Implant in the form of a wrapped cuff electrode assembly

Abstract

The present invention relates to a medical implant in the form of a wound cuff electrode assembly, or more specifically a cuff electrode, comprising a flexible and biocompatible film-like carrier substrate, which takes the form of a tube having a tube length by being wound around a winding axis in a first region, the tube having a rectilinear cylindrical cavity delimited radially to the winding axis by a surface of the carrier substrate, on which at least one electrode surface is mounted, the at least one electrode surface being connected via at least one electric wire integrated in the carrier substrate to a non-stretchable contact assembly, on which the at least one electric wire is connected to a power and / or discharge wire leading to an implantable electrical supply unit formed separately from the implant. The invention relates to a medical implant in the form of a wound cuff electrode assembly, which has a spatial longitudinal extension oriented parallel to the winding axis, which contact assembly is fixedly bonded to the carrier substrate along a bonding region and has a bonding region length oriented parallel to the winding axis, the contact assembly in orthogonal projection relative to the winding axis overlapping the first region of the carrier substrate wound to form the tube. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present invention relates to a medical implant in the form of a wound cuff electrode assembly, in particular a cuff electrode suitable for extravascular or extraneural fastening along an internal vessel or nerve fiber bundle, the cuff electrode having a flexible and biocompatible film-like carrier substrate wound around a winding axis and taking the form of a tube having a tube length in a first region, the tube being held against the winding axis by a surface of the carrier substrate carrying at least one electrode surface. radial direction The implant has a linear cylindrical cavity delimited by at least one electrical wire that is connected via at least one electrical wire integrated in the carrier substrate to a non-stretchable contact assembly, at least one electrical wire being connected to a power supply and / or discharge wire leading to an implantable electrical supply unit that is formed separately from the implant. [Background technology]

[0002] Cuff electrodes of the above type are often also attached for recording and applying electrical signals to or from body vessels, particularly to nerve bundles. For this purpose, the cuff electrode has a flexible and biocompatible carrier substrate, the surface of which facing the nerve bundle has attached thereto at least one, and preferably several, electrodes, which must be bonded in intimate physical contact with the surface of the nerve bundle.

[0003] Such a type of cuff electrode is disclosed in WO 2016 / 055512. The carrier substrate of the cuff electrode comprises a polyimide film with mechanical film pretensioning for automatic rolling in the cross-sectional direction at least around the winding axis. The process of rolling the cuff electrode around the nerve bundle brings the individual electrodes of the cuff electrode into direct surface contact with the epineurium of the nerve bundle. The cuff electrode attaches itself to the cylindrical outer surface of the nerve bundle by a forced form-fitting connection, overlapping each other so that the overlapping carrier substrate regions slide loosely over each other throughout the rolling or winding process.

[0004] Electrical wires leading from the individual electrodes of the cuff electrode each extend into the polyimide film, are electrically insulated, and terminate at lateral end regions of the polyimide film that are spatially separated from the wrapped region of the cuff electrode, whereupon the ends of the electrical wires are each connected via an electrical contact assembly to a power supply and a discharge wire, via which the cuff electrode is connected to an implantable electrical supply unit located separately from the cuff electrode within the body. Summary of the Invention [Problem to be solved by the invention]

[0005] Due to the natural sensitivity of nerve fibers to external mechanical influences, the mechanical load acting on the nerve fiber bundle must be kept as low as possible, on the one hand, it must be ensured that the cuff electrode surrounds the nerve fiber bundle sufficiently stably to guarantee a durable and fixed attachment of the cuff electrode along the nerve fiber bundle as possible.

[0006] Practical experience with the use of cuff electrodes shows that, while loose winding of the carrier substrate around the nerve fiber bundle, sometimes in multiple layers, allows dynamic radial expansion of the cuff electrode, thereby enabling it 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 wound shape, thereby subjecting the nerve fiber bundle to significant mechanical stresses that may lead to irreversible damage.

[0007] DE 44 33 111 A1 describes a cuff electrode comprising a flexible multi-layer substrate made of non-conductive silicon on which are mounted raised electrodes made of conductive silicon. Conductive paths leading to the electrodes extend between the non-conductive layers and are manufactured from conductive silicon. The rolled shape of the cuff electrode is created by setting different pre-stresses in the multi-layer structure of the cuff electrode. [Means for solving the problem]

[0008] The object of the present invention is to further develop a cuff electrode with a flexible and biocompatible film-like carrier substrate in such a way that it can apply a force or pressure effect on the nerve fiber bundles as uniformly and gently as possible in the simplest possible ways, the carrier substrate being wound around a winding axis in the first region, so as to take the form of a tube, said tube having a straight cylindrical cavity delimited radially to said winding axis by a surface of said carrier substrate, on said cavity at least one electrode surface being connected via at least one electric wire integrated in said carrier substrate to a non-elastic contact assembly, on which the electric wire is connected to a supply and / or discharge wire leading to an implantable electrical supply unit formed separately from the implant. This should apply in particular in cases where the cuff electrode is stressed by tensions acting along the supply and / or discharge wires, which may be caused for example by the movements of the body itself.

[0009] The solution to the problem underlying the present invention is defined in claim 1. Features which further develop the solution concept are the subject matter of the subclaims and can also be found in the further description.

[0010] According to the solution, a medical implant designed in the form of a wound cuff electrode assembly according to the features of the introductory part of claim 1 is characterized in that the contact assembly is directly and firmly bonded to the carrier substrate along a dimensionally stable bonding area, the bonding area having a spatial extent oriented parallel to the winding axis, the contact assembly in orthogonal projection to the winding axis overlapping a first area of ​​the carrier substrate that is wound to form a tube.

[0011] The inventive design of the cuff electrode involves a special design and application of a contact assembly to a carrier substrate region of the cuff electrode, which is based on experience gained with the known cuff electrode according to WO2016055512, which takes the form of a tube through a rolling or winding process and in the implanted state locally surrounds the nerve fiber bundles. In the known cuff electrode, the region of the film-like carrier substrate directly and integrally adjacent to the first region of the carrier substrate, which is rolled to form a tube, is substantially band- or strip-shaped. All electric wires connected to the electrodes of the cuff electrode run along the band-shaped carrier substrate region. The band-shaped carrier substrate region has a length oriented essentially parallel to the winding axis and is locally connected in the center to the carrier substrate region, which is rolled to form a tube, by a narrow band section formed perpendicularly. In the event of a tension or thrust acting along the band-shaped carrier substrate oriented parallel to the winding axis, an asymmetric force is applied to the region of the carrier substrate, which is rolled to form a tube. Along the winding axis, on one side of the winding carrier substrate, the resulting stress conditions can cause tighter winding and associated contraction, and on the opposite side of the winding carrier substrate area, can cause expansion and associated localized relaxation, which subjects the intrinsic nerve bundles to significant non-uniform pressure or force effects.

[0012] The embodiment according to the solution prevents such a situation of asymmetrical stress acting on the nerve bundle in that the contact assembly made of a non-flexible material, such as ceramic, acts as a kind of force coupler, transmitting tension and / or thrust forces acting along the feed and / or discharge lines as uniformly as possible to the carrier substrate area wound to form the tube, in that it is applied around the nerve bundle like a cuff. This also avoids asymmetrical winding shapes, where one end of the tube has a smaller diameter and the other end has a larger diameter. Advantageously, the transmission of forces via the contact assembly to the carrier substrate area wound to form the tube is uniform along the entire axial length of the tube. In this way, any shear forces acting on the nerve bundle can be avoided. Advantageously, the contact assembly and the carrier substrate are connected via a coupling area with a coupling area length oriented parallel to the winding length, which corresponds maximally to the mutual overlap between the contact assembly and the tube in the orthogonal projection on the winding axis. Here, it is particularly advantageous if the longitudinal extension of the contact assembly is equal to or greater than the tube length.

[0013] Example embodiments may include contact assemblies in which the dimensions of the longitudinal extensions, tube lengths, and lengths of the bonding regions are different from one another, but in these cases the contact assemblies must be able to be firmly bonded to the carrier substrate such that the longitudinal extensions, tube lengths, and lengths of the bonding regions of the contact assemblies each have a common central axis oriented perpendicular to the winding axis.

[0014] Preferably, the contact assembly comprises a plate-shaped carrier on which at least one electric wire on the cuff electrode side is in contact with an electrode attached to the carrier, preferably by means of a microflex contact. The electrode on the carrier side is then connected to a further electrode surface which is applied separately to the carrier and to which the power supply and / or discharge wires leading to a separate supply unit are electrically connected by means of a welded, soldered or adhesive connection. The plate-shaped carrier can of course have a plurality of such electrode / electrode surface pairs, via which a corresponding number of electric wires on the cuff electrode side are combined into one cable strand and connected to the corresponding power supply and / or discharge wires.

[0015] The power supply and / or discharge wire or multiple power supply and discharge wires combined with the plate-shaped carrier into one cable strand are surrounded by an elastic material which is joined fluid-tight to the carrier substrate in the joining area. The elastic material which fluid-tightly surrounds the at least one power supply and / or discharge wire in a tube or matrix form a strand having a longitudinal extension, the length of which is determined according to the separate positioning in the body of the cuff electrode and the supply unit.

[0016] Compared to the carrier width, the plate-shaped carrier has a much longer dimension, the carrier length, with its longitudinal extension oriented parallel to the winding axis. The relatively narrow carrier shape is preferably dimensioned in such a way that it is embedded without or substantially without shape change in the strand along which the at least one power supply and / or discharge wire is integrated. Specific forms of embodiment are described in more detail below.

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

[0018] In a further preferred embodiment, the strands or tubes envisage a strand extension adjacent to the contact assembly, on which second fastening means of the same type as the first fastening means described above are formed and attached directly or indirectly. In this way, tension and / or thrust forces acting along the supply and / or discharge wires can be transmitted in a biased or symmetrically distributed manner with respect to the forcing electrode arrangement along the nerve bundle.

[0019] All electrical conductor structures applied to the carrier substrate, including at least one electrode surface and at least one wire electrically connected to the electrode surface, are each integrally fabricated, preferably by a metal deposition process, such that there are no junctions along the electrical conductor structure and no associated discontinuous electrical impedance differences. [Brief description of the drawings]

[0020] The invention will now be described by way of example embodiments with reference to the drawings, without limiting the general inventive concept. [Figure 1] 1 shows an example embodiment of a medical implant designed according to the solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] FIG. 1 shows a cuff electrode 1 configured in the form of a wound cuff electrode assembly with a carrier substrate 2 configured in the form of a film, 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, which is wound to form a tube, maintains its wound shape due to the tension inherent in the material imposed by a suitable treatment of the film-like carrier substrate 2, for example by heat treatment, and has a rectilinear cylindrical cavity 6 axially open on both sides. Facing the rectilinear cylindrical cavity 6, on the surface of the first region 3 of the carrier substrate 2, which is wound to form a tube, there is at least one electrode surface 7, preferably several such electrode surfaces, in each case in direct physical contact with the outer wall of the nerve fiber bundle, not shown in further detail. Each of the electrode surfaces 7 is in integral contact with an electric wire 8, all of which extend into the carrier substrate 2 so as to be electrically insulated.

[0022] The second region 4 of the carrier substrate 2, which is integrally and directly adjacent to the first region 3 of the carrier substrate 2, has a side edge 9 facing away from the first region 3, along which the ends of the electric wires 8 are arranged next to each other and contact electrodes attached via microflex contacts 10 to a contact assembly 11. The contact assembly 11 is preferably configured in the form of a plate-shaped carrier 12 with a ceramic plate and has a longitudinal extension 13. The length of the carrier 12 is much greater than its width.

[0023] The electrodes mounted on the plate-shaped carrier 12 connect each electric wire 8 to an electrical contact surface 14 at the top of the plate-shaped carrier 12, on which the power supply and / or discharge wires 15 are electrically contacted by soldering, gluing or welding connections and are connected to the contact assembly 11 towards the left side as shown in FIG. 1. All power supply and discharge wires 15 connected to each contact surface 14 are combined into a cable strand 15* and lead to a supply unit 16, formed separately from the cuff electrode 1, which provides control signals and electrical energy for operating the cuff electrode 1, for example. The wire-like power supply and discharge wires 15 combined into the cable strand 15* are connected to the supply unit 16 via a liquid-tight plug connection (not shown) for separate operation of the supply unit 16, for example for replacement. For electrical insulation and protection from the moist body environment, the cable strand 15* including all power supply and discharge wires 15 is surrounded by or embedded in a silicone tube 17.

[0024] The tension or thrust 18 acting along the silicon strands 17 acts as evenly distributed as possible along the entire length 19 of the first region 3 of the carrier substrate 2 wound to form a tube, and the joint area 20 between the contact assembly 11 and the second region 4 of the carrier substrate 2, where the carrier substrate 2 is joined to the surface of the plate-like carrier 12 of the contact assembly 11 with a firmly bonded joint connection, is at least partially, preferably completely, arranged in an orthogonal projection with respect to the winding axis 5 and overlaps with the axial extension 19 of the region 3 of the carrier substrate 2 wound to form a tube, as shown in FIG. 1. Regardless of the actual dimensions of each length of the contact assembly 11, the joint area 20 and the first region 3 of the carrier substrate 2 wound to form a tube, the longitudinal extension (13) of the contact assembly (11), the tube length (19) and the joint area length (21) preferably have a common central axis (24) oriented perpendicular to the winding axis (5).

[0025] 1, the bonding area 20 has a longitudinal extension 21 that corresponds approximately to the length 19 of the portion 3 of the carrier substrate 2 that is wound to form a tube. In this case, the transmission of forces by the contact assembly 11 to the carrier substrate 2 is carried out via the bonding area 20 evenly over the entire length 19.

[0026] Optionally, fastening means 22, 22' can be provided either on the one hand to the cuff electrode 1 along the winding axis 5 or on the other hand to the cuff electrode 1, which can be positioned around the circumference of the nerve bundle when a force is applied like the cuff electrode 1. The fastening means 22, 22' can be in the form of a wound cuff or a known helical structure, preferably made of a silicone material. The fastening means 22 on the left side of the figure is attached directly to the silicone strands 17 via a connection 23. The connection 23 is preferably designed as an integral adhesive connection, i.e. the fastening means 22, the connection 23 and the silicone strands 17 are made from the same material as part of a uniform manufacturing process. The connection 23 can be configured in the form of a seamless transition between the silicone strands 17 and the fastening means 22 to a spatially combined shape, for example in the form of a straight, zigzag, wavy, spiral or helical connecting arm. The fastening means 22', also optionally provided on the right side of the cuff electrode 1, is attached to the strand extension 17'. In this case too, the connection portion 23' can be designed in a similar manner as above. [Explanation of symbols]

[0027] 1 Cuff electrode 2 Carrier Board 3. First area of ​​carrier substrate 4. Second area of ​​carrier substrate 5 Reel shaft 6 Straight cylindrical cavity 7 Electrode surface 8 Electrical Conductors 9 Carrier board connection edge 10 Microflex Contacts 11 Contact Assembly 12 Plate carrier 13 Longitudinal extension of contact assembly 14 Electrode surface 15 Power supply and / or discharge section 15* Cable Strands 16 Supply Unit 17 Silicone Strand 17' Stranded Wire Extension 18 Thrust-Tension 19 Length of the second region 3 of the carrier substrate that is rolled to form a tube 20 Joint area 21 Length of the joint area 22, 22' Fastening means 23, 23' Connection 24 Center axis

Claims

[Claim 1] 1. A medical implant of a wraparound cuff electrode, comprising: The medical implant comprises: a flexible, biocompatible film; A non-flexible contact assembly (11); Equipped with the film has a first region (3), the first region (3) being wound around an imaginary winding axis (5), the first region (3) forming a tube delimiting a cylindrical cavity in a radial direction with respect to the imaginary winding axis (5), the film having at least one electrode surface (7) on an inner surface of the first region (3), the film having at least one electric wire (8) arranged on the film, the at least one electric wire (8) being connected to the rigid contact assembly (11), in which the at least one electric wire (8) is connected to a power supply line (15), the power supply line (15) being connected to an implantable electrical supply (16) separate from the implant, The non-flexible contact assembly (11) has a plate-shaped carrier (12) having a carrier length longer than a carrier width, the longitudinal extension of the contact assembly (11) extends parallel to the imaginary winding axis (5), and the non-flexible contact assembly (11) is bonded to the film along a bonding area (20) having a bonding area length (21) extending parallel to the imaginary winding axis (5); On the plate carrier (12), the at least one electric wire (8) is connected to an electrical contact to which at least one power supply line (15) is electrically connected; the non-flexible contact assembly (11) is arranged to overlap the first region (3) forming the tube when projected orthogonally with respect to the imaginary winding axis (5); At least one of the power supply lines (15) and the plate-like carrier (12) are both surrounded by an elastic material (17) in the joining area, thereby providing a liquid-tight connection between the power supply line (15) and the plate-like carrier (12). A medical implant characterized by:

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