DE102010030007A1 - Magnetic resonance-compliant microscope for use in operating microscope system, has actuator for controlling adjustable mechanism of microscope and formed as electroactive polymer actuator - Google Patents

Abstract

The microscope (2) has an actuator for controlling an adjustable mechanism (4) of the microscope and formed as an electroactive polymer (EAP) actuator i.e. dielectric elastomer actuator, where the microscope is attached on a stand (3). The adjustable mechanism is formed as a focusing mechanism, a zoom mechanism and/or a positioning mechanism, and is coupled with an optical device e.g. shutter, lens, diaphragm and/or mirror. The adjustable mechanism is formed of a non-magnetic material, where spatial position of the microscope is adjustable by the stand.

Description

The present invention relates to an MR-compatible microscope according to the preamble of claim 1. The abbreviation "MR" stands for magnetic resonance imaging (also MRI) or in general for based on the principles of nuclear magnetic resonance spectroscopy imaging methods.

With such MR methods, sectional images of the body can be generated which allow an assessment of the organs (for example differentiation of healthy and diseased tissue) and thus of pathological organ changes. Since with MR methods in particular also soft tissues of the body can be displayed well, images of high resolution can be generated and it is possible to dispense with X-radiation or other ionizing radiation, magnetic resonance tomography plays an important role in medical imaging for diagnostics as well as for support during a procedure Surgery. Magnetic resonance imaging is also referred to as magnetic resonance imaging and abbreviated as MRI (Magnetic Resonance Imaging) or NMR (Nuclear Magnetic Resonance). Reference should be made to the extensive specialist literature on the mode of operation of MR methods and the construction of corresponding tomographs and their image processing programs.

Commonly used MR devices require high magnetic field strengths for good signal quality. Large devices for use in human medicine usually generate magnetic field strengths of 1 to 3 Tesla, for research purposes field strengths of more than 10 Tesla are used. Metals in the immediate vicinity or in the body of a patient can disturb the magnetic fields and thus the imaging. In-body metals can become. also relocate or heat, as far as these metals are magnetic or magnetizable. Diamagnetic metals are generally not a problem. Vice versa, electrical devices in the vicinity of MR devices can be disturbed or even damaged by their strong magnetic fields. Due to the situation described, MR-assisted operations are currently very complicated if the procedure is to be performed with the aid of surgical microscopes. Frequently, the MR device and the surgical microscope are accommodated in different rooms or parts of rooms, and the patient must be transported back and forth between these rooms or parts of the room during the operation. As a result, the orientation of the patient in the respective devices is changed in each case, the images generated by the surgical microscope and the MR device must each be newly correlated with each other.

To solve this problem, sporadically MR-suitable microscopes are specified in the prior art.

For example, the EP 1 152 275 B1 the use of an ironless surgical microscope on an ironless tripod in the space of the MR device. As a drive, a so-called air motor is used, which generates no magnetic field, and has a housed in a cavity and driven by a gas flow turbine. Such a drive can be used for example for focusing or zoom adjustment.

A surgical microscope manufactured and distributed by the Applicant, LEICA M690, uses powerful low-noise electric motors as actuators to control the microscope's displacement mechanisms, such as zoom magnification, focusing, and xy unit displacement. Electromotive drives are due to their iron-containing components (more generally, magnetic or magnetizable components) not MRI-capable, they are bulky, heavy, mostly noisy in operation and must be provided with a mechanical transmission and cams for appropriate control of the elements.

To avoid the latter problems proposes the DE 198 22 256 A1 electric direct drives (linear drives) as actuators before. Although such linear drives can control the adjustment mechanisms of a microscope without cams and transmission elements or transmission, but are not used for MR-assisted operations.

Pneumatic or air motors have proven to be inaccurate in the practice of surgical microscopy, technically awkward and noisy.

There is therefore a desire for improved MR-compatible microscopes, which avoid the disadvantages of the above-described prior art.

According to the invention, an MR-compatible microscope with the respective features of the independent patent claims is proposed. Advantageous embodiments will become apparent from the respective dependent claims and the following description.

The microscope according to the invention has at least one actuator for controlling at least one adjustment mechanism of the microscope, wherein said at least one actuator as electroactive polymer (EAP) actuator is configured. The adjusting mechanism may be a focusing mechanism, a zoom mechanism and / or a positioning mechanism on the microscope. The adjustment mechanism can be coupled to an optical component, such as a shutter, a lens, a diaphragm and / or a mirror. These mechanisms are known per se, so that will not be discussed here in detail. For example, is from the German patent number 10 2006 040 797 the Applicant a focusing mechanism, namely a focus drive, with a direct drive (linear drive) known. This eliminates the need for a focus drive otherwise existing additional transmission elements, and there is a significant weight reduction and noise minimization. In the MR-compatible microscope according to the invention, such a focus drive (z adjustment) can now be realized with an EAP actuator. A positioning mechanism is for example from the DE 103 30 581 A1 known. Here, the positioning mechanism is interposed between a surgical microscope and an associated tripod to move the surgical microscope in a (xy) plane perpendicular to the optical axis of the surgical microscope. The adjusting mechanism has a gearbox with a coupling plate, gears and an electric drive. According to the invention, in such an adjustment mechanism, the drive can be replaced with its transmission by an EAP actuator. Finally, out of the DE 195 41 237 B4 a zoom mechanism (pancratic magnification system) known. In the case described there, a first and a second optical component (lens element), which can be displaced along a common optical axis, are arranged downstream of a third, fixedly arranged optical component. By means of a defined displacement of the first two optical components, a magnification variation is possible, wherein the first optical component can be shifted in order to set a focus to a desired object plane. The drives described in the cited document for displacing the first two optical components can be replaced according to the invention by EAP actuators in order to make the associated microscope MR-compatible.

The actuators of the microscope according to the invention can thus be formed entirely from non-magnetic material, in the present case the terms "non-magnetic", "iron-free" and "MR-compatible" in the same sense understood as non-magnetic and non-magnetizable or diamagnetic should be. In this sense, it is advantageous if the entire microscope, in particular the adjusting mechanisms themselves, is formed of non-magnetic material. These include metals, metal alloys and steel alloys that are free of iron, cobalt and nickel.

According to a second aspect, the present invention relates to a tripod-mounted MR-compatible microscope, the spatial position of which is adjustable by means of a tripod to which the microscope is attached, wherein clutches and / or brakes are provided for the tripod adjustment. Tripods for holding microscopes are known per se from the specialist literature. Clutches and brakes are used in such tripods to adjust the respective tripod arms relative to each other and then determine to move to the desired position of the microscope and then maintain. According to the invention, said clutches and / or brakes are designed as electroactive polymer (EAP) clutches or brakes. In particular, it is advantageous if the described MR-compatible microscope according to the first aspect of the invention is used as a tripod-mounted microscope according to the second aspect of the invention.

Electroactive polymers (EAP) are known per se, especially as "artificial muscle". For this purpose, reference is again made to the relevant specialist literature. According to the invention, such electroactive polymers are used for the actuators for controlling the adjustment mechanisms of an MR-compatible microscope. This measure combines the following advantages: It eliminates voluminous and heavy motors, including their gearbox and cams to control the adjustment mechanisms; The control can be carried out by means of electroactive polymer actuators noiseless, jerk-free, wear-resistant, low maintenance and reproducible. Moreover, electroactive polymer actuators can be made entirely of non-magnetic material. The EAPs thus bring a wealth of advantages and also allow MR-assisted surgery on the microscope.

Electroactive polymers are to be distinguished from piezoelectric elements, which achieve high power densities, but only comparatively small relative expansions (0.1 percent). For larger displacement paths require piezoceramic actuators enormous mechanical reinforcement. In contrast, electroactive polymers have relative extents of 10 to 100 percent, sometimes even more than 300 percent, which is in the range of the human muscle (20 percent) and surpass it. Electroactive polymer actuators are also referred to as Dielectric Elastomer Actuators (DEA). By applying a voltage across the polymer material used there, the DEAs are contracted or expanded in a direction perpendicular to the voltage drop. The relative expansion is proportional to the square of the applied voltage and to the dielectric constant. To drive the DEAs are often used voltages above 1 kV. By arrangement as a stack or tube, the DEAs cause stronger driving forces or displacement paths. For more information on the properties, arrangements, design and operation of electroactive polymers and EAP actuators, see the publication RE Pelrine, RD Kornbluh, JP Joseph, Sensors and Actuators A 64 (1998) 77-85. Electrostriction of polymeric dielectrics with compliant electrodes as a means of actuation , referenced.

The use of electroactive polymers for a tripod or hexapod for moving an attached object is disclosed in the Laid Open Publication DE 10 2005 052 983 A1 proposed. Moreover, in the DE 10 2005 001 439 B4 proposed an electromechanical control element with an elastically deformable, electrically insulating polymer body, which converts an externally applied control voltage simultaneously into a change in the geometry of this control element and an accompanying electrical signal. This signal should make it possible to monitor the mechanical switching behavior of the control electronically ("built-in feedback function").

The EAP actuators used according to the invention have the advantages of low production costs, low mechanical complexity, high robustness and low weight compared to existing actuator concepts. By using stacked EAP actuators, a displacement of a few centimeters can be guaranteed with a load capacity of a few kilograms. Thus, such electroactive polymer actuators are well suited for MR-compatible surgical microscopes. In surgical microscopes usually the object is held in its position while the optics of the surgical microscope in the X- / Y-direction (possibly also in the Z-direction) is moved. The individual movements can be accomplished via the mentioned EAP actuators. Furthermore, EAP actuators can be used for a shift of lenses in the surgical microscope (for focusing and / or zoom adjustment) as well as for operating shutters, screens, mirrors and other optical components.

The described mode of operation of the electroactive polymers can also be used for the construction of EAP couplings and brakes. For example, two brake disks can be moved towards one another via at least one EAP actuator arranged on a brake disk and pressed against one another or moved away from one another again in order to realize a brake. Another possibility of realizing a brake or a lockable coupling is to introduce an EAP element between two mutually movable parts in such a way that when applying a corresponding voltage and the resulting change in shape of the EAP element latter pressed firmly against the two parts is so that they are not further relative to each other with appropriate storage. Finally, for example, it is still possible to regulate the distance between two mutually movable parts via an EAP element such that upon application of a corresponding voltage and the resulting shape changes of the EAP element, the two parts are pressed against each other, so that a relative movement each other is no longer possible. With regard to these and other possible embodiments of brakes and / or clutches using EAP elements, reference is also made to the exemplary embodiments.

With regard to the other aspects of the design and operation of EAP clutches or brakes, reference should be made explicitly and completely to the statements made in connection with the EAP actuators. All there described advantages can be achieved in the present case. To avoid unnecessary redundancies, a repetition of the already described facts is dispensed with, without wishing to diminish the corresponding disclosure.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described in detail below with reference to the drawing.

figure description

1 shows the schematic overall view of an MR-compatible microscope, which is attached to a tripod,

2 shows a zoom mechanism for a MR-compatible microscope and

3 shows an embodiment of an EAP coupling in two working positions, namely freely movable ( 3a ) and found ( 3b ), while

4 shows another embodiment of an EAP clutch or EAP brake, wherein 4a the freely movable state and 4b illustrates the detected state.

1 schematically shows a surgical microscope system 1 with a MR-compatible microscope 2 that over a tripod 3 is adjustable in its spatial position. Such a surgical microscope system is known in principle from the prior art, which is why the following statements are limited only to aspects that relate to the claimed invention. The tripod 3 has a rotatably mounted stand base 3a and movable support arms 3b . 3c that have couplings 8th . 9 are movably and lockably connected. The support arm 3c is about another clutch 10 with the holding arm 5 connected, who finally got the microscope 2 and an adjustment mechanism 4 wearing. adjustment 4 and microscope 2 can be positioned anywhere in the room via said stand construction. For this purpose, the couplings 8th . 9 and 10 solved, allowing a relative adjustment of the support arms 3b and 3c and the support arm 5 relative to each other and to the tripod foot 3a becomes possible. By detecting the couplings 8th to 10 the microscope stops 2 in the selected position.

In the example described here is the tripod 3 formed of non-magnetic material, in particular the couplings 8th to 10 have releasable parking brakes, which are designed as EAP brakes. The couplings can consequently as EAP couplings 8th to 10 be designated. Examples of such EAP couplings show the 3 and 4 , The tripod 3 is therefore MR-compatible. The MR-compatible microscope 2 is via an adjustment mechanism 4 , here a positioning mechanism, in one to the optical axis 6 of the surgical microscope 2 vertical plane 7 transversely movable in two mutually perpendicular (X / Y) directions. An adjustment of the microscope 2 in. said plane 7 can be achieved by using two EAP actuators in the adjustment mechanism 4 be achieved. Also all other components of the adjustment mechanism 4 are MR-capable or made of non-magnetic material. In the above general and specific part of the description has been the adjustment mechanism 4 in the broadest sense described as belonging to the microscope. It is expedient if other adjustment mechanisms, such as a focusing mechanism (z-adjustment) or a zoom mechanism, EAP actuators for driving and are formed in the rest of non-magnetic material.

Based on 2 the activation of a zoom mechanism with an EAP actuator should be described. In the 2 very schematically shown side partial sectional view of a surgical microscope is - apart from the present application according to aspects - the DE 195 41 237 B4 taken and described in detail in this document. In this respect, reference is explicitly made to the statements there, not only for the purpose of sufficient disclosure, the exact functioning and the exact structure of the surgical microscope according to 2 to have to describe.

Merely for ease of understanding, the essential components of the 2 Operation Microscope described briefly: In the housing 11 of the surgical microscope 2 is a fixed focal main lens 12 arranged that is penetrated by both stereoscopic observation beam paths. The main objective 12 Subordinated is a zoom system 20 , the three optical components 13 . 14 and 15 (Lens elements). The first and second optical components 13 . 14 are each along the common optical axis 17 in a defined relationship to each other displaced. The optical component 15 is stationary in the zoom system 20 arranged. In addition to the magnification variation is by moving the first optical component 13 also to focus on a desired object level. Regarding further details of the optical components, please refer to the DE 195 41 237 B4 directed.

The defined shifting of the two optical elements 13 and 14 takes place in the illustrated embodiment according to 2 through two separate EAP actuators 19 respectively. 18 , In this way, an MR-capable zoom system 20 including focusing and zoom mechanism are provided, provided that all other components are also MR suitable, ie formed of non-magnetic material.

The EAP actuators 18 and 19 are only shown schematically, wherein the inner hatched rectangular area is to represent an EAP element, which changes in shape defined when creating a corresponding electrical voltage. As a result, as described in detail at the beginning, a defined movement of a component coupled to the EAP element (in this case, the optical components 13 and 14 ) be achieved. So far, for example, used as drives stepper motors can thus be replaced by MR-capable EAP actuators. For the control of the EAP actuators provided controls and control units are not in the interests of clarity 2 shown.

In 2 Also shown is a lighting unit, here a fiber optic light guide 23 and a two-element illumination optics 24 and 25 having. The illumination beam path is by means of a deflection element 26 through the main lens 12 directed in the direction of the object plane. A stereoscopic binocular tube known in its construction and its operation is with 16 designated. Between the binocular tube 16 and the zoom system 20 is also a deflection or beam splitter element 27 arranged in the stereoscopic observation beam paths, via which a certain portion of the observation beam or paths in the direction of a documentation unit 28 is decoupled. For deflecting the decoupled part is another deflecting element 29 intended. Further details on the extraction and the presented documentation unit 28 can be found said patent.

The 3 and 4 show schematic diagrams of an EAP clutch or an EAP brake 33 , where the 3a and 4a each the free state and the 3b and 4b each clarify the braked or detected state. In the figures, the reference numeral 31 and 32 two mutually movable parts, for example, mutually corresponding end pieces of a tripod joint or brake shoes a brake. The representation of the parts 31 . 32 is made very schematically, since only the principle of operation is to be explained. With 30 is in each case an EAP element, ie an electroactive polymer, referred to, which in itself can have the same structure and the same operation as a dielectric Elastomeraktuator (DEA), as it is explained in detail in the introduction to the description. It should again be noted that by arranging as a stack or tube said DEAs can cause or achieve stronger driving forces and displacement paths. "U _of" and "U _a" is intended one of the EAP element 30 non-applied voltage means to be.

The two relatively moving parts 31 . 32 are in the embodiment according to 3 when the voltage applied to the EAP element is switched off, ie not applied 30 away from each other, ie to each other. In the case of an EAP clutch in a tripod, as in 1 is shown (couplings 8th . 9 and 10 ) would be the corresponding tripod arms ( 3a . 3b . 3c and 5 ) Free to each other freely. When switching on a corresponding voltage and applying to the EAP element 30 There is a corresponding change in shape, ie a contraction in a spatial dimension and a length expansion in the space dimension perpendicular thereto. With appropriate arrangement of the EAP element can in this way the in 3b shown state can be achieved, in which the two parts 31 and 32 be pressed on each other. For example, by appropriate surface design of the superimposed surfaces of the parts 31 and 32 a braking effect or complete immobility of the parts 31 and 32 be achieved relative to each other. Transfer to the tripod according to 1 this means that the corresponding EAP couplings 8th . 9 respectively. 10 assume a braked / locked state, so that the respective support and support arms would be motionless relative to each other, causing the microscope 2 remains in the intended position.

The embodiment according to 3 can also be realized for another form of brake, such as in particular 3a can be made clear: the parts 31 and 32 can be interpreted as brake shoes, between which a rotating workpiece (wheel) is located, the axis of rotation, for example, in the plane of the drawing and perpendicular to the longitudinal axes of the parts 31 and 32 lies. By switching on a corresponding voltage and applying to the EAP element 30 reduces the distance between the two brake shoes 31 and 32 to each other, so that the rotating workpiece is clamped between the brake shoes and thus the rotation comes to a standstill.

Based on 4 is another embodiment of an EAP clutch or -Brake 33 be explained. In case of a clutch put the parts 31 and 32 In turn, two mutually movable joint parts. In the case of 4a exists between the parts 31 and 32 and the intermediate EAP element 30 sufficient space for relative movement of the parts 31 and 32 to enable each other. When switching on a corresponding voltage and applying to the EAP element 30 With an appropriate arrangement of this element, an expansion of the same occurs in a direction perpendicular to the longitudinal direction of the parts 31 . 32 , with the result that the gap required for relative movement to each other is completely from the EAP element 30 is completed. With appropriate storage of the parts 31 and 32 These can not avoid, so that a braking effect or a statement of the parts 31 and 32 relative to each other. The corresponding realized EAP coupling would be in the 4b state shown.

Again, the embodiment according to 4 be transferred to an EAP brake. These are the parts 31 and 32 as rotating relative to each other. With appropriate storage leads in 4b shown state to a deceleration of the rotation with subsequent standstill.

LIST OF REFERENCE NUMBERS

1

Surgical microscope system

2

microscope

3

tripod

3a

stand base

3b-c

carrying arms

4

adjustment

5

holding arm

6

optical axis

7

level

8-10

clutches

11

casing

12

main objective

13, 14, 15

optical components, lens elements

16

binocular

17

optical axis

18, 19

EAP actuator

20

Zoom system

23

optical fiber

24, 25

illumination optics

26

deflecting

27

deflecting

28

documentation unit

29

deflecting

30

EAP element

31, 32

part

33

EAP clutch, brake

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1152275 B1 [0005]
• DE 19822256 A1 [0007]
• DE 102006040797 [0011]
• DE 10330581 A1 [0011]
• DE 19541237 B4 [0011, 0028, 0029]
• DE 102005052983 A1 [0016]
• DE 102005001439 B4 [0016]

Cited non-patent literature

• RE Pelrine, RD Kornbluh, JP Joseph, Sensors and Actuators A 64 (1998) 77-85 [0015] Electrostriction of polymeric dielectrics with compliant electrodes as a means of actuation.

Claims (7)

MR-compatible microscope ( 2 ) with at least one actuator for controlling an adjusting mechanism ( 4 ) of the microscope ( 2 ), characterized in that the at least one actuator as an electroactive polymer (EAP) actuator ( 18 . 19 ) is configured. MR-compatible microscope according to claim 1, characterized in that the adjusting mechanism ( 4 ) is a focusing mechanism, zooming mechanism and / or positioning mechanism. MR-compatible microscope according to claim 1 or 2, characterized in that the adjusting mechanism ( 4 ) is coupled to an optical component, such as a shutter, a lens, a diaphragm and / or a mirror. MR-compatible microscope according to one of claims 1 to 3, characterized in that the adjusting mechanism ( 4 ) is formed of non-magnetic material. MR-compatible microscope according to one of claims 1 to 4, characterized in that the microscope ( 2 ) is formed of non-magnetic material. Tripod-mounted MR-compatible microscope, its spatial position by means of a tripod ( 3 ) to which the microscope ( 2 ), wherein for the tripod adjustment clutches and / or brakes ( 8th - 10 ), characterized in that the clutches and / or brakes ( 8th - 10 ) as electroactive polymer (EAP) couplings or brakes ( 33 ) are configured. MR-compatible microscope according to claim 6 with a microscope ( 2 ) according to one of claims 1 to 5.

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