed. The switch preferably connects the transceiver to the rectifier of the electrode device for rectifying received energy. This allows energy to be rectified and to be used, e.g., for to be buffered, for generating an electrical impulse or for sending. Further, the switch preferably disconnects the transceiver from the at least one electrode of the electrode device for rectifying received energy and/or for determining a coupling to the electrode device. Thus, a current through the surrounding area and corresponding losses can be avoided while no influence of the surrounding area, a contact thereto or direct delivery of an electrical impulse is needed.
The switch preferably can connect the transceiver to at least one electrode of the electrode device for forming the resonant circuit with the surrounding area and disconnects the rectifier, such that the energy of the resonant circuit (RC) is not consumed by the rectifier, in particular simultaneously, for determining and/or sending the characteristic of the resonant circuit.
Particularly preferably, the switch is realized by or forms part of the rectifier. Using switches, in particular semiconductor switches, for forming the rectifier is advantageous compared to diodes since losses due to the threshold of the diodes can be avoided. Further, these switches can be used for disconnecting and/or disabling the rectifier, such that it does not consume energy form or provided to the transceiver.
The electrode device can comprise the rectifier for rectifying energy supplied to the electrode device, preferably from outside and/or in a wireless manner. The rectifier in particular comprises semiconductor switches, preferably in a H-bridge configuration. The rectifier in a H-bridge configuration or other full-wave rectifiers have a higher efficiency than half-wave rectifiers. Moreover, rectifiers comprising semiconductor switches are much more efficient compared to com- mon diode-type rectifiers. Thus, using a rectifier with semiconductor switches and/or in a H-bridge configuration is particularly advantageous for the field of wireless applications the electrode device is typically used for.
Further, the rectifier with semiconductor switches in a H-Bridge configuration allows for deactivating the rectifier by opening each switch. This particular mode according to the present invention allows for improving sending capabilities and/or detectability of the characteristic of the resonant circuit. A rectifier with semiconductor switches in other configurations can be used as well. Preferably, the rectifier has a rectifying mode which is well known in the art for normal operation and a sending mode, wherein the rectifier disconnects its input and/or provides an invariable connection between its input and output. In particular, each switch of the rectifier that connects the input is opened or disconnected in the sending mode. Thus, the rectifier does not consume or does only to a min- er extend consume energy.
In the rectifying mode of the rectifier, energy received by the electrode device is rectified by the rectifier such that the electrode device can be supplied with energy and/or information. In the sending mode, the transceiver associated with or connected to the rectifier can be used for sending the sensed signal and/or for determining the characteristic of the resonant circuit. This in particular is supported since signal energy and/or energy stored in the resonant circuit is or are not consumed by the rectifier. The rectifier preferably does not consume the energy of a signal that is to be sent via the transceiver and/or the energy of or stored in the resonant circuit, e.g., if the post-ringing is to be analyzed. Thus, the sending performance and/or the ability of analyzing the post-ringing can be improved and/or the transceiver can be used for receiving energy and for sending purposes and/or providing separate transceivers in the electrode device can be omitted. For this purpose, the rectifier can be decoupled and/or disconnected such that the energy of the signal and/or stored in the resonant circuit is or are not consumed by the rectifier. This can be obtained by opening a switch, in particular for disconnecting the rectifier. A further aspect of the present invention, which can be realized independently as well, relates to the arrangement with at least one implantable electrode device, wherein, the electrode device comprises a switch connecting one node of a transceiver of the electrode device directly to one of the electrodes of the electrode device. A further aspect of the present invention, which can be realized independently as well, relates to a method for characterizing a contact of electrodes of an implantable electrode device to a surrounding area and/or for sending a signal with the implantable electrode device, wherein a switch is used to connect one node of a transceiver of the electrode device directly to one of the electrodes. This allows for an increased influence of the contacts of the electrodes to the surrounding area and/or for directly sending the sensed signal by the electrode device.
Connecting one node of the transceiver directly to one of the electrodes using a switch advantageously allows for increasing the influence of the contact between the electrodes and the surrounding area on the characteristic of the resonant circuit. This allows for a more exact and/or reliable characterization, analysis and/or verification of the contact. Further, sensing a signal from the surrounding area can be improved, e.g., by reducing signal energy losses. Disconnecting, e.g. by opening the switch, can prevent energy losses via the electrodes if receiving and rectifying is intended.
Energy is preferably transmitted to the electrode device in an alternating manner, in particular by means of an alternating time-varying magnetic field and/or an alternating current. The rectifier of the electrode device preferably consumes and/or transforms the energy provided to the electrode device, in particular by rectifying this energy for supplying the electrode device.
For characterizing a contact of electrodes of an implantable electrode device to a surrounding area and/or for sending a signal with the implantable electrode device, a switch preferably is opened if it is desired to send a signal and/or to determine a characteristic of the resonant circuit such that the energy of the signal or of the resonant circuit is not consumed by a rectifier for rectifying energy supplied to the electrode device.
The low input impendence of the rectifier in its normal operation mode i.e. when an alternating current is converted into at least substantially direct current, leads to major losses of the resonant circuit. The switch of the electrode device can be opened, in particular if it is desired to send a signal and/or to determine a characteristic of the resonant circuit, such that the energy of the signal or the energy stored in or of the resonant circuit is not consumed by a rectifier for rectifying energy supplied to the electrode device.
According to a further aspect of the present invention, the implantable electrode device preferably comprises at least two electrodes for sensing the signal from the surrounding area and/or for delivering the electrical impulse. The signal preferably can be an intracardiac potential or voltage, a (bio-) potential as an ECG signal, an EEG signal, an EMG signal or the like. Alternatively or additionally, the implantable electrode device can comprise a sensor, preferably with electrodes, for sensing the signal, in particular corresponding to a glucose value, blood pressure or the like.
The signal optionally can comprise or correspond to the characteristic of the resonant circuit or can correspond to it. In particular, the signal can correspond to the oscillating current of the resonant circuit, which can be sensed from the resonant circuit by directly electrically connecting or indirectly coupling, e.g. of the resonant circuit to the analysis means and/or the transceiver. The characteristic of the resonant circuit optionally can comprise the signal, in particular if the signal acts on the resonant circuit via at least one electrode of the electrode device.
The energy, characteristic and/or signals sent and/or received by the electrode device and/or the control unit can be transmitted acoustically, visually, mechanically, hydraulically, electrically and/or pneumatically. Particularly preferably, the energy, characteristic and/or signal is sent and/or transmitted via the time- varying magnetic field.
The implantable electrode device can be adapted for sending the characteristic of the resonant circuit and/or the sensed signal, preferably in a wireless manner by means of a time-varying magnetic field. The electrode device can comprise a transceiver, in particular a coil and/or an antenna, that can form part of the resonant circuit and/or the resonance means. Preferably, the transceiver does not need to comprise any active part. The electrode device can be suppliable with energy exclusively in a wireless manner by means of the time-varying magnetic field. Energy can be transferred to the electrode device, in particular to the transceiver of the electrode device, via the time-varying magnetic field, preferably providing the resonant circuit with energy and/or causing an oscillation of the resonant circuit.
The electrode device preferably is adapted for generating electrical impulses and/or for delivering electrical impulses via the electrodes. Hence, the electrode device can have a double functionality. It is possible, that the electrode device can sense a signal, in particular corresponding to the electrical activity of a heart, and, at the same time or intermittingly, the electrode device can be used or configured for a pacemaker or defibrillator functionality, i.e. for delivering the electrical impulse. As a synergetic effect, the signal sensed by the electrode device can be used for triggering the stimulation or pacemaker functionality, i.e. for delivering the electrical impulse. Therefore, it is preferred that the electrode device senses the signal and receives a control signal synchronized to the sensed signal for triggering generation or delivery of the electrical impulse.
The implantable electrode device preferably is an at least basically passive de- vice, wherein the energy needed for operation is provided by the signal to be sensed itself and/or the power needed for operation is supplied by means of the time-varying magnetic field. The electrode device preferably exclusively delivers less energy by means of generating the time-varying magnetic field and/or by delivering electrical impulses than the amount of energy received by means of the time-varying magnetic field and/or the sensed signal. The electrode device preferably is configured to be supplied with energy exclusively by the intrinsic energy of the sensed signal and/or in a wireless manner by means of the time-varying magnetic field. The signal sensed by the electrode device and/or the characteristic of the resonant circuit can be transmitted in a wireless manner, and the power can be supplied by means of the time-varying magnetic field or the signal itself. Thus, advantageously, no wire, cable, lead or the like is needed and, hence, the reliability can be improved significantly. Furthermore, by using a passive topology and/or a wireless power supply, no battery is needed within the electrode device. This is particularly advantageous for achieving a small form factor, because the size for a portable and/or wireless sensing device is strictly limited to larger form factors if a battery is needed.
The electrode device preferably comprises the transceiver for sending the signal in a wireless manner, preferably a coil and/or an antenna, which can form part of the resonant circuit. The resonance means preferably comprises or is formed by the transceiver, in particular a coil and/or an antenna. Preferably, the transceiver is adapted for sending the characteristic of the resonant circuit and/or the signal in a wireless manner by means of the time- varying magnetic field and/or wherein the transceiver is configured to be supplied with energy exclusively in a wireless manner by means of the time-varying magnetic field. The transceiver preferably emits energy, in particular the signal and/or energy corresponding to the oscillation of the resonant circuit, in particular exclusively by generating a corresponding time-varying magnetic field. The transceiver of the electrode device preferably acts as or is part of the resonance means, which preferably is associated to the electrode of the electrode device and forms the resonant circuit with the surrounding area.
Preferably, at least one electrode is connected to the transceiver of the electrode device, in particular via an amplifier for amplifying the sensed signal and/or the characteristics of the resonant circuit. The transceiver can be configured for generating the time-varying magnetic field corresponding to the signal and/or to the characteristic of the resonant circuit. Signals sensed inside or close to a heart are much stronger and, hence, more reliable and robust than voltages or potentials that can be detected via the skin of a body. Nevertheless, amplification can be advantageous for a good signal-to-noise ratio if the signal is transmitted and/or received. Different, independent transceivers can be used for supplying the electrode device with energy, sending the signal and/or transmitting the characteristic of the resonant circuit or a corresponding value.
An energy buffer can be used in the electrode device and is preferably connected to the output of the rectifier. The energy buffer can smooth the power, e.g. the internal voltage. The energy buffer typically is a capacitor, in particular with a ca- pacity for a few seconds or minutes of sending the signal in order to keep the form factor as small as possible.
The electrode device can comprise a supervisory component that preferably is adapted for controlling at least one switch and may comprise a timer for a delayed controlling, i.e. switching the switch. Switches in the rectifier can be used either for directing the signal or for directing energy flow inside the electrode device. The supervisory component preferably can deactivate the rectifier if analyzing the characteristic of the resonant circuit and/or if sending the sensed signal is or are desired. In particular, the supervisory component can be adapted for activating and/or deactivating the normal operation and/or the sending mode of the rectifier.
It is preferred that the supervisory component can be supplied by the rectifier and/or by the energy buffer. The supervisory component can be or comprise a controller, microcontroller or the like. It can be adapted for receiving and/or decoding information, in particular sent via the time-varying magnetic field. Alternatively or additionally, the supervisory component can be adapted for preprocessing or coding information to be sent by the electrode device, in particular in- formation corresponding to the sensed signal or the sensed signal and/or the characteristic of the resonant circuit.
The arrangement or system can comprise the electrode device and, in addition, a receiver, in particular a control unit with a receiver, adapted for receiving the signal and/or characteristic of the resonant circuit transmitted via the time- varying magnetic field.
With respect to the intracardiac electrography, such an arrangement or system can comprise at least one electrode device inside or close to the heart as well as a receiver for receiving the signal sensed by the electrode device. The receiver can be placed inside or outside the body and, preferably, comprises a transmit coil and/or a receive coil and/or a magnetic field sensor, in particular a magnetometer, for receiving the signal and/or the characteristic of the resonant circuit. Using the transmit coil can be advantageous as such a coil can be used for both supply- ing the electrode device with energy and receiving the signal. A receive coil can be much more sensitive to the signal and is cheaper than the magnetic field sensor. The magnetic field sensor or magnetometer is preferred with respect to its high sensitivity. A control device can be a further part of the control unit, arrangement and/or system. Preferably, this control device is configured for transmitting energy to the electrode device and/or for controlling the electrode device in a wireless manner by means of the time-varying magnetic field. The receiver and/or the control device can be implanted as well and/or can form a joint constructional unit, and/or forming the control unit. The control unit does not need to comprise both the receiver and the control device. These can be realized and/or used separately as well. An implantable control device and/or receiver enables a short distance to the electrode device leading to a good control unit signal quality and low losses for wireless energy transmission.
The control unit, in particular the receiver and/or the control device, can comprise a, preferably rechargeable, battery that may be rechargeable by an inductive coupling method. Thus, a transportable system can be provided, wherein a lead- less, wireless and/or cableless electrode device can be used for sensing a signal close to its source and the other component(s) can be used for controlling and/or supplying with energy.
For example, the control unit can comprise the receiver and the control device can be realized separately. One or both of them can be implanted or not, in particular at different locations. However, it is preferred that the receiver and the control device are forming a joint constructional unit.
An electrical signal, in particular an (intracardiac) ECG and/or an EMG signal, can be automatically sensed from a surrounding tissue by an implanted electrode device and/or an electrical signal corresponding to the characteristic of the resonant circuit is generated, wherein the signal is converted into a corresponding time-varying magnetic field, wherein the signal is transmitted to the receiver in a wireless manner, and wherein the signal is converted into an electrical signal by the receiver. It is preferred that the control device triggers the electrode device in a wireless manner by means of the time-varying magnetic field for generating and/or delivering the electric impulse. Preferably, the triggering is synchronized by or to the signal and/or the characteristic of the resonant circuit. Furthermore, the electrode device can be supplied with energy by the control device in a wireless manner by means of the time-varying magnetic filed.
The implanted electrode device is used in particular for sensing a signal corresponding to the electrical heart activity and/or for pacing, in particular for a pacemaker or defibrillator functionality. However, the present invention is not restricted to these. Rather, the electrode device can generally sense any type of, preferably electrical, signals, e.g., signals caused by the brain, muscles and nerves as well as electrochemical processes or the like. The electrode device further can be used implemented inaccessibly, e.g. for detecting a signal corresponding to the characteristics of a liquid flowing through an inaccessible pipe, vessel or the like. The signal to be sensed, e.g., can be a characteristic of a sample, in particular an electrical or electrochemical characteristic. The electrical impulse can be used for obtaining electrical or electrochemical reactions as well.
It is pointed out that the inventive method typically is a full-automatic process, wherein a signal and/or the characteristic of the resonant circuit is or are automatically sensed, transmitted, analyzed and/or used for controlling, i.e. for triggering the generation and/or delivery of a pacing electrical impulse. No human and in particular no healthcare professional or the like is needed either for configuring the method or for performing it. Further, the methods of the present invention are not restricted to a human or animal body. Rather, the methods can be applied in production, chemistry and further fields of technology as well.
For example, in manufacturing technology a signal from the surrounding area is sensed by a preferably implantable electrode device, which can be placed inside a reaction vessel, a pipe or the like and/or can be used for electrolysis, electroa- nalysis or the like. A signal can be sensed from the surrounding area (tissue) can correspond to a characteristic of the resonant circuit is generated by the electrode device, e.g., by sensing oscillations of the resonant circuit. The signal and/or characteristic can be converted into a corresponding time- varying magnetic field, and the signal and/or characteristic is or are transmitted to a receiver in a wireless manner, which converts the signal and/or characteristic back into an electrical signal. Alternatively or additionally, the characteristic of the resonant circuit can be transmitted electrically. Preferably, the electrical im- pulse can comprise the characteristic of the resonant circuit or a corresponding voltage, current or the like, which can be used for transmitting the characteristic of the resonant circuit, in particular to the analysis means.
Further, it is preferred that the electrode device is controlled in a wireless manner by means of the time- varying magnetic field for generating and/or delivering an electrical impulse, in particular for electrolysis, electroanalysis or the like. Preferably, the electrode device is triggered, wherein the triggering is synchronized by or to the signal and/or to the characteristic of the resonant circuit of the electrode device.
The electrode device can be supplied with energy in a wireless manner by means of the time-varying magnetic field.
The inventive arrangement and/or method can provide characterizing, analyzing and/or verifying the contact of the electrode of the electrode device and, thus, allows for a failsafe electrode device. The stimulation efficiency can be improved by delivering electrical impulses close to the target. The inventive method further can provide advantages regarding the reliability of sensed signals as these can be covered close to its source. Converting the signal, characteristic and/or energy to a corresponding time-varying magnetic filed allows for the advantageous wireless transmission and/or for omitting wire connections. Moreover, a wireless control of the electrode device and/or wireless energy supply of the electrode device enables a robust assembly. Thus, the error probability can be reduced by omitting wire connections. According to a further aspect of the present invention, which can be realized independently as well, the implantable electrode device can be supplied with energy controlled depending on at least one parameter corresponding to a distance and/or coupling factor to the electrode device. Multiple electrode devices can be supplied with energy controlled depending on at least one individual parameter corresponding to the respective distance and/or coupling factor. In particular individual transmission characteristics, in particular frequencies and/or polarities preferably of time-varying magnetic filed, are used for separately supplying the electrode devices.
Supplying one or more electrode devices can be controlled as follows. First, energy is sent towards the electrode device, preferably by means of the time- varying magnetic field. The sent energy preferably is at least partially received by the electrode device causing the electrode device to return energy, in particu- lar comprising a signal, oscillation of the resonant circuit, postringing, information of the amount or density of received energy, modulation or the like. The returned energy preferably is received, in particular by the receiver, and a receive power level of the received energy or a corresponding value is determined. The amount of energy to be sent towards the electrode device, preferably by the con- trol device, is controlled with or depending on the receive power level or the corresponding value. Preferably, multiple electrode devices are individually provided with energy, wherein the amount and/or density of the energy sent towards the respective electrode device depends on the coupling and/or distance of the respective electrode device, preferably to the associated control device. Since dif- ferent electrode devices will have different positions in a body, distances from the control device or receiver, and/or different coupling factors occur, which can be considered for individually sourcing the respective electrode devices.
One or more of the aforementioned aspects can be combined in any combination. In one example, an arrangement can be used for delivering an electrical impulse and contact verification only. In a second example, an arrangement can be used for sensing and contact verification only. In a third example, an arrangement can be used for contact characterization and/or verification and, preferably, for controlling mentioned or further means based thereon. Further, the characteristic of the resonant circuit can be used for placing and/or arrangement of the compo- nents of the arrangement alternatively or additionally to characterizing contracts of the electrode to the surrounding area, sensing the signal and/or delivering the electrical impulse. The preceding is a simplified summary of the invention to provide an understanding of some aspects of the invention. This summary is neither an extensive nor exhaustive overview of the invention and its various embodiments. It is intended neither to identify key or critical elements of the invention nor to delineate the scope of the invention but to present selected concepts of the invention in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the invention are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below. Further advantages, properties, features and aspects of the present invention are obtained from the claims and from the following description of preferred exemplary embodiments with reference to the drawings.
In the figures:
Fig. 1 is a schematic view of a proposed electrode device;
Fig. 2 is a schematic view of a proposed electrode device according to a second embodiment;
Fig. 3 is a schematic diagram of a magnetization curve of a transceiver of the electrode device according to the present invention;
Fig. 4 is a schematic sectional view of a core element of a transceiver according to the present invention;
Fig. 5 is a schematic view of a rectifier circuit according to the present invention; Fig. 6 is a schematic view rectifier circuit according to the present invention according to second embodiment of the present invention;
Fig. 7A-7C is a timing diagram of a supervisory component according to the present invention;
Fig. 8 is a schematic view of an amplifier according to the present invention;
Fig. 9 is a schematic view of an arrangement according to the present invention;
Fig. 10 is a schematic view of a control unit according to the present invention;
Fig. 11 is a schematic diagram of the time profile of a magnetic field and an induced voltage;
Fig. 12 is a schematic block diagram of an arrangement according to a further embodiment of the present invention; and
Fig. 13 is a schematic view of an arrangement according to the present invention with a further embodiment of a proposed electrode device.
In the figures the same reference numerals are used for the same parts or parts of the same type, components and the like, where corresponding or similar advantages and properties are obtained even if a repeated description is omitted.
Electrode Device
Fig. 1 is a schematical sectional view of a proposed implantable electrode device 1 which can be used for sensing a signal S, in particular an intracardiac electro- gram, and/or for delivering an electrical impulse P. However, the present invention is not restricted to this. For example, the electrode device 1 can be used for sensing and/or monitoring bio-potentials and/or bio-signals, in particular for ECG, EEG, ERG, EMG and EUG as well as for detecting glucose concentration, blood pressure or phonocardiography signals, wherein the electrodes can be part of a sensor. Furthermore, the electrode device 1 preferably can be used for stimulation purposes like pacing and/or defibrillating as well. Moreover, the electrode device 1 can be used for other purposes and at other locations, in particular in the human or animal body. The electrode device 1 preferably comprises at least two electrodes 2. It can be constructed without a battery or the like. In the example shown, the electrode device 1 comprises a preferably implantable, waterproof, hermetical sealed, insulated and/or insulating housing 3, wherein the housing 3 preferably incorporates components of the electrode device 1, and the electrodes 2 are preferably inte- grated in the housing 3, or attached thereon.
The electrode device 1 can be very compact and in particular configured substantially rod-shaped or cylindrical. In the example shown, the length of the electrode device 1 is less than 3 cm, preferably less than 2 cm, in particular less than 1,5 cm. The diameter is preferably at most 1 cm, preferably less than 8 mm, in particular 5 mm or less. A retaining device can be attached to the electrode device 1, preferably an anchor or a screw which allows the electrode device 1 to be anchored in the heart muscle. According to a further embodiment shown in Fig. 2, a multiplicity of linked elements E are used to form a preferably elongated electrode device 1, in particular of a length greater than 10 cm, preferably greater than 12 cm, in particular greater than 15 cm and/or smaller than 25 cm, preferably smaller than 22 cm, in particular smaller than 18 cm, and/or of a diameter smaller than 5 mm, preferably smaller than 4 mm, in particular smaller than 3 mm and/or greater than 0,5 mm, preferably greater than 1 mm, in particular greater than 1,5 mm. This shape advantageously supports delivery of an electrical impulse P across a heart, e.g., for defibrillation. At least one, two or all of the elements E can be adapted to store energy and/or to be supplied with energy by means of the time-varying magnetic field H. Preferably, elements E can be added and/or removed, e.g., by removing cap 49, removing (cutting away) one or more elements E and closing the electrode device 1, in particular by fixing cap 49 at electrode device 1 or a preferably flexible housing. Thus, the size, in particular the length, of electrode device 1 can be adapted in each individual case. The electrode device 1 in Fig. 2 can comprise one or more of the components of the embodiment shown in and discussed referring to Fig. 1 and 13, in particular forming an electronic module 50. Alternatively or additionally, one or more of the components can be part of the elements E as well.
In the example shown in Fig. 2, the electrode device 1 preferably comprises at least a transceiver 4 and the electrodes 2, wherein a transceiver 4 and, preferably, an amplifier 6, a rectifier 7, a supervisory component 15 and/or a pulse forming device 16, are preferably placed inside the housing. At least one, preferably more than one, electrode 2, are preferably integrated in the electrically installed housing 3 or attached thereon. Thus, it is possible to achieve a compact electrode device 1 comprising an at least basically smooth surface. In the example shown, the electrodes 2 are allocated on opposite sides. However, the electrodes 2 can also be arranged, for example, circumferential, at one and or at the other end of the electrode device 1 or the housing 3.
In the following, preferred embodiments or implementations of components and operating methods of the electrode device 1 are discussed in further detail. Nevertheless, similar or different solutions may exist.
Time- Varying Magnetic Field H
The time-varying magnetic field H in the sense of the present invention is preferably generated by the electrode device 1 while sending, e.g. the signal S and/or the characteristic of the resonant circuit RC by the electrode device 1 is intended. The time-varying magnetic field H can be generated externally and/or remote of the electrode device 1 if energy transfer to the electrode device 1 and/or delivery of an electrical impulse P is intended. The time-varying magnetic field H can be composed by different sources, in particular if energy transfer to the electrode device 1 and transfer of the signal S and/or of the characteristic of the resonant circuit is or are performed at the same time. Thus, the in the present invention, "time-varying magnetic field H" can have different sources which are not individually named. Preferably, the term "magnetic field H" in the sense of the present invention incorporates any field or wave comprising a magnetic component, e.g. electromagnetic waves or the like.
The electrode device 1 preferably comprises means for sensing and sending the signal S and/or the characteristic of the resonant circuit RC, the rectifier 7 for rectifying energy received by the transceiver 4, a delay means for generating a delay between reception of the energy and generation of the electrical impulse P, and/or a protection means to prevent or block generation and/or delivery of electrical impulses P when delivery is not intended. Furthermore, the electrode device 1 can also be implemented by other structural elements having a corresponding function.
In the following, methods and/or components for controlling and/or generating an electrical impulse P for stimulation, in particular of the surrounding area 5 or the corresponding heart, using electrode device 1 are explained in further detail. Transceiver
The electrode device 1 preferably comprises transceiver 4 for receiving and/or sending purposes. The transceiver 4 can be provided with energy in a wireless manner, in particular by the time-varying magnetic field H. Preferably, a current is induced in the transceiver 4, in particular coil 21, by the time-varying magnetic field H. Alternatively or additionally, the transceiver 4 may comprise an antenna and/or is adapted for receiving energy from electromagnetic waves or the like. The transceiver 4 can be used for sending purposes, preferably by generating the time-varying magnetic field H, in particular corresponding to a current through transceiver 4. The transceiver 4 can comprise a coil 21, a coil core 20 and/or core elements 22, in particular made of a soft magnetic material or ultrasoft magnetic material, for example in the form of wires or strips (cf. Fig. 4). Such a material has a very low coactive field strength which corresponds to the minimum field strength HI and in particular is less than 0.1 mT. The saturation field strengths of the material are less than about 0.01 to 3 mT. The coil core 20 preferably consists of nonmagnetic or completely or partially of said soft magnetic or ultrasoft magnetic material or a combination of various such magnetic materials.
For instance, the transceiver 4 comprises a coil 21 preferably having a high number of turns, preferably at least 100 turns, in particular at least 1,000 turns, particularly preferably 2,000 turns or more. In the example shown, the coil 21 has substantially 3,000 turns or more. In the example shown, the coil inside diameter is preferably 1 to 3 mm, the coil outside diameter is preferably 2 to 6 mm and the coil length is preferably 10 to 30 mm. In general, ferrites or ferromagnetic metal powder and/or compound materials, in particular laminated structures, can be used as core materials or soft magnetic materials. An advantage is that as a result of the poor electrical conductivity, these materials only exhibit low eddy current losses.
The proposed transceiver 4 can permit the generation of relatively strong electrical impulses P, currents or voltages, in particular an electrical impulse P having a voltage of preferably at least 100 mV, in particular at least 1 V and a time duration of substantially 0.1 ms or more, in particular if stimulation function is intended. In particular, this relatively strong and relatively long-lived electrical impulse P can also be achieved with the soft magnetic core material. A magnetic resetting pulse as with the Wiegand wires or the like can be used. However, a combination with other magnetic materials or structures is possible.
The transceiver 4 can be configured such that a pulse-like induction voltage (preferably electrical impulse P or corresponding thereto) is generated, in particular for stimulation, when a minimum field strength HI of the, e.g., external magnetic field H acting on the electrode device 1 or transceiver 4 is exceeded (cf. Fig. 3 and 11). For this purpose, the transceiver 4 can have an optional coil core 20 which exhibits an abrupt change in the magnetization, i.e. bitable magnetic properties, when the minimum field strength HI is exceeded. This abrupt change in magnetization or magnetic polarization results in the desired pulse-like induction voltage in the associated coil 21. Alternatively or additionally, a reed relay or switch 14 and/or switch 13 in series with at least one electrode 2 can be used for generation and/or delivery of the electrical impulse P. The switches 13 and/or 14 can be formed by and/or comprise semiconductor devices, in particular semiconductor switches. In order to achieve the aforesaid bitable magnetic behavior of the coil core 20, as shown in the diagram according to Fig. 3 as an example, in the example shown the coil core 20 is preferably constructed of at least one core element 22, preferably of a plurality of core elements 22 (cf. Fig. 4). The individual core elements 22 preferably have a diameter of about 50 to 500 μπι, in particular substantially 100 μπι and/or a length of 5 to 20 mm, in particular substantially 15 mm.
The core elements 22 and/or the coil core 20 is or are particularly preferably so- called Wiegand wires as described in US 3,820,090 and/or supplied by HID Corp., 333 St. Street, North, Heaven, CT 06473, USA under the trade name "Wiegand Effect Sensors" or so-called impulse wires as supplied by Tyco Electronics AMP GmbH, Siemenstrasse 13, 67336 Speyer, Germany. In the Wiegand wires the soft and hard magnetic layers or core elements 22 are formed of the same material, the different magnetic properties being achieved in particular by mechanical reforming.
With regard to the possible structure and/or the materials used, reference is made supplementarily, additionally or alternatively to the article "Power Generating Device Using Compound Magnetic Wire" by A. Matsushita et al. published in the journal "Journal of Applied Physics", Vol. 87, No. 9, 1st May 2000, page 6307 to 6309 and to the article "A Soft Magnetic Wire for Sensor Applications" by M. Vazquez et al. published in the journal "J. Phys. D: Appl. Phys.", Vol. 29, 1996, pages 939 and 949, which are introduced as additional disclosure.
With a core 20 comprising soft and hard magnetic components, voltage pulses having a steep edge can be produced with relatively slow field changes of the time-varying magnetic field H. A defined mechanical prestress/pretorsion of a soft-magnetic constituent, which can be set using manufacturing parameters (selection of material, tempering and annealing treatments) preferably is used to achieve a defined Barkhausen effect in a magnetic reversal. Thus, voltage pulses having a steep edge can be produced.
The hard-magnetic constituent and soft magnetic constituent can mechanically support one another. The hard-magnetic constituent can be demagnetized in an activated condition. The soft magnetic constituent preferably has a coercivity field strength which is below the field strength of the time-varying magnetic field H in the examination zone. The hard-magnetic constituent preferably has a coercivity field strength which is higher than the field strength of the alternating field in the examination zone. The hard-magnetic constituent can be demagnetized in an activated condition. The soft magnetic constituent can have coercivity field strength which is below the field strength of the alternating field in the examination zone.
According to one aspect, the core 20 comprises the soft magnetic constituent and a hard-magnetic constituent which preferably concentrically surrounds the core so that the two constituents can be drawn together and thus formed as a unit. If the core of has a rectangular cross section, the exterior portion can be connected to the core by rolling the hard-magnetic constituent onto the core, preferably at both sides and/or by annealing. Alternatively or additionally, core 20 can comprise mixed materials with soft magnetic and hard-magnetic constitutes and/or a corresponding one-compound material. The core 20 can comprise material, in particular amorphous or mixed material, preferably forming a strip.
According to a further aspect, a wire having a hard-magnetic constituent and a soft magnetic constituent can be used. In Fig. 4, the hard-magnetic constituent can form the outer core elements 22 and soft magnetic constituent can form the inner core element 22. Preferably, core 20 is formed by the core elements 22 as a composite elongated member and/or strip. However, different arrangements are possible. For instance, the hard-magnetic constituent can be disposed at an exterior of an elongated member, and the soft magnetic constituent can be disposed in an interior of an elongated member. The composite member can also be formed of a wire consisting of the soft magnetic constituent disposed inside a tube consisting of the hard-magnetic constituent. Further, a foil, strip, loop and/or ring including the soft magnetic constituent and hard-magnetic constituent formed into a composite elongated member can be used as core 20.
The core 20 can be used without a coil for generating magnetic field pulses. Particularly preferred, transceiver 4, in particular coil 21, is associated with core 20, in particular such that the high field changes can be used for generating electrical impulse P. Alternatively or additionally, core 20 can be realized using ferrit or different material with high magnetic permeability and/or with low electrical conductivity, which can help prevent eddy currents.
It is possible to use more than one transceiver 4 for the electrode device 1, in particular at least one for receiving energy and one for sending purposes. These transceivers 4 may comprise different coils, in particular coils of a different number of turns. For example, it can be preferred that the transceiver 4 for receiving energy and/or for verifying the contact of the electrodes 2 to the surrounding area can comprise at least 500 turns, preferably at least 1.000 turns, in particular 2.000 turns or more. A transceiver 4 for sending purposes can com- prise a lower number of turns, for example more than 5, preferably more than 50 turns and/or less than 500 turns, preferably less than 200 turns. If different transceivers 4 are used, it is particularly preferred to realize them using a joint core or a coil, wherein the sending part can be contacted using a center tap. Thus, advantages regarding consumption of space can be obtained.
Generation of Electrical Impulse P
The electrical impulse P for stimulation can be a current delivered by the electrode 2, a voltage at the electrode 3 and/or across at least two electrodes 2. The electrical impulse P can be generated by providing energy to the electrode 2 directly, using a switch and/or other means. In the following, a particular operation scheme for generating an electrical impulse P using the arrangement A is described in detail. A switch 13 preferably connects and/or disconnects the output of rectifier 7 and/or buffer 9 to or from an electrode 2 and/or a pulse forming device 16 of the electrode device 1. Closing switch 13 can allow for generating at least one electrical impulse P and/or for delivering electrical impulses P via the electrodes 2. This is particularly preferred if the electrode device 1 is used for stimulation, e.g. pacing.
According to a particular operation scheme, the electrode device 1 is configured such that an electrical impulse P is only generated and delivered when a (first) minimum field strength of the magnetic field HI is exceeded. Furthermore, this or another pulse generation or triggering is preferably only made possible after respective previous activation.
The impulse generation and triggering preferably takes place as a result of the external magnetic field H acting on the transceiver 4 being varied in time so that when a first minimum magnetic field strength HI is exceeded (cf. Fig. 3).
According to one aspect, an abrupt change in the magnetization of the core elements 22 or the coil 21 takes place as shown in the schematic magnetization curve according to Fig. 11. As a result of the inverse Wiedemann effect, this abrupt change in the magnetization results in a pulse-shaped induction voltage (electrical impulse P in Fig. 11) in the allocated coil 21 of the electrode device 1. This first minimum field strength HI is therefore a switching threshold. Alternatively or additionally, a delay means, switch 14, in particular a reed relay, and/or a protection means may be activated or controlled by the first minimum magnetic field strength HI .
The induced voltage pulses can have an amplitude of up to about 5 V and are about 5 to 100 μ≤ long. In order to achieve a preferably longer pulse duration, as is usual for cardiac stimulation, the optional pulse forming device 16 is preferably used that can realize a smoothing filter function, a low pass filter function and/or just an inductivity. The induced voltage pulse can thus in particular be stretched in time. Alternatively or additionally, a longer pulse duration can also be achieved by bundling a plurality of core elements 22 in the coil 21, in particu- lar so that the pulse forming device 11 can be completely omitted. If the core 20 and/or core elements 22 are used, rectifier 7 and/or energy storing device 9 might not be needed.
The magnitude of the minimum field strength HI depends on various factors, in particular the manufacturing conditions of the core elements 22 if used. The minimum field strength HI is preferably between 0.5 and 20 mT, in particular between 1 to 10 mT and is quite particularly preferably about 2 mT, in particular when impulse wires or Wiegand wires are used. These values are already substantially above the values for magnetic fields usually permissible in public so that any triggering of an electrical impulse P by interference fields usually expected is eliminated.
According to a further aspect, the minimum field strength HI can be higher than 0.01 mT, preferably higher than 0.05 mT and/or when bistable strips are used. This enables operation even if the time-varying magnetic field H is generated in further away, e.g. more than 2 cm, preferably more than 3 cm, in particular more than 4 cm.
In one example with a transceiver 4 with optional individual core elements 22 or coil core 20 having bistable magnetic properties, in particular in the preferred structure of layers having alternately soft and hard magnetic properties (Fig. 4), can be used in various ways. In the example shown, preferably asymmetrical behavior is achieved on running through the magnetization curve or hysteresis. For resetting or attaining the starting point, that is activation for the triggering of the next impulse, the polarity of the coil core 20 is (completely) reversed by the external magnetic field H having the opposite direction when the second minimum field strength H2 is exceeded, as can be deduced from the magnetization curve in Fig. 11. It should be noted that in said processes in each case only the polarity of the soft magnetic material layers is reversed whilst the magnetization of the hard magnetic material layers is thus retained. In principle, however, higher magnetic fields H can also be used to reverse the polarity of the hard magnetic layers if required.
In the example shown, the external magnetic field H, in particular generated by a control device 28, is used both for controlling (triggering) the generation and de- livery of an electrical impulse P by the electrode device 1 and also for supplying the electrode device 1 with the energy necessary for generating the electrical impulse P. In addition, the magnetic field H is preferably also used for said activation of the electrode device 1 for in order to enable generation of the next electri- cal impulse. However, this can be also be effected in another manner or by another signal.
The external magnetic field H preferably runs at least substantially parallel to the longitudinal direction of the coil core 20 or the core elements 22.
Figure 11 shows schematically a preferred time profile VI of the external magnetic field H acting on the electrode device 1 and the corresponding time profile V2 of the voltage U induced in the electrode device 1 or its transceiver 4. Such a profile preferably is used for the stimulation functionality.
The magnetic field H is preferably generated intermittently and/or as an alternating field. The magnetic field H preferably has a switch-on ratio of less than 0.5, in particular less than 0.25, particularly preferably substantially 0.1 or less. The field strength of the magnetic field H preferably has a substantially ramp- shaped or sawtooth-shaped time profile, at least during the switch-on times as indicated in Fig. 11.
The magnetic field H can be alternately generated with an opposite field direc- tion for alternate generation of an electrical impulse P and activation of the electrode device 1 before generation of the next electrical impulse P. The activation preferably takes place only shortly before generating the next electrical impulse P, as indicated in Fig. 11. The frequency of the magnetic field H in one example is only a few Hz, in particular less than 3 Hz and corresponds in particular to the desired frequency of the electrical impulses P to be generated. Alternatively or additionally, the magnetic field H can comprise much higher frequencies, e.g. of a few Hz or in the kHz range, in particular for controlling and/or transmitting of energy. The fre- quency of only a few Hz may be used and/or part of the magnetic field H for triggering purposes and/or if a direct generation of the electrical impulse P is intended.
High- and Low-Energy Electrical Impulse P
The electrode device 1 can provide a high-energy mode and a low-energy mode, wherein the energy delivered by the electrode device 1 for each stimulation by delivering an electrical impulse P via the electrodes 2 in the high-energy mode is higher than the energy delivered for each stimulation in the low-energy mode, preferably at least 50 or 100 times, in particular 200 times. Thus, defibrillation and cardiac pacing can be supported simultaneously and/or by one electrode device 1.
The high-energy electrical impulse P can be generated when the electrode device 1 is supplied with energy or controlled by means of time-varying magnetic field H of a first transmission characteristic, in particular a first frequency and/or polarity. A low-energy electrical impulse P can be generated by electrode device 1 independently when the stimulation device is supplied with energy or controlled by means of the time-varying magnetic field H of a different second transmission characteristic, in particular a different second frequency and/or polarity of time- varying magnetic field H. Thus, different modes can be controlled, activated and/or synchronized.
Signal S
The signal S preferably is sensed across two or more electrodes 2, preferably is amplified by amplifier 6, and/or converted to a corresponding time-varying magnetic field H by means of one ore more transceivers 4. Alternatively or additionally, the characteristic of the resonant circuit RC can be amplified and/or con- verted.
The electrodes 2 preferably are configured for sensing the signal S from and/or delivering the electrical impulse P to the surrounding area 5, in particular a surrounding tissue, sample, conducting liquid or the like. In the example shown, the surrounding area 5 preferably is a tissue of as a heart. For operation, the elec- trode device 1 can be implanted into or close to the heart, wherein the heart forms the surrounding area 5 of the electrode device 1.
The signal S can be an electrical potential, a voltage and/or a current, in particu- lar for controlling or related to the heartbeat, that can be sensed by the electrodes 2. In the example shown, the signal S can be sensed e.g. by measuring a voltage across two or more electrodes 2. The electrode device 1 can comprise more than two electrodes 2 as well. The signal S to be sensed preferably is a ECG signal S or corresponds to it. Nevertheless, the signal S can be another electrical body signal S, e.g. related to muscles, alternatively or additionally. Further, signal S can be related to a sample or an analysis result, in particular of an electroanaly- sis. The signal S further can correspond to a characteristic of a resonant circuit RC of the electrode device 1. The characteristic of the resonant circuit can be sent using the signal S. The resonant circuit RC preferably is formed at least with a resonance means RM and/or the surrounding area 5 of the implantable electrode device 1 via the electrodes 2. In particular, the characteristic can be used for characterizing and/or verifying the contact of the electrodes 2 with the surrounding area 5, and/or for optimizing a relative position and/or orientation of the electrode device 1 to a remote analysis means 48, which will be described later in further detail, e.g., referring to Fig. 13.
The signal S and/or the characteristic of the resonant circuit can be transmitted using different forms of energy transfer, e.g. acoustic, ultrasonic, visual, light, mechanical, pneumatical, hydraulical, electrical, or further different energy transfer methods. Particularly preferably, The signal S, the characteristic of the resonant circuit and/or corresponding energy is transferred using time-varying magnetic field H. Preferably, details of the sending process apply mutatis mutandis to sending a characteristic of the resonant circuit RC.
Amplifier
Amplifying signal S and/ or the characteristic of the resonant circuit can be rea- sonable for sending this signal S. Therefore, an amplifier 6 can be provided. The signal S can be led to the input of amplifier 6, in particular via a closed switch 10 preferably connecting at least one electrode 2 to the amplifier 6.
The preferably amplified signal S in the following can drive the transceiver 4 for generating the time-varying magnetic field H, preferably corresponding to signal S, that can be used for sending, i.e., for transmitting the information sensed by the electrodes 2. The transceiver 4 preferably is formed by or comprises one or more coils 21 for generating time-variable magnetic filed H. Additionally or alternatively, the transceiver 4 comprises or is formed by an antenna or the like.
The amplifier 6 preferably is connected or connectable to at least one electrode 2 at its input and/or its output to the transceiver 4. The amplifier 6 can be realized as shown in Fig. 8. A push-pull output stage of amplifier 8 can comprise MOSFETs M5 and M6, wherein, preferably, MOSFET M5 is of the n-channel type and/or MOSFET M6 is of the p-channel type. The gates of MOSFETS M5 and M6 preferably are controlled by the signal S sensed via electrodes 2 or a corresponding value, voltage, current or the like. The amplified signal S preferably is delivered at the node connected to the drains of MOSFETS M5 and M6 and/or to transceiver 4. Alternatively or additionally, an oscillating current of resonant circuit RC can be amplified, mutatis mutandis, in particular if different transceivers 4, in particular coils 29, 46, are used to form the resonant circuit RC and for sending. Nevertheless, other solutions are possible.
Supplying Electrode Device with Energy
Preferably, electrode device 1 is passive in the meaning of receiving more energy, in particular by means of time-varying magnetic field H, than delivering, in particular by means of sending the signal S, the characteristic of the resonant circuit R and/or delivering electrical impulses P.
The electrode device 1 can be supplied with energy by means of time-varying magnetic filed H generated outside the electrode device 1 inducing a current into the transceiver 4, in particular if the transceiver 4 comprises a coil 21 as depicted in Fig. 1. Sending the signal S can be performed using the intrinsic energy of the sensed signal S, in particular if the optional amplifier 6 is omitted. It is preferred that energy is transmitted to the electrode device 1 in a wireless manner by means of the time-varying magnetic filed H for energy supply, in particular if an amplifier 6 is used. In a preferred alternative, the electrode device is supplied using the intrinsic energy of signal S from the surrounding area 5, accumulated over some time, preferably by rectifying and/or buffering it, in particular over more than 500 ms, more than Is or more than 2 s, and/or less than 10 s, in particular less than 5 s.
Energy Buffer
The electrode device 1 preferably comprises an energy buffer 9, in particular a capacitor. The energy buffer 9 can be connected to the output of rectifier 7. Thus, the rectified energy delivered by rectifier 7 can be smoothed by energy buffer 9. It is preferred that the energy buffer 9 is no battery, accumulator or the like. In particular, it is an energy storing device which is at least basically based on physical effects, preferably including supercaps, TaN capacitors or the like. Nevertheless, other solutions can be possible. The energy buffer 9 can have a maximum capacity for generation and/or delivery of five electrical impulses P or less, preferably for two, in particular for one electrical impulse P and/or for transmitting the signal S and/or the characteristic of the resonant circuit RC less than 60 sec, preferably less than 5 sec, in particular 3 sec. or less. In the example shown, the energy buffer 9 can have a capacity of less than 500 μΡ, preferably less than 300 μΡ, in particular less than 200 Ρ.
A current induced into the transceiver 4 by the time-varying magnetic field H can be rectified by rectifier 7 and stored in energy buffer 9, preferably resulting in a rising voltage across the energy buffer 9. This voltage can be used for gener- ating electrical impulse P and/or for supplying, e.g., the amplifier 6. Alternatively or additionally, the energy stored in the energy buffer 9 can be used for supplying a supervisory component 15.
Rectifier Energy received by transceiver 4 preferably can be transmitted to the rectifier 7. In particular, the transceiver 4 and the rectifier 7 are electrically connected. The rectifier 7 preferably is adapted to transform energy from a time-varying or alternating nature to a substantially continuous one. In particular, an alternating current or voltage can be rectified.
Diodes in a bridge configuration can be used for rectifying. As shown in Fig. 5 or 6, the rectifier 7 for commutation preferably comprises semiconductor switches 8 A to 8D with a control port instead or additionally to (intrinsic) diodes. These switches 8A to 8D can have a threshold voltage in the area of a zero-crossing, particularly in contrast to diodes having a threshold voltage of about 0.4 to 0.8 V. Particularly preferably, the semiconductor switches 8A to 8D, in particular MOSFETs or the like, of the rectifier 7 have a threshold voltage of about zero and/or are biased at about threshold. In the example shown, the threshold voltages and/or a biasing offsets from threshold are less than ±200 mV, in particular less than ±100 mV or ±50 mV. By this measure, a voltage drop across the devices forming the rectifier 7 can be minimized and/or avoided. Thus, the rectifier 7 with semiconductor switches 8A to 8D can allow for reduced power losses and/or more efficient rectifying.
In the following, an example for operating the rectifier 7 is given. If the potential of node Kl is higher than the potential of node K2, semiconductor switch 8B, preferably a n-channel-MOSFET, is conducting and connects node K3 to node K2. Furthermore, semiconductor switch 8C, preferably a p-channel-MOSFET, is conducting and connects node K4 to node Kl. Semiconductor switches 8 A and 8D are non-conducting or having a high resistance and/or impedance as long as the potential of node Kl is higher than the potential of node K2.
If potential of node K2 is higher than the potential of node Kl, semiconductor switches 8A and 8D are conducting and semiconductor switches 8B and 8C having a high resistance behavior. Thus, node K3 preferably is always connected to the one of the nodes Kl and K2 with the higher potential and node K4 always is connected to the one of the notes Kl and K2 with the lower potential leading to the rectifying behavior. The control ports or steering ports, in particular gates, of the semiconductor switches 8A to 8D can be connected and/or contacted via inductive elements I as shown in Fig. 6. Typically, semiconductor switches 8A to 8D comprise an intrinsic capacitive behavior at their control ports that can be compensated for using the inductive elements I. Furthermore, Zener diodes Z may be used to prevent over-voltage at the control ports of semiconductor switches 8A to 8D. Additionally or alternatively to the inductive elements I, resistors R can be provided at the control ports of semiconductor switches 8A to 8D. This enables independent control of each of the semiconductor switches 8A to 8D, in particular by control- ling the potentials at nodes K5 to K8. Preferably, semiconductor switches 8A to 8D can be opened such that the rectifier 7 is deactivated and/or does not consume energy from transceiver 4.
Sender and Receiver Mode
It is preferred that the electrode device 1 provides two different work modes or functions, a first one for sending the signal S sensed and/or the characteristic of the resonant circuit RC, and a second one for generation and/or delivery of the electrical impulse P for stimulation purposes.
For sending the signal S and/or for sending and/or determining the characteristic of the resonant circuit RC, the supervisory component 15 and/or electrode device
I can connect the amplifier 6 to the electrode 2, e.g., by closing switch 10, disconnecting the rectifier 7, e.g. by opening switch 11, and/or bridging the rectifier 7 and/or connecting transceiver 4 to one electrode 2, in particular by closing switch 12. Alternatively or additionally, in particular if rectifier 7 comprises semiconductor switches 8A to 8D (cf. Fig. 5 and 6), switch 11 and/or switch 12 can be omitted and their function can be realized using switches 8A to 8D. Opening switch 11 can correspond to opening switches 8A and 8C. Closing switch 12 can correspond to closing switch 8B. Switch 8D should be opened as well in order to prevent a short across energy buffer 9. Here, switches 8 A to 8D preferably are controlled independently from each other and/or by the supervisory component 15. This in the following is discussed in further detail. Optionally, switches
I I and 12 can be realized together by using a changeover switch, in particular al- ternatively connecting the transceiver 4 to the rectifier 7 or to the electrode 2. The energy supplied in a wireless manner can preferably be rectified by a rectifier 7, in particular comprising semiconductor switches 8A to 8D. While sending the signal S and/or a characteristic of the resonant circuit RC, a switch 11 can be opened such that the signal S is not rectified by rectifier 7 in order to improve the sending performance of the transceiver 4. A further switch 12 may be used to connect one node of the transceiver 4 directly to one of the electrodes 2 and/or to close the current circuit if a two-way rectifier 7 is used, that would possibly block the sending process. As will be described in context of implementations for rectifier 7, switches 11 and/or 12 can be omitted if a rectifier 7 with semiconductor switches is used.
Opening or closing switches 8A and 8C can replace opening or closing switch 11. Opening or closing switch 8B can replace opening or closing switch 12. Thus, switch 11 and/or 12 can be omitted and their function can be realized using switches 8A to 8D.
Referring to Fig. 5, optional resistors R can be added to rectifier 7. Resulting nodes K5, K6, K7 and K8 can be used for deactivating rectifier 7. In particular, a high potential can be chosen for nodes K5 and K7, and a low potential can be chosen for nodes K6 and K8, such that semiconductor switches 8 A, 8B, 8C and 8D are continuously in their high-ohmic state (open). Different solutions may exist for permanently opening each of the semiconductor switches of rectifier 7 for deactivating it.
After rectifying has been performed, the energy can be stored in the energy buffer 9, in particular a capacitor. The energy buffer 9 preferably is connected to the rectifier 7, in particular to nodes K3 and K4. Preferably, the energy buffer 9 is adapted for storing the energy needed for five electrical impulses P or less, in particular for generating only one single electrical impulse. Thus, the energy buffer 9 can be very small, in particular much smaller than a storing device as a battery or the like. Electrode device 1 preferably comprises rectifier 7 for rectifying energy supplied to the electrode device 1 and a means for deactivating and/or disconnecting the rectifier, preferably enabling the transceiver 4 to be used for sending purposes as well.
In particular, switch 11 opens if it is desired to send a signal S and/or to determine or send the characteristic of the resonant circuit RC, preferably such that the energy of the signal S and/or of the resonant circuit RC is or are not consumed by the rectifier 7.
If transceiver 4, in particular coil 21, is used for receiving energy in order to supply electrode device 1 with energy, it is preferred to use rectifier 7 to rectify this energy. The rectified energy can be stored in energy storing means 9, and can be used for providing an electrical impulse P or different further purposes already discussed above.
If energy is received by means of time-varying magnetic field H or an alternative form of alternating energy, this energy preferably is rectified using rectifier 7. For a high efficiency, rectifier 7 preferably is adapted to consume and/or transform as much energy as possible. In particular, rectifier 7 provides a low input impedance, e.g., less than 10 Ω. If transceiver 4, in particular coil 21, is to be used for sending signal S and/or for forming resonant circuit RC, this behavior of rectifier 7 can be disadvantageous.
According to the present invention, one or more optional switches 11 can be used to disconnect rectifier 7, in particular such that rectifier 7 does not consume energy of signal S and/or energy of resonant circuit RC. Alternatively or additionally, an active rectifier 7, in particular comprising MOSFETS 8A to 8D, can be used, in particular as discussed referring to Fig. 5 and 6 and 13. Particularly preferably, a means is provided to open each of switches 8A to 8D, in particular such that rectifier 7 achieves a high input impedance of preferably several kQ, and/or such that rectifier 7 does not consume energy anymore. This allows for reducing energy losses while sending signal S and/or determining the characteristic of the resonant circuit RC is intended. Supervisory Component 15
The supervisory component 15 can be adapted for processing and/or coding the signal S sensed by the electrode device 1 and/or the characteristic of the resonant circuit RC. For example, the signal S sensed by the electrode device 1, information corresponding to the signal S, to an internal status of the electrode device 1 or of the supervisory component 15, and/or information corresponding to the characteristic of the resonant circuit RC can be coded by the supervisory component 15 and the coded signal S, information and/or the characteristic of the reso- nant circuit RC can be sent by the electrode device 1. This can enable a reduced error probability and/or power consumption.
The supervisory component 15 can be adapted for processing and/or decoding information, in particular commands received via the time-varying magnetic field H. Hence, it is possible to control the electrode device 1 in an easy and reliable way. The electrode device 1 can be synchronized or particular information can be requested this way. It is possible to address or control a particular one among several electrode devices 1, in particular by controlling or addressing and/or selecting one supervisory component 15.
The supervisory component 15 can be adapted for controlling one or more of the switches 10 to 14, preferably using separate leads and/or a bus system as shown in the example. In particular, the supervisory component 15 controls switch 13 for different possible purposes.
The time or time span and/or other control schemes, timings, variables or the like can be preset within the supervisory component 15 and/or can be controlled by the signal S and/or by commands from outside, in particular via time-varying magnetic field H of a particular shape or comprising a modulation, coding or the like.
The supervisory component 15 and/or the electrode device 1 can be adapted for closing the switch 13 only if switch 10 is open, in particular disconnecting the amplifier 6 or different sending means, in oder to prevent damaging the input of amplifier 6 during delivery of an electrical impulse P. The supervisory component 15 and/or the electrode device 1 can be adapted for opening switch 11 if it is desired to send a signal S such that the energy of the signal S is not consumed by rectifier 7. Switch 11 preferably connects the trans- ceiver and the rectifier 7 of the electrode device 1, in particular such that energy received can be rectified and stored and/or used for generating an electrical impulse P.
Depending on the architecture used for rectifier 7, it can be necessary to close switch 12 in order to allow for current flowing through the transceiver 4. Thus, it is preferred that the supervisory component 15 and/or the electrode device 1 is adapted for closing switch 12 while sending the signal S is intended. Additionally or alternatively, the supervisory component 15 can be adapted for controlling switches inside the rectifier 7 or for controlling further switches, biasing net- works or the like not shown in Fig. 1, in particular inside the amplifier 6 or a pulse forming device 16.
It is preferred to use a supervisory component 15 with a low power consumption, in particular in the nW regime. Fig. 7A to 7C show typical timing diagrams of the supervisory component 15. VCC can correspond to the rectified voltage delivered by the rectifier 7. Preferably, the voltage delivered by rectifier 7 is smoothed by energy buffer 9. Fig. 7A shows an example for the rectified voltage and/or for a voltage associated with the energy buffer 9, which in the following will be called process voltage. As soon as the energy transmission by means of the time-varying magnetic field H starts, the process voltage rises up, in particular exceeding the pinch off voltage VTH of the supervisory component 15, i.e. its minimum operation voltage.
Fig. 7B and 7C are showing an inverted and a non-inverted reset signal, respec- tively. The supervisory component 15 can be configured such that the reset signal shown in Fig. 7B keeps low although the process voltage exceeds the pinch of voltage VTH leading to an active reset. As shown in Fig. 7C, the non-inverted reset signal has a high level, leading to an active reset, too. Thus, for the time span of tRp (typically a few ms to 100 ms) starting from the time when the pro- cess voltage exceeds VTH, the reset for the supervisory component 15 keeps ac- tive. Thus, disturbance of initialization of the supervisory component 15 can be prevented. Afterwards, the non-inverted reset signal switches to high and/or the inverted reset signal switches to low such that the supervisory component 15 starts working.
The electrode device 1, in particular supervisory component 15, preferably comprises or is implemented as at least one controller, microcontroller, processor, any other preferably programmable circuit or the like. For instance, a microcontroller with a low power consumption and/or a sleep mode for energy saving purposes can be used, in particular an Atmel AT tiny 10 or any controller of the tiny series provided by Atmel Cooperation, 2325 Orchard Parkway, San Jose, Ca 95131.
Preferably, the supervisory component 15 can be programmed in advance and/or by signals transmitted via the time- varying magnetic field H. The supervisory component 15 can comprise a decoding means for decoding a signal provided by the time varying magnetic field H and, preferably received by electrode device 1.
Therefore, the magnetic field H may comprise modulated information that can be demodulated by the supervisory component 15 and/or the rectifier 7, in particular an amplitude modulation that automatically can be demodulated by rectifier 7.
This information can be used for programming and/or controlling the supervisory component 15.
Pulse Forming Device 16
The pulse forming device 16 preferably is connected to the rectifier 7 and/or energy buffer 9 at its input, and/or to the electrode 2 at its output. The pulse forming device 16 preferably is configured for smoothing the electrical impulse P, e.g., by limiting the slew rate. The pulse forming device 16 can be realized as a filter, a low pass filter or the like. Preferably, the pulse forming device 16 comprises a capacitor 18 preferably parallel to the electrodes 2 and/or a resistor 19, in particular connecting the input of the pulse forming device 16 to the capacitor 18. Additionally or alternatively, an inductive element, in particular a coil, can also be used for pulse forming. The pulse forming device 16 can be used for forming or reforming a pulse-like (induction) voltage which is generated or de- livered by transceiver 4 and/or energy buffer 9. The reformed electrical impulse P can then be delivered for stimulation via the connected electrodes 2.
Analysis Means
The electrode device 1 optionally can comprise an analysis means 48 for analyzing a signal S, which preferably can be sensed via the electrode 2 and/or for detecting, characterizing or analyzing a characteristic of a resonant circuit RC, which will be described later in further detail. The analysis means 48 can be part of the amplifier 6 or placed in front of its input.
The analysis means 48 can be configured for detecting peaks and/or patterns in the signal S, e.g., a P-wave, R-wave and/or S-wave of an electrical activity of a heart. Alternatively or additionally, the analysis means 48 can be used or adapted for characterizing the resonant circuit RC, in particular a resonance frequency and/or losses. The signal S, analyzed signal S and/or characteristic and/or a result of this analysis can be sent, in particular by means and/or of a time-varying magnetic field H. The supervisory component 15 can be adapted for controlling the analysis means 48, in particular in a pre-defined manner or by means of the time- varying magnetic field H.
Delay Means
The supervisory component 15 and/or semiconductor switch 13 can provide or act as a means for generating a delay between reception of the energy and the generating of at least one of the electrical impulses P. If energy is received and preferably rectified, the supervisory component 15 or a different means may control the semiconductor switch 13 to get into or keep the high resistance state (open) directly. Afterwards, the energy delivered to the electrode device 1 can be stored in the energy buffer 9 for a particular time span, in particular greater than 1 ms, preferably 10 ms and/or less than 500 ms, preferably less than 300 ms. Afterwards, the semiconductor switch 13 can be switched into its low resistance state, in particular by the supervisory component 15 and/or if a threshold is passed by the voltage across or the energy stored in energy buffer 9 and/or if the magnetic field strength passes a minimum field strength (e.g. HI), and the electrical impulse P can be generated and/or delivered.
Switch 13 can be normally open (disconnected) and can be closed, preferably af- ter the energy buffer 9 has been charged, after a particular time span and/or at a particular time. The switch 13 can be closed by the supervisory component 15 and/or for delivery of the electrical impulse P. Hence, the supervisory component 15 and/or switch 13 can act as a delay means for delaying delivery of the electrical impulse P. The electrode device 1, in particular the supervisory component 15, preferably comprises a timer for delaying controlling one ore more of the switches 11 to 14.
Switch 14 can be provided that does not need to be controllable by supervisory component 15. Switch 14 preferably is adapted to connect and/or disconnect the pulse forming device 16 and/or one or more of the electrodes 2, preferably to the rectifier 7 and/or buffer 9. It is preferred that switch 14 can be controlled from outside and/or directly e.g. using the magnetic field H. For example, switch 14 is a reed switch that can be closed using at least a magnetic field of a particular, minimum field strength e.g. minimum field strength HI (cf. Fig. 3). The mini- mum field strength HI preferably is higher than the field strength of the time- varying magnetic field H used for energy transmission to the electrode device 1. Thus, generation and/or delivery of the electrical impulse P can be controlled independently from transmitting energy to the electrode device 1 using switch 14. Protection Means
A protection means preferably is adapted to prevent generation and/or to block delivery of electrical impulses P for time span greater than 0.5 ms, preferably greater than 1.0 ms and/or less than 100 ms, preferably less than 20 ms, in par- ticular 10 ms or less, in particular after an electrical impulse P has been finished. Thus, generation and/or delivery of an electrical impulse P can be prevented or blocked during a short time span that has been found to be sufficient for preventing unwanted electrical impulses P that may occur due to a disturbance event, and at the same time a generation of a following electrical impulse P is not af- fected. In one example, the switch 13 is basically closed (conducting) and an electrical impulse P can be delivered as soon as a sufficient amount of energy is available. After generation and/or delivery of the electrical impulse P is finished, switch 13 can be opened to prevent any further delivery of an electrical impulse P that might be not intended. Thus, the supervisory component 15 together with switch 13 can form a protection means for protecting against unwanted delivery of electrical impulses P, e.g., due to any failures or disturbances with effects on the transceiver 4.
The electrode device 1 preferably comprises the protection means, in particular realized by supervisory component 15 and/or (semiconductor) switch 13 as already mentioned. The semiconductor switch 13 preferably connects the rectifier 7 and/or the storing element 9 to at least one of the electrodes 2. The semiconductor switch 13 can be provided in series with at least one of the electrodes 2. Thus, generating an electrical impulse P and/or delivery of the electrical impulse P can be blocked by semiconductor switch 13. Preferably, the semiconductor switch 13 has a high resistance state for blocking generation and/or delivery of electrical impulses P as well as a low resistance state for generating an electrical impulse P or for enabling its generation. The state in particular is controlled by the supervisory component 15.
For example, energy is transmitted to the electrode device 1 and a first electrical impulse P is generated and/or delivered. As long as this first electrical impulse P is generated, the semiconductor switch 13 is conducting, i.e. closed, and/or the supervisory component 15 generates a corresponding signal that leads to a conducting semiconductor switch 13. After delivery of the first electrical impulse P, the supervisory component 15 generates a signal controlling the semiconductor switch 13 such that it changes from a low resistance state (closed) to a high resistance state (open) for blocking generation and/or delivery of further electrical impulses P. Preferably, the supervisory component 15 holds this state for a particular time span. Afterwards, the supervisory component 15 can change the control signal in order to switch the (semiconductor) switch 13 into a low resistance state. With switch 13 in low-resistance state, the next electrical impulse P can be generated and/or delivered. By this measure, any generation or delivery of an electrical impulse P caused by a disturbance or the like can be prevented.
Arrangement A
In the following, arrangement A comprising at least one electrode device 1 and, preferably, an analysis means 48, is described with reference to Fig. 9 depicting a schematical sectional view of a body 41. The electrode device 1 preferably is surrounded by surrounding area 5, in particular implanted in the heart or the heart muscle of a patient, who is shown in Fig. 9 only schematically and in part. The electrode device 1 can be implanted, for example, as described in US 5,411,535 A. The electrode device 1 in arrangement A preferably can be placed close to or insight the heart, since the signal S advantageously is much stronger sensed close to the source than externally, e.g., on the skin.
A system preferably comprises at least one electrode device 1 and a control unit 31, the control unit 31 comprising a receiver 24 and, preferably, comprising analysis means 48 and/or control device 28. However, the analysis means 48 can be realized separately, inside electrode device 1 or in other combinations as well.
In the example shown, the proposed arrangement A is configured or works as a capturing system for an intracardiac electrogram and/or as a cardiac pacemaker and/or defibrillator. However, the present invention is not restricted to this. For example, the arrangement A can, additionally or alternatively, operate for capturing human body signals and/or bio-potentials e.g. ECG signals, EEG signals, ERG signals, EMG signals, EOG signals and/or signals corresponding to a glu- cose concentration, a blood pressure and/or acoustic signals for phono cardiography or the like. Furthermore, the arrangement A can work as a stimulation system, as a defibrillator or can be used for other purposes and at other locations, in particular in the human or animal body. Referring to the introductory part, arrangement A and/or system can be used in different fields of technology as well. Receiver 24
The receiver 24 preferably is adapted for receiving information, preferably by means of time-varying magnetic field H and/or from the electrode device 1. A receiving means, in particular a coil 29, can be assigned to receiver 24. The time- varying magnetic field H can be converted to a current by coil 29. This current can be received, amplified and/or analyzed by means of receiver 24.
The receiver 24 can comprise an input amplifier 33, preferably a low-noise amplifier. This input amplifier 33 can be used amplification of a signal received via coil 29. Alternatively or additionally, receiver 24 can comprise one or more internal magnetic field sensors 27 and/or external magnetic field sensors 30, in particular magnetometers, for receiving and/or detecting the time-varying magnetic field H from the electrode device 1, an information provided by the time-varying magnetic field H, and/or the signal S, and/or the characteristic of the resonant circuit RC. Magnetic field sensors 27, 30 can provide a higher input sensitivity than coil 29. Thus, using magnetic field sensors 27, 30 for receiving signal S and/or the characteristic of the resonant circuit RC can be improved.
Control Device 28
The electrode device 1 is preferably supplied with energy by the control device
28 in a wireless manner by means of the time-varying magnetic field H, which will now be described in further detail.
The control device 28 preferably is adapted for providing energy and/or control signals to the electrode device 1, preferably by means of the time-varying magnetic field H. In particular, control device 28 can provide energy or signals to a transmitter, in particular coil 29, for generating the time-varying magnetic field H.
Control device 28 preferably generates an amplified a power-signal, for example a sawtooth signal, a sign wave or the like. This power-signal is provided to coil
29 for generating a corresponding magnetic field H. Furthermore, the control de- vice 28 can comprise means for generating specific power-signal shapes as peaks, modulation, coding or the like for controlling the electrode device 1.
A power amplifier 34 can be provided by control device 28. Preferably, power amplifier 34 provides energy to coil 26 in order to allow for generating sufficiently strong time-varying magnetic fields H for supplying electrode device 1.
Control device 28 preferably generates an amplified power-signal, for example a sawtooth signal, a sine wave or the like. The power signal, in particular a current, switched current or the like, can be provided to coil 29 for generating a corresponding magnetic field H. The power signal and/or the corresponding time- varying magnetic field H can have specific shapes, in particular peaks, modulation, coding or the like, preferably for controlling, triggering and/or synchronizing one or more electrode devices 1.
The power-signal and/or the result of the analyses of signal S and/or the characteristic of the resonant circuit RC can be used by the control device 28, and the control device 28 may generate a specific time-varying magnetic field H, of a special shape, minimum field strength, coding or the like, in particular by coil 29.
For example, a strong sine wave can be used for transferring energy; information, in particular in form of peaks and/or modulation, can be superposed to the power-signal primarily used for energy transfer. The control device 28 fur- ther can be controllable or synchronable, preferably to a bioelectrical activity of heart 5, in particular to the signal S and/or the characteristic of the resonant circuit RC sent by the electrode device 1. Preferably, the control device 28 can control the electrode device 1 to send a sensed signal S and/or the characteristic of the resonant circuit RC.
The control device 28 can be configured such that the magnetic field H for controlling electrode device 1 and/or for supplying it with energy is generated intermittently. In particular, the control device 28 is configured such that the magnetic field H has a switch-on ratio of less than 0.5, in particular less than 0.25, par- ticularly preferably substantially 0.1 or less. Depending on the configuration, the electrode device 1 can also be used independently of the receiver 24 and/or the control unit 28. For example, it is possible that the electrode device 1 can be supplied with energy and/or controlled by another device, optionally even by a nuclear spin tomograph or the like, with suitable matching. Thus, further possible uses are obtained which go substantially beyond the possible uses of conventional sensing and/or stimulation systems.
Control Unit 31
The arrangement A preferably comprises the, in particular implantable, control unit 31, preferably comprising at least one of the receiver 24 and the control device 28 and, preferably, the implantable electrode device 1 separate there from. Alternatively or additionally, the receiver 24 and/or control device 28 can be realized independently of control unit 31 and/or from each other as well, in particular with separate housings and/or placed at different locations.
Fig. 10 shows a schematical view of control unit 31 comprising receiver 24 and control device 28. In the example shown, the receiver 24 and control device 28 are assigned to a common transceiver, in particular coil 29, for receiving and/or generating the time-varying magnetic field H. The transceiver of receiver 24 and/or control device 28 preferably is part of control unit 31 as well.
The control unit 31, the receiver 24 and/or the control device 28 preferably comprises an energy storage device, preferably battery 32, in particular a rechargeable battery.
The receiver 24, the control device 28 and the coil 29 can form control unit 31 with a common and/or implantable case. Battery 32 preferably can be charged in an inductive manner, in particular via coil 29. Independent and/or shared coils can be used for receiving energy, receiving signal S and/or the characteristic of resonant circuit, sending energy and/or sending control signals. Fig. 10 shows the receiver 24 preferably comprising an input amplifier 33, preferably a low noise amplifier. The control unit 31, and/or the control device 28, preferably comprises a power amplifier 34. The control unit 31, receiver 24 and/or control device 28 are preferably arranged in a flexible housing in particular for implanting it directly above the heart near the thoracic wall. To achieve this flexibility, the control unit 31 can be embedded in a silicon cushion. However other soft materials can also be used. The control unit 31, in particular receiver 24 and/or control device 28, can be implanted as present-day cardiac pacemakers. However, it is not absolutely essential to implant the receiver 24 and/or the control device 28. In principle, each of them can also be used separately and/or in the non-implanted state, that is, as an external device for receiving a signal S and/or the characteristic of the reso- nant circuit RC from the electrode device 1 and/or for controlling and/or supplying with energy of the electrode device 1.
The coil 29 can optionally be provided with a ferromagnetic, soft-magnetic or ul- trasoft magnetic core or a half-sided cladding or another shoe or conducting ele- ment to concentrate the magnetic flux. Alternatively or additionally, the coil 29 can comprise antenna-like elements or the transceiver of receiver 24 and/or control device 28 can comprise an antenna.
Coil 29 preferably comprises a sending portion or coil 25 and/or a receiving por- tion or coil 26. The sending coil 25 can comprise a lower number or turns than the receiving coil 26.
Preferably, coil 26 is assigned to receiver 24 and/or coil 25 is assigned to the control unit 28. Thus, coil 29 can comprise a tap that can divide the number of windings of coil 29 asymmetrically, such that only a few turns are used for sending purposes and more or all turns are used for receiving purposes. Moreover, a magnetic field sensor 30 can be used for receiving or detecting magnetic field H. The receiver can comprise the magnetic field sensor 30 as well as the coil 26 or 29. The magnetic field sensor 30 can be a sensor of the fluxgate type or the like. The receiver 24 can preferably receive or take up the time-varying magnetic field H from electrode device 1, preferably comprising or corresponding to the signal S, and/or the characteristic of the resonant circuit RC, and/or the required heart information, via a separate receiving coil (not shown) and/or magnetic filed sen- sor 30, and/or via the (common) coil 29, in particular so that the generation of electrical impulses P by the electrode device 1 can be controlled using signal S and/or the characteristic of the resonant circuit RC. For example, reference is also made here to US 5,411,535 A. Additional electrodes or sensors (not shown) can also be connected directly to the control device 28 or the receiver 24.
Control unit 31 can be adapted to verify or characterize the contact of the electrodes 2 of the electrode device 1 to the surrounding area 5 by receiving energy from the electrode device 1 comprising information or corresponding to the characteristic of the resonant circuit RC, and by analyzing the energy. Alterna- tively or additionally, control unit 31 further is adapted to identify a malfunction, in particular of a heart, by analyzing the signal S.
Control unit 31 preferably further is adapted for transmitting energy to the at least one implantable electrode device 1 in a wireless manner by means of the time-varying magnetic field H.
Control unit 31 further can be adapted for receiving energy from, in particular returned by, the at least one electrode device 1 exclusively in a wireless manner by means of time-varying magnetic field H, in particular using transmit coil 25, re- ceive coil 26, and/or a magnetic field sensor 27, 30, in particular a magnetometer.
Transmitting Signal S An preferably electrical signal S, in particular an intracardiac ECG, EEG and/or EMG signal, is preferably automatically sensed from the surrounding area 5 (tissue) by the implantable and/or implanted electrode device 1. The electrode device 1 converts the signal S into a corresponding time-varying magnetic field H as already described in detail. This signal S is transmitted to the receiver 24 in a wireless manner and the receiver 24, in particular the associated coil 26 and/or 29, preferably converts the signal S into an electrical signal S.
The receiver 24 can receive and, preferably, analyze the signal S, the characteristic of the resonant circuit, and/or the time varying magnetic field H sent by electrode device 1. Preferably, the signal S is received by means of coil 29 and/or by means of the magnetic field sensor 30 and/or internal magnetic field sensor 27.
The incoming signal S, characteristic of the resonant circuit RC and/or a corresponding signal, current or voltage can be amplified and/or analyzed. A data output and/or a display for delivery of the signal S, the analyzed signal S or the like can be provided (not shown). It is particularly preferred that specific values or timings corresponding to the electrical activity of the heart 5 can be analyzed and, preferably, provided to the control device 28.
Triggering Electrical Impulse P
If a stimulation function is intended, the control device 28 can trigger the electrode device 1 in a wireless manner by means of the time-varying magnetic field H for generating and/or delivering at least one electrical impulse P.
It is particularly preferred that the triggering is synchronized by or to the signal S and/or the characteristic of the resonant circuit RC sent by the electrode device 1. The received signal S and/or the characteristic of the resonant circuit RC preferably is converted to an electrical signal S by the receiver 2 and/or coil 29 and/or magnetic field sensor 27, 30. According to one aspect, the incoming signal S is analyzed, in particular with analysis means 48 and/or compared to a predefined value or range and an action is initiated by reaching or passing it.
Multi-Site Stimulation
Preferably, the arrangement A comprises different electrode devices 1 placed in some distance, in particular in a distance greater than 1 cm, preferably greater than 2 cm and/or less than 20 cm, preferably less than 15 cm. It is particularly preferred that at least one of the electrode devices 1 comprises a delay means for generating a delay between reception of the energy and the generation of at least one of the electrical impulses as already explained in detail. Thus, different electrode devices 1 can generate electrical impulses P with a delay between a first electrical impulse P generated by the first electrode device 1 and a second electrical impulse P generated by the second electrode device 1 which preferably comprises the delay means in this example.
Alternatively or additionally, different electrode devices 1 can be controlled, triggered and/or activated to deliver electrical impulses P, to sense signal S and/or to transmit the characteristic of the resonant circuit RC independently, in particular by means of time-varying magnetic field H of different transmission characteristics, in particular different frequencies and/or polarities. Thus, a common, additive stimulation can be adapted to the natural behavior of an object to be stimulated.
For example, the heart can be stimulated and/or sensed at a first position and, after a short delay, at a second position, preferably according to its typical or natural activation and/or stimulation. Therefore, the second electrode device 1 may comprise a reed relay as delay means that can block the delivery and/or generation of the electrical impulse for the particular time span until a minimum field strength for triggering is exceeded (delay means / protection means).
In a stimulation system with more than two electrode devices 1 , it is particularly preferred that all electrode devices 1 or at least one less than the number of electrode devices 1 actually used comprise delay means, in particular (micro-) reed relays 14. Then, different electrode devices 1 can be triggered independently, in particular if, as preferred, the different reed relays of different electrode devices 3 comprising different thresholds, i.e. different minimum magnetic field strengths for triggering. Alternatively or additionally, different frequencies or polarities of the time-varying magnetic field H can be used for addressing, selecting and/or controlling different electrode devices 1. According to the example shown in Fig. 9, a plurality of electrode devices 1 can be used which, in particular, can be controlled and/or supplied with energy by a common control device 28. Particular advantages of the invention reside in the possibility that the wireless electrode device 1 can be implanted in more suitable regions for sensing and/or stimulation, in particular, of the heart muscle, than is possible with wire-bound electrodes. Moreover, a plurality of electrode devices 1 can be implanted at different locations whereby improved sensing and/or stimulation and, in particular, better cardiac dynamics can be achieved. The electrode devices 1 can then be implanted at different locations, for example.
As a result, if different minimum field strengths are used for the electrode devices 1 , different desired phase shifts, energy differences or the like of the electrical impulses P delivered by the individual electrode devices 1 can be achieved. In particular, the delay means can be used for synchronizing the electrode device 1 additionally or alternatively.
Charging the Control Device
Figure 12 shows another embodiment of the proposed arrangement A comprising the control device 28, the electrode device 1 and an external charging device 35 in a schematic diagram similar to a block diagram. Charging of implanted receiver 24, control unit 31 and/or analysis means 48 can be carried out mutatis mutandis.
In this embodiment, a plurality of short magnetic field pulses can be generated as a sequence by the control device 28 during the switch-on time of the magnetic field H, i.e. during the switch-on phases. In particular, it is thus achieved that the coil core 21 always changes its magnetization far below the saturation state. Thus, a minimum energy consumption can be achieved.
In the example shown in Fig. 12, bipolar magnetic field pulses are preferably generated by means of a power amplifier, in particular a bridge of switching transistors Ml to M4 (e.g. MOSFETS, also in complementary design) or other switching semiconductor components. Also indicated in Fig. 12 are the coil 29, a control and the energy storage device or battery 32 of the control device 2. The control can, for example, comprise one or two signal generators V3 and V4. Preferably connected in parallel to the battery 32 is a smoothing capacitor 37. In addition, separating electronics 38 such as a switch or the like can be provided, in particular for deactivating control device 28 by disconnecting battery 32.
The control device 28 or its coil 29 is preferably configured such that the control device 28 or its battery 32 can be inductively charged in the implanted state, in particular via the coil 29 or a different receiving means. For generating the required magnetic or electromagnetic field during charging, the charging device 35 can be equipped with a suitable coil 39 and a corresponding power supply, in particular an alternating current supply 40. Contact Verification and Positioning
In the following, verifying and/or characterizing the contact of at least one electrode 2 of the electrode device 1 to the surrounding area as well as a method for optimized positioning is described referring to the embodiment shown in Fig. 13, showing an arrangement A, in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device 1.
It has to be pointed out that any of the components discussed referring to the preceding embodiments, in particular of Fig. 1 and 2, can be used in the present em- bodiment, and vice versa. In particular, the supervisory component 15, switch 10, switch 13, switch 14, amplifier 6 and/or core 20 can be applied to the embodiment of Fig. 13 as well. Additional resonance means RM, switches 11 and/or 12 as well as capacitors 45 and/or 47 can be applied to the embodiment of Fig. 1 or Fig. 2 as well.
Electrode device 1 of Fig. 13 can be adapted or perform for any of the preceding aspects and/or the same reference numerals are used for same parts or parts of the same type and the same or similar features, advantages or properties can be achieved even without a repeated description. Resonance Means RM
The electrode device 1 of Fig. 13 comprises a resonance means RM preferably associated to the electrodes 2 for forming a resonant circuit RC with the sur- rounding area 5 via the electrodes 2.
The resonance means RM preferably comprises transceiver 4 of the electrode device 1, in particular coil 21. In particular, transceiver 4 further comprises intrinsic capacities, e.g., inter-winding capacities 44, additional capacitor 45, and/or losses, e.g., due to the finite conductivity of coil 21. Thus, the resonance means RM can be formed by or with transceiver 4. Optionally, additional elements, in particular the additional capacitor 45, can be part of the resonance means RM. In the example shown, coil 21 is used as resonance means RM or part of it and as transceiver 4 for sending the characteristic of the resonant circuit RC, the signal S, a corresponding value and/or for receiving energy by means of time-varying magnetic field H. Alternatively or additionally, resonance means RM can be realized separately, in particular by means of a separate coil 46 and/or capacitor 47, preferably connected to the electrodes 2. In particular, a separate transceiver for receiving energy and/or for sending signal S and/or the characteristic of the resonant circuit can be provided.
Resonant Circuit RC
The resonance means RM particularly preferably can be connected to the electrodes 2 such that the resonant circuit RC with the surrounding area 5 can be realized. It can be sufficient to realize this resonant circuit RC on demand and/or from time to time only. For example, switches 12 can be provided for connecting the resonance means RM directly or indirectly to the electrodes 2 and, preferably, via the electrodes 2 to the surrounding area 5. It is further preferred that the surrounding area 5 is at least substantially electrically conducting and/or in contact to at least two different of the electrodes 2. Thus, the electrodes 2 are preferably connected via the surrounding area 5, in particular wherein the surrounding area 5 provides a more or less resistive behavior. For example, the surrounding area 5 connecting the electrodes 2 provides a resistance of more than 10 Ω, preferably more than 100 Ω, in particular more than 1.000 Ω, and/or less than 100 kQ, preferably less than 10 kQ, across the elec- trodes 2 unless no failure occurs. The resistance provided by the surrounding area 5 preferably forms part of resonant circuit RC and, in particular, affects a characteristic of the resonant RC, in particular losses, a damping factor and/or a resonance frequency of the resonant circuit RC. If the properties of the electrical contact between the electrodes 2 and the surrounding area 5 varies, this has an influence on the characteristics of the resonant circuit RC. In particular, if a contact failure causes an increasing or decreasing resistance between at least one of the electrodes 2 and the surrounding area 5, the characteristics of the resonant circuit RC will be subject of a change as well. Ac- cording to the present invention, monitoring the characteristic of the resonant circuit RC can be used for verifying proper contact of the electrodes 2 to the surrounding area 5 and/or to detect changes in the contact properties which can act as an indicator of malfunction, aging, or a different failure. Further, the electrical characteristics of the surrounding area 5 can be determined.
For characterizing the contact of the electrodes 2 of the implantable electrode device 1 to the surrounding area 5, it is preferred that the resonance means RM of the electrode device 1 is used to form the resonant circuit RC with the surrounding area 5 via at least two electrodes 2, preferably wherein the characteris- tic of the resonant circuit RC indicates the electrical contact of the electrodes 2 to the surrounding area 5, and/or the electrical resistance across the electrodes 2.
The resonant circuit RC can comprise at least one coil 29, 46 and an associated capacitor, in particular a self-capacity 44 of coil 29, 46, stray capacities due to leads, and/or an optional capacitor 45, 47.
For determining the characteristic of the resonant circuit RC it is preferred that the resonance means RM is directly or indirectly connected to the electrodes 2, in particular such that the contact of the electrodes 2 with the surrounding area 5 has an influence on the characteristic of the resonant circuit RC. One or more switches 12 can be used to directly connect resonance means RM to one or more of the electrodes 2.
Resonance means RM permanently can be connected to rectifier 7. For determin- ing the characteristic of the resonant circuit RC, rectifier 7 is controlled differently than discussed referring to Fig. 5 and 6. In particular, switches 8A and 8D can be continuously open and/or switches 8B and 8C are continuously closed connecting node Kl to node K4 and node K2 to K3, or vice versa. This is an example for using rectifier 7 for directly connecting resonance means RM to energy buffer 9. Thus, energy buffer 9 can become part of resonant circuit RC.
Energy buffer 9 can be used to replace optional capacitor 45 leading to a cheaper and less complex solution. Further, energy buffer 9 and/or rectifier 7 can connect resonance means RM to the electrodes 2, preferably realizing the resonant circuit RC with the surrounding area 5. Optionally, parts of energy buffer 9 can be deactivated in order to achieve a sufficiently high resonance frequency of resonant circuit RC. Further, the resonance frequency can be controlled thereby.
According to a further aspect, a separate resonance means RM for forming reso- nant circuit RC and/or determining the characteristic of the resonant circuit RC can be realized using coil 46 and/or capacitor 47. Preferably, coil 46 and capacitor 47 are forming a resonant circuit RC with the surrounding area 5. Coil 46 and/or capacitor 47 can be configured such that a resonance frequency of corresponding resonant circuit RC results, which is different to that the transceiver 4 is sensitive or selective to for supplying electrode device 1 with energy and/or to send signal S. Thus, determining the characteristic of the resonant circuit RC and either supplying the electrode device 1 with energy or sending signal S can be activated separately by choosing different transmission characteristics, preferably frequencies and/or polarities, in particular by generating and/or providing the electrode device with time-varying magnetic field H of different frequencies and/or polarities.
The resonant circuit RC preferably is provided with energy such that an electrical oscillation of the resonant circuit RC is caused. Energy can be provided internal- ly, in particular by energy buffer 9, or externally using a wire connection. In the present embodiment, energy can be provided to the resonance means RM by means of the time-varying magnetic field H for energizing the resonant circuit RC. Particularly preferably, the electrode device 1, in particular the resonance means RM, is provided with energy exclusively in a wireless manner by means of time-varying magnetic field H. In particular, time-varying magnetic field H is provided to transceiver 4, in particular coil 21 and/or coil 46, inducing a current to resonance means RM. This current energizes the resonant circuit RC, preferably causing a decrying oscillation. The frequency and/or decay behavior or a corresponding value can be used for determining or as the characteristic of the reso- nant circuit RC.
Energizing the resonant circuit RC preferably results in oscillation, in particular in an oscillating current, which preferably keeps oscillating after providing energy has been stopped. In particular, this oscillation decays after stopping the ener- gy transfer to the electrode device 1 depending on and/or indicating losses of the resonant circuit RC. The oscillating current preferably generates a corresponding time-varying magnetic field H after energy transfer has been stopped, in particular by the oscillating current flowing through the transceiver 4, e.g. coil 21 and/or coil 42. Since the oscillating current, in particular causing the corresponding os- cillating or alternating time-varying magnetic field H, preferably remains and/or is detected after stopping the energy transfer, this is referred to as "post-ringing".
Sourcing the electrode device 1 can cover providing energy to the resonant circuit RC. This allows for analyzing the characteristic of the resonant circuit with- out an additional sourcing procedure and/or after energy transfer for sourcing the electrode device 1 and/or for generating the electrical impulse P has been stopped. Alternatively or additionally, energy can be provided separately the resonant circuit RC, with a different transmission characteristic, and/or by the electrode device 1, its energy storing means 9 or the like.
The characteristic of the resonant circuit RC can be analyzed and/or stored inside electrode device 1 or can be transmitted using a wire connection. Particularly preferably, the characteristic of the resonant circuit RC is sent in a wireless manner by means of time-varying magnetic field H. In particular, energizing resonant circuit RC causes an oscillating current through resonance means RM, in particu- lar through coil 21 and/or coil 46, generating a time-varying magnetic field H corresponding to this current. Thus, the energized resonant circuit RC leads to generation of time-varying magnetic field H corresponding to the characteristic of the resonant circuit RC.
According to one aspect, the contact of the electrodes 2 with the surrounding area influences the characteristic of the resonant circuit RC. The characteristic of the resonant circuit RC can be determined, indicating the electrical contact of the electrodes 2 to the surrounding area 5 and/or the electrical characteristic of the surrounding area 5, in particular the resistance across the electrodes 2. The characteristic of the resonant circuit RC can be determined by observing, in particular receiving, the post ringing, corresponding current and/or time-varying magnetic field H which preferably automatically results after energy has been provided to the resonant circuit RC.
According to a further aspect, the contact of the electrodes 2 with the surrounding area optionally can, but does not need to influence the characteristic of the resonant circuit RC. The post ringing, corresponding current and/or time-varying magnetic field H which, preferably automatically, results after energy has been provided to the resonant circuit RC can be used for determining a distance, coupling factor or respective change, in particular for optimized placement, which will be discussed later in further detail.
In the example shown, coil 21 and/or coil 46 can be used for sending the charac- teristic of the resonant circuit RC and/or the post ringing. Alternatively or additionally, an antenna or different type of transceiver 4 can be used as well.
It is preferred that the resonance means RM comprises or is formed by transceiver 4, in particular a coil 21, 46 and/or an antenna, preferably wherein the trans- ceiver 4 is adapted for sending the characteristic of the resonant circuit RC and/or signal S in a wireless manner by means of the time-varying magnetic field H and/or wherein the transceiver 4 is configured to be supplied with energy exclusively in a wireless manner by means of the time-varying magnetic field H. This allows for omitting any cable connection which might cause failures. A resonance frequency of resonant circuit RC can be influenced and/or controlled by modifying the inductivity of coil 29, 46 and/or of the associated capacity. The resonant circuit RC preferably is configured to have a resonance frequency of more than 10 Hz, preferably more than 100 Hz, in particular more than 1.000 Hz, and/or less than 1000 MHz, preferably less than 10 MHz. Particularly preferably, the resonant circuit RC has a resonance frequency inside of one of the ISM-bands as defined by ITU-R, RR Nos. 5.138 and 5.150, in particular from 6.765 to 6.795 MHz, from 13.553 to 13.567 MHz, from 26,975 to 27,283 MHz, from 40.66 to 40.7 MHz, from 433.05 to 434.79 MHz, 902 to 928 MHz, and/or 2,4 to 2,56 Hz.
In a further preferred alternative, in electrode device 1 , a first transceiver 4, in particular coil 21 , can be used for providing the electrode device 1 with energy for delivery of electrical impulse P, and a second transceiver 4, in particular coil 46, can be used for sending signal S and/or for forming the resonant circuit RC, preferably, with the surrounding area 5 via the electrodes 2. This in particular allows coil 21 to be optimized for receiving energy and/or coil 46 for transmitting signal S and/or the characteristic of the resonant circuit RC, in particular the post-ringing signal.
Analysis Means - Post Ringing Aspects
Returning to Fig. 9, arrangement A preferably comprises at least one analysis means 48, the analysis means 48 being preferably adapted for receiving the sig- nal S and/or for receiving energy of, in particular returned by, the electrode device 1. The returned energy preferably comprises or corresponds to the characteristic of the resonant circuit RC. The energy transmitted from the electrode device 1 and received by the analysis means 48 can be transmitted wired, by means of sound, light, electricity, pressure or the like and, particularly preferably, by time- varying magnetic field H and/or the magnetic component of a electromagnetic field, which preferably is used in detection.
In particular, the transceiver 4 of the electrode device 1, in response to the reception of energy, automatically generates the time-varying magnetic field H corre- sponding to the characteristic of the resonant circuit RC, in particular using a current oscillating in the resonant circuit RC. This in particular can achieved by forming the resonant circuit RC with the transceiver 4.
According to one aspect, a value corresponding to the decay behavior or differ- ent characteristic of the resonant circuit RC is determined by analysis means 48 and, preferably, is compared to a specific, predefined and/or previous value or range. In particular when a threshold is passed, an error can be detected by analysis means 48 and, preferably, this error is signaled by analysis means 48 and/or an information for handling is provided, in particular wherein this information is used for adapting energy transfer to electrode device 1. Alternatively or additionally, this information can be used for increasing or decreasing the strength of electrical impulse P delivered by electrode device 1.
Analysis means 48 alternatively or additionally can detect the frequency of the signal provided to it, in particular the frequency of the post-ringing and/or a resonance frequency of resonant circuit RC. The resonance frequency preferably depends on the amount of damping caused by the surrounding area 5 and/or the contact between the electrodes 2 and the surrounding area 5. Even though this dependency might not be that strong compared to a quality factor or damping factor of resonant circuit RC, this characteristic of resonant circuit RC provides the advantage that the absolute value does not depend on a coupling factor and/or distance between electrode device 1 and analysis means 48, receiver 24, control device 28, and/or control unit 31. Thus, detecting a variation in frequency preferably is used for an indication of the electrical contact of the electrodes 2 to the surrounding area 5, an electrical characteristic of the surrounding area 5 and/or of the electrical resistance across the electrodes 2. The absolute frequency and/or a frequency shift can be used for verifying the contact of the electrodes 2 with the surrounding area 5. The absolute frequency, e.g., can be used for comparison to a predefined value or range. The relative value does not demand for a prede- fined value, but needs previous result for comparison, which preferably is controlled to correspond to an acceptable contact by external means.
Analysis means 48 can determine a decay behavior and/or a frequency shift. Thus, two independent indicators can used for detecting a problem and/or error. These indicators can be used for verifying the electrical contact of the electrodes 2 with the surrounding area 5 as well as for determining and/or verifying and/or achieving a proper coupling of electrode device 1 to analysis means 48 and/or receiver 24 and/or control device 28 and/or control unit 31. Both the frequency and the decay behavior can be analyzed and/or combined for a better or more reliable result.
In a particular embodiment, the characteristic of resonant circuit RC is provided by resonance means RM of electrode device 1 via time-varying electromagnetic field H which is received by control unit 31 and provided to analysis means 48. Alternatively or additionally, analysis means 48 can comprise a receiving means, in particular a coil and/or magnetic field sensor, for receiving the characteristic of resonant circuit RC via time-varying magnetic field H.
A signal corresponding to post-ringing of resonant circuit RC preferably is provided to analysis means 48. The post-ringing preferably comprises a decay behavior and/or a frequency of resonant circuit RC forming characteristics of resonant circuits RC. However, different characteristics may exist.
Analysis means 48 preferably is adapted for determining the decay behavior, in particular by measuring a corresponding decay of an amplitude of a signal provided to analysis means 48 corresponding to the characteristic of resonant circuit RC. This can be used for determining a damping factor, quality factor or the like.
Analysis means can deduce a behavior of the electrical contact of the electrodes 2 to the surrounding area 5, an electrical characteristic of the surrounding area 5, and/or the electrical resistance across the electrodes 2. Further, analysis means 48 preferably verifies a proper contact and/or determines and/or signals any failure or problem, in particular if identifying that the contact resistance is increased.
Contact Verification
In the following, an example for operating with the resonant circuit RC for contact verification is given. However, different applications for using the post ringing of the resonant circuit may exist. A short magnetic field pulse can be generated, preferably time-varying magnetic field H activated over a time span, preferably of more than 1 μ8, in particular more than 1 ms, and/or less than 1 s, arrives at the electrode device 1, energizing and preferably causing oscillations in the resonant circuit RC.
The oscillations caused by energizing the resonance means RM and/or resonant circuit RC continue after energizing has been stopped, in particular after the time-varying magnetic field H providing energy to electrode device 1 has been deactivated, and is damped due to losses of the resonant circuit RC.
The contact of the electrodes 2 to the surrounding area 5, a capacitive behavior and/or the resistance across the electrodes 2 caused by the surrounding area 5 preferably have an impact on these losses or further characteristics of the resonant circuit RC.
The oscillations can be detected directly at the resonant circuit RC, in particular at coil 29 and/or coil 46. More preferably, a separate receiver, in particular coil 29 and/or magnetic field sensor 27, 30 can be used. By monitoring and/or analyzing a signal corresponding to the oscillation, a status of the electrode device 1 can be determined.
The arrangement A can comprise analysis means 48 for analyzing the characteristic of resonant circuit RC. Analysis means 48 can be part of electrode device 1 and/or realized separately, in particular implanted as well. Electrode device 1 can comprise one or more analysis means 48, in particular as depicted in Fig. 13 using dashed lines. The analysis means 48 in Fig. 13 preferably is coupled to resonant circuit RC.
Particularly preferably, analysis means 48 forms part of control unit 31 (cf. Fig. 9 and 10). Analysis means 48 can be realized and/or placed separately as well, which is depicted in Fig. 9 using dashed lines. In particular, receiver 24 can comprise analysis means 48.
Receiver 24 and/or analysis means 48 preferably is or are adapted to be deac- tivated when the control device 28 transmits energy to the electrode device 1 for protecting their input against overvoltage, in particular for protecting amplifier 33. Alternatively or additionally, the input of receiver 24 can be protected by connecting Zener diodes, by disconnecting using a switch, semiconductor switch or the like, preferably for disconnecting the transceiver, in particular coil 29, from the input of receiver 24 and/or analysis means 48.
If analysis means 48 is realized externally, in particular forming part of control unit 31, a characteristic of the resonant circuit RC can be provided to analysis means 48 using a wire connection. However, providing the characteristic of resonant circuit RC via the time-varying magnetic field H is preferred. The analysis means 48 can be adapted to receiving the characteristic of the resonant circuit RC in a wireless manner, in particular by means of time-varying magnetic field H.
The analysis means 48 can be configured for determining a characteristic of the resonant circuit RC indicating the electrical contact of the electrodes 2 to the surrounding area 5 and/or the electrical characteristic of the surrounding area 5, in particular an electrical resistance across the electrodes 2. Analysis means 48, additionally or alternatively, can be used for analyzing sensed signal S as described above.
The resonance means RM of electrode device 1 can be used for forming the resonant circuit RC with the surrounding area 5 via the electrodes 2, wherein the resonance means RM simultaneously can be used for supplying the electrode device 1 and/or for generating an electrical impulse P, preferably for stimulation purposes.
In particular, a permanent connection of the resonance means RM to the electrodes 2 can be provided, resonant circuit RC is formed with the surrounding area 5 via the electrodes 2 and, thus, each of the additional components of electrode device 1 discussed previously are optional. However, more complex solutions with further aspects are preferred due to more efficient stimulation, sensing, and/or transmission. According to one aspect of the present invention, a varying decay behavior is detected. In particular, a reduced damping factor can be determined if the decay of the post ringing is reduced, or vice versa. A reduced damping factor can be interpreted as to be caused by an increased contact resistance. This can be handled and/or signaled, in particular as soon as a threshold is reached and/or a range is passed.
According to a further aspect of the present invention, a frequency shift is detected. In particular, an increased frequency is associated with a reduced contact ca- pacitance and/or a decreased frequency is associated with an increased contact capacitance. Alternatively or additionally, an increased frequency is associated with reduced losses of the resonant circuit and/or an increased contact resistance and/or a decreased frequency is associated with increased losses of the resonant circuit and/or a decreased contact resistance. This can be handled and/or sig- naled, in particular as soon as a threshold is reached and/or a range is passed.
According to a further aspect of the present invention, a frequency shift as well as a variation in decay is detected and both of them can be used for more reliably determining a characteristic or problem of the contact, for instance by perform- ing a cross-check for checking plausibility of the detection results. Further, the a characteristic of the contact can be deducted by each of them and the results can be cross-checked, combined and/or an average can be formed for achieving an increased reliability and/or accuracy. An increased contact resistance can be associated with a problem. Further, a reduced damping factor and an increased fre- quency occurring simultaneously can be associated with a more reliable indication for a problem. Thus, a problem can be detected with higher thresholds for one of the damping factor and the frequency and/or with lower thresholds for each of them for occurring simultaneously. A problem can be handled and/or signaled, in particular as soon as a threshold is reached and/or a range is passed.
Compensating for Contact Problem
Electrode device 1 can be sourced with energy adaptively, preferably depending on the characteristic of the resonant circuit RC. Alternatively or additionally, the electrode device 1 can adapt and/or can be informed to adapt the amount of ener- gy to be delivered for generating electrical impulse P. In particular, a preset value, parameter or the like is determined with the characteristic of the resonant circuit for compensating for a variation of the contact characteristic of the contact between the electrode device 1 and the surrounding area 5.
The contact information and/or the characteristic of the resonant circuit RC can be used for adaptively controlling the amount of energy applied to the electrode device 1. In particular, e.g., after detecting an increased contact resistance of the electrode(s) 2 to the surrounding area 5, the energy provided to the electrode device 1, in particular for delivering electrical impulse P, and/or the energy provided by means of the electrical impulse P can be adapted or increased, which can compensate for possible influences on the stimulation efficiency of electrode device 1. This adaption method can be supported by control unit 31 and/or analysis means 48 which preferably receives the characteristic of the resonant circuit RC from the electrode device 1 and adapts the amount of energy provided to the electrode device 1 and/or the amount of energy provided with one electrical impulse P considering the characteristic of resonant circuit RC.
Position-Finding Method
The absolute strength of the signal, in particular the strength or amplitude of the time-varying magnetic field H received by analysis means 48 from the electrode device 1 , can be used as an indication for coupling or a coupling factor and, thus, for a placement, direction and/or distance of analysis means 48 and electrode device 1 to each other.
If the strength or amplitude of time-varying magnetic field H provided by electrode device 1 is not as high as expected, in particular after comparison to a reference value, range or the like, a coupling problem can be determined. Further, coupling can be optimized by modifying positions, in particular relative positions, of parts of arrangement A. In particular, analysis means 48 and/or control unit 31 can be moved and/or rotated. Afterwards, the strength of time- varying magnetic field H provided by electrode device 1 can be estimated once more by analysis means 48. If the strength of the incoming signal and/or time-varying magnetic field H is increased, the movement can be stopped and/or repeated. If the strength of the signal and/or time-varying magnetic field H is decreased, the modification of arrangement A can be undone and/or a different movement can be chosen.
Particularly preferably, the coupling of a transceiver of the analysis means 48, in particular coil 29, to the transceiver 4 of the electrode device 1 is determined and/or optimized. However, in the present embodiment the transceiver of or associated with the analysis means 48 is considered to form a constructional unit with further components of the analysis means 48, thus, the position of the analysis means 48 corresponds to the position of its transceiver. Further, the transceiver 4 of the electrode device 1 preferably is part of a constructional unit formed by the electrode device 1 and, thus, the position of its transceiver 4 corresponds to the position of the electrode device 1. However, if separate and/or remote transceivers are used either at one or both sides, these preferably are relevant for determining the coupling and further preferably are considered to form the position of the associated electrode device 1 and/or analysis means 48.
Thus, repeated determination of the characteristics of the resonant circuit RC, in particular of a resonance frequency, decay behavior, quality factor and/or of an absolute value of the strength and/or amplitude of a signal and/or time-varying magnetic field H corresponding to the characteristic of resonant circuit RC, can be used either for characterizing and/or verifying contact of the electrodes 2 with the surrounding area 5 and/or for optimizing coupling of the electrode device 1 with receiver 24, control device 28, control unit 31, and/or analysis means 48.
This coupling optimization method can be used independently as well, even if the resonant circuit RC is formed independently of the electrodes 2 and the surrounding area 5. In a particular embodiment, transceiver 4 of electrode device 1, in particular coil 21, is used to form resonant circuit RC. In particular, one or more additional capacitors 44, and/or configuring rectifier 7 to having a continuous connection to energy buffer 9 or parts of energy buffer 9 can be used for forming resonant circuit RC with or without involving electrodes 2 and/or the surrounding area 5. The characteristics of resonant circuit RC can be well known in advance, in particular prior to implanting electrode device 1. For optimizing arrangement A, in particular for optimizing a position and/or orientation of electrode device 1 and/or control device 28, control unit 31, receiver 24 or a corresponding trans- ceiver, in particular coil 29, coil 26, and/or coil 25, energy can be provided to electrode device 1 and resulting post-ringing provided by the inventive resonant circuit RC can be analyzed.
Repeatedly energizing resonant circuit RC and analyzing the resulting post- ringing, in particular the strength of time-varying magnetic field H detected after deactivation of energy transfer to electrode device 1, can be used for iterative optimizing coupling, orientation, and/or positioning of components of arrangement A. Thus, coupling can be optimized with only minor or even not any modification of electrode device 1 by providing an analysis means 48 that is capable of interpretation of post-ringing or a corresponding signal, preferably comparing a strength of time-varying magnetic field H received or of a corresponding signal, comparing it to a reference value, which can be a value of a recent measurement, and/or indicating whether the coupling is increased, decreased, and/or sufficient considering a predefined value or range.
The coupling, the distance, the characteristic of the resonant circuit RC, the characteristic of the contact of the electrode(s) 2 and/or further results provided the analysis means 48 can be signaled to (external) means, e.g., gauge, display, indicator or the like for placement. In particular, if the electrode device 1 already is implanted and the analysis means 48, control unit 31, receiver 24 and/or control device 28 is to be implanted or placed at the body as well, the coupling or distance can be presented. Further, a placement and/or orientation of any of the aforementioned components can be controlled and/or verified by the inventive method mutatis mutandis.
Multiple Resonant Circuits
Resonance means RM and/or resonant circuits RC of different electrode devices preferably can be selected using different frequencies and/or polarities of the time-varying magnetic field H. If more than electrode device 1 is available in ar- rangement A, resonance means RM of different resonance frequencies can be used for different ones of the electrode devices 1. Preferably, the resonance means RM and/or corresponding resonant circuits RC receive energy at the individual resonance frequency much more efficiently than at different frequencies. Thus, a selective energy transfer to resonance means RM of different ones of electrode devices 1 can be provided. Thus, the contact of the electrodes 2 of different ones of the electrode devices 1 can be analyzed and/or verified independently.
It is preferred that control unit 31 is adapted to generate the time- varying magnetic field H with different transmission characteristics at least essentially corresponding to characteristics of resonance means RM and/or resonant circuits RC of different ones of the electrode devices 1. Thus, the control unit 31 can induce post-ringing in different ones of the electrode devices 1 selectively. Alternatively or additionally, resonance means RM and/or resonant circuits RC of different ones of the electrode devices 1 are configured to provide different resonance frequencies, which preferably leads to post-ringing at least basically at those frequencies. This allows for characterizing and/or verifying contacts of electrodes 2 and/or determining an electrical characteristic of surrounding areas 5 of different ones of the electrode devices 1 simultaneously, in particular by observing and/or determining the decay behavior of the post-ringing at those different frequencies.
The electrode device 1 can comprise at least two independent transceivers 4, in particular coil 21 and coil 46. Further, it is preferred that these transceivers 4 are selective to time-varying magnetic field H of different transmission characteristics, in particular frequencies or polarities. This allows for selective activating sensing signal S and/or delivering electrical impulse P on the one hand, and sourcing resonant circuit RC on the other hand, in particular for verifying the contact of electrodes 2 with the surrounding area 5. Further, optional switches 11 and/or optional switches 12 can be omitted if separate transceivers 4 are used for sending signal S and/or the characteristic of the resonant circuit RC and/or for receiving energy.
Summary One aspect of the present invention, relates to an arrangement A, in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one, preferably two, implantable electrode devices 1, the electrode device 1 providing a resonance means RM preferably adapted for receiving energy by means of the time-varying magnetic field H.
According to a further aspect, the resonance means preferably forms part of resonant circuit RC configured to oscillate if provided with energy. According to a further aspect, the oscillation, in particular after stopping or as soon as energy transmission to the electrode device has been stopped, preferably is used for generating a time-varying magnetic field H, in particular electromagnetic field, corresponding to characteristics of resonant circuit RC. According to a further aspect, the arrangement A preferably further provides analysis means 48 adapted for receiving the time-varying magnetic field H, in particular electromagnetic field, caused by the oscillation of the resonant circuit RC. In particular, the magnetic field H and/or a magnetic part of the electromagnetic field can be detected by the induction voltage in a detecting coil or by means of a sensitive magnetic field detector.
According to a further aspect, the magnetic field H can be used for determining an absolute strength of this time-varying magnetic field and/or a corresponding value at the receiving position. Alternatively or additionally, magnetic field H can be used for determining a characteristic of the resonant circuit RC, in particular for verifying a status of the electrode device, which does not absolutely necessary must comprise an external electrode for some aspects of the present invention. According to a further aspect of the present invention, that can be realized independently as well, analysis means 48 is used to receive and determine the characteristic of the resonant circuit RC, wherein the resonant circuit RC is formed by resonance means RM configured for receiving energy and for transmitting time- varying magnetic field H. According to a further aspect, the resonance means RM forms a resonant circuit RC inside the implantable electrode device 1 or part of it, for determining a relative position, distance, and/or orientation of the means 48 to the electrode device 1.
According to a further aspect, the relative position, distance, and/or orientation of the means 48 to the electrode device 1 is used for iteratively modifying positions and/or orientations of means 48 and electrode device 1 to each other for optimizing a coupling between means 48 and electrode device 1.
According to a further aspect, that can be realized independently as well, energy is provided to electrode device 1 by means of time-varying magnetic field H, a different component of time-varying magnetic field H and/or time-varying magnetic field H at a different time is generated by electrode device 1 using the ener- gy provided to it.
According to a further aspect, the time-varying magnetic field H is generated by means of a resonant circuit RC of electrode device 1 is used for determining the distance between the electrode device 1 and an analysis means 48 by determining the absolute strength of the time-varying magnetic field H generated by the electrode device 1 at the position of the analysis means 48.
A further aspect relates to, in particular repeatedly, modifying the position and/or orientation of the analysis means 48 to the electrode device 1 and observing a strength variation of the time-varying magnetic field H provided by the resonance means RM of electrode device 1, in particular for placement, implanting and/or assuring proper coupling during lifetime.
Preferably, the energy transmission to the electrode device 1 is stopped avoiding disturbance by the energy transmitting means, in particular control device 28 and/or the transceiver or coil associated therewith.
A postringing of the coil which sends energy to the electrode device 1, which could disturb the detection of the postringing of the elctrode device. A filter, in particular a low pass or bandpass filter and/or a means for limiting a rise time, can be provided, which preferably is associated with, in particular connected to, the transceiver of the control device 28, the analysis means 48 and/or the receiver 24. This allows for omitting disturbance and/or disruption of the postringing form the electrode device 1.
Alternatively or additionally, sending energy can be stopped avoiding a postringing on the sender site. Preferably, a current of the transceiver or coil of the control device 28 is stopped in a zero-crossing and/or if the current reaches zero. Thus, generation of harmonics or ringing can be avoided. This avoids disturb- ance of receiving the post-ringing form the electrode device 1, in particular of the corresponding time-varying magnetic field H. This simplifies and/or enhances the analysis of the characteristic of resonant circuit RC.
The postringing signal preferably is sent out by the electrode device 1, in particu- lar transceiver 4. The postringing signal preferably is detected by the receiver 24, the analysis means 48, the control unit 31 or different detection means. The postringing of the electrode device 1 preferably is recorded and/or fitted with a damped sinusoidal, preferably by means of a microcontroller, in particular embedded in receiver 24, the analysis means 48, the control unit 31, a separate transmitter unit and/or in a separate housing. This fitting can be used for obtaining, in particular both and/or separately, the resonance frequency and the damping factor, wherein the damping factor preferably is sensitive to and/or influenced by the real part of the impedance of the surrounding area 5, in particular impedance of the surrounding area 5 and/or tissue impedance.
According to a further aspect of the present invention, which can be realized independently as well, the amount of energy to be transmitted to the electrode device 1 is controlled depending on a coupling of to the electrode device 1 and/or a distance to the electrode device 1. In particular, the time span for transmitting energy to the electrode device 1 and/or the strength or amplitude of the time- varying magnetic field H used for transmitting energy to the electrode device 1 can be controlled depending on the distance and/or a coupling factor.
A strength, amplitude or corresponding value of the time-varying magnetic field H generated by the electrode device 1, preferably corresponding to the postring- ing and/or oscillating current of the resonant circuit RC, can be used for determining a coupling factor and/or distance, in particular relative distance. In particular, the receiver 24 detects the strength, the amplitude and/or the corresponding value, which can be used to determine and/or control the energy transfer to the electrode device 1. The coupling factor, distance or corresponding value preferably is used to adapt the amount and/or density of energy delivered to supply the electrode device 1. The control device 28 can use coupling factor, distance or corresponding value, a change or variation rate thereof for generating the time-varying magnetic field H for supplying the electrode device 1 depending thereon.
For supplying the electrode device 1, the time- varying magnetic field H can be generated, in particular by control device 28, which is stronger (higher density) and/or generated over a longer time span (longer duration) if the distance increases and/or the coupling factor to the electrode device 1 decreases. Alternatively or additionally, for supplying the electrode device 1, the time- vary ing magnetic field H can be generated, in particular by control device 28, which is weaken (lower density) and/or generated over a shorter time span (shorter duration) if the distance decreases and/or the coupling factor increases.
By controlling the duration and/or density of the time-varying magnetic field H for providing energy to the electrode device 1, the energy received by the electrode device 1 can be kept at least substantially constant, in particular with a variation less than 50 %, 30 % or 10 %, even if the coupling and/or distance to the electrode device 1, in particular of the electrode device 1 to the receiver 24, control device 28 and/or the transceiver or coil associated therewith, varies.
It is not absolutely necessary that the postringing is used to determine the distance, coupling or corresponding value. In a preferred alternative, switching of a bistable or soft magnetic element, strip, Wiegand wire or the like can be received remote of the electrode device 1 for determining the distance or coupling factor. In particular, an amplitude of a change in magnetic field strength and/or corresponding time-varying magnetic filed H is analyzed for determining the distance, coupling factor and/or corresponding value. Alternatively or additionally, the distance or coupling factor or corresponding value can be determined by analyz- ing the electrical impulse P, in particular a strength or amplitude thereof reaching receiver 24 or a different receiving means, which preferably comprises at least one electrode in contact with the surrounding area 5. Thus, a voltage or current amplitude can be used for determining the distance, coupling factor and/or corresponding value. Further different solutions may exist.
According to a further aspect of the present invention, which can be realized independently as well, the position of the electrode device 1 in its implanted state and/or an optimum position for the receiver 24 and/or control device 28 can be determined. The control device 28 and/or the receiver 24 can be moved, e.g. line- by-line, linear scanning, rotating, iterative or the like. The electrode device 1 preferably is provided with energy multiple times, preferably in time and/or location intervals.
The post ringing can be detected remote of the electrode device 1, preferably at the location from which the electrode device 1 is sourced. However the locations of the receiver 24, control device 28 or corresponding transceiver or coils do not need to be identical. In particular, only one of them needs to be moved. If the receiver 24 is moved, the energy received by the receiver 24 varies depending on the distance and/or coupling factor. If the control device 28 is moved, the energy transmitted by the electrode device 1 may vary. If both of them are moved, in particular in a similar manner, the variation will be stronger and, thus, can be detected more easily and/or accurately.
Thus, the amount or amplitude of the received energy can be used for determining the distance, the coupling factor or corresponding value, which in the following can be used to control the energy provided to the time-varying magnetic field H for supplying the electrode device 1 with energy and/or for keeping constant the amount and/or density of energy provided to the electrode device 1.
The distance, coupling factor, position of the electrode device 1 and/or the relative position of the electrode device 1 to the receiver 24 and/or control device 28 preferably is or are determined by receiving and analyzing the time-varying magnetic field H. However, different transmission methods can be used as well. For example, a sound or ultrasound signal, an electrical signal, an electromagnet- ic wave, an electrostatic field or the like can be provided by the electrode device 1 for determining the distance, coupling factor, position, a corresponding value and/or for sending a signal corresponding to the postringing or a different signal. According to a further aspect, the electrode device 1 is provided with energy and transmits energy corresponding to the postringing, wherein the energy transmission to and/or from the electrode device 1 can be carried out using the time- varying magnetic field H, a sound, ultrasound, electrical field, electromagnetic wave, light, each wireless or wired, wherein each transmission to and from the electrode device can be carried out either with the same or different transmission methods and/or media.
Individual features, aspects and elements of the individual embodiments and variants can be arbitrarily combined with one another or used in other stimulation systems or electrode devices.
Reference List
1 Electrode Device 38 Separating Electronics
2 Electrode 39 Coil
3 Housing 45 40 Supply
4 Transceiver 41 Body
5 Surrounding Area 42 Skin
6 Amplifier 43 Ribs
7 Rectifier 44 Capacitance
8A Semiconductor Switch 50 45 Resistance
8B Semiconductor Switch 46 Coil
8C Semiconductor Switch 47 Capacitor
8D Semiconductor Switch 48 Analysis Means
9 Energy Buffer 49 Cap
10 Switch 55 50 Electrode Module
11 Switch
12 Switch A Arrangement
13 Switch E Element
14 Switch H Magnetic Field
15 Supervisory Component 60 HI Minimum Field Strength
16 Pulse Forming Device H2 Minimum Field Strength
17 Housing I Inductive Element
18 Capacitor Kl to K8 Node
19 Resistor Ml Transistor
20 Core 65 M2 Transistor
21 Coil M3 Transistor
22 Core element M4 Transistor
23 System M5 MOSFET
24 Receiver M6 MOSFET
25 Transmit Coil 70 P Electrical Impulse
26 Receive Coil R Resistor
27 Magnetic Field Sensor RC Resonant Circuit
28 Control Device RM Resonance Means
29 Coil S Signal
30 Magnetic Field Sensor 75 VI Time Profile
31 Control Unit V2 Time Profile
32 Battery V3 Signal Generator
33 Amplifier V4 Signal Generator
34 Power Amplifier Z Zener Diode
35 Changing Device 80
36 Control
37 Smoothing Capacitor

Claims

Claims:
1. An arrangement (A), in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device (1), the electrode device (1) comprising a resonant circuit (RC) with a resonance means (RM) for forming a resonant circuit (RC) with the surrounding area (5) via the electrode (2) and/or for generating a time-varying magnetic field (H) corresponding to an oscillation of the resonant circuit (RC), wherein the arrangement (A) further comprises an analysis means (48) for determining a characteristic of the resonant circuit (RC) indicating the electrical contact of the electrode (2) to the surrounding area (5) and/or for determining a wireless coupling of the electrode device (1) with the analysis means (48).
2. The arrangement of claim 1, wherein the resonance means (RM) is associat- ed, preferably coupled, to an electrode (2) of the electrode device (1) for forming a resonant circuit (RC) with the surrounding area (5) via the electrode (2).
3. The arrangement of claim 2, wherein analysis means (48) is configured for determining a characteristic of the resonant circuit (RC) indicating the electrical contact of the electrode (2) to the surrounding area (5) and/or an electrical characteristic of the surrounding area (5).
4. The arrangement of any one of the preceding claims, wherein the analysis means (48) is configured for repeatedly determining a wireless coupling of the electrode device (1) and the analysis means (48) to each other by measuring a strength of the time-varying magnetic field (H) corresponding to an oscillation of the resonant circuit (RC) at a position distant to the electrode device (1) or at the position of the analysis means (48).
5. The arrangement of any one of the preceding claims, wherein analysis means (48) is placed separately remote from the electrode device (1).
6. The arrangement of any one of the preceding claims, wherein the resonance means (RM) is configured for generating a time-varying magnetic field (H) cor- responding to an oscillation of the resonant circuit (RC).
7. The arrangement of any one of the preceding claims, wherein the resonance means (RM) comprises or is formed by a transceiver (4) for sending the characteristic of the resonant circuit (RC) and/or for sending a signal (S) in a wireless manner by means of the time-varying magnetic field (H).
8. The arrangement of any one of the preceding claims, wherein the electrode device (1) comprises a transceiver (4), and at least one switch (11, 12) for disconnecting the transceiver (4) from a rectifier (7), and/or for connecting the transceiver (4) to a surrounding area (5) via at least one electrode (2).
9. An arrangement (A), in particular for capturing an intracardiac electrogram and/or for cardiac pacing, with at least one implantable electrode device (1), in particular according to any one of the preceding claims, the electrode device (1) comprising:
a transceiver (4) for generating a time-varying magnetic field (H),
a rectifier (7) for rectifying energy provided to the electrode device (1), and at least one switch (11, 12) for disconnecting the transceiver (4) from the rectifier (7), and/or for connecting the transceiver (4) to a surrounding area (5) via at least one electrode (2).
10. The arrangement of claim 8 or 9, wherein the switch (11, 12) opens, preferably disconnecting the transceiver (4) from the rectifier (7), if it is desired to send a signal (S) and/or to determine a characteristic of a resonant circuit (RC), such that the energy of the signal (S) and/or of the resonant circuit (RC) is or are not consumed by the rectifier (7).
11. The arrangement of any one of claims 8 to 10, wherein the transceiver (4) forms a resonant circuit (RC) with a surrounding area (5) of the electrode device (1) when connected to the at least one electrode (2) by the switch (1 1, 12).
12. The arrangement of any one of claims 8 to 11, wherein the switch (11, 12) disconnects the rectifier (7) for sending a signal (S) sensed from the surrounding area (5).
13. The arrangement of any one of claims 8 to 12, wherein the switch (11, 12) connects the transceiver (4) to the at least one electrode (2) of the electrode de- vice (1) for sending the signal S and/or forming the resonant circuit (RC) with the surrounding area (5) via the electrode (2).
14. The arrangement of any one of claims 8 to 13, wherein the switch (11, 12) connects the transceiver (4) to the rectifier (7) of the electrode device (1) for rectifying received energy.
15. The arrangement of any one of claims 8 to 14, wherein the switch (11, 12) disconnects the transceiver (4) from the at least one electrode (2) of the electrode device (1) for rectifying received energy and/or for determining a coupling to the electrode device (1).
16. The arrangement of any one of claims 8 to 15, wherein the switch (11, 12) connects the transceiver (4) to at least one electrode (2) of the electrode device (1) for forming the resonant circuit (RC) with the surrounding area (5) and disconnects the rectifier (7), such that the energy of the resonant circuit (RC) is not consumed by the rectifier (7), in particular simultaneously, for determining and/or sending the characteristic of the resonant circuit (RC).
17. The arrangement of any one of claims 8 to 16, wherein the switch (11, 12) is realized by or forms part of the rectifier (7).
18. The arrangement of any one of claims 8 to 17, wherein the switch (11, 12) is a changeover and/or semiconductor switch (11, 12) preferably connecting the transceiver (4) to the rectifier (7) or to the electrode (2) alternatively.
19. The arrangement of any one of the preceding claims, wherein the electrode device (1), preferably the transceiver (4), is adapted for sending the characteristic of the resonant circuit (RC) and/or the signal (S) in a wireless manner, preferably by means of a time-varying magnetic field (H).
20. The arrangement of any one of claims 7 to 19, wherein the transceiver (4) is or comprises a coil (21, 46) and/or an antenna.
21. The arrangement of any one of the preceding claims, wherein the electrode device (1), preferably the transceiver (4), is suppliable with energy exclusively in a wireless manner by means of a time-varying magnetic field (H).
22. The arrangement of any one of claims 7 to 21, wherein the transceiver (4) of the electrode device (1), in response to reception of energy, automatically generates a time-varying magnetic field (H) corresponding to the characteristic of the resonant circuit (RC).
23. The arrangement of any one of the preceding claims, wherein the electrode device (1) is adapted to partially return energy provided to the electrode device (1) after energy transfer to the electrode device (1) has been stopped, preferably wherein the returned energy indicating the characteristic of the resonant circuit (RC).
24. The arrangement of any one of the preceding claims, wherein the analysis means (48) is adapted for receiving the signal (S), the characteristic of the resonant circuit and/or energy sent, in particular returned, by the electrode device (1).
25. The arrangement of claim 24, wherein the analysis means (48) is adapted to verify and/or characterize the contact of the electrodes (2) of the electrode device (1) to the surrounding area (5) by analyzing the characteristic of the resonant circuit and/or energy sent, in particular returned, by the electrode device (1).
26. The arrangement of claim 24 or 25, wherein the analysis means (48) is adapted to identify a malfunction, in particular of a heart, by analyzing the signal (S).
27. The arrangement of any one of claims 24 to 26, wherein the analysis means (48) is adapted to determine a strength of the signal (S), the characteristic of the resonant circuit and/or energy sent, in particular returned, by the electrode device (1) for determining a coupling factor.
28. The arrangement of any one of the preceding claims, wherein the arrange- ment comprises a control unit (31), preferably comprising the analysis means
(48), which is adapted: a) for transmitting energy to the at least one implantable electrode device (1) in a wireless manner, preferably by means of a time-varying magnetic field (H); and/or
b) for receiving energy, the signal (S) and/or the characteristic of the resonant circuit (RC) from, in particular returned by, the at least one electrode device (1) exclusively in a wireless manner, preferably by means of a time-varying magnetic field (H), in particular using a transmit coil (25) and/or a receive coil (26) and/or a magnetic field sensor (27, 30), in particular a magnetometer.
29. The arrangement of any one of the preceding claims, wherein the characteristic of the resonant circuit (RC) comprises a resonant frequency and a decay behavior of the resonant circuit (RC), a corresponding value, a corresponding current, and/or a corresponding time-varying magnetic field
30. A method for characterizing a contact of electrodes (2) of at least one implantable electrode device (1) to a surrounding area (5), wherein a resonance means (RM) of the electrode device (1) is used to form a resonant circuit (RC) with the surrounding area (5) via at least one electrode (2) of the electrode device (1), and wherein a characteristic of the resonant circuit (RC) indicating the electrical contact of the electrodes (2) to the surrounding area (5) and/or an electrical characteristic of the surrounding area (5) is determined.
31. The method of claim 30, wherein a switch (11, 12) of the implantable electrode device (1) is opened if it is desired to determine the characteristic of the resonant circuit (RC), such that the energy of the resonant circuit (RC) is not consumed by a rectifier (7) of the electrode device (1), preferably wherein the switch (11, 12) is used to connect one node of a transceiver (4) of the of the electrode device (1) directly to an electrode (2) of electrode device (1).
32. A method for sending a signal (S) and/or for determining and/or sending a characteristic of a resonant circuit (RC) of an implantable electrode device (1), in particular according to claim 30 or 31, wherein a switch (11) of an implantable electrode device (1) is opened if it is desired to send a signal (S) and/or to determine and/or to send the characteristic of a resonant circuit (RC) of the electrode device (1) formed with the surrounding area (5), such that the energy of the sig- nal (S) and/or the resonant circuit (RC) is or are not or to a minor extend consumed by a rectifier (7) of the electrode device (1) for rectifying energy supplied to the electrode device (1); and/or wherein a switch (12) is used to connect one node of a transceiver (4) of the of the electrode device (1) directly to an electrode (2) of electrode device (1).
33. The method of claim 30 to 32, wherein the characteristic of the resonant circuit (RC), in particular losses, the decay behavior and/or a resonance frequency of in the resonant circuit (RC), a corresponding oscillating current and/or a corresponding time-varying magnetic field (H) is or are used for determining, in particular remote determining in a wireless manner, a characteristic of the electrical contact of at least one electrode (2) to the surrounding area (5), an electrical characteristic of the surrounding area (5) and/or an electrical resistance across the electrodes (2).
34. The method of claim 30 to 33, wherein an electrical behavior of the contact between the electrodes (2) and the surrounding area (5) is used to modify the losses and/or the resonance frequency of the resonant circuit (RC).
35. The method of any one of claims 30 to 34, wherein the losses and/or the resonance frequency of the resonant circuit (RC), and/or a corresponding oscillating current and/or time-varying magnetic field H is or are used for characterizing and/or verifying the contact between the electrodes (2) and the surrounding area (5), in particular a contact resistance and/or capacitance.
36. The method of any one of claims 30 to 35, wherein losses and/or the resonance frequency of the resonant circuit (RC) and/or a corresponding value is or are compared to a reference value or range, in particular wherein a contact failure is detected, handled and/or notified if the losses and/or the resonance frequency and/or the corresponding value goes beyond this reference value or range.
37. A method for optimizing a coupling between an implantable electrode device (1) and an analysis means (48) remote there from, in particular according to any one of claims 30 to 36, the method comprising: a) providing energy to the electrode device (1) causing a resonant circuit (RC) of the electrode device (1) to oscillate and to transmit energy corresponding to this oscillation to the analysis means (48) in an exclusively wireless manner, and b) receiving the energy corresponding to the oscillation and determining its power level or a corresponding value at the analysis means (48), and
c) changing the relative position and/or orientation of the electrode device (1) and the analysis means (48) to each other, repeating steps a) and b), comparing the resulting power levels corresponding to the different relative positions and/or orientations, and interpreting the relative position and/or orientation corresponding to the higher one of the power levels as to providing the higher coupling of the electrode device (1) and the analysis means (48) to each other.
38. The method of claim 37, wherein the position and/or orientation of a transceiver of the electrode device to a transceiver of the analysis means is determined.
39. The method of any one of claims 30 or 38, wherein the electrode device (1) is adapted for electro analysis and/or electrolysis in a production environment, and/or wherein the electrode device (1) is adapted for sensing, and/or wherein the analysis means is positioned outside a body with the implanted electrode device, in particular outside a reaction vessel, and/or automatically and/or by the user and/or for control or verification purposes, and/or wherein the method is used in fields of technology different than treatment of the human or animal body by surgery or therapy and diagnostic methods practiced on the human or animal body.
40. The method of any one of claims 30 to 39, wherein the electrode device (1) sends the energy, the signal (S) and/or the characteristic of the resonant circuit
(RC), preferably exclusively in a wireless manner, in particular by means of a time-varying magnetic field (H); and/or
41. The method of any one of claims 30 to 40, wherein the electrode device (1) is supplied with energy exclusively in a wireless manner, preferably by means of a time-varying magnetic field (H).
42. The method of any one of claims 30 to 41, wherein the resonance means (RM) is supplied with energy exclusively in a wireless manner by means of the time-varying magnetic field (H), preferably inducing oscillating currents in the resonant circuit (RC), in particular wherein the oscillating currents of the reso- nant circuit (RC) are used to generate a corresponding time-varying magnetic field (H).
43. The method of any one of claims 30 to 42, wherein energy is transmitted to the electrode device (1) and at least partially returned by the electrode device (1), both preferably in a wireless manner by means of the time-varying magnetic field (H), the returned energy indicating the characteristic of the resonant circuit (RC).
44. The method of any one of claims 30 to 43, wherein the characteristic of the resonant circuit (RC) comprises both the resonant frequency and the decay behavior of the resonant circuit (RC), preferably wherein the resonant frequency and the decay behavior are used in combination, in particular for crosschecking, and/or for more precise and/or reliable characterizing the contact of the electrodes (2) to the surrounding are (5) and/or optimizing the coupling.
45. Use of a power level for characterizing, verifying and/or optimizing a coupling of an electrode device (1), wherein energy is provided to the electrode device (1), wherein the energy causes an oscillation of a resonant circuit (RC) of the electrode device, wherein the electrode device (1) emits power corresponding to the oscillation, wherein the power is received, and wherein power level of the received power is determined.
46. The use of claim 45, wherein the coupling of the electrode device, preferably to a receiving means, or a corresponding value is inferred from the power level.
47. The use of claim 45 or 46, wherein the power level, in particular the coupling or corresponding value, is used for optimizing a placement of the electrode device, preferably relative to the receiving means.
48. Use of a characteristic of a resonant circuit (RC) of an implantable electrode device (1) for characterizing a contact of at least one electrode (2) of the elec- trode device (1) to its surrounding area (5), wherein energy is provided to the electrode device (1), wherein the energy causes an oscillation of the resonant circuit (RC), wherein the electrode device (1) emits power corresponding to the oscillation, wherein the power is received, and wherein the characteristic of the resonant circuit (RC) is determined from the received power.
49. The use of claim 48, wherein the characteristic of the contact or a corresponding value is inferred from the characteristic of the resonant circuit (RC).
50. The use of any one of claims 48 or 49, wherein the characteristic of the resonant circuit (RC), in particular the characteristic of the contact, is used to select a strength of an electrical impulse (P) to be delivered by the electrode device (1) or a corresponding parameter.
51. The use of any one of claims 48 to 50, wherein the power transmission from and/or to the electrode device (1) are carried out exclusively in a wireless manner, preferably using a time-varying magnetic field (H).
52. The use of any one of claims 45 to 51, wherein the characteristic of the reso- nant circuit (RC) comprises a resonance frequency and a decay behavior of the resonant circuit (RC).
53. The use of any one of claims 45 to 52, wherein the energy provided to the electrode device (1) is sent by a control device (28) and is adjusted or controlled in response to a distance and/or coupling factor to the electrode device (1).
54. A method for supplying an implantable electrode device (1) with energy, in particular with one or more of the features of any one of claims 30 to 53, wherein supplying the electrode device (1) with energy is controlled depending on at least one parameter corresponding to a distance and/or coupling factor to the electrode device (1).
55. The method of claim 53 or 54, wherein multiple electrode devices (1) are supplied with energy controlled depending on at least one individual parameter corresponding to the respective distance and/or coupling factor.
56. The method of any one of claims 53 to 55, wherein
a) energy is sent towards the electrode device ( 1 ),
b) the sent energy is at least partially received by the electrode device ( 1) causing the electrode device (1) to return energy,
c) the returned energy is received and a receive power level of the received returned energy or a corresponding value is determined, and
d) the amount of energy to be sent towards the electrode device ( 1) is controlled with the receive power level or the corresponding value.
57. The method of claim 56, wherein the sent energy causes a resonant circuit (RC) of the electrode device (1) to oscillate and to return energy corresponding to the oscillation.
58. The method of claim 56 or 57, wherein more power is sent towards the electrode device (1) when the power of the received energy or the corresponding value decreases and/or is less than a predetermined threshold or range.
59. The method of any one of claims 56 to 58, wherein less power is sent towards the electrode device (1) when the power of the received energy or the cor¬ responding value increases and/or is higher than a predetermined threshold or range.
60. The method of any one of claims 56 to 59, wherein the energy, preferably in both directions, is transmitted in an exclusively wireless manner, in particular by means of a time-varying magnetic field (H), by sound, by ultrasound, by an electromagnetic wave, and/or by an electric field.
61. The method of claim 60, wherein the amount of energy to be sent towards the electrode device (1) corresponds to an amplitude and/or duration of the time- varying field (H) for sending energy towards the electrode device (1).
62. The method of any one of claims 56 to 61 , wherein the energy comprises or is at least one of: A signal, a control command, a modulation or further information, preferably corresponding to the amount, density or further characteristic of the energy sent towards, received by and/or returned by the electrode device CD-
63, The method of any one of claims 56 to 62, wherein an influence of a distance and/or coupling factor to the electrode device (1) or a variation thereof on the received energy is automatically compensated, preferably wherein the received energy varies less than 50 %, more preferably less than 20 %, in particular less than 10 .
64, The method of any one of claims 56 to 63, wherein the energy to be sent, which is at least partially received by the electrode device (1), is automatically controlled such that the received energy is kept approximately constant, preferably wherein the received energy varies less than 50 , more preferably less than 20 %, in particular less than 10 %.
PCT/EP2011/003849 2010-07-30 2011-08-01 Implantable electrode device, in particular for sensing an intracardiac electrogram WO2012013360A1 (en)

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