Implant in the form of a wrap-around electrode arrangement

Abstract

A medical implant in the form of a cuff electrode assembly, or cuff electrode (1), comprising a flexible, biocompatible, film-like carrier substrate (2) which, in a first region (3), assumes the shape of a tube by winding around a winding axis (5), the tube comprising a straight, cylindrical cavity (6) which is bounded radially to the winding axis (5) by a surface of the carrier substrate to which at least one electrode surface (7) is attached, which is connected via at least one electrical conductor (8) integrated within the carrier substrate (2) to a non-flexible contact arrangement (11), to which the electrical conductor (8) is connected to an electrical supply and / or discharge lead (15) leading to an implantable electrical supply unit (16) formed separately from the implant, wherein the contact arrangement (11) has a spatial longitudinal extent (13) which is oriented parallel to the winding axis (5).The contact arrangement (11) is firmly joined to the carrier substrate (2) along a dimensionally stable joining area (20), overlaps the first area (3) of the carrier substrate (2) wound into a tube in an orthogonal projection to the winding axis (5), and is arranged relative to the carrier substrate (2) such that the longitudinal extent (13) of the contact arrangement (11) and a tube length (19) associated with the first area (3) of the carrier substrate (2) wound into a tube overlap maximally in an orthogonal projection to the winding axis (5), wherein the joining area (20) between the contact arrangement (11) and the carrier substrate (2) has a joining area length (21) oriented parallel to the winding axis (5), which maximally overlaps the longitudinal extent (13) of the contact arrangement (11) and the tube length (19) in an orthogonal projection to the winding axis. (5) corresponds, and the contact arrangement (11) is so firmly joined relative to the carrier substrate (2),so that the longitudinal extent (13) of the contact arrangement (11), the tube length (19) and the joining area length (21) each have a common central axis (24) oriented orthogonally to the winding axis (5).

Description

Technical area

[0001] The invention relates to a medical implant in the form of a wound cuff electrode arrangement, in short cuff electrode, suitable for extravascular or extraneuronal attachment along an intracorporeal vessel or a nerve fiber bundle, which has a flexible, biocompatible, film-like carrier substrate which, in a first region, takes on the shape of a tube by winding around a winding axis. The tube comprises a straight, cylindrical cavity which is delimited by a surface of the carrier substrate radially to the winding axis, to which at least one electrode surface is attached, which is connected via at least one electrical line integrated within the carrier substrate to a non-flexible contact arrangement, to which the at least one electrical line is connected to an electrical supply and / or discharge line which leads to an implantable electrical supply unit which is designed separately from the implant. State of the art

[0002] Cuff electrodes of the aforementioned type are typically used to detect and apply electrical signals from or to intracorporeal vessels, particularly nerve cords. Cuff electrodes comprise a flexible, biocompatible, foil-like carrier substrate, to whose surface facing the nerve cord at least one, preferably a plurality of, electrodes are attached. These electrodes are intended to be brought into intimate physical contact with the surface of a nerve cord.

[0003] Such a cuff electrode is disclosed in WO 2016 / 055512 A1. The carrier substrate of the cuff electrode consists of a polyimide film, which has been mechanically pre-stressed for the purpose of at least partially self-winding around a winding axis. As the cuff electrode is wound around the nerve cord, the individual electrodes of the cuff electrode come into direct surface contact with the epineurium of a nerve fiber bundle. The cuff electrode adheres to the cylindrical outer surface of the nerve fiber bundle by means of a force-applied form-fitting connection, with the carrier substrate regions, which overlap as a result of the rolling or winding process, lying loosely on top of one another.

[0004] The electrical lines leading from the individual electrodes of the cuff electrode each run electrically insulated within the polyimide film and end at a side edge region of the polyimide film, which is spatially spaced from the wound region of the cuff electrode and at which the ends of the electrical lines are each connected via an electrical contact arrangement to electrical supply and discharge lines, via which the cuff electrode is connected to an implantable electrical supply unit, which is located intracorporeally separately from the cuff electrode.

[0005] Due to the natural sensitivity of nerve fibers to external mechanical influences, it is important, on the one hand, to keep the mechanical stress exerted on the nerve fiber bundle by the cuff electrode as low as possible. On the other hand, it is important to ensure that the cuff electrode surrounds the nerve fiber bundle with sufficient stability to ensure the cuff electrode is joined as permanently and permanently as possible along the nerve fiber bundle.

[0006] Practical experience with the use of cuff electrodes shows, on the one hand, that the loose winding of the carrier substrate, which is sometimes arranged in multiple layers around a nerve fiber bundle, enables a dynamic radial expansion of the cuff electrode, which enables the cuff electrode to adapt to natural changes in the shape of the nerve fiber bundle. On the other hand, external forces acting on the cuff electrode can significantly deform its winding geometry, whereby the nerve fiber bundle can be exposed to considerable mechanical stresses that can lead to irreversible damage.

[0007] The document DE 44 33 111 A1 discloses a cuff electrode which can be applied as an extraneural, cuff-shaped electrode around a biological tissue, e.g. a nerve, and provides raised electrodes on a foil made of non-conductive material layers, which are contacted via conductor tracks arranged between the non-conductive layers, of which at least one layer consists of shape memory metal to ensure the cuff-shaped. Description of the invention

[0008] The invention is based on the object of developing a cuff electrode which has a flexible, biocompatible, film-like carrier substrate which, in a first region, takes on the shape of a tube by winding around a winding axis, said tube comprising a straight, cylindrical cavity which is delimited by a surface of the carrier substrate radially to the winding axis, to which at least one electrode surface is attached, which is connected via at least one electrical line integrated within the carrier substrate to a non-flexible contact arrangement, to which the electrical line is connected to an electrical supply and / or discharge line which leads to an implantable electrical supply unit which is designed separately from the implant, in such a way that the most uniform and gentle effect of force or pressure on the nerve fibre bundle is ensured by the cuff electrode using the simplest possible means.This should apply in particular to those cases in which the cuff electrode is subjected to tensile forces acting along the electrical supply and / or discharge lines, such as those caused by the body's own movements.

[0009] The solution to the problem underlying the invention is defined in claim 1. Further features of the solution concept are the subject of the dependent claims and the further description.

[0010] According to the solution, the medical implant, which is designed in the form of a wound cuff electrode arrangement, is characterized by the combination of the following features: The medical implant in the form of a wound cuff electrode arrangement, abbreviated to cuff electrode, comprises a flexible, biocompatible, foil-like carrier substrate which, in a first region, takes on the shape of a tube by winding around a winding axis. The tube comprises a straight, cylindrical cavity which is delimited by a surface of the carrier substrate radially to the winding axis, to which at least one electrode surface is attached, which is connected via at least one electrical line integrated within the carrier substrate to a non-flexible contact arrangement, to which the electrical line is connected to an electrical supply and / or discharge line which leads to an implantable electrical supply unit formed separately from the implant, wherein the contact arrangement has a spatial longitudinal extension oriented parallel to the winding axis and is firmly joined to the carrier substrate along a dimensionally stable joining region.in orthogonal projection to the winding axis, overlaps with the first region of the carrier substrate wound into a tube and is arranged relative to the carrier substrate in such a way that the longitudinal extent of the contact arrangement and a tube length associated with the first region of the carrier substrate wound into a tube maximally overlap in orthogonal projection to the winding axis, wherein the joining region between the contact arrangement and the carrier substrate has a joining region length oriented parallel to the winding axis, which corresponds at most to a mutual overlap of the longitudinal extent of the contact arrangement and the tube length in orthogonal projection to the winding axis, and the contact arrangement is firmly joined relative to the carrier substrate in such a way that the longitudinal extent of the contact arrangement, the tube length and the joining region length each have a common central axis oriented orthogonally to the winding axis.

[0011] The design of the cuff electrode according to the invention, which concerns a special design and attachment of the contact arrangement relative to the carrier substrate region of the cuff electrode, which takes on the shape of a tube through a rolling or winding process and, when implanted, lies locally around a nerve fiber bundle, is based on experience gained with a known cuff electrode according to the publication WO 2016 / 055512 A1. In the known cuff electrode, that region of the foil-shaped carrier substrate that directly adjoins the first region of the carrier substrate wound into a tube is essentially band- or strip-shaped. All electrical conductors connected to the electrodes of the cuff electrode run along the band-shaped carrier substrate region.The band-shaped carrier substrate region has a longitudinal extension oriented essentially parallel to the winding axis and is connected locally to the carrier substrate region wound into a tube via a rectangularly shaped, narrow band section in the center. Tensile or shear forces acting along the band-shaped carrier substrate oriented parallel to the winding axis result in an asymmetrical force acting on the carrier substrate region wound into a tube. The resulting stress conditions can lead to a tighter winding along the winding axis on one side of the wound carrier substrate region and a constriction, and on the opposite side of the wound carrier substrate region to a widening and a constriction, whereby the inner nerve cord is exposed to a significantly heterogeneous pressure or force effect.

[0012] The design according to the solution, however, avoids such asymmetrical loading situations acting on the nerve cord. The contact arrangement, made of a non-flexible material, e.g., ceramic, serves as a type of force coupler that transmits tensile and / or shear forces acting along the electrical supply and / or discharge line as evenly as possible to the carrier substrate region, which is wound into a tube and fits around a nerve fiber strand like a cuff. This avoids an asymmetrical winding geometry, in which one end of the tube has a small diameter and the other end has an enlarged diameter. Preferably, the force is introduced via the contact arrangement onto the carrier substrate region wound into a tube evenly along the entire axial length of the tube. In this way, any shear forces acting on the nerve cord can be avoided.The contact arrangement and the carrier substrate are connected via a joining area with a joining area length oriented parallel to the winding axis, which corresponds at most to the mutual overlap between the contact arrangement and the tube in a projection orthogonal to the winding axis. It is particularly advantageous if the longitudinal extent of the contact arrangement is equal to or greater than the tube length.

[0013] Embodiments are also conceivable in which the dimensions of the longitudinal extent of the contact arrangement, the tube length and the joining area longitudinal extent differ from one another, but even in these cases it must be ensured that the contact arrangement is firmly joined relative to the carrier substrate in such a way that the longitudinal extent of the contact arrangement, the tube length and the joining area length each have a common central axis oriented orthogonally to the winding axis.

[0014] The contact arrangement preferably comprises a plate-shaped carrier, on which the at least one cuff-electrode-side electrical line is contacted with an electrode attached to the carrier, preferably by means of a microflex contact. The carrier-side electrode is in turn connected to another separate electrode surface applied to the carrier, to which the electrical supply and / or discharge line leading to the separate supply unit is electrically connected by means of a welded, soldered, or bonded connection. Naturally, a plurality of such electrode / electrode surface pairs are located on the plate-shaped carrier, via which a corresponding number of cuff-electrode-side electrical lines are connected to corresponding electrical supply and / or discharge lines combined to form a cable harness.

[0015] The electrical supply and / or discharge line, or the plurality of electrical supply and discharge lines combined into a cable harness, together with the plate-shaped carrier, is enclosed by an elastic material that is joined to the carrier substrate in a fluid-tight manner in the joining area. The elastic material, which surrounds the at least one electrical supply and / or discharge line in a fluid-tight, tubular, or matrix-like manner, forms the shape of a strand with a longitudinal extension whose length is determined by the separate intracorporeal location of the cuff electrode and supply unit.

[0016] The plate-shaped carrier has a carrier length that is much greater than its carrier width, and its longitudinal extension is oriented parallel to the winding axis. The relatively narrow carrier shape is preferably dimensioned such that it is embedded within the strand along which the at least one electrical supply and / or discharge line is integrated, without or without significant change in shape. A specific embodiment is explained in more detail below.

[0017] In a preferred embodiment, for the purpose of additionally distributing the forces acting on the nerve fiber bundle via the cuff electrode, at least one additional fastening means, in the form of a wound sleeve or a helical structure, is attached adjacent to the cuff electrode along the strand or tube containing the at least one electrical supply and / or discharge line. The additional fastening means, like the cuff electrode, comprises a straight-cylindrical cavity aligned coaxially with the winding axis.

[0018] In a further preferred embodiment, the strand or tube provides a strand extension adjoining the contact arrangement in the strand's longitudinal extension, to which a second fastening means similar to the above-mentioned first fastening means is formed and attached directly or indirectly. In this way, the tensile or shear forces acting along the supply and / or discharge line can be distributed or transmitted along the nerve cord in a manner symmetrical to the force electrode arrangement.

[0019] All electrical conductor structures applied to the carrier substrate, each comprising the at least one electrode surface and the electrical line electrically connected at least to the electrode surface, are each produced in one piece, preferably by means of a metal deposition process, so that no joints and associated discontinuous electrical impedance jumps are present along the electrical conductor structure. Brief description of the invention

[0020] The invention is described below, without limiting the general inventive concept, using an exemplary embodiment with reference to the drawing. It shows: Fig. 1 Embodiment of a medical implant designed according to the solution. Ways of implementing the invention, industrial applicability

[0021] Fig. 1 shows a cuff electrode 1 configured in the manner of a wound cuff electrode arrangement, which provides a foil-like carrier substrate 2, preferably made of a polyimide film. The carrier substrate 2 has two integrally connected regions 3, 4, of which the first region 3 of the carrier substrate 2 is wound around a winding axis 5. The first region 3 of the carrier substrate 2, wound into a tube, retains its wound shape due to material-inherent tension forces, which are impressed by a suitable treatment of the foil-like carrier substrate 2, for example, by means of a heat treatment, and comprises a straight-cylindrical cavity 6, which is open axially on both sides.At least one electrode surface 7, preferably a plurality of such electrode surfaces, is applied to the surface of the tubularly wound first region 3 of the carrier substrate 2 facing the straight-cylindrical cavity 6. Each of the electrode surfaces 7 is in direct physical contact with the outer wall of a nerve fiber bundle (not shown). Each of the electrode surfaces 7 is integrally connected to an electrical line 8, all of which run electrically insulated within the carrier substrate 2.

[0022] The second region 4 of the carrier substrate, which directly adjoins the first region 3 of the carrier substrate 2 in one piece, has a side edge 9 facing away from the first region 3, along which the electrical lines 8 end in a side-by-side arrangement and are each contacted via a microflex contact 10 with an electrode mounted on the contact arrangement 11. The contact arrangement 11 is in the form of a plate-shaped carrier 12, preferably consisting of a ceramic plate, and has a longitudinal extension 13. The length of the carrier 12 is much greater than its width.

[0023] The electrodes attached to the plate-shaped carrier 12 connect the electrical lines 8 each to an electrical contact surface 14 applied to the upper side of the plate-shaped carrier 12, on which an electrical supply and / or discharge line 15 is electrically contacted by means of a soldering, bonding or welding connection, which is arranged laterally to the contact arrangement 11, in the image representation according to Fig. 1 to the left. All supply and discharge lines 15 connected to the respective contact surfaces 14 are combined to form a cable harness 15*, which leads to a supply unit 16 designed separately from the cuff electrode 1, which supply unit provides, for example, control signals as well as electrical energy for operating the cuff electrode 1. The wire-shaped supply and discharge lines 15, each combined to form a cable harness 15*, are connected to the supply unit 16 via a fluid-tight plug connection (not shown) for separate handling of the supply unit 16, e.g. for the purpose of replacement. For electrical insulation as well as for the purpose of protection against the moist intracorporeal environment, the cable harness 15* comprising all electrical supply and / or discharge lines 15 is surrounded by a silicone hose 17 or embedded in a silicone strand 17.

[0024] In order to ensure that tensile or shear forces 18 acting along the silicone strand 17 are distributed as evenly as possible along the entire length 19 of the first region 3 of the carrier substrate 2 wound up into a tube, the joining region 20 between the contact arrangement 11 and the second region 4 of the carrier substrate 2, in which the carrier substrate 2 is joined to the surface of the platelet-shaped carrier 12 of the contact arrangement 11 by means of a fixed joining connection, is at least partially, preferably completely, in an orthogonal projection to the winding axis 5, as in Fig. 1, overlapping the axial extension 19 of the region 3 of the carrier substrate 2 wound into a tube. Regardless of the actual dimensioning of the respective lengths of the contact arrangement 11, the joining region 20 and the first region 3 of the carrier substrate 2 wound into a tube, the longitudinal extension (13) of the contact arrangement (11), the tube length (19) and the joining region length (21) preferably each have a common central axis (24) oriented orthogonally to the winding axis (5).

[0025] In the case of Fig. 1, the joining region 20 has a longitudinal extension 21 that approximately corresponds to the length 19 of the tubularly wound section 3 of the carrier substrate 2. In this case, force is transmitted from the contact arrangement 11 via the joining region 20 to the carrier substrate 2 evenly over the entire length 19.

[0026] Optionally, it is possible to provide a fastening means 22, 22' on one side of the cuff electrode 1 or on both sides of the cuff electrode 1 along the winding axis 5, which fastening means 22, 22' can nestle around the outer circumference of a nerve strand when subjected to force, just like the cuff electrode 1. The fastening means 22, 22' can be in the form of a winding sleeve or a known helical structure, preferably made of a silicone material. The fastening means 22 on the left in the image is attached directly to the silicone strand 17 via a connection 23. The connection 23 is preferably designed as a one-piece material connection, i.e. the fastening means 22, the connection 23 and the silicone strand 17 are each made of the same material within the framework of a uniform manufacturing process.The connection 23 can be configured in the form of a seamless transition between the silicone strand 17 and the fastening means 22, or even a spatial joining geometry, for example, in the form of a straight, zigzag, wavy, spiral, or helical connecting arm. The fastening means 22', which is also optionally provided on the right side of the cuff electrode 1, is attached to a strand extension 17'. In this case, the connection 23' can also be configured in the same way as described above. List of reference symbols 1 cuff electrode 2 Carrier substrate 3 First area of ​​the carrier substrate 4 Second area of ​​the carrier substrate 5 winding axis 6 Straight cylindrical cavity 7 Electrode surface 8 Electrical conductor 9 Connecting end edge of the carrier substrate 10 Microflex contact 11 Contact arrangement 12 plate-shaped carriers 13 Longitudinal extension of the contact arrangement 14 Electrode area 15 Electrical supply and / or discharge 15* Cable harness 16 supply unit 17 silicone strands 17' strand extension 18 Thrust-tensile forces 19 Length of the second region 3 of the carrier substrate wound into a tube 20 Joining area 21 Length of the joining area 22.22' fasteners 23, 23' connection 24 Central axis

Claims

[1] A medical implant in the form of a wound cuff electrode arrangement, abbreviated to cuff electrode (1), comprising a flexible, biocompatible, film-like carrier substrate (2) which, in a first region (3), takes on the shape of a tube by winding around a winding axis (5), said tube comprising a straight, cylindrical cavity (6) which is delimited by a surface of the carrier substrate radially to the winding axis (5), to which at least one electrode surface (7) is attached, which is connected via at least one electrical line (8) integrated within the carrier substrate (2) to a non-flexible contact arrangement (11), to which the electrical line (8) is connected to an electrical supply and / or discharge line (15) which leads to an implantable electrical supply unit (16) formed separately from the implant, wherein the contact arrangement (11) has a spatial longitudinal extension (13) which is oriented parallel to the winding axis (5),is firmly joined to the carrier substrate (2) along a dimensionally stable joining region (20), overlaps in orthogonal projection to the winding axis (5) with the first region (3) of the carrier substrate (2) wound into a tube, and is arranged relative to the carrier substrate (2) in such a way that the longitudinal extent (13) of the contact arrangement (11) and a tube length (19) assigned to the first region (3) of the carrier substrate (2) wound into a tube maximally overlap in orthogonal projection to the winding axis (5), wherein the joining region (20) between the contact arrangement (11) and the carrier substrate (2) has a joining region length (21) oriented parallel to the winding axis (5), which at most corresponds to a mutual overlap of the longitudinal extent (13) of the contact arrangement (11) and the tube length (19) in orthogonal projection to the winding axis (5), and the contact arrangement (11) is firmly joined relative to the carrier substrate (2) in such a way thatso that the longitudinal extension (13) of the contact arrangement (11), the tube length (19) and the joining area length (21) each have a common central axis (24) oriented orthogonally to the winding axis (5). [2] Medical implant according to claim 1, characterized by that the carrier substrate (2) has, in one piece and adjacent to the first region (3) wound into the tube, a second flat carrier substrate region (4) with a side edge (9) laterally delimiting the carrier substrate (2), at which side edge the at least one electrical line (8) within the joining region (20) is electrically connected to the contact arrangement (11). [3] Medical implant according to claim 1 or 2, characterized byin that the contact arrangement (11) has a plate-shaped carrier (12) to which the at least one electrical line (8) is contacted by means of an electrical contact (15), preferably in the form of a microflex contact, which is electrically connected to an electrode (14) applied to the plate-shaped carrier (12), to which electrode the electrical supply and / or discharge line (15) is electrically connected, and in that the electrical supply and / or discharge line (15) together with the plate-shaped carrier (12) is enclosed by an elastic material which is joined to the carrier substrate (2) in a fluid-tight manner in the joining region (20). [4] Medical implant according to claim 3, characterized byin that the elastic material enclosing the at least one electrical supply and / or discharge line (15) is designed in the manner of a strand (17), with a strand longitudinal extent which is oriented parallel to the winding axis (5) at least in a region directly adjacent to the contact arrangement (11), and in that in the region of the strand (17) containing the at least one electrical supply and / or discharge line (15), a first fastening means (22) comprising a straight-cylindrical cavity, in the manner of a winding sleeve or a helical structure, is attached directly or indirectly, the straight-cylindrical cavity of which is oriented coaxially to the winding axis (5). [5] Medical implant according to claim 4, characterized bythat the strand (17) provides a strand extension (17') opposite the contact arrangement (11) in the strand longitudinal extension, to which a second fastening means (22') in the manner of the first fastening means (22) is attached directly or indirectly. [6] Medical implant according to one of claims 1 to 5, characterized by that the first region (3) of the carrier substrate (2) wound to form the tube has at least one winding around the winding axis, which has at least one winding region in which the carrier substrate (2) overlaps itself radially to the winding axis (5), lying loosely against one another.

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