WO2009023905A1

WO2009023905A1 - Transcutaneous energy transfer coil assemblies and systems

Info

Publication number: WO2009023905A1
Application number: PCT/AU2008/001193
Authority: WO
Inventors: Amrita Singh; Francesca Paris; Lee Thomas Glanzmann; Peter Joseph Ayre
Original assignee: Ventrassist Pty Ltd
Priority date: 2007-08-17
Filing date: 2008-08-18
Publication date: 2009-02-26

Abstract

An energy transfer system, such as a transcutaneous system, comprises a primary coil device having a first quantity, shape or orientation of locating magnets and a secondary coil device configured for energy and/or data transfer with the primary coil device, the secondary coil device having a second quantity, shape or orientation of locating magnets. The first quantity, shape or orientation of locating magnets is different to the second quantity. The primary coil locating magnets and the secondary coil locating magnets are arranged such that the secondary coil device positionable in two or more different orientations with respect to the primary coil device.

Description

TRANSCUTANEOUS ENERGY TRANSFER COIL ASSEMBLIES AND SYSTEMS

TECHNICAL FIELD

The present invention relates to coil assemblies for use with transcutaneous energy transmission systems (TETS') and more specifically relating to the magnetic positioning and centring systems for use with these TETS.

BACKGROUND ART

TETS are known in the art for use in wirelessly transmitting power to and from implanted medical devices (IMDs) such as ventricle assist devices (VADs), rotary blood pumps, neural stimulators, and cochlear implants. These TETS typically include a respective coil of wire mounted in close transcutaneous relationship on internal and external sides of a skin layer of a patient to transmit and receive electrical signals across the skin layer without the need for a permanent wound in the patient's skin. When one coil is energised with an electrical current, a second electrical current is induced in the other coil. In this manner, power and electrical signals can be transmitted across the skin layer. Additionally, by using a coded grounded signal within the normal AC signal supplied to the first coil, data may be transmitted across the skin layer. The main advantage of using TETS is that it removes the need for a permanent exit site or wound in the patient to power active IMDs and as such reduces the risk of infection and medical complications for these patients.

There have been previous attempts to improve TETS based technology with respect to locating the externally placed transcutaneous energy transfer (TET) coil on the patient and these improvements have experienced varying degrees of success. Examples of methods include using adhesive tape, body slings with pockets therein for receiving the external TET coil, or hook and loop fasteners (eg VELCRO® hook and loop fasteners, where VELCRO® is a registered trade mark of Velcro Industries BV) to hold the external TET coil on the patient' s skin surface in close transcutaneous relationship with the implanted TET coil. Other examples of earlier TETS technology rely on central positioning magnets positioned in the centre of both the externally and internally mounted coils. These central positioning magnets are oppositely biased so that the magnets are attracted to each other and allow the user the properly align the coils in proper position without being able to see the implanted or internally mounted coil assembly. The patient also gains tactile feedback as to proper orientation to gain maximum efficiency of the transmission between the two coils. This type of configuration is described in: US-A-5,948,006; US-B-6,327,504; USRE32947; and US-A-4,352,960. These basic concepts of TETS have been further improved and developed in US-A-

4,726,378 and US-A-4,736,747, where the distance between the central positioning magnets of the external TET coils and the skin layer is able to be adjusted to provide differential attractive force to different patients to overcome the problem differing skin thicknesses.

A disadvantage with the above described magnet configurations is that, when in use, the permanent magnets heat up dramatically because they are electrically conductive and in the centre of the magnetic flux flowing around the coils. For implanted applications, TETS should not increase the internal body temperature of the patient by more than about 2 degrees Celsius. Larger increases in temperature may lead the patients experiencing serious adverse medical events including localised burning, organ failure and generalised discomfort. This may not be an issue with low power drain devices, such as cochlear implants. However, this problem is further exacerbated by the use of high drain IMDs, such as rotary blood pumps that commonly require between 1 to 50 watts of power to operate.

Another disadvantage with the use of such magnets is that the patient can experience pressure sores on their skin layer at the site of the central magnet. At least one of the embodiments of the present invention aims to overcome or to ameliorate one or more of the disadvantages associated with the above mentioned prior art, or to provide a useful alternative thereto.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an energy transfer system comprising: a primary coil device having a first quantity of locating magnets; and a secondary coil device configured for energy and/or data transfer with the primary coil device, the secondary coil device having a second quantity of locating magnets being different to the first quantity, wherein the primary coil locating magnets and the secondary coil locating magnets are arranged such that the secondary coil device positionable in two or more different orientations with respect to the primary coil device.

The system may be configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices may be TET coil devices. There is potential for causing pressure sores and patient discomfort on a patient's skin layer at the location of the patient's skin layer between two of the attracted locating magnets. Therefore, by being able to position the secondary TET coil device in two or more different orientations with respect to the primary coil device, the patient skin regions between internal and external magnets can be changed to reduce the contact time of the skin portion between two magnets and to relieve the patient from possible discomfort due to otherwise continual pressure on one region of the patient's skin.

Optionally, the first quantity of locating magnets is spaced from a central region of the primary coil device. Optionally, the second quantity of locating magnets is spaced from a central region of the secondary coil device. Optionally, the first quantity of locating magnets is situated in or on a circumferential portion of the primary coil device. Optionally, the second quantity of locating magnets is situated in or on a circumferential portion of the secondary coil device.

Optionally, the first and second quantities of locating magnets comprises a number of locating magnets on the primary and secondary coil devices. The first quantity may be two or more and the second quantity may be one or more.

The primary coil may be configured to be implanted beneath a skin layer of a patient and the secondary coil is configured to align with the primary coil, when implanted, on an external portion of the skin layer of the patient.

Optionally, the first quantity of locating magnets is in the range of two to twelve and the second quantity of magnets may be in the range of one to eleven. Alternatively, the first quantity of locating magnets may be six and the second quantity of magnets may be in the range of one to five.

Optionally, the first quantity of locating magnets is radially spaced about a circumferential portion of the primary coil device. Each of the locating magnets may be of a similar respective size.

Alternatively, the first quantity of locating magnets may comprise a ring magnet. Further alternatively, the first quantity of locating magnets may comprise a non-continuous - A -

ring magnet. The non-continuous ring magnet may form an arc of up to 359°. The first quantity of locating magnets may comprise two or more arcuate magnets. The two or more arcuate magnets form an arc in the range of 20° to 89.5°.

Optionally, the polarity of the locating magnets of the first quantity is parallel to a first coil device central axis and the polarity of the locating magnets of the second quantity is parallel to a second coil device central axis.

Optionally, the primary and secondary coil devices are encapsulated in a flexible material.

According to another embodiment there is provided a magnetic system for positioning primary and secondary components of a data and/or energy transfer device relative to each other in two or more desired orientations, the primary and secondary components each comprising at least one antenna coil, the magnetic system comprising: at least one magnetic member mounted in or on the primary component; and at least one magnetic member mounted in or on the secondary component, wherein the number and/or configuration and/or orientation of the at least one magnetic member of the primary component differs from the number and/or configuration and/or orientation of the at least one magnetic member of the secondary component.

Optionally, the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices are TET coil devices. Optionally, the at least one magnetic member of the primary component is spaced from a central region of the primary coil device. Further optionally, the at least one magnetic member of the secondary component is spaced from a central region of the secondary coil device.

Optionally, the at least one magnetic member of the primary component is situated in or on a circumferential portion of the primary coil device. Also, the at least one magnetic member of the secondary coil device may be situated in or on a circumferential portion of the secondary coil device.

The one or more magnetic members of the primary component may comprise two to twelve magnetic members and the one or more magnetic members of the secondary component may comprise one to eleven magnetic members. Alternatively, the first quantity of locating magnets may be six and the second quantity of magnets may be in the range of one to five. Optionally, each of the locating magnets is of a similar respective size.

According to another aspect of the present invention there is provided an alignment system for an energy and/or data transfer coil system comprising a primary energy transfer coil assembly alignable with a secondary energy transfer coil assembly to allow energy and/or data transfer therebetween, wherein in the alignment system both of the primary and secondary energy transfer coil assemblies comprise at least one magnetic member and the at least one magnetic member of the primary energy transfer coil assembly differs in number and/or configuration and/or orientation relative to the at least one magnetic member of the secondary energy transfer coil assembly. Optionally, the system is configured for transcutaneous energy and/or data transfer

(TET), and the primary and secondary coil assemblies are TET coil assemblies.

Optionally, the at least one magnetic member of the primary component is spaced from a central region of the primary coil device. The at least one magnetic member of the secondary component may be spaced from a central region of the secondary coil device. The at least one magnetic member of the primary component may be situated in or on a circumferential portion of the primary coil device. Optionally, the at least one magnetic member of the secondary coil device is situated in or on a circumferential portion of the secondary coil device.

Optionally, the one or more magnetic members of the primary component comprises two to twelve magnetic members and the one or more magnetic members of the secondary component comprises one to eleven magnetic members.

The first quantity of locating magnets may be six and the second quantity of magnets may be in the range of one to five.

Optionally, each of the locating magnets is of a similar respective size. According to another aspect there is provided an energy transfer system comprising a primary coil device, and a secondary coil device configured for energy and/or data transfer with the primary coil device, the primary and secondary coil devices each having one or more magnets associated therewith for magnetic coupling of the first and second coil devices in an aligned orientation, the one or more magnets of each device being spaced from the centre of their respective devices and configured to allow the devices to be coupled magnetically to each other in two or more orientations while maintaining alignment of the coil devices.

Optionally, the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices are TET coil devices.

The at least one locating magnet of each of the primary and secondary coil devices may be situated in or on a circumferential portion of their respective coil device.

Optionally, any of the above described systems may be arranged for providing energy from a controller to an implantable blood pump.

Optionally, the primary coil device or primary component (depending on the above described aspect concerned) is implantable and connectable to an implantable blood pump and the secondary coil device or secondary component (depending on the above described aspect concerned) is connectable to a controller and/or power supply for the blood pump, the primary and secondary coil devices or components are configured for energy and/or data transfer between the blood pump and said controller and/or power supply.

In an alternative embodiment there is provided a coil assembly comprising: at least one coil encapsulated within a housing and at least one positioning magnet; characterised in that the positioning magnet is disposed at a location about the circumference of said coil. Optionally, said location is at a radial distance from the circumference sufficient to prevent or limit heating of the positioning magnets by EMF flux generated by the coil, when energised. Optionally, said heating is less than 2 degrees Celsius. Optionally, the radial distance is greater than 2mm. The coil assembly may interact with a second coil assembly to transmit electrical signals. The coil assembly may be hermetically sealed and suitable for human implantation. The housing may be constructed of silicone.

Optionally, the coil assembly forms part of a TETS. The TETS may be used to power an EVID.

According to another alternative embodiment, there is provided a TETS coil assembly comprising at least one coil encapsulated within a housing, and at least one positioning magnet for allowing said assembly to be positioned near a like or similar assembly for interaction therebetween, characterized in that said magnet is disposed remotely from the centre of said coil. Optionally, the assembly comprises at least one coil encapsulated within a housing, and at least one positioning magnet for allowing said assembly to be positioned near a like or similar assembly for interaction therebetween, characterized in that said magnet is disposed peripherally outside said coil.

As will be understood, any one of the above optional features may in principle be used with any one of the above described aspects of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates a schematic view of system that may be used with any of the embodiments of the present invention;

Figure 2 illustrates a transparent perspective view of an internal TET coil assembly in accordance an embodiment of the present invention; Figure 3 illustrates a transparent perspective view of an external TET coil assembly of a system in accordance with an embodiment of the present invention;

Figure 4 illustrates a transparent plan view of the internal and external TET coil assemblies depicted in Figures 2 and 3 in operable engagement with each other and the leads are at 60 degrees to each other; Figure 5 illustrates a transparent plan view of the internal and external TET coil assemblies depicted in Fig. 1 and 2 in operable engagement with each other and their leads are aligned with each other;

Figures 6 to 13 and 16 to 21 illustrate transparent views of alternative embodiments of internal and external TET coil assemblies; and Figures 14 and 15 illustrate perspective views of alternative embodiments of TET coil assemblies.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to Figure 1, a Transcutaneous Energy and/or Data Transfer System (TETS) is disclosed which comprises an internal, or implantable, transcutaneous energy and/or data transfer (TET) coil assembly 50 and an external TET coil assembly 51 which electrically interconnect components internally disposable within a patient with externally disposable components, where in use the implanted and external TET coil assemblies 50, 51 are separated by a skin layer SL of the patient.

In this example, the internal, or implantable, components comprise a blood pump 52, for example a left ventricular assist device (LVAD), connected by a lead Ll to an internal controller 53. The internal controller 53 includes a small battery, preferably a lithium ion rechargeable battery 54, encapsulated within a biocompatible housing 55, such as an injection moulded silicone housing, or a titanium housing. The internal controller 53 is electrically connected by a lead L2 to the internal TET coil assembly 50 which is mounted in parallel to and just beneath the skin layer SL of the patient. The blood pump 52 may be any type of blood pump. For example, it may be of a type implanted directly below the patient's heart, such as the VentrAssist® LVAD by Ventracor Limited, Sydney Australia, or it may be implanted in the thoracic region of the patient, such as the pump disclosed in US-B-6530876. The internal TET coil assembly 50 may be implanted, for example, in the abdominal region of the patient, also as disclosed in US-B-6530876. However, the type and location of blood pump and internal TET coil assembly are not limited to these examples.

The internal TET coil assembly 50 is electrically inductively couplable to the external TET coil assembly 51 which in use is configured to occur across the patient's skin layer SL. The external TET coil assembly 51 is mounted at least approximately in parallel to the internal coil assembly 50 on the opposite, external side of the skin layer SL. It is preferred that the distance between the internal and external coil assemblies 50,51 is kept to a minimum to increase efficiency of energy and/or data transfer between the internal and external coil assemblies 50,51. The internal TET coil assembly 50 would therefore preferably be mounted immediately below the skin layer SL, and the external TET coil assembly 51 would preferably be mounted or positioned on or as close to the skin layer SL as possible. The external coil assembly 51 is connectable by a lead 56 to an external controller 57, which includes a rechargeable battery, such as a lithium ion battery, to act as a power supply. The external controller 57 is also selectively connectable to an alternative power supply, such as mains power which is used either to supply power to the controller or to recharge the battery in the external controller 57. The external controller 57 is also connectable to a PC running a

Graphical User Interface (GUI) 58, which may be used: to update the software components; download results and data; and/or adjust the operating parameters of the blood pump 52 or the overall system.

Internal coil assembly 50 and external coil assembly 51 cooperate, when in use, to transmit electrical signals across the electrical gap made by the skin layer SL. The electrical signals transferred are one or both of energy/power supply or data. As will be understood, the TETS is configured to allow power supply to be directed from the external coil assembly 51 to the internal coil assembly 50, while data transmission can occur in both directions.

Figures 2 to 5 illustrate, where like reference numerals denote like parts, a first embodiment of a primary coil device or primary component in the form of an internal TET coil assembly 50 and a first embodiment of a secondary coil device in the form of an external TET coil assembly 51, each TET coil assembly 50, 51 being configurable for use with the above example of a TETS described with reference to Figure 1.

Internal TET coil assembly 50 includes a coil 59 of electrically conductive wire encapsulated within a housing 60 comprising a biocompatible material, preferably flexible, such as silicon. In this embodiment, the coil 59 forms a generally planar, pancake shape having an external diameter of about 50mm, but which may be in the range of 30mm to 70mm, or more preferably 40mm to 60mm. The coil 59 of this embodiment has a central void region 61 having a diameter of about 20mm, but which may be in the range of 3mm to 40 mm, or more preferably 10mm to 30mm. In this embodiment, the coil 59 is formed from spiral windings of Litz wire due to its relatively low resistance and high conductivity.

Depending on the gauge of the Litz wire, which for example may be about 16AWG to 22 AWG, the coil 59 may comprise about seven to thirteen turns or windings. The coil 59 is integrally joined to a lead 62 which joins the coil 59 at its beginning and end windings. The lead 62 is itself encapsulated in this embodiment in silicon, however may be encapsulated in any appropriate material.

The external TET coil assembly 51 includes a coil 63 of electrically conductive wire encapsulated within a housing 64 comprising a biocompatible material, preferably flexible, such as silicon. In this embodiment, the external coil 63, also having a planar, pancake shape, is larger in diameter than the internal coil 59 at about 60mm. However it may be in the range of 35mm to 80mm, or preferably 50 mm to 80mm. In alternative embodiments, the external coil has the same or relatively smaller diameter compared to the internal coil. The external coil 63 has a central void region 74 having a diameter of about 30mm, but which may be in the range of 5mm to 50 mm, or more preferably 20mm to 40mm. In this embodiment, the external coil 63 is formed from spiral windings of Litz wire with the same or similar properties as described above with reference to the internal coil 59.

The encapsulation of each of the internal and external coils 59, 63 in silicon increases the overall diameter of the respective housings 60, 64 by about 5mm to 20mm in addition to the external diameters of their respective coils 59, 63, depending on size and location of their respective locating magnets, as will be described below.

In use when energised with an electrical current, the external coil 63 transmits an electrical signal to internal coil 59 across the patient's skin layer SL. As explained above with reference to Figure 1, the two coils should be aligned in parallel and adjacent to each other on alternate sides of the patient's skin layer SL. Misalignment of the coils may decrease efficiency of transmission and may result in adverse heating of the localised area. Locating magnets, or magnetic members, are employed to aid in alignment of the coils 59, 63. In this embodiment, with particular reference to Figure 2, the magnets, or magnetic members are in the form of six permanent magnets 65 in the internal coil assembly 50 positioned around the coil 5 and spaced apart at equal intervals. Also in this embodiment, with particular reference to Figure 3, the external TET coil assembly 51 includes locating magnets, or magnetic members, in the form of three permanent magnets 67 situated in a circumferential region 68 of the assembly 51. The magnets in this embodiment are all of similar size, having a diameter of about 10mm and a height of about 5mm, but may have a diameter in the range of 4mm-20mm and depth of 2mm to 10mm or more. Having fewer similar sized magnets 67 on the external coil assembly 51 relative to the magnets 65 on the internal coil assembly 50 reduces the overall size of the external coil assembly 51 when compared to the internal coil assembly 50. These permanent magnets 65, 67 are preferably relatively strong in terms of field strength, are constructed of rare earth components and have a holding strength of about 2.4N at a 5mm separation gap. As will be understood, this is a non-limiting example of magnets which may be used with the preferred embodiments. In alternative embodiments, the holding strength between two magnets at a 5mm separation gap may be about 0.2N to 7N at a 5mm separation gap, depending on the dimensions of the magnets. Figures 4 and 5 illustrate two alternative coupling orientations of the internal and external coil assemblies 50, 51. For convenience of illustration, the skin layer SL of the patient is not shown in either of Figures 4 or 5. Figure 4 illustrates the two coil assemblies 50, 51 whose leads 62, 69 are relatively offset by about 60 degrees, and Figure 5 illustrates the two coil assemblies 50, 51, where their respective leads 62, 69 are in parallel alignment. There is no discernable difference in overall energy transfer performance between the relative coil configurations illustrated in Figures 4 and 5. However, there is a great potential benefit gained in patient comfort. As determined by the inventors, by locating or positioning the external coil assembly 51 with respect to the internal coil assembly 50 by using magnets, there is potential for causing pressure sores and patient discomfort on the patient's skin layer SL at the region of the patient's skin layer immediately between and about two of the attracted locating magnets. This is due to restriction, or "pinching" and/or rubbing on the skin layer SL between magnetically coupled internal and external magnets. The risk and potential severity of such pressure sores and discomfort increases with time of connection between magnets. Also, patients may need to have the external TET coil assembly 51 magnetically attached to their skin layer SL for considerable periods of time (up to 24 hours per day) for several months or years. Therefore, by having the ability to select, in this embodiment, between two different connection orientations (with respect to the internal and external magnet configurations) allows the patient to halve the total time a particular point on their skin layer SL will undergo "pinching" between two magnetically attracted and connected magnets. It also allows the patient relief from pinching at a particular magnet coupling location on their skin. While the embodiments of the internal and external coil assemblies 50, 51 illustrated in Figures 2 to 5 include six internal and three external magnets 65, 67, it will be understood that other embodiments may comprise different numbers, configurations or orientations of magnets which still provide the ability to alter the orientation of the external TET coil assembly 51 with respect to the internal TET coil assembly 50, while maintaining relatively close alignment between the coils 59, 63. For example, as illustrated in Figures 6 and 7 where like reference numerals denote like parts, the internal TET coil assembly 50 may comprise four magnets 65, and the external TET coil assembly 51 may comprise three magnets 67. As will be understood, this allows magnetic coupling between the two assemblies 50, 51 in four different orientations, where in each orientation, a different one of the magnets 59 on the internal TET coil assembly 50 is not coupled to a corresponding magnet 63 on the external TET coil assembly 51. This allows the patient to relieve one of four skin layer regions associated with the four internal magnets 65 from being under pressure at any given time.

Figures 8 and 9 illustrate another alternative embodiment where like reference numerals denote like parts. In the external coil assembly 51 of this embodiment, illustrated in Figure 8, there are only two permanent magnets 67 positioned around the circumference of the coil 63. This configuration may be used to minimise the overall size and bulk of the external coil assembly 51. In the internal coil assembly 50', illustrated in Figure 9, there is included first and second coils 59a,b, each having a void 61a,b, and three permanent magnets 65 positioned around the circumference of the coils 59a,b. In this embodiment, two coils 59a,b have been encapsulated within the internal TET coil assembly 50 to allow the patient to alternate between TET connection between either internal coil 59a,b. This provides a similar advantage to the above described embodiments in minimising discomfort and reducing the possibility of getting pressure sores.

Figure 10 illustrates another alternative embodiment of an internal TET coil assembly

50 where like reference numerals denote like parts. This embodiment may be used in conjunction with the external TET coil assemblies 51 illustrated in Figures 3, 7 and 8. In this embodiment, a ring magnet 70 is employed in place of the magnets 65 used in the above described embodiments. The polarity of the ring magnet 70 in this embodiment is parallel with the ring magnet's central axis. In this way, the magnets 67 of the external coil assembly

51 can be selectively positioned or located on the patient skin layer SL in a theoretically infinite number of axial positions relative to the ring magnet 70. Figure 11 illustrates another alternative embodiment of an internal TET coil assembly

50 where like reference numerals denote like parts. This embodiment is similar to the embodiment described with reference to Figure 10, however in this embodiment, the ring magnet 70' of the internal TET coil is broken, or non-continuous, having ends 71, 72. By having a non-continuous ring magnet 70', there is a reduction in increased magnetic flux during TET which may be associated with ring magnets and which may cause localised heating proximate the ring magnet. Whereas the gap may only be small, for example such that the magnet 70' scribes an arc of up to 359°, it may also be convenient to have a gap between the two ends 71,72 to provide a passage for the lead 69 to pass from the coil 63. Figures 12 and 13 illustrate further alternative embodiments of internal TET coil assemblies where like reference numerals denote like parts. The embodiments illustrated in Figures 12 and 13 comprise two and three arcuate magnets 73, respectively, which may be coupled with an external TET coil assembly such as those described with reference to Figures 3, 7 and 8. In the embodiments illustrated in Figures 12 and 13, the arcuate magnets may form an arc in the range of 20° to 89.5°. The polarity of the arcuate magnets 73 in these embodiments is parallel with the central axis of the internal coil 59 about which they are located. Similarly to the embodiments described above with reference to Figures 10 and 11, the internal coil assembly 50 of this embodiment may be selectively coupled with external TET coil assemblies 51 such as those illustrated in Figures 3, 7 and 8 in a plurality of relative radial orientations while still maintaining alignment between the two coils 59, 63.

Figure 14 illustrates another embodiment of the present invention where an internal coil assembly 78 in provided and where like reference numerals denote like parts. This coil assembly 78 includes a coil (not shown in this embodiment) similar to the coil 59 described with reference to aforementioned embodiments of the internal TET coil assembly, encapsulated within the housing 79 in a planar, pancake shape configuration. As per the previously described embodiments, the centre of the pancake shape is hollow, or has a void

61, as the coil in this embodiment rotates, or is wound, around the centre rather than crossing the centre and this may lead to improvements in transmission efficiency. Additionally, this embodiment does not include a central positioning magnet which is commonly included within the prior art and this may also further improve efficiency of EMF transfer and reduce heat generation, as opposed to the prior art examples.

This embodiment includes a first positioning strap 80 that is laid over the assembly 78. The strap 80 is adapted to fit over the assembly 78 and secure the internal coil assembly 78 in place. The first strap 80 is preferably coated or made of a velour or DACRON™ material.

This velour or DACRON™ material is suitable for implantation and allows tissue to ingrow into the first strap 80 securing it in place when implanted.

The first strap 80 includes at either end a positioning magnet 81 which has been integrally moulded into the first strap 80. When the first strap 80 is laid over the assembly 78, the assembly 78 is trapped in place and the positioning magnets 81 allow internal coil assembly 78 to be located and secured by an external coil assembly mounted on the outside of the patient's skin layer.

In this embodiment, the positioning magnets 81 are located about the circumference of the encapsulated coil, however they are not integrally moulded into the housing 79 rather included within the strap 80. The main advantage is that a doctor can position the strap 80 optimally within the body of the patient by using stitching.

Additionally, the embodiment of the internal TET coil assembly 78 illustrated in

Figure 14 may be also used in external environments as an external TET coil assembly. However in external environments, the velour or Dacron™ is replaced with silicone moulding. Figure 15 depicts another embodiment where like reference numerals denote like parts and which provides an improvement over the embodiment illustrated in Figurel4. This embodiment includes a first strap 80 and second strap 82. The second strap 82 provides additional support and fixation for the coil assembly 78. Figures 16 to 19 illustrate another alternative embodiment where like reference numerals denote like parts. The internal and external coil assemblies of this embodiment are similar to the embodiment described above with reference to Figures 2 to 5, but in this embodiment, the coils do not comprise a central void.

As will be understood, while the above described embodiments have been described with reference to particular numbers of internal and external magnets, the number of magnets in alternative embodiments may comprise more or fewer magnets than the embodiments provided. For example, the internal and external TET coil assemblies may comprise a number of magnets in the range of one to twelve. As will be understood, however, if the magnets used on each of the internal and external TET coil assemblies are of a similar size, the number of magnets used internally will be greater than the number of magnets used externally. Also, in each case, the polarity of the magnets will be aligned with the central axis of the coil about which they are located, be it the coil of the internal or external coil assembly. The magnets on the internal TET coil assembly also have the same direction of polarity, as do the magnets on the external TET coil assembly, for example such that when the internal coil is implanted, the magnet surfaces closest to the patient's skin layer will all have either north or south polarity. It should be noted that the coils 59, 63 of the embodiments illustrated in Figures 6, 7 and 10 to 13 are shown schematically and for convenience as a shaded annulus shape, however in practice, they would take the form of a wound coil similar to those illustrated in Figures 2 to 5 and 8. In each of the above described embodiments, the magnets and the coils are encapsulated to prevent or limit fluid ingress. This encapsulation is accomplished with silicon, being a material that is biocompatible and relatively impermeable to fluids, but may be encapsulated in alternative embodiments in materials having similar qualities including but not limited to polyetheretherketone (PEEK), titanium alloys or gold. In all embodiments, the magnets are situated far enough away from their respective coils not to be adversely affected by the EMF flux produced around the coils. If the magnets are too close to their respective coils, they may experience heating by the interaction of the EMF flux present during TET. The EMF flux is generally reduced exponentially when the distance between the magnets and the outer edge of the coil is insufficient. The minimum required distances between the outer edge of the coils and their respective magnets may differ with changes in the overall amount of magnetic flux flowing about the coils when in use. As power transferred between internal and external coils increases, so to does the magnetic flux flowing between the coils 5. This leads to a required increase in the minimum distance between the magnets and the outer edges of their respective coils. In the above described embodiments, the preferred minimum radial distance between the magnets and their respective coils is greater than 2mm from the outer edge of the coil to the magnets and preferably about 3mm radial distance but may alternatively be greater, at about 10mm radial distance.

In the prior art (eg US-A-4,726,378), the positioning magnets are positioned within the centre of the coil and thus exposing the magnets to the full amount or maximum amount of EMF flux and in these situations the magnets are significantly heated beyond the point where they are unsuitable for safe human implantation. In some instances of the prior art, the magnets were heated, in normal operating conditions to drive an implantable blood pump, to about 80 degrees Celsius. Preferably, increases of temperature of the internal coil or magnets should be no greater than 2 degrees Celsius, which may prevent discomfort or serious adverse events affecting the patient. In at least some of the above described embodiments, the internal coil assembly 50 is adapted to deliver between 1-50 Watts to the device to which it is connected and is arranged to provide an overall temperature increase, if any, of no more than 2 degrees Celsius.

As will be understood, unless the context requires or suggests otherwise, features of any one of the above described embodiments may be used in conjunction with another one or more of the above described embodiments.

While the invention has been described in reference to its preferred embodiments, it is to be understood that the words which have been used are words of description rather than limitation and that changes may be made to the invention without departing from its scope as defined by the appended claims. For example, whereas the preferred embodiments have been described with reference to use with an implanted blood pump, it will be understood that the TET system may be useful in other implantable medical device applications.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

A reference herein to prior art information is not an admission that the information forms part of the common general knowledge in the art in Australia.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

1. An energy transfer system comprising: a primary coil device having a first quantity of locating magnets; and a secondary coil device configured for energy and/or data transfer with the primary coil device, the secondary coil device having a second quantity of locating magnets being different to the first quantity, wherein the primary coil locating magnets and the secondary coil locating magnets are arranged such that the secondary coil device positionable in two or more different orientations with respect to the primary coil device.

2. The system of claim 1 wherein the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices are TET coil devices.

3. The system of claim 1 or 2 wherein the first quantity of locating magnets is spaced from a central region of the primary coil device.

4. The system of any one of the preceding claims wherein the second quantity of locating magnets is spaced from a central region of the secondary coil device.

5. The system of any one of the preceding claims wherein the first quantity of locating magnets is situated in or on a circumferential portion of the primary coil device.

6. The system of any one of the preceding claims wherein the second quantity of locating magnets is situated in or on a circumferential portion of the secondary coil device.

7. The system of any one of the preceding claims, wherein the first and second quantities of locating magnets comprises the number of locating magnets on the primary and secondary coil devices.

8. The system of any one of the preceding claims wherein the first quantity is two or more and the second quantity is one or more.

9. The system of any one of the preceding claims, wherein the primary coil is configured to be implanted beneath a skin layer of a patient and the secondary coil is configured to align with the primary coil, when implanted, on an external portion of the skin layer of the patient.

10. The system of any one of the preceding claims where the first quantity of locating magnets is in the range of two to twelve and the second quantity of magnets is in the range of one to eleven.

11. The system of any one of claims 1 to 9 where the first quantity of locating magnets is six and the second quantity of magnets is in the range of one to five.

12. The system of any one of claims 10 or 11 wherein the first quantity of locating magnets is radially spaced about a circumferential portion of the primary coil device.

13. The system of any one of the preceding claims wherein each of the locating magnets is of a similar respective size.

14. The system of any one of claims 1 to 9 wherein the first quantity of locating magnets comprises a ring magnet.

15. The system of any one of claims 1 to 9 wherein the first quantity of locating magnets comprises a non-continuous ring magnet.

16. The system of claim 15 wherein the non-continuous ring magnet forms an arc of up to 359°.

17. The system of claim 15 wherein the first quantity of locating magnets comprises two or more arcuate magnets.

18. The system of claim 17 wherein the two or more arcuate magnets form an arc in the range of 20° to 89.5°.

19. The system of any one of the preceding claims wherein the polarity of the locating magnets of the first quantity is parallel to a first coil device central axis and the polarity of the locating magnets of the second quantity is parallel to a second coil device central axis.

20. The system of any one of the preceding claims wherein the primary and secondary coil devices are encapsulated in a flexible material.

21. A magnetic system for positioning primary and secondary components of a data and/or energy transfer device relative to each other in two or more desired orientations, the primary and secondary components each comprising at least one antenna coil, the magnetic system comprising: at least one magnetic member mounted in or on the primary component; and at least one magnetic member mounted in or on the secondary component, wherein the number and/or configuration and/or orientation of the at least one magnetic member of the primary component differs from the number and/or configuration and/or orientation of the at least one magnetic member of the secondary component.

22. The system of claim 21 wherein the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices are TET coil devices.

23. The system of claim 21 or 22 wherein the at least one magnetic member of the primary component is spaced from a central region of the primary coil device.

24. The system of any one of claims 21 to 23 wherein the at least one magnetic member of the secondary component is spaced from a central region of the secondary coil device.

25. The system of any one of claims 21 to 24 wherein the at least one magnetic member of the primary component is situated in or on a circumferential portion of the primary coil device.

26. The system of any one of claims 21 to 25 wherein the at least one magnetic member of the secondary coil device is situated in or on a circumferential portion of the secondary coil device.

27. The system of any one of claims 21 to 26 wherein the one or more magnetic members of the primary component comprises two to twelve magnetic members and the one or more magnetic members of the secondary component comprises one to eleven magnetic members.

28. The system of any one of claims 21 to 26 where the first quantity of locating magnets is six and the second quantity of magnets is in the range of one to five.

29. The system of any one of claims 21 to 28 wherein each of the locating magnets is of a similar respective size.

30. An alignment system for an energy and/or data transfer coil system comprising a primary energy transfer coil assembly alignable with a secondary energy transfer coil assembly to allow energy and/or data transfer therebetween, wherein in the alignment system both of the primary and secondary energy transfer coil assemblies comprise at least one magnetic member and the at least one magnetic member of the primary energy transfer coil assembly differs in number and/or configuration and/or orientation relative to the at least one magnetic member of the secondary energy transfer coil assembly.

31. The system of claim 30 wherein the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil assemblies are TET coil assemblies.

32. The system of claim 30 or 31 wherein the at least one magnetic member of the primary component is spaced from a central region of the primary coil device.

33. The system of any one of claims 30 to 32 wherein the at least one magnetic member of the secondary component is spaced from a central region of the secondary coil device.

34. The system of any one of claims 30 to 33 wherein the at least one magnetic member of the primary component is situated in or on a circumferential portion of the primary coil device.

35. The system of any one of claims 30 to 34 wherein the at least one magnetic member of the secondary coil device is situated in or on a circumferential portion of the secondary coil device.

36. The system of any one of claims 30 to 35 wherein the one or more magnetic members of the primary component comprises two to twelve magnetic members and the one or more magnetic members of the secondary component comprises one to eleven magnetic members.

37. The system of any one of claims 30 to 35 where the first quantity of locating magnets is six and the second quantity of magnets is in the range of one to five.

38. The system of any one of claims 30 to 37 wherein each of the locating magnets is of a similar respective size.

39. An energy transfer system comprising a primary coil device, and a secondary coil device configured for energy and/or data transfer with the primary coil device, the primary and secondary coil devices each having one or more magnets associated therewith for magnetic coupling of the first and second coil devices in an aligned orientation, the one or more magnets of each device being spaced from the centre of their respective devices and configured to allow the devices to be coupled magnetically to each other in two or more orientations while maintaining alignment of the coil devices.

40. The system of claim 39 wherein the system is configured for transcutaneous energy and/or data transfer (TET), and the primary and secondary coil devices are TET coil devices.

41. The system of claim 39 or 40 wherein the at least one locating magnet of each of the primary and secondary coil devices are situated in or on a circumferential portion of their respective coil device.

42. The system of any one of the preceding claims arranged for providing energy from a controller to an implantable blood pump.