Nerve cuff, method and apparatus for manufacturing same

A nerve cuff comprising a wall band member having an inner surface defining a lumen when the wall band member is in a closed configuration for receiving a nerve therethrough. At least one longitudinal and contiguous conductor extends within the lumen. The conductor is insulated and has at least one exposed portion thereby providing an electrode. When mounting the nerve cuff to a nerve, each electrode is in electrical communication with the nerve. A multi-channel nerve cuff further comprises a plurality of longitudinal ridges formed on the inner surface with each adjacent pair of ridges defining a longitudinal chamber. Each chamber comprises a respective conductor extending therein. When mounting the multi-channel nerve cuff to the nerve, the ridges abut the nerve providing for each chamber to isolate respective longitudinal portions of the nerve. A method and an apparatus for manufacturing such nerve cuffs are also disclosed.

FIELD OF THE INVENTION

The present invention relates to a nerve cuff for stimulating and monitoring electrical activity in nerve tissues in human beings and other creatures possessing a nervous system. The present invention also relates to method and apparatus for manufacturing a nerve cuff.

BACKGROUND OF THE INVENTION

Various types of cuff transducers intended for use as electrical or chemical interfaces with neural tissue have been described in the literature. These nerve cuffs typically have a tubular biocompatible dielectric material wall. In nerve cuffs designed to provide an electrical interface to tissues inside the nerve cuff, the inside of the nerve cuff wall supports one or more metal electrodes. Leads from the electrodes extend through and are supported by the nerve cuff wall. The nerve cuff walls must be sufficiently rigid to support the leads and electrodes. The leads may be connected to suitable signal-conditioning devices or electrical stimulation devices.

Nerve cuff electrodes have been used in stimulation systems with the goal of providing partial voluntary control of muscles that have been paralyzed as a result of lesions caused by spinal cord injury, stroke, or other central neurological system disorders. In some cases, partial motor function may be restored by stimulating motor neurons or muscles below the level of the lesion. Nerve cuffs may also be used as sources for the measurement of the neurological signal of the peripheral nervous system and for feedback of closed-loop functional electrical stimulation (FES) systems.

As such, there is increasing interest in the use of nerve cuffs to preferentially monitor and/or stimulate activity in selected axons within a nerve bundle. Hoffer et al., U.S. Pat. No. 5,824,027, which is incorporated herein by reference in its entirety, describes a multi-channel nerve cuff having longitudinal ridges extending along the interior walls of the nerve cuff.

The ridges divide the volume between the nerve cuff wall and the tissues within the nerve cuff into separate chambers. Electrodes are located in the chambers. This cuff structure can provide improved nerve signal recording selectivity and enhanced stimulation selectivity as compared to conventional nerve cuffs which lack separate chambers.

Fabricating a multi-chamber, multi-channel nerve cuff having one or more independent electrodes in each of several chambers is challenging, especially where the cuff is small in size. It is frequently desirable to provide nerve cuffs having internal diameters of only 2-3 mm. The challenge is compounded by the fact that such cuffs should be fabricated from material which is sufficiently flexible to minimize damage to delicate neural tissue, such as may occur with compression, sharp bending and/or stretching of the tissue. Suitable materials, such as biocompatible silicone compositions may stretch when they are manipulated. This flexibility in the nerve cuff wall may make it difficult to place electrodes in precisely determined locations and to keep the electrodes in position.

Tyler, et al. U.S. Pat. No. 5,634,462, which is incorporated herein by reference in its entirety, describes multi-channel nerve cuffs constructed of stiff material. The Tyler et al. nerve cuffs are designed to deform and even penetrate a nerve, with the objective off approximating electrodes to more centrally located axons in nerves. A problem with this type of device is the possibility that the nerve could be damaged by the nerve cuff.

There is a need for methods to more readily accurately fabricate multi-channel nerve cuffs. Nerve cuffs used for making recordings of electrical activity within nerve tissues should provide good electrical isolation of the tissues within the nerve cuffs. There is also a need for nerve cuffs which may provide better isolation from externally generated electrical noise than is provided by current cuff designs. There is further needed a nerve cuff that may be used effectively to selectively stimulate or record from targeted subpopulations of nerve fibers in a nerve and may be used on nerves which could be damaged by penetration.

OBJECTS OF THE INVENTION

An object of the present invention to provide a nerve cuff.

Another object of the present invention is to provide a multi-channel nerve cuff.

A further object of the present invention is to provide a method of manufacturing a nerve cuff.

Another object of the present invention is to provide an apparatus for manufacturing a nerve cuff.

SUMMARY OF THE INVENTION

in accordance with an aspect of the present invention there is provided a nerve cuff comprising: a wall band member having an inner surface defining a lumen when the wall band member is in a closed configuration for receiving a nerve therethrough; and at least one longitudinal and contiguous conductor extending within the lumen, the conductor being insulated and having at least one exposed portion thereof, thereby providing an electrode, wherein, when mounting the nerve cuff to a nerve, each electrode is in electrical communication with the nerve.

In an embodiment, this nerve cuff further comprises a plurality of longitudinal ridges formed on the inner surface, each adjacent pair of ridges defining a longitudinal chamber, each chamber comprising a respective conductor extending therein, wherein, when mounting the nerve cuff to the nerve, the ridges abut the nerve providing for each chamber to isolate respective longitudinal portions of the nerve.

In accordance with another aspect of the present invention, there is provided a nerve cuff comprising: a wall band member having an inner surface defining a lumen when the wall band member is in a closed configuration for receiving a nerve therethrough; at least one longitudinal protuberance on the inner surface extending within said lumen; and at least one electrode mounted to the longitudinal protuberance, wherein, when mounting the nerve cuff to a nerve, the at least one longitudinal protuberance provides for the electrode to be in contact with or at least near the surface of the nerve.

In an embodiment, this nerve cuff further comprises a plurality of longitudinal ridges formed on the inner surface, each adjacent pair of said ridges defining a longitudinal chamber, each chamber comprising a longitudinal protuberance extending therein, wherein, when mounting the nerve cuff to a nerve, the ridges abut the nerve providing for each chamber to isolate respective longitudinal portions of the nerve.

In accordance with a further aspect of the present invention, there is provided a nerve cuff comprising: a wall band member having an inner surface defining a lumen when the wall band member is in a closed configuration for receiving a nerve therethrough; a plurality of longitudinal ridges formed on the inner surface, each adjacent pair of ridges defining a longitudinal chamber; a longitudinal protuberance extending within each chamber; and a longitudinal and contiguous conductor mounted to each longitudinal protuberance, the conductor being insulated and having at least one exposed portion thereof thereby providing an electrode, wherein, when mounting the nerve cuff to a nerve, the ridges abut the nerve providing for each chamber to isolate respective longitudinal portions of the nerve, each longitudinal protuberance providing for an electrode to be in contact with or at least near the surface of the nerve.

In accordance with yet another aspect of the present invention there is provided a method of manufacturing a nerve cuff, the method comprising: (a) providing a mold comprising a plurality of longitudinal grooves; (b) positioning longitudinal conductors coated with insulation within respective longitudinal grooves; (c) applying flexible bio-compatible material on the mold with the longitudinal conductors positioned therein; (d) curing the flexible bio-compatible material so as to provide a wall band member with the longitudinal conductors adhered thereto; (e) ejecting the wall band member with the adhered longitudinal conductors; and (f) removing lengths of the insulation on the longitudinal conductors thereby providing electrodes.

In an embodiment, step (b) further comprises positioning longitudinal tubes within the longitudinal grooves, step (c) comprising applying flexible bio-compatible material on the mold with the longitudinal conductors and the longitudinal tubes positioned therein, curing in step (d) providing for the longitudinal tubes to adhere to the wall band member and step (e) comprising ejecting the wall band member with the adhered longitudinal conductors and longitudinal tubes.

In accordance with yet a further aspect of the invention, there is provided an apparatus for manufacturing a nerve cuff, the apparatus comprising: a base; at least one open mold formed within the top face of the base, the mold comprising longitudinal grooves for positioning longitudinal conductors therein; end plates positioned near each end of the base, each end plate comprising alignment holes for aligning the conductors positioned in said grooves; and first and second conductor clamps for clamping the conductors near each longitudinal end thereof respectively, at least one of the first and second conductor clamps being so moveable as to tighten the clamped conductors, wherein when the conductors are positioned in the grooves and tightened, a flexible bio-compatible material can be applied to said mould for providing the nerve cuff.

In an embodiment, the longitudinal grooves comprise conductor grooves for receiving conductors therein and tubing grooves for receiving tubes therein. In an embodiment, the tubing grooves comprise ridge grooves for positioning ridge tubes therein and closure element grooves for receiving closure element tubes therein.

In accordance with still another aspect of the present invention, there is provided a multi-channel nerve cuff comprising a wall band member having an inner surface defining a lumen when said wall band member is in a closed configuration for receiving a nerve therethrough, the inner surface defining a plurality of channels, each channel including a plurality of electrodes, each electrode of a same channel provided from a same conductor, wherein, when mounting the nerve cuff to a nerve, each electrode is in electrical communication with the nerve.

In an embodiment, the electrodes of the same conductor comprise indifferent electrodes and recording electrodes.

Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Generally stated, an implantable interface in the form of a nerve cuff, hereinafter referred to as “nerve cuff”, according to an illustrative embodiment of the present invention is used for stimulating and/or monitoring electrical activity in nerve tissues in human beings or other creatures possessing nervous systems. The interface may have particular application in functional electrical stimulation (“FES”) of the neuromuscular system.

Referring toFIGS. 1 and 2, there is shown a non-limitative illustrative embodiment of a nerve cuff10in a closed configuration (FIG. 1) and in an open configuration (FIG. 2). The nerve cuff10has a wall member20in the form of a band which has a generally tubular configuration when in a closed configuration, as shown inFIG. 1. This wall band member or wall member20defines a lumen30, when it is in the closed configuration, which is sized to receive a nerve or other bodily tissue. The surface of the wall band member20which defines the lumen30and which is interfaced to a nerve N (seeFIG. 14) is the inner surface of the wall band member20. A closure22allows the nerve cuff10to be opened to receive a nerve N (seeFIG. 14) or other bodily tissue in lumen30. Closure22may then be closed to isolate the bodily tissue within lumen30. The closure22may be any suitable closure, however, the closure22advantageously comprises interdigitating closing elements24affixed on either lateral side of the wall band member20combined with a sealing tube25. Closure22may be secured in a closed configuration by inserting a rod-like member (not shown) through interdigitated closing members24.

Five longitudinal ridges31,32,33,34and35and four longitudinal conductors in the form of pairs of elevated contiguous electrode wires (41,42), (43,44), (45,46) and (47,48) extending along the inner surface within the lumen30delimitate, in alternating disposition, eight chambers51,52,53,54,55,56,57and58, as best seen inFIG. 2. It is to be understood that while the nerve cuff10of the illustrative embodiment contains eight chambers51,52,53,54,55,56,57and58, the nerve cuff10may have a different number of chambers and/or ridges and/or pairs of elevated electrodes, depending on the application.

The example shown herein is a multi-channel nerve cuff10, yet nerve cuffs with a single channel can also be provided within scope of the present invention. It should also be noted that the longitudinal conductors exemplified herein are not limited to pairs of wires but include other suitable conductors known in the art.

Other types of electrodes can also be provided within the scope of the invention. Hence, rather than longitudinal contiguous conductors short discontinuous conducting elements, whether wires or other elements can also be contemplated.

Furthermore, in another embodiment, the wall member20may have a port (such as an opening) located within one or more of the chambers51,52,53,54,55,56,57and58so as to allow connection to an agent delivery system for agents such as, for example, a pharmaceutical agent.

FIG. 14, illustrates the nerve cuff10in use mounted to a nerve N and secured thereto via closure22. The ridges31,32,33,34and35abut the nerve N, providing for each chamber54,55,56,57and58to isolate respective longitudinal regions of the nerve N. The electrodes (referenced herein below) are in contact or at least substantially near the nerve N.

In the following description, the specific components used are meant as examples only so as to describe a functional realization of the illustrative embodiment and are not meant to limit the present invention to these specific components.

Wall Member

The wall member20may be made by molding implant grade silicone, for example room temperature vulcanizing (RTV) silicone. It is to be understood that other suitable implant grade may be used.

Ridges

The ridges31,32,33,34and35consist of generally parallel commercial silicone tubing such as, for example, 0.025″×0.012″ silicone tubing from Allied Biomedical (AlliedSil™). The ridges31,32,33,34and35enclose a ground wire36, which may be fabricated using, for example, a hard temper type of wire such as 316 LVM wire, 1×19×0.0012; 0.006 (Fort Wayne Metals Production Number 72073; Hard temper), with a 0.003″ thick ETFE insulation for a total outer diameter of 0.012″. The ground wire36comprises a lead36aand a contact section36b. The ground wire contact section36b, which is de-insulated, is sequentially passed through the tubing forming the ridges31,32,33,34and35in a systematic pattern so that the ground wire contact portion36bis exposed between any two consecutive ridges31,32,33,34and35. As for the ground wire lead36a, it remains insulated over the entire length from the edge of the nerve cuff10to its end for connection to some further interface or device (not shown).

In its suggested routing, the ground wire contact section36bis first inserted through the proximal end33aof the middle ridge33to its distal end33b, then goes from the distal end33bof the middle ridge33to the distal end of an adjacent ridge, for example the distal end32bof ridge32, to its proximal end32a. From the proximal end32aof ridge32the ground wire contact section38bgoes to the proximal end31aof outer ridge31, to its distal end31b. From the distal end31bof ridge31the ground wire contact section36bgoes to the distal end32bof ridge32, to its proximal end32a. Finally, from the proximal end32aof ridge32the ground wire contact section36bgoes to the proximal end33aof middle ridge33, to its distal end33b. This crisscross pattern is continued through ridges34and35until it makes a final pass from the proximal end33aof the middle ridge33to its distal end33b.

The result is that the middle ridge33encloses three passes of the ground wire contact section36b, the intermediate ridges32,34enclose two passes of the ground wire contact section36band the outermost ground wire ridges31,35enclose one pass of the ground wire contact section36b.

In order to prevent the ends of the ridges31,32,33,34and35tubing from being deformed, the radius of curvature of the ground wire contact section36bas it exits the tubing may be approximately 0.8 mm and the contact section36bmay be generally straight between adjacent ridges. A jig can also be used in order to provide for the loops of ground wire to be consistent.

Once the ground wire36has been positioned within the ridges31,32,33,34and35, the end of each ridge31,32,33,34and35is sealed with an adhesive silicone plug37. The length of the adhesive silicone plug37inside each ridge31,32,33,34and35being generally from about 1.0 mm to 1.5 mm and protruding in a generally dome shape.

Electrodes

The wire used for the electrode wires (41,42), (43,44), (45,46) and (47,48) may be, for example, a 316 LVM wire, 1×19×0.0012; 0.006 (Fort Wayne Metals Production Number 72073; Hard temper), with a 0.003″ thick ETFE insulation (Tempflex) for a total outer diameter of 0.012″ or PT—Ir 70-30.

As best seen inFIG. 3, the pairs of electrode wires (41,42), (43,44), (45,46) and (47,48) may be positioned on top of longitudinal protuberances26, extending along the inner surface into the lumen30, so as to be generally at the same level as the ridges31,32,33,34and35relative to the inner surface of the wall band member20. This elevation with respect to the surface of the wall member20allows the electrode wires (41,42), (43,44), (45,46) and (47,48) to be located at least near the surface the nerve or to be in contact with the nerve, this diminishes the nerve/electrode impedance and results in higher sensibility to nerve activity.

In an another embodiment, the protuberances26may be omitted so that the electrode wires (41,42), (43,44), (45,46) and (47,48) or other conducting elements lay directly upon the surface of the wall member20. In still another embodiment, the electrode wires (41,42), (43,44), (45,46) and (47,48) or other conducting elements may be embedded within the protuberances26, the protuberances may be apertured in order to expose the electrode wires or other conductors. In yet another embodiment, the electrode wires (41,42), (43,44), (45,46) and (47,48) or other conducting elements are embedded within the wall member20, with the wall member20being apertured in order to expose the electrode wires or other conductors.

Referring back toFIG. 2, the pairs of electrode wires (41,42), (43,44), (45,46) and (47,48) are used to create electrodes (61a,61b,62), (63a,63b,64), (65a,65b,66) and (67a,67b,68), respectively, in “tri-polar” or “quasi-tri-polar” configurations. This means that each electrode channel71,72,73and74comprises two indifferent electrodes (61a,61b), (63a,63b), (65a,65b) and (67a,67b) and one recording electrode62,64,66and68, respectively. The indifferent electrodes (61a,61b), (63a,63b), (65a,65b) and (67a,67b) may be advantageously positioned symmetrically with respect to the total length of the nerve cuff10, a first set of indifferent electrodes61a,63a,65aand67abeing located near the proximal end10aof the nerve cuff10and a second set of indifferent electrodes61b,63b,65band67bbeing located near the distal end10bof the nerve cuff10. The recording electrodes62,64,66and68may be advantageously located in the center10cof the nerve cuff10.

The electrodes (61a,61b,62), (63a,63b,64), (65a,65b,66) and (67a,67b,68) may be created by removing part of the ETFE insulation of the corresponding electrode wires (41,42), (43,44), (45,46) and (47,48). By creating the indifferent electrodes (61a,61b), (63a,63b), (65a,65b) and (67a,67b) from the same electrode wire41,43,45and47for each corresponding electrode channel71,72,73and74, this avoids welding and provides a proper impedance match. The recording electrodes64,64,66and68may be created from the remaining electrode wire42,44,46and48of each corresponding electrode channel71,72,73and74. The method used for the creation of the electrodes (61a,61b,62), (63a,63b,64), (65a,65b,66) and (67a,67b,68) will be further described later on.

In another alternative embodiment (not shown), the pairs of electrode wires (41,42), (43,44), (45,46) and (47,48) may be used to create electrodes in “bi-polar” configurations. This means that each electrode channel71,72,73and74comprises one indifferent electrode and one recording electrode. The indifferent electrodes and the recording electrodes may be positioned at opposed ends of the nerve cuff10. For example, the indifferent electrodes may be located near the proximal end10aof the nerve cuff10and the recording electrodes may be located near the distal10bend of the nerve cuff10.

Therefore, a single longitudinal and contiguous conductor such as a pair of insulated wires can be used to provide for one or more electrodes when removing lengths thereof, hence facilitating the manufacturing of such nerve cuffs as well as their efficacy.

Electrode Capping

The electrode wires (41,42), (43,44), (45,46) and (47,48) are positioned so as to protrude approximately 2.0 mm beyond the wall member20. The protruding ends of the electrode wires (41,42), (43,44), (45,46) and (47,48) are covered by RTV silicone forming an electrode cap49, as may be seen inFIGS. 1,2and4A. However, before the application of the RTV silicone, the outer surface83of the ETFE insulation on the protruding end of the electrode wires (41,42), (43,44), (45,46) and (47,48) is etched to ensure proper bonding of the RTV silicone forming the cap49.

In another embodiment the electrode wires (41,42), (43,44), (45,46) and (47,48) may be cut or positioned so as not to protrude beyond the wall member20(not shown). In this embodiment, some RTV silicone would flow over the end of the electrode wires (41,42), (43,44), (45,46) and (47,48) and mainly bond to the exposed inner surface82of the ETFE insulation, as shown inFIG. 4B. The issue with this embodiment is that the inner surface82of the ETFE insulation may not be etched because the etching solution may migrate to the core81of the electrode wires (41,42), (43,44), (45,46) and (47,48). Thus, the bonding of the RTV silicone to the electrode wires (41,42), (43,44), (45,46) and (47,48) is not as strong as in the illustrative embodiment. Therefore, the silicone cap49could possibly separate from the end of the electrode wires (41,42), (43,44), (45,46) and (47,48) and allow for the core81to be exposed.

Closure

The closure22is fabricated from a single length of implant grade commercial silicone tubing, for example AlliedSil™ Tubing 0.012″×0.025″. In the illustrative embodiment shown inFIGS. 1 and 2, the tubing is cut into closing elements24in the form of tubular links on each side of the nerve cuff10to realize a piano hinge interlocking system. The closing elements24on one side of the nerve cuff10are combined with a sealing tube25extending the whole length of the nerve cuff10. When the nerve cuff10is in a closed configuration, as best seen inFIG. 1, the sealing tube25rest right under the closure22filling the space between outer ridges31and35, effectively creating a seal preventing bodily fluids from passing through the closure22. As mentioned previously, the closure22may be secured in the closed configuration by inserting a rod-like member, for example a standard permanent polypropylene suture wire, through the interdigitated closing members24.

It is to be understood that the sealing tube25may be any other suitable sealing means bridging the gap between outer ridges31and35, or may be filled instead of hollow.

Cuff Width, Nerve Circumference, Ridge and Closing Members Tubing Diameter Relation

For a single nerve cuff10, Equation 1 shows the relationship between nerve cuff width (W), nerve circumference (NC), ridge tubing diameter (φRT) and closing members tubing diameter (CE).
NC=W+4.1416·CE−6.2832·φRT−2.3939 mm.  Equation 1
Manufacturing

The nerve cuff10may be manufactured using a cast silicone process performed in an apparatus100for manufacturing a nerve cuff having open molds102A and102B, as shown inFIGS. 5 and 6. Although the illustrated embodiment of the molding apparatus100shows two molds102A and102B, it is to be understood that the molding apparatus100may have a single mold or more than two molds.

The molds102A and102B are formed within the top face of a base104on which are operatively connected electrode wire clamps106, tubing clamps108, end plates109and tightness adjustment mechanisms200. Guiding members110, which are inserted into guiding slots111, are used to properly align the end plates109and tightness adjustment mechanisms200to base104, while securing members112interact with securing slots113to secure the electrode wire clamps106, the tubing clamps108and the end plates109to the base104.

A coating is applied to the molds102A and102B to prevent the RTV Silicone form bonding to the molds102A and102B. The coating may be, for example, a one time spray-on baked finish Teflon coating (ProteKote 840) by Pro-Tek Coatings or Poly-Ond by Polycoatings. The coating may be, for example a spray-on baked finish as PFA coating (420-703 Primer and 857-210 Topcoat) by Dupont or Liquid bath process deposition (Poly-Ond by Polycoatings) to give but a few examples.

Referring toFIGS. 7 and 8, the molds102A and102B grooves130may be created in the base104using wire electric discharge machining (EDM) or high speed CNC machining. The grooves130serve to properly retain the silicone tubes24,31,32,33,34and35and electrode wires41,42,43,44,45,46,47and48during the molding process. The two grooves130athat retain the closing elements24tubing are not as deep as the ridges31,32,33,34and35tubing grooves130band the electrode wires41,42,43,44,45,46,47and48grooves130cdue to the cuff geometry.

Referring now toFIG. 13, the closing elements24tubing and ridges31,32,33,34and35tubing are secured into their respective grooves130aand130bby the tubing clamps108and associated securing members112. As for the electrode wires41,42,43,44,45,46,47and48, they are aligned in their respective grooves130cby having each of their ends pass through alignment holes122in the end plates109, best seen inFIG. 9, secured at one end using wire clamps106and associated securing members112, and their tightness adjusted using the tightness adjustment mechanism200.

Referring toFIGS. 10 and 11, the tightness adjustment mechanism200includes a main body201and an electrode clamp202, which may be secured to the main body201using associated securing members212and corresponding securing slots213. Since the electrode wires41,42,43,44,45,46,47and48secured by the tightness adjustment mechanism200comprise part of the final product, 2 flexible silicone rubber plates are glued on the main body201and the electrode clamp202, best seen inFIG. 6, to protect the electrode wires41,42,43,44,45,46,47and48when secured by the electrode clamp202. The flexible silicone rubber plates made of high-consistency rubber (HCR) are cut in commercial implantable sheet grade from Allie Biomedical. When the electrode wires41,42,43,44,45,46,47and48are secured between the main body201and the electrode clamp202, the tightness of the electrode wires41,42,43,44,45,46,47and48may be adjusted by rotating the tightness adjustment member214. The tightness adjustment member212, which is inserted in a threaded hole215within the main body201, may be rotated until it enters in contact with the end plate109, which displaces the tightness adjustment mechanism200away from the base104of the molding apparatus100. The tightness adjustment member214may then be rotated, moving the tightness adjustment mechanism200farther away, until the desired tightness of the electrode wires41,42,43,44,45,46,47and48is achieved.

The method for manufacturing of the nerve cuff10is depicted by the flow diagram shown inFIG. 12. The steps of the method are indicated by blocks302to334. The method begins at block302where the mold is cleaned, for example with a 70% 2-propanol solution.

Then, at block304, the electrode wires41,42,43,44,45,46,47and48are cut to appropriate lengths and etched. The etching ensures an appropriate adherence between the RTV silicone and ETFE coated electrode wires41,42,43,44,45,46,47and48.

At block306, the electrode wires41,42,43,44,45,46,47and48are inserted inside the alignment holes122of the end plates109, which are then positioned such that the electrode wires41,42,43,44,45,46,47and48rest in their corresponding grooves130cand secured to the base104of the molding apparatus100using the guiding members110and securing members112. The strain of the electrode wires41,42,43,44,45,46,47and48is then adjusted with tightness adjustment mechanism200.

At block308, the closing elements24tubing and the ridges31,32,33,34and35tubing are placed in their respective grooves130aand130b. Advantageously, small stainless steel rods may be positioned inside the closing elements24tubing and the ridges31,32,33,34and35tubing in order to prevent movement during the molding process and insure their proper alignment. The electrode wire clamps106and tubing clamps108are then tightened, using their respective securing members112, to prevent displacement of the closing elements24tubing, the ridges31,32,33,34and35tubing and the electrode wires41,42,43,44,45,46,47and48.

Then, at block310, implant grade silicone120, for example RTV silicone, is poured onto the mold102to form the wall member20. The wall member20serves to adhere to and support the closing elements24along both edges of the nerve cuff10, the ridges31,32,33,34and35and the electrode wires41,42,43,44,45,46,47and48. To ensure that the thickness of the wall member20is generally uniform throughout the nerve cuff10, excess silicone is removed with, for example, a clean Teflon coated razor blade using flat surfaces105, as may be seen inFIG. 13, on each side of the mold102as guides. Advantageously, the length of the mold102may be twice the length of the nerve cuff10. This is to help stabilize the razor blade movement over the implant grade silicone120and provide a good surface finish. It is advantageous, in order to avoid flash (spilling), the blade is passed a second time hence, step310can be repeated which will result in a more consistent thickness.

At block312, the wall member20is ejected from the mold102. It is to be understood that the wall member20is not to be ejected from the mold102until a suitable amount of time has elapsed since the pouring of the implant grade silicone120to allow the implant grade silicone120to properly cure. This period of time may vary depending on the type of implant grade silicone120used, for example a period of 24 hours may be used in the case of RTV silicone.

At block314, the electrodes (61a,61b,62), (63a,63b,64), (65a,65b,66) and (67a,67b,68) are created by removing lengths of ETFE insulation from the electrode wires41,42,43,44,45,46,47and48. The ETFE insulation may be removed using, for example, a CO2TEA (transverse excited atmospheric) laser for a first rough pass followed by an Excimer laser to remove the thin layer of coating that may have been left by the CO2TEA, thus exposing the core81of the electrode wires41,42,43,44,45,46,47and48. The indifferent electrodes (61a,61b), (63a,63b), (65a,65b) and (67a,67b) being positioned generally symmetrically at the extremities of the nerve cuff10while the recording electrodes are generally positioned in the center of the nerve cuff10with respect to its total length.

Then, at block316, the closing elements24are cut from the closing elements24tubing using, for example, a Nd-Yag laser (or a Co2 TEA laser) for example, such that the closing elements24on each side of the nerve cuff10form an interdigitating pattern such as shown inFIG. 2.

At block318, the electrode wires41,42,43,44,45,46,47and48are cut using, for example, a Nd-Yag laser (or a Co2 TEA laser) or cutters, such that they protrude beyond the desired length of the wall member20by approximately 2.0 mm.

At block320, the unused portion of the wall member20is cut to the desired length using, for example, pliers, cutters and the like.

Then, at block322, the sealing tube25is bound between one set of closing elements24and one of the ridges31or35tubing at the extremities of the nerve cuff10using, for example, implantable grade silicone. In the illustrative embodiment shown inFIG. 2, the sealing tube25is bound between one set of closing elements24and the tuning of ridge35.

At block324, the protruding ends of the electrode wires41,42,43,44,45,46,47and48are covered by implantable grade silicone, forming an electrode cap49as shown inFIG. 4A.

At block326, the ETFE coating of the contact section36bof the ground wire36is removed using, for example, a scalpel. The length of the contact section36bwill vary depending on the length of the nerve cuff10. The contact section36bof the ground wire36is then inserted inside the proximal end33aof central ridge33tubing and follows the path defined previously in the description of the illustrative embodiment nerve cuff10.

Then, at block328, the proximal ends31a,32a,33a,34aand35aand distal ends31b,32b,33b,34band35bof the ridges31,32,33,34and35tubing are sealed with implantable grade silicone to prevent displacement of the ground wire36. The implantable grade silicone introduced at each end of each ridges31,32,33,34and35forms sealing caps37as shown inFIGS. 1 and 2.

At block330, a connector (not shown) may be connected to the contact section36bof the ground wire36and to the electrode wires41,42,43,44,45,46,47and48for connection of the nerve cuff10to some further interface or device (not shown).

At block332, the nerve cuff10is cleaned with, for example, a 70% 2-propanol solution and, at block234, it is package sterile packaging for storage or shipment.

Although the present invention has been described by way of particular embodiments and examples thereof, it should be noted that it will be apparent to persons skilled in the art that modifications may be applied to the present particular embodiment without departing from the scope of the present invention.