CA2266999A1 - Implantable interfaces with embedded signal carriers and methods for fabricating same - Google Patents
Implantable interfaces with embedded signal carriers and methods for fabricating same Download PDFInfo
- Publication number
- CA2266999A1 CA2266999A1 CA 2266999 CA2266999A CA2266999A1 CA 2266999 A1 CA2266999 A1 CA 2266999A1 CA 2266999 CA2266999 CA 2266999 CA 2266999 A CA2266999 A CA 2266999A CA 2266999 A1 CA2266999 A1 CA 2266999A1
- Authority
- CA
- Canada
- Prior art keywords
- signal
- signal carrier
- interface
- carrier members
- members
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/02—Details
- A61N1/04—Electrodes
- A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
- A61N1/0551—Spinal or peripheral nerve electrodes
- A61N1/0556—Cuff electrodes
Landscapes
- Health & Medical Sciences (AREA)
- Neurology (AREA)
- Neurosurgery (AREA)
- Orthopedic Medicine & Surgery (AREA)
- Cardiology (AREA)
- Heart & Thoracic Surgery (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Radiology & Medical Imaging (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Electrotherapy Devices (AREA)
Abstract
An implantable interface has a layer of parallel signal carrier members, such as wires, bonded together by a layer of flexible biocompatible bonding agent. The wires have sheaths surrounding electrical conductors. The sheaths are apertured at selected locations to expose the electrical conductors to provide electrodes. The interface may have interengageable closure members along its sides so that it may be used as a nerve cuff. The interface can be highly mechanically compliant and also provides good shielding against electrical interference. The wires may be extended to provide well supported axially extending leads. The apertures may be cut with a computer controlled laser. Where the closure members include interdigitating tubular members the tubular members may also be cut with a laser, thereby providing an accurately formed nerve cuff.
Description
IMPLANTABLE INTERFACES WITH EMBEDDED
SIGNAL CARRIERS AND METHODS FOR
FABRICATING SAME
Technical Field This invention relates to implantable interfaces to bodily tissues. The invention has particular application to multi-channel interface structures which may be implanted to permit stimulation and/or monitoring of internal body tissues, such as nerves. The interfaces may be provided in the form of nerve cuffs. The interfaces may provide electrical, optical and/or chemical connections to selected bodily tissues.
Background Nerve cuffs may be used for purposes including directing electrical or chemical stimulation to specific tissues and monitoring electrical and/or- chemical activity in the vicinity of selected tissues. Nerve cuffs have applications in many areas including closed loop control of Functional Electrical Stimulation FES. A closed loop FES system is described, for example, in Hoffer, U.S. patent No. 4,750,499 entitled CLOSED-LOOP, IMPLANTED-SENSOR, FUNCTIONAL
ELECTRICAL STIMULATION SYSTEM FOR PARTTAT, RESTORATION OF MOTOR FUNCTIONS.
SIGNAL CARRIERS AND METHODS FOR
FABRICATING SAME
Technical Field This invention relates to implantable interfaces to bodily tissues. The invention has particular application to multi-channel interface structures which may be implanted to permit stimulation and/or monitoring of internal body tissues, such as nerves. The interfaces may be provided in the form of nerve cuffs. The interfaces may provide electrical, optical and/or chemical connections to selected bodily tissues.
Background Nerve cuffs may be used for purposes including directing electrical or chemical stimulation to specific tissues and monitoring electrical and/or- chemical activity in the vicinity of selected tissues. Nerve cuffs have applications in many areas including closed loop control of Functional Electrical Stimulation FES. A closed loop FES system is described, for example, in Hoffer, U.S. patent No. 4,750,499 entitled CLOSED-LOOP, IMPLANTED-SENSOR, FUNCTIONAL
ELECTRICAL STIMULATION SYSTEM FOR PARTTAT, RESTORATION OF MOTOR FUNCTIONS.
A nerve cuff typically has an outer wall which can be used to isolate a tissue of interest, in vivo, inside a lumen defined by the cuff wall. Nerve cuffs which are designed to be chronically implanted are made from suitable biocompatible materials such as medical grades of silicone.
Description of Prior Art.
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 dielectric material wall. In cuffs designed to provide an electrical interface to tissues in the cuff, the inside of the cuff wall supports one or more metal electrodes. Leads from the electrodes extend through and are supported by the cuff wall.
The 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.
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. patent No.
5, 824, 027 describes a multichannel nerve cuff having longitudinal ridges extending along the interior walls of the cuff.
The ridges divide the volume between the cuff wall and the tissues within the 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.
S
Fabricating a multicontact, multichambered 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 can occur with compression, sharp bending and/or stretching of the tissue. Suitable materials, such as biocompatible silicone compositions can stretch when they are manipulated. This flexibility in the cuff wall can make it difficult to place electrodes in precisely determined locations and to keep the electrodes in position.
Tyler, et al. U.S. patent No. 5,634,462 describes multichannel nerve cuffs constructed of stiff material. The Tyler et al. cuffs are designed to deform and even penetrate a nerve, with the objective of 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 cuff.
Description of Prior Art.
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 dielectric material wall. In cuffs designed to provide an electrical interface to tissues in the cuff, the inside of the cuff wall supports one or more metal electrodes. Leads from the electrodes extend through and are supported by the cuff wall.
The 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.
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. patent No.
5, 824, 027 describes a multichannel nerve cuff having longitudinal ridges extending along the interior walls of the cuff.
The ridges divide the volume between the cuff wall and the tissues within the 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.
S
Fabricating a multicontact, multichambered 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 can occur with compression, sharp bending and/or stretching of the tissue. Suitable materials, such as biocompatible silicone compositions can stretch when they are manipulated. This flexibility in the cuff wall can make it difficult to place electrodes in precisely determined locations and to keep the electrodes in position.
Tyler, et al. U.S. patent No. 5,634,462 describes multichannel nerve cuffs constructed of stiff material. The Tyler et al. cuffs are designed to deform and even penetrate a nerve, with the objective of 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 cuff.
There is a need for methods to more readily accurately fabricate multichannel nerve cuffs. Cuffs for making recordings of electrical activity within nerve tissues should provide good electrical isolation of the tissues within the cuffs.
There is a need for nerve cuffs which can provide better isolation from externally generated electrical noise than is provided by current cuff designs.
Summar~of Invention This invention provides implantable interfaces to bodily tissues, such as nerves. The interfaces comprise a plurality of signal carrier members which may be, for example, electrical wires, optical fibers or catheters. The signal carrier members are arranged parallel to one another in a layer. Each of the signal carrier members includes a signal carrier, such as an electrical conductor or a tube for carrying pharmaceuticals or other chemicals. The signal carriers may be exposed at selected locations to provide an interface to tissues adjacent those selected locations. Providing a layer of parallel signal carrier members facilitates the precise positioning of electrodes or other electrical, optical or chemical interface points. The improved accuracy with which interfaces may be fabricated according to the invention is especially advantageous where the interfaces are multi-channel interfaces, such as multi-channel nerve cuffs.
There is a need for nerve cuffs which can provide better isolation from externally generated electrical noise than is provided by current cuff designs.
Summar~of Invention This invention provides implantable interfaces to bodily tissues, such as nerves. The interfaces comprise a plurality of signal carrier members which may be, for example, electrical wires, optical fibers or catheters. The signal carrier members are arranged parallel to one another in a layer. Each of the signal carrier members includes a signal carrier, such as an electrical conductor or a tube for carrying pharmaceuticals or other chemicals. The signal carriers may be exposed at selected locations to provide an interface to tissues adjacent those selected locations. Providing a layer of parallel signal carrier members facilitates the precise positioning of electrodes or other electrical, optical or chemical interface points. The improved accuracy with which interfaces may be fabricated according to the invention is especially advantageous where the interfaces are multi-channel interfaces, such as multi-channel nerve cuffs.
Accordingly, the invention provides an interface comprising a plurality of parallel elongated signal conducting members embedded in flexible biocompatible material. The signal carrier members each comprise a signal conductor. The signal conductors of one or more of the signal conducting members are exposed in apertures in the biocompatible material. In preferred embodiments of the invention the signal carrier members comprise sheaths surrounding the signal conductors and the sheaths of one or more of the signal carrier members are apertured to expose the signal conductor.
The interface may be provided as a nerve cuff having a longitudinal axis wherein the signal carrier members extend parallel to the axis. In some embodiments of the invention the signal conducting members each comprise an insulated electrical wire. In such embodiments it is preferable that a plurality of the signal conductors are electrically shorted together at each end of the nerve cuff. This electrically isolates the interior of the nerve cuff.
Another aspect of the invention provides a method for fabricating an interface to a biological tissue. The method comprises: providing a plurality of elongated signal carrier members each comprising a signal conductor; arranging the signal carrier members parallel to one another in a substantially continuous layer; bonding the signal carrying members together with a flexible biocompatible adhesive material; and, cutting through material overlying the signal conductors of one or more of the signal carrier members to expose the signal conductors at selected locations. Preferably cutting through the sheaths of the one or more signal carrier members comprises laser cutting.
Most preferably the laser cutting is performed with a laser emitting ultraviolet light.
Additional features and advantages of the invention are set out below.
Brief Description of Drawines In drawings which illustrate non-limiting embodiments of the invention, Figure 1 is a perspective view of an interface according to the invention formed as a nerve cuff;
Figure 2 is a perspective view of a planar interface according to the invention;
Figure 3A is a section through a projecting electrode in the interface of Figure 2;
Figures 3B, 3C, 3D and 3E show examples of various alternative kinds of electrodes which may be used in the rove ntion;
Figure 4 is a partial section through the nerve cuff of Figure 1;
Figure 5 is a flow chart illustrating a method of the invention;
Figure 6 is an isometric view of a ribbonizing fixture for use in a method of the invention;
Figure 7 is a plan view of a nerve cuff comprising a layer of bonded together signal carrier members ready to be laser cut;
Figure 8 is a partial sectional isometric view of a nerve cuff type interface having a layer of signal carriers on its outer surface and an inner surface having sculpted ridges;
Figure 9 shows a section through a nerve cuff type interface made using non-sheathed electrical conductors embedded in a flexible biocompatible bonding agent;
Figure 10 shows a section through an interface according to an alternative embodiment of the invention wherein a layer of signal carrier members is bonded together with a minimal amount of bonding agent; and, Figures 11A and 11B are respectively transverse and longitudinal sections through a nerve cuff type interface according to the invention with a layer of signal carrier members on an inner surface and a plurality of chambers defined by longitudinal ridge members and circumferential end seals.
_ g _ Description Figures 1 and 2 show implantable interfaces 10 and l0A according to the invention. Interface 10 of Figure 1 is a nerve cuff. Interface 10 has a wall member 20 which has a tubular configuration. Wall member 20 encloses a lumen 30 which is sized to receive a nerve or other bodily tissue. A
suitable closure 22 allows interface 10 to be opened to receive a nerve or other tissue in lumen 30. Closure 22 can then be closed to isolate the tissues within lumen 30. Closure 22 may be any suitable closure, however, closure 22 preferably comprises interdigitating tubular members 23 affixed on either side of wall member 20. Closure 22 may be secured in a closed configuration by inserting a rod-like member through tubular members 23.
Closures of this type are described in detail in Kallesoe et al., U.S. patent No. 5,487,756 which is incorporated herein by reference. Tubes 23 are preferably attached so that they are approximately flush with the interior surfaces of lumen 30 as shown in Figure 4.
Wall member 20 comprises a biocompatible flexible layer 25 and a plurality of elongated signal carrier members 27 embedded in flexible layer 25. The signal carrier members 27 each comprise a signal carrier 40 encased in an insulating sheath 42 (See Fig. 3). Signal carrier members 27 are at least generally parallel to one another and are preferably closely spaced so that they form an essentially continuous layer.
Signal carrier members 27 may comprise carriers for electrical signals, chemical signals or optical signals. Where interface 10 is used for electrical stimulation or recording then signal carrier members 27 may comprise electrical wires. Where interface 10 is used for chemically stimulating tissues or monitoring chemicals inside lumen 30 then signal carrier members 27 comprise catheters for carrying chemicals into or out of lumen 30. Signal carrier members 27 may also comprise optical fibers for optically or thermally stimulating tissues in lumen 30 or for monitoring for light inside lumen 30.
The sheaths 42 of some of signal carrier members 27 are cut away at apertures 32 to expose the signal carriers 40 to lumen 30. Because this invention provides particular advantages where the signal carrier members comprise electrical conductors the following description will focus mainly on the case where signal carrier members 27 comprise electrical conductors 40 surrounded by an electrically insulating sheath 42. In this case, electrical conductors 40 may be bent outwardly through apertures 32 to provide electrodes 36 which project inwardly into lumen 30. Where this is done aperture 32 should be sealed with an electrically insulating sealer 44, such as a silicone adhesive, as shown in Figure 3A.
Electrical conductors 40 may themselves constitute electrodes. In the alternative, electrode structures may be affixed to electrical conductors 40 by micro-welding, ultrasonic welding, soldering, bonding with a biocompatible electrically conductive adhesive, or other suitable attachment means.
Figures 3B through 3E show various non-limiting examples of electrode structures which may be used with the invention. As shown in Figure 3B an electrode may be made by simply making an aperture extending to the electrical conductor 40 of a signal carrier member 2?. As shown in Figures 3C and 3D, projecting wire electrodes 36A or 36B may be formed by bending a projecting electrical conductor 40 to provide smooth electrodes unlikely to traumatize nerve tissue and also to provide increased electrode surface area. As shown in Figure 3E an electrode may also comprise a separate electrode element 37 suitably attached to a projecting electrical conductor 40.
The signal carrier members 27 which are connected to electrodes 36 are coupled to leads 28 which may be connected to devices for conditioning and recording electrical signals from within lumen 30 and/or devices for electrically stimulating tissues within lumen 30. It is generally desirable to reduce the size, fragility and complexity of electrodes and leads. It is therefore preferable to use a single continuous signal carrier member 27 to serve as both the electrode 36 and the lead 28.
This minimizes breakage at joints and corrosion which can occur when electrical currents pass through joints between dissimilar metals. The invention could also be practised by providing leads which are not integral with signal carrier members 27 but are connected to signal carrier members 27 in any suitable way.
It can be appreciated that interface 10 can provide good support to lead 28 without sacrificing the mechanical compliance of interface 10. Leads 28 leave interface 10 in an axial direction (i.e. generally parallel to signal carrier members 27 in wall 20 of interface 10). Therefore, wall 20 does not need to be reinforced to support leads 28.
It is known that it is generally desirable to provide a low-impedance path around lumen 30 so that electrical potential differences arising from outside lumen 30 do not affect the electrical signals at electrodes 36. Such electrical interference signals may be generated by external sources such as muscles, the heart, or electrical noise sources in the general environment.
Interfaces according to this invention can provide such a current bypass in a particularly advantageous way.
As shown in Figures 1 and 2, apertures 32A may be provided in the insulating sheaths 42 of those signal carrying members 27 (in this case electrical wires) which are not connected to electrodes 36. Apertures 32A are located in lumen near both ends of interface 10. An electrical conductor 34 __..~.~...~ .._ . _ . . .._...~~.~. __ _r.. .
connects together the conductors 40 of signal carrying members 27 that are exposed at apertures 32A.. Those signal carrying members 27 not connected to electrodes 36 therefore provide a short circuit which equalizes electrical potentials at the ends of S lumen 30. The signal carrying members 27 also shield lumen 30 from alternating electrical currents and noise caused by transient electrical disturbances.
It is desirable for an interface 10 to be very compliant so that it can adapt to the shape of any tissues received within lumen 30. The interface 10 of Figure 1 can be made highly compliant by using a thin layer of an appropriate material for layer 25. Layer 25 may, for example, be made from medical grade silicone elastic adhesive, such as the "Medical Grade High Strength RTV Adhesive" part number 40076 available from Applied Silicone Corporation of Ventura, California, U.S.A. Layer 25 preferably has a thickness in the range of about 0.1 mm to about 0.3 mm.
Preferably interface 10 is also compliant along its length. Therefore, signal carrier members 27 should be quite flexible. For example, signal carrier members 27 may comprise Teflon coated stainless steel wire such as the wire available from Cooner Wire Co. of California under part No. AS 631. This wire has a signal conductor consisting of 10 strands of stainless steel wire each having a diameter of 0.0009 inches encased in a sheath having a thickness in the range of 0.003 inches to 0.004 inches consisting of four layers of FEP Tellon. Such Teflon coated CoonerTM wires have an outer diameter of about 0.011 inches.
Where a nerve-cuff type interface 10 as shown in Figure 1 is a multi-channel nerve cuff then preferably the lumen of the nerve cuff is shaped to form compartments so that each individual electrodes or group of electrodes is located in its own compartment. This tends to enhance the isolation of the electrodes from one another. Hoffer et al., U.S. patent No.
5,824,027, which is incorporated herein by reference describes a nerve which is provided with longitudinal ridges and end seals which define compartments inside the lumen of a nerve cuff.
Compartments as described by Hoffer et al. are preferably used in multi-channel nerve cuffs according to this invention. Figure 8 shows a nerve cuff which includes such compartments formed by longitudinally extending ridge members 62. The nerve cuffs of Figures 9, 11A and 11B also have such compartments formed by ridge members 62 and circumferential end seals 64.
Figure 2 shows an alternative interface l0A
according to the invention which has a flexible, generally planar configuration. Interface l0A of Figure 2 might be used, for example, to interface with larger tissue structures such as muscles.
Interfaces 10 and l0A of Figures 1 and 2 and interface l0E of Figures 11A and 11B are constructed so that a layer of signal carrier members 27 lies against or near to the tissues of interest. Interfaces according to the invention could also be constructed with layer 25 lying against the tissues of interest as shown, for example, in Figure 8. In interface 10B, layer 25 lies on the inside of the lumen 30. Where this alternative construction is adopted apertures 32 and 32A which expose signal conductors 40 must penetrate layer 25 as well as insulating sheaths 42. Figure 8 shows a nerve-cuff type interface lOB.
Figure 9 shows a further alternative interface 10 C
according to the invention. Interface lOC comprises a plurality of unsheathed electrical conductors 40 arranged generally parallel to one another in a layer. Electrical conductors 40 are bonded together and insulated by a layer 25 of insulating, flexible, biocompatible material, such as a medical grade silicone adhesive. As noted above, ridges 62 and circumferential seals 64 may be provided in lumen 30. Ridges 62 and seals 64 may be formed integrally with layer 25 or may be separate components affixed to layer 25 in a suitable manner, for example with a suitable adhesive.
Figure 10 shows a portion of a further alternative interface 10D according to the invention wherein a layer of closely spaced generally parallel signal carrier members 27 are bonded together in a very thin flexible layer of bonding material 25.
Figures 11A and 11B show another further alternative cuff-type interface l0E according to the invention.
Interface l0E has longitudinally extending soft tubular ridge members 62 inside lumen 30 and circumferential end seals 64 which define cavities into which electrodes 36 project.
Interfaces according to the invention may be made according to the following method which is illustrated in Figure 5. First, lengths of signal carrier members 27 are provided (step 210).
Where the signal carrier members 27 have Teflon sheaths 42 it is desirable to etch the Teflon so that the signal carrier members 27 will adhere to layer 25. The etching step (step 212)may be performed by carefully cleaning signal carrier members 27 with a suitable solvent (step 212A), such as acetone, to remove any oils from the surface of sheaths 42.
Signal carrier members 27 may then be etched in an etchant (step 212B)such as TetraEtchTM, which is manufactured by W.L.
Gore. It has been found that etching signal carrier members for about 30-60 seconds at room temperature is sufficient when using TetraEtch to etch the Cooner wires described above. It is desirable to seal the ends of signal carrier members 27 to prevent the etchant from migrating into signal carriers 27 between sheath 42 and signal carrier 40. After etching the signal carrier members 27 are rinsed (step 212C) for several minutes in water at a temperature of at least 180°F (boiling water may be used) to remove the etchant. The signal carrier members 27 are then ultrasonically cleaned in a suitable degreasing solvent, such as acetone, for several minutes (step 212D).
The clean etched signal carrier members 27 are then ready to be assembled into a ribbon structure. This may be done with the use of a ribboning fixture 50 as shown in Figure 6.
Ribboning fixture 50 has a generally flat upper surface 51. A
shallow parallel-sided groove 52 is defined on upper surface 51 between a pair of vertical steps 54. The width of groove 52 depends on the desired size of the implant being made. The region of upper surface 51 between steps 54 is coated with a sticky substance. Regions 58 of upper surface 51 outside groove 52 are non-sticky. The sticky surface in region 56 may be an upper face of a piece of double-sided masking tape. The non-sticky surfaces in regions 58 may be the non-sticky surfaces of pieces of polyimide tape.
Signal carrier members 27 are laid in groove 52 (step 214). Each signal carrier member 27 is laid against its neighbour to form a planar ribbon of parallel signal carrier members 27 extending the width of groove 52. Sticky surface 56 holds signal carrier members in place. Those signal carrier members 27 which will not be connected to external devices are preferably slightly longer than groove 52 and are laid in groove 52 with their ends projecting slightly out of each end of groove 52. Those signal carrier members 27A of signal carrier members 27 which will be connected to external devices can be longer.
The parts of signal carrier members 27A which extend out of groove 52 will form leads 29 for connection to the external devices. The external devices may include stimulus generating devices or signal conditioning and recording devices. Where the signal carrier members comprise catheters then the external devices may include fluid transport device. Where the signal carrier members comprise optical fibers then the external devices might include light detectors and/or light generating devices. Where the signal carrier members comprise electrical conductors then the external devices may include electrical signal generators and/or recorders.
If the signal carrier members comprise as yet unsheathed electrical conductors as, for example, would be encountered in the construction of the cuff lOC of Figure 10, then the unsheathed electrical conductors may be stretched parallel to one another along groove 52 and spaced slightly above the lower surface of groove 52.
- lg -When the signal carrier members 27 are aligned in fixture 50 then signal carrier members may be bonded together with a suitable bonding agent (step 220). This may be done by filling groove 52 with a biocompatible silicone adhesive elastomer. For example, the medical grade silicone adhesive described above which is available under part number 40076 from Applied Silicone may be used. The bonding agent is applied in a thin layer on top of the ribbon of signal carrier members 27.
Ribboning fixture 50 may be used as a depth gauge to ensure that layer 25 will have a desired thickness. The bonding agent may be used to fill groove 52 to the level of the top edges of walls 54. This ensures that a thin but consistent layer of bonding agent is applied to signal carrier members 27. Preferably the layer of bonding agent has a thickness in the range of about 0.1 mm to about 0.3mm so that when it cures the interface will have the desired mechanical characteristics. The bonding agent is then allowed to cure.
If the interface being built will present electrodes or other interfaces which will project from the side on which the bonding agent is applied, as described above, then it may be desirable to mask small areas of signal carrier members 27 surrounding the desired locations of electrodes. If the bonding agent is prevented from forming a layer in these small areas then it will be easier to form electrodes (or other interfaces) as described below.
After the bonding agent has cured to form a layer 25 holding signal carrier members 27 together then the cured bonding agent and signal carrier members 27 may be removed as a unit from ribboning fixture 50. Any excess bonding agent can then be trimmed off. If a cuff type interface is being made then suitable closure members may be affixed along either side of the ribbon of signal carrier members 27 (step 222).
The preferred embodiment of the invention provides a closure 22 comprising interdigitating tubular members 23 as described in Kallesoe et al., U.S. patent No. 5,487,756, which is incorporated herein by reference. Closure 22 may be fabricated from continuous tubes 60 (Fig. 7) affixed along either side of the ribbon of signal carrier members 27. Tubes 60 are preferably silicone tubes which may be affixed with a biocompatible silicone adhesive such as the adhesive mentioned above.
Next the various apertures 32 and 32A required in the interface are cut in signal carrier members 27 (step 224). An inventive feature of some of the methods of the invention is the use of a laser cutter to cut apertures 32. The laser cutter can also cut tubes 60 to form an interdigitating set of tubular members 23 affixed along each edge of the ribbon of signal carrier members 27.
Step 224 is preferably carried out with a computer controlled laser which can be programmed to make cuts along the dashed lines shown in Figure 7 on a properly aligned interface structure. Means for computer controlling a laser to make cuts at specific points on a two dimensional surface are well known to those skilled in the art and will therefore not be described here in any detail. By way of example only, the implant assembly may be mounted on a table below a laser source mounted to a computer controlled X-Y positioner. The X-Y positioner can then be moved to cause a cutting laser beam to remove material from areas 32 and 32A of Figure 7. The laser can locate precisely electrodes 36.
Because signal carrier members 27 extend the full length of the interface being fabricated, an electrode (in the case that the signal carrier member is an electrical conductor) may be formed on a signal carrier member 27 at any point along the length of the interface. The precision with which the electrode may be located in the longitudinal direction is limited by the precision of the laser cutting machine. The precision with which electrodes 36 may be placed in the transverse direction also high because signal carrier members 27 can be located accurately before the application of a bonding agent.
The laser may also be used to cut away tubes 60 to form tubular closure members 23. The use of a cutting laser to cut tubes 60 permits the ready fabrication of very tightly interdigitating tubular members 23.
The inventors' preferred practice for laser cutting S step 224 is to first trace the cutting laser along the dashed lines shown in Figure 7 on tubes 60 so as to form tubular members 23. Then the laser is set to scan along the perimeters of apertures 32 and 32A. The number of laser scans is selected so that the laser cuts through the sheaths of signal carrier members 27 around the perimeters of apertures 32 and 32A.
The precise control afforded by a laser cutter allows the perimeters of apertures 32 and 32A to be very precisely defined and cleanly cut. If necessary, then the laser is also scanned across conductors 40 enough times to cut through conductors 40 in selected locations. Finally the material covering apertures 32 and 32A is removed mechanically (for example with tweezers).
While it would be possible to laser ablate all of the material which must be removed to create apertures 32 and 32A, this would be very time consuming. It is currently more practical to cut around the perimeters of apertures 32 and 32A and mechanically remove the material within the perimeter to expose the electrical conductor 40 (or other signal carrier), as described above.
Up to the point of laser cutting the same construction can be used to make interfaces which will have different patterns of electrodes. This provides a significant advantage over prior art techniques for fabricating nerve cuffs wherein holes are formed in a cuff wall to receive leads for individual electrodes and the individual leads must be handled separately.
It can be appreciated that when the signal carrier members are sheathed in Teflon and the tubes 60 are made from silicone then the laser used for cutting openings 32 and tubes 60 should be capable of removing both Teflon and silicone.
In general, the inventors believe that lasers operating in the ultraviolet range of the electromagnetic spectrum are to be preferred for laser cutting step 224. Lasers operating in the ultraviolet region remove materials such as Tellon or silicone by photo-ablation which produces a cleaner cut than is produced by infrared lasers which cause much more localized heating of the material being cut.
Most preferably the wavelength of the laser used in step 224 is be in the range of about 150 nm to about 400 nm. It has been found that a frequency quadrupled Nd:YAG laser operating at a wavelength of 266nm is capable of removing both Teflon and silicone and is otherwise satisfactory for use in the invention. Other suitable lasers may also be used.
As noted above, where it is desired to form projecting electrodes 36 (Figure 3A) then the laser can also be used to ~~... _..~.~.~._:__._ .
sever the conductor 40 of signal carrier members 27 at apertures 32. This may be done by scanning the laser repeatedly across the conductor 40 at the end of aperture 32 away from leads 29.
After the laser cutting steps have been completed then electrodes 36 may be erected, shorting wires 34 may be connected to the conductors exposed by apertures 32A and the ends of signal carrier members 27 and the apertures around electrodes 36 may be sealed with a suitable sealer 44 (Fig. 3) (step 228). Shorting wires 34 may be thin stainless steel strand which is loosely woven through the wires exposed in apertures 32A so as not to affect the mechanical compliance of interface 10. Shorting wire 34 may be secured by bending its ends back, for example.
Where the signal carrier members 27 comprise one or more small catheters then the laser can be used to cut a hole through the wall of each catheter at a desired location as shown in Figure 11A which shows a catheter 27B having an aperture 65 which establishes a fluid connection with lumen 30. Fluids can then be introduced through the catheter to the location of the aperture (or withdrawn through the catheter).
Finally, if desired, longitudinal isolating ridges 62 and/or end seals 64 may be adhered to the interface structure.
The isolating ridges and end seals may comprise, for example, thin tubes of silicone affixed to the interface with a silicone adhesive. Isolating ridges and end seals are described in Hoffer et al., U.S. patent No. 5,824,027 which is incorporated herein by reference. At some time prior to completion of the interface the ends of signal carrier members 27 should be sealed with a suitable sealant,( such as the medical grade silicone adhesive described above).
Where layer 25 will be on the interior of a nerve cuff, as shown for example in Figure 8, the isolation ridges 62 and /
or end seals 64 may be directly laser machined in layer 25. That is, a laser cutter may be used to remove material from the portions of layer 25 surrounding electrodes 36 (or other stimulation or recording sites) to form chambers surrounding the electrodes 36. This may be done in the same operation as cutting apertures 32 and 32A. In the further alternative, layer may be molded to provide isolation ridges 62 and/or end seals 64 before it is cured.
Those skilled in the art will recognize that the foregoing fabrication methods have been successfully used for manufacturing pre-production prototype interfaces according to the invention. The methods may be altered in various ways for the manufacture of interfaces in production quantities.
~___ _._~_.. _r_~..~.._ _ As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example, while the invention has been described as using insulated wires which include a sheath surrounding an electrical conductor, the invention could also be practised by embedding a layer of parallel, closely spaced apart, non-insulated electrical conductors in a flexible, electrically insulating, biocompatible bonding agent. Apertures could then be cut in the bonding agent to expose the electrical conductors at selected locations.
While typical nerve cuffs have circumferences in the range of 6 mm to 10 mm, the interfaces and techniques described above may be adjusted to produce interfaces of larger or smaller sizes without deviating from the invention.
While the invention has so far described as providing an interface which includes a layer of signal carrier members all of the same type, the same interface could include two or more types of signal carrier members. The signal carrier members could be selected from: electrical conductors, optical fibers, and small catheters (tubes for carrying chemicals). For example, in the interface l0E of Figures 11A and 11B one of signal carrier members 27 comprises a catheter 27B while other ones of signal __..~_ . ~_.~ . T__~~~.__._..
carrier members 27 comprise electrical conductors connected to electrodes 36.
While the invention has described the laser cutting step as holding an interface stationary while a laser is moved, of course, all that is necessary is that the laser beam be moved relative to the interface being made. The laser beam could be held fixed while the interface is moved on an X-Y table or both the interface and laser beam may be moved in a manner such that the laser beam cuts the interface as desired.
While the above description describes interfaces which are connected by leads to external devices, signal processing units such as, but not limited to, electrical amplifiers and filters, pharmaceutical delivery systems and/or optical illuminators, amplifiers and filters could be attached to the interface and controlled by suitable wireless means all without affecting the basic structure of the interface.
Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
The interface may be provided as a nerve cuff having a longitudinal axis wherein the signal carrier members extend parallel to the axis. In some embodiments of the invention the signal conducting members each comprise an insulated electrical wire. In such embodiments it is preferable that a plurality of the signal conductors are electrically shorted together at each end of the nerve cuff. This electrically isolates the interior of the nerve cuff.
Another aspect of the invention provides a method for fabricating an interface to a biological tissue. The method comprises: providing a plurality of elongated signal carrier members each comprising a signal conductor; arranging the signal carrier members parallel to one another in a substantially continuous layer; bonding the signal carrying members together with a flexible biocompatible adhesive material; and, cutting through material overlying the signal conductors of one or more of the signal carrier members to expose the signal conductors at selected locations. Preferably cutting through the sheaths of the one or more signal carrier members comprises laser cutting.
Most preferably the laser cutting is performed with a laser emitting ultraviolet light.
Additional features and advantages of the invention are set out below.
Brief Description of Drawines In drawings which illustrate non-limiting embodiments of the invention, Figure 1 is a perspective view of an interface according to the invention formed as a nerve cuff;
Figure 2 is a perspective view of a planar interface according to the invention;
Figure 3A is a section through a projecting electrode in the interface of Figure 2;
Figures 3B, 3C, 3D and 3E show examples of various alternative kinds of electrodes which may be used in the rove ntion;
Figure 4 is a partial section through the nerve cuff of Figure 1;
Figure 5 is a flow chart illustrating a method of the invention;
Figure 6 is an isometric view of a ribbonizing fixture for use in a method of the invention;
Figure 7 is a plan view of a nerve cuff comprising a layer of bonded together signal carrier members ready to be laser cut;
Figure 8 is a partial sectional isometric view of a nerve cuff type interface having a layer of signal carriers on its outer surface and an inner surface having sculpted ridges;
Figure 9 shows a section through a nerve cuff type interface made using non-sheathed electrical conductors embedded in a flexible biocompatible bonding agent;
Figure 10 shows a section through an interface according to an alternative embodiment of the invention wherein a layer of signal carrier members is bonded together with a minimal amount of bonding agent; and, Figures 11A and 11B are respectively transverse and longitudinal sections through a nerve cuff type interface according to the invention with a layer of signal carrier members on an inner surface and a plurality of chambers defined by longitudinal ridge members and circumferential end seals.
_ g _ Description Figures 1 and 2 show implantable interfaces 10 and l0A according to the invention. Interface 10 of Figure 1 is a nerve cuff. Interface 10 has a wall member 20 which has a tubular configuration. Wall member 20 encloses a lumen 30 which is sized to receive a nerve or other bodily tissue. A
suitable closure 22 allows interface 10 to be opened to receive a nerve or other tissue in lumen 30. Closure 22 can then be closed to isolate the tissues within lumen 30. Closure 22 may be any suitable closure, however, closure 22 preferably comprises interdigitating tubular members 23 affixed on either side of wall member 20. Closure 22 may be secured in a closed configuration by inserting a rod-like member through tubular members 23.
Closures of this type are described in detail in Kallesoe et al., U.S. patent No. 5,487,756 which is incorporated herein by reference. Tubes 23 are preferably attached so that they are approximately flush with the interior surfaces of lumen 30 as shown in Figure 4.
Wall member 20 comprises a biocompatible flexible layer 25 and a plurality of elongated signal carrier members 27 embedded in flexible layer 25. The signal carrier members 27 each comprise a signal carrier 40 encased in an insulating sheath 42 (See Fig. 3). Signal carrier members 27 are at least generally parallel to one another and are preferably closely spaced so that they form an essentially continuous layer.
Signal carrier members 27 may comprise carriers for electrical signals, chemical signals or optical signals. Where interface 10 is used for electrical stimulation or recording then signal carrier members 27 may comprise electrical wires. Where interface 10 is used for chemically stimulating tissues or monitoring chemicals inside lumen 30 then signal carrier members 27 comprise catheters for carrying chemicals into or out of lumen 30. Signal carrier members 27 may also comprise optical fibers for optically or thermally stimulating tissues in lumen 30 or for monitoring for light inside lumen 30.
The sheaths 42 of some of signal carrier members 27 are cut away at apertures 32 to expose the signal carriers 40 to lumen 30. Because this invention provides particular advantages where the signal carrier members comprise electrical conductors the following description will focus mainly on the case where signal carrier members 27 comprise electrical conductors 40 surrounded by an electrically insulating sheath 42. In this case, electrical conductors 40 may be bent outwardly through apertures 32 to provide electrodes 36 which project inwardly into lumen 30. Where this is done aperture 32 should be sealed with an electrically insulating sealer 44, such as a silicone adhesive, as shown in Figure 3A.
Electrical conductors 40 may themselves constitute electrodes. In the alternative, electrode structures may be affixed to electrical conductors 40 by micro-welding, ultrasonic welding, soldering, bonding with a biocompatible electrically conductive adhesive, or other suitable attachment means.
Figures 3B through 3E show various non-limiting examples of electrode structures which may be used with the invention. As shown in Figure 3B an electrode may be made by simply making an aperture extending to the electrical conductor 40 of a signal carrier member 2?. As shown in Figures 3C and 3D, projecting wire electrodes 36A or 36B may be formed by bending a projecting electrical conductor 40 to provide smooth electrodes unlikely to traumatize nerve tissue and also to provide increased electrode surface area. As shown in Figure 3E an electrode may also comprise a separate electrode element 37 suitably attached to a projecting electrical conductor 40.
The signal carrier members 27 which are connected to electrodes 36 are coupled to leads 28 which may be connected to devices for conditioning and recording electrical signals from within lumen 30 and/or devices for electrically stimulating tissues within lumen 30. It is generally desirable to reduce the size, fragility and complexity of electrodes and leads. It is therefore preferable to use a single continuous signal carrier member 27 to serve as both the electrode 36 and the lead 28.
This minimizes breakage at joints and corrosion which can occur when electrical currents pass through joints between dissimilar metals. The invention could also be practised by providing leads which are not integral with signal carrier members 27 but are connected to signal carrier members 27 in any suitable way.
It can be appreciated that interface 10 can provide good support to lead 28 without sacrificing the mechanical compliance of interface 10. Leads 28 leave interface 10 in an axial direction (i.e. generally parallel to signal carrier members 27 in wall 20 of interface 10). Therefore, wall 20 does not need to be reinforced to support leads 28.
It is known that it is generally desirable to provide a low-impedance path around lumen 30 so that electrical potential differences arising from outside lumen 30 do not affect the electrical signals at electrodes 36. Such electrical interference signals may be generated by external sources such as muscles, the heart, or electrical noise sources in the general environment.
Interfaces according to this invention can provide such a current bypass in a particularly advantageous way.
As shown in Figures 1 and 2, apertures 32A may be provided in the insulating sheaths 42 of those signal carrying members 27 (in this case electrical wires) which are not connected to electrodes 36. Apertures 32A are located in lumen near both ends of interface 10. An electrical conductor 34 __..~.~...~ .._ . _ . . .._...~~.~. __ _r.. .
connects together the conductors 40 of signal carrying members 27 that are exposed at apertures 32A.. Those signal carrying members 27 not connected to electrodes 36 therefore provide a short circuit which equalizes electrical potentials at the ends of S lumen 30. The signal carrying members 27 also shield lumen 30 from alternating electrical currents and noise caused by transient electrical disturbances.
It is desirable for an interface 10 to be very compliant so that it can adapt to the shape of any tissues received within lumen 30. The interface 10 of Figure 1 can be made highly compliant by using a thin layer of an appropriate material for layer 25. Layer 25 may, for example, be made from medical grade silicone elastic adhesive, such as the "Medical Grade High Strength RTV Adhesive" part number 40076 available from Applied Silicone Corporation of Ventura, California, U.S.A. Layer 25 preferably has a thickness in the range of about 0.1 mm to about 0.3 mm.
Preferably interface 10 is also compliant along its length. Therefore, signal carrier members 27 should be quite flexible. For example, signal carrier members 27 may comprise Teflon coated stainless steel wire such as the wire available from Cooner Wire Co. of California under part No. AS 631. This wire has a signal conductor consisting of 10 strands of stainless steel wire each having a diameter of 0.0009 inches encased in a sheath having a thickness in the range of 0.003 inches to 0.004 inches consisting of four layers of FEP Tellon. Such Teflon coated CoonerTM wires have an outer diameter of about 0.011 inches.
Where a nerve-cuff type interface 10 as shown in Figure 1 is a multi-channel nerve cuff then preferably the lumen of the nerve cuff is shaped to form compartments so that each individual electrodes or group of electrodes is located in its own compartment. This tends to enhance the isolation of the electrodes from one another. Hoffer et al., U.S. patent No.
5,824,027, which is incorporated herein by reference describes a nerve which is provided with longitudinal ridges and end seals which define compartments inside the lumen of a nerve cuff.
Compartments as described by Hoffer et al. are preferably used in multi-channel nerve cuffs according to this invention. Figure 8 shows a nerve cuff which includes such compartments formed by longitudinally extending ridge members 62. The nerve cuffs of Figures 9, 11A and 11B also have such compartments formed by ridge members 62 and circumferential end seals 64.
Figure 2 shows an alternative interface l0A
according to the invention which has a flexible, generally planar configuration. Interface l0A of Figure 2 might be used, for example, to interface with larger tissue structures such as muscles.
Interfaces 10 and l0A of Figures 1 and 2 and interface l0E of Figures 11A and 11B are constructed so that a layer of signal carrier members 27 lies against or near to the tissues of interest. Interfaces according to the invention could also be constructed with layer 25 lying against the tissues of interest as shown, for example, in Figure 8. In interface 10B, layer 25 lies on the inside of the lumen 30. Where this alternative construction is adopted apertures 32 and 32A which expose signal conductors 40 must penetrate layer 25 as well as insulating sheaths 42. Figure 8 shows a nerve-cuff type interface lOB.
Figure 9 shows a further alternative interface 10 C
according to the invention. Interface lOC comprises a plurality of unsheathed electrical conductors 40 arranged generally parallel to one another in a layer. Electrical conductors 40 are bonded together and insulated by a layer 25 of insulating, flexible, biocompatible material, such as a medical grade silicone adhesive. As noted above, ridges 62 and circumferential seals 64 may be provided in lumen 30. Ridges 62 and seals 64 may be formed integrally with layer 25 or may be separate components affixed to layer 25 in a suitable manner, for example with a suitable adhesive.
Figure 10 shows a portion of a further alternative interface 10D according to the invention wherein a layer of closely spaced generally parallel signal carrier members 27 are bonded together in a very thin flexible layer of bonding material 25.
Figures 11A and 11B show another further alternative cuff-type interface l0E according to the invention.
Interface l0E has longitudinally extending soft tubular ridge members 62 inside lumen 30 and circumferential end seals 64 which define cavities into which electrodes 36 project.
Interfaces according to the invention may be made according to the following method which is illustrated in Figure 5. First, lengths of signal carrier members 27 are provided (step 210).
Where the signal carrier members 27 have Teflon sheaths 42 it is desirable to etch the Teflon so that the signal carrier members 27 will adhere to layer 25. The etching step (step 212)may be performed by carefully cleaning signal carrier members 27 with a suitable solvent (step 212A), such as acetone, to remove any oils from the surface of sheaths 42.
Signal carrier members 27 may then be etched in an etchant (step 212B)such as TetraEtchTM, which is manufactured by W.L.
Gore. It has been found that etching signal carrier members for about 30-60 seconds at room temperature is sufficient when using TetraEtch to etch the Cooner wires described above. It is desirable to seal the ends of signal carrier members 27 to prevent the etchant from migrating into signal carriers 27 between sheath 42 and signal carrier 40. After etching the signal carrier members 27 are rinsed (step 212C) for several minutes in water at a temperature of at least 180°F (boiling water may be used) to remove the etchant. The signal carrier members 27 are then ultrasonically cleaned in a suitable degreasing solvent, such as acetone, for several minutes (step 212D).
The clean etched signal carrier members 27 are then ready to be assembled into a ribbon structure. This may be done with the use of a ribboning fixture 50 as shown in Figure 6.
Ribboning fixture 50 has a generally flat upper surface 51. A
shallow parallel-sided groove 52 is defined on upper surface 51 between a pair of vertical steps 54. The width of groove 52 depends on the desired size of the implant being made. The region of upper surface 51 between steps 54 is coated with a sticky substance. Regions 58 of upper surface 51 outside groove 52 are non-sticky. The sticky surface in region 56 may be an upper face of a piece of double-sided masking tape. The non-sticky surfaces in regions 58 may be the non-sticky surfaces of pieces of polyimide tape.
Signal carrier members 27 are laid in groove 52 (step 214). Each signal carrier member 27 is laid against its neighbour to form a planar ribbon of parallel signal carrier members 27 extending the width of groove 52. Sticky surface 56 holds signal carrier members in place. Those signal carrier members 27 which will not be connected to external devices are preferably slightly longer than groove 52 and are laid in groove 52 with their ends projecting slightly out of each end of groove 52. Those signal carrier members 27A of signal carrier members 27 which will be connected to external devices can be longer.
The parts of signal carrier members 27A which extend out of groove 52 will form leads 29 for connection to the external devices. The external devices may include stimulus generating devices or signal conditioning and recording devices. Where the signal carrier members comprise catheters then the external devices may include fluid transport device. Where the signal carrier members comprise optical fibers then the external devices might include light detectors and/or light generating devices. Where the signal carrier members comprise electrical conductors then the external devices may include electrical signal generators and/or recorders.
If the signal carrier members comprise as yet unsheathed electrical conductors as, for example, would be encountered in the construction of the cuff lOC of Figure 10, then the unsheathed electrical conductors may be stretched parallel to one another along groove 52 and spaced slightly above the lower surface of groove 52.
- lg -When the signal carrier members 27 are aligned in fixture 50 then signal carrier members may be bonded together with a suitable bonding agent (step 220). This may be done by filling groove 52 with a biocompatible silicone adhesive elastomer. For example, the medical grade silicone adhesive described above which is available under part number 40076 from Applied Silicone may be used. The bonding agent is applied in a thin layer on top of the ribbon of signal carrier members 27.
Ribboning fixture 50 may be used as a depth gauge to ensure that layer 25 will have a desired thickness. The bonding agent may be used to fill groove 52 to the level of the top edges of walls 54. This ensures that a thin but consistent layer of bonding agent is applied to signal carrier members 27. Preferably the layer of bonding agent has a thickness in the range of about 0.1 mm to about 0.3mm so that when it cures the interface will have the desired mechanical characteristics. The bonding agent is then allowed to cure.
If the interface being built will present electrodes or other interfaces which will project from the side on which the bonding agent is applied, as described above, then it may be desirable to mask small areas of signal carrier members 27 surrounding the desired locations of electrodes. If the bonding agent is prevented from forming a layer in these small areas then it will be easier to form electrodes (or other interfaces) as described below.
After the bonding agent has cured to form a layer 25 holding signal carrier members 27 together then the cured bonding agent and signal carrier members 27 may be removed as a unit from ribboning fixture 50. Any excess bonding agent can then be trimmed off. If a cuff type interface is being made then suitable closure members may be affixed along either side of the ribbon of signal carrier members 27 (step 222).
The preferred embodiment of the invention provides a closure 22 comprising interdigitating tubular members 23 as described in Kallesoe et al., U.S. patent No. 5,487,756, which is incorporated herein by reference. Closure 22 may be fabricated from continuous tubes 60 (Fig. 7) affixed along either side of the ribbon of signal carrier members 27. Tubes 60 are preferably silicone tubes which may be affixed with a biocompatible silicone adhesive such as the adhesive mentioned above.
Next the various apertures 32 and 32A required in the interface are cut in signal carrier members 27 (step 224). An inventive feature of some of the methods of the invention is the use of a laser cutter to cut apertures 32. The laser cutter can also cut tubes 60 to form an interdigitating set of tubular members 23 affixed along each edge of the ribbon of signal carrier members 27.
Step 224 is preferably carried out with a computer controlled laser which can be programmed to make cuts along the dashed lines shown in Figure 7 on a properly aligned interface structure. Means for computer controlling a laser to make cuts at specific points on a two dimensional surface are well known to those skilled in the art and will therefore not be described here in any detail. By way of example only, the implant assembly may be mounted on a table below a laser source mounted to a computer controlled X-Y positioner. The X-Y positioner can then be moved to cause a cutting laser beam to remove material from areas 32 and 32A of Figure 7. The laser can locate precisely electrodes 36.
Because signal carrier members 27 extend the full length of the interface being fabricated, an electrode (in the case that the signal carrier member is an electrical conductor) may be formed on a signal carrier member 27 at any point along the length of the interface. The precision with which the electrode may be located in the longitudinal direction is limited by the precision of the laser cutting machine. The precision with which electrodes 36 may be placed in the transverse direction also high because signal carrier members 27 can be located accurately before the application of a bonding agent.
The laser may also be used to cut away tubes 60 to form tubular closure members 23. The use of a cutting laser to cut tubes 60 permits the ready fabrication of very tightly interdigitating tubular members 23.
The inventors' preferred practice for laser cutting S step 224 is to first trace the cutting laser along the dashed lines shown in Figure 7 on tubes 60 so as to form tubular members 23. Then the laser is set to scan along the perimeters of apertures 32 and 32A. The number of laser scans is selected so that the laser cuts through the sheaths of signal carrier members 27 around the perimeters of apertures 32 and 32A.
The precise control afforded by a laser cutter allows the perimeters of apertures 32 and 32A to be very precisely defined and cleanly cut. If necessary, then the laser is also scanned across conductors 40 enough times to cut through conductors 40 in selected locations. Finally the material covering apertures 32 and 32A is removed mechanically (for example with tweezers).
While it would be possible to laser ablate all of the material which must be removed to create apertures 32 and 32A, this would be very time consuming. It is currently more practical to cut around the perimeters of apertures 32 and 32A and mechanically remove the material within the perimeter to expose the electrical conductor 40 (or other signal carrier), as described above.
Up to the point of laser cutting the same construction can be used to make interfaces which will have different patterns of electrodes. This provides a significant advantage over prior art techniques for fabricating nerve cuffs wherein holes are formed in a cuff wall to receive leads for individual electrodes and the individual leads must be handled separately.
It can be appreciated that when the signal carrier members are sheathed in Teflon and the tubes 60 are made from silicone then the laser used for cutting openings 32 and tubes 60 should be capable of removing both Teflon and silicone.
In general, the inventors believe that lasers operating in the ultraviolet range of the electromagnetic spectrum are to be preferred for laser cutting step 224. Lasers operating in the ultraviolet region remove materials such as Tellon or silicone by photo-ablation which produces a cleaner cut than is produced by infrared lasers which cause much more localized heating of the material being cut.
Most preferably the wavelength of the laser used in step 224 is be in the range of about 150 nm to about 400 nm. It has been found that a frequency quadrupled Nd:YAG laser operating at a wavelength of 266nm is capable of removing both Teflon and silicone and is otherwise satisfactory for use in the invention. Other suitable lasers may also be used.
As noted above, where it is desired to form projecting electrodes 36 (Figure 3A) then the laser can also be used to ~~... _..~.~.~._:__._ .
sever the conductor 40 of signal carrier members 27 at apertures 32. This may be done by scanning the laser repeatedly across the conductor 40 at the end of aperture 32 away from leads 29.
After the laser cutting steps have been completed then electrodes 36 may be erected, shorting wires 34 may be connected to the conductors exposed by apertures 32A and the ends of signal carrier members 27 and the apertures around electrodes 36 may be sealed with a suitable sealer 44 (Fig. 3) (step 228). Shorting wires 34 may be thin stainless steel strand which is loosely woven through the wires exposed in apertures 32A so as not to affect the mechanical compliance of interface 10. Shorting wire 34 may be secured by bending its ends back, for example.
Where the signal carrier members 27 comprise one or more small catheters then the laser can be used to cut a hole through the wall of each catheter at a desired location as shown in Figure 11A which shows a catheter 27B having an aperture 65 which establishes a fluid connection with lumen 30. Fluids can then be introduced through the catheter to the location of the aperture (or withdrawn through the catheter).
Finally, if desired, longitudinal isolating ridges 62 and/or end seals 64 may be adhered to the interface structure.
The isolating ridges and end seals may comprise, for example, thin tubes of silicone affixed to the interface with a silicone adhesive. Isolating ridges and end seals are described in Hoffer et al., U.S. patent No. 5,824,027 which is incorporated herein by reference. At some time prior to completion of the interface the ends of signal carrier members 27 should be sealed with a suitable sealant,( such as the medical grade silicone adhesive described above).
Where layer 25 will be on the interior of a nerve cuff, as shown for example in Figure 8, the isolation ridges 62 and /
or end seals 64 may be directly laser machined in layer 25. That is, a laser cutter may be used to remove material from the portions of layer 25 surrounding electrodes 36 (or other stimulation or recording sites) to form chambers surrounding the electrodes 36. This may be done in the same operation as cutting apertures 32 and 32A. In the further alternative, layer may be molded to provide isolation ridges 62 and/or end seals 64 before it is cured.
Those skilled in the art will recognize that the foregoing fabrication methods have been successfully used for manufacturing pre-production prototype interfaces according to the invention. The methods may be altered in various ways for the manufacture of interfaces in production quantities.
~___ _._~_.. _r_~..~.._ _ As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example, while the invention has been described as using insulated wires which include a sheath surrounding an electrical conductor, the invention could also be practised by embedding a layer of parallel, closely spaced apart, non-insulated electrical conductors in a flexible, electrically insulating, biocompatible bonding agent. Apertures could then be cut in the bonding agent to expose the electrical conductors at selected locations.
While typical nerve cuffs have circumferences in the range of 6 mm to 10 mm, the interfaces and techniques described above may be adjusted to produce interfaces of larger or smaller sizes without deviating from the invention.
While the invention has so far described as providing an interface which includes a layer of signal carrier members all of the same type, the same interface could include two or more types of signal carrier members. The signal carrier members could be selected from: electrical conductors, optical fibers, and small catheters (tubes for carrying chemicals). For example, in the interface l0E of Figures 11A and 11B one of signal carrier members 27 comprises a catheter 27B while other ones of signal __..~_ . ~_.~ . T__~~~.__._..
carrier members 27 comprise electrical conductors connected to electrodes 36.
While the invention has described the laser cutting step as holding an interface stationary while a laser is moved, of course, all that is necessary is that the laser beam be moved relative to the interface being made. The laser beam could be held fixed while the interface is moved on an X-Y table or both the interface and laser beam may be moved in a manner such that the laser beam cuts the interface as desired.
While the above description describes interfaces which are connected by leads to external devices, signal processing units such as, but not limited to, electrical amplifiers and filters, pharmaceutical delivery systems and/or optical illuminators, amplifiers and filters could be attached to the interface and controlled by suitable wireless means all without affecting the basic structure of the interface.
Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
Claims (22)
1. An interface comprising a plurality of parallel elongated signal conducting members embedded in flexible biocompatible material, the signal carrier members each comprising a signal conductor, the material overlying one or more of the signal conducting members being apertured to expose the signal conductor.
2. The interface of claim 1 provided as a nerve cuff having a longitudinal axis wherein the signal carrier members extend parallel to the axis.
3. The interface of claim 1 wherein the signal carrier members are packed adjacent to one another in a substantially continuous layer.
4. The interface of claim 3 wherein the signal conducting members each comprise an insulated electrical wire.
5. The interface of claim 4 wherein a plurality of the signal conductors are electrically shorted together at each end of the nerve cuff.
6. The interface of claim 1 provided as a nerve cuff and comprising mating closure mechanisms on opposed edges of the nerve cuff wherein the nerve cuff may be bent about an axis parallel with the signal conducting members and the closure mechanisms engaged with one another to form a generally cylindrical cuff surrounding a lumen with the exposed portions of the signal conductors in the lumen.
7. The interface of claim 1 wherein one or more of the signal carrier members extends continuously to form a lead.
8. The interface of claim 1 wherein the flexible biocompatible material comprises a silicone adhesive.
9. The interface of claim 8 wherein the silicone adhesive is in a layer having a thickness in the range of 0.1 mm to 0.3 mm.
10. A method for fabricating an interface to a biological tissue, the method comprising:
a) providing a plurality of elongated signal carrier members each comprising a signal conductor;
b) arranging the signal carrier members parallel to one another in a substantially continuous layer;
c) bonding the signal carrying members together with a flexible biocompatible adhesive material; and, d) cutting through material overlying the signal conductors of one or more of the signal carrier members to expose the signal conductors at selected locations.
a) providing a plurality of elongated signal carrier members each comprising a signal conductor;
b) arranging the signal carrier members parallel to one another in a substantially continuous layer;
c) bonding the signal carrying members together with a flexible biocompatible adhesive material; and, d) cutting through material overlying the signal conductors of one or more of the signal carrier members to expose the signal conductors at selected locations.
11. The method of claim 10 wherein each signal carrier member comprises an outer sheath surrounding the signal conductor and cutting through material overlying the signal conductors comprises cutting through the sheath.
12. The method of claim 10 wherein the signal carrier members comprise electrical conductors, cutting the sheaths comprises exposing the electrical conductors of a plurality of the signal carrier members at spaced apart locations on each of the signal carrier members and the method includes connecting the electrical conductors of the plurality of signal carrier members with a shorting conductor.
13. The method of claim 10 wherein cutting through the sheaths of the one or more signal carrier members comprises laser cutting.
14. The method of claim 13 wherein the signal carrier members comprise insulated electrical wires.
15. The method of claim 14 wherein the sheath comprises Teflon insulation.
16. The method of claim 15 comprising etching the Teflon sheaths prior to bonding the signal carrier members together.
17. The method of claim 16 wherein the laser cutting is performed with an ultraviolet laser.
18. The method of claim 17 wherein the laser cutting is performed with a frequency quadrupled Nd:YAG laser operating at a wavelength of approximately 266 nm.
19. The method of claim 14 comprising cutting through one or more of the exposed signal conductors and bending the exposed cut signal conductor outwardly.
20. The method of claim 10 wherein the signal carrier members comprise tubes.
21. The method of claim 10 wherein the signal carrier members comprise optical fibers.
22. The method of claim 10 comprising bonding first and second pieces of tubing along either side of the nerve cuff and subsequently laser cutting the first and second pieces of tubing to form interdigitating closure members.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2266999 CA2266999A1 (en) | 1999-03-26 | 1999-03-26 | Implantable interfaces with embedded signal carriers and methods for fabricating same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2266999 CA2266999A1 (en) | 1999-03-26 | 1999-03-26 | Implantable interfaces with embedded signal carriers and methods for fabricating same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2266999A1 true CA2266999A1 (en) | 2000-09-26 |
Family
ID=29588639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2266999 Abandoned CA2266999A1 (en) | 1999-03-26 | 1999-03-26 | Implantable interfaces with embedded signal carriers and methods for fabricating same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2266999A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007140597A1 (en) | 2006-06-02 | 2007-12-13 | Victhom Human Bionics Inc. | Nerve cuff, method and apparatus for manufacturing same |
| WO2008025155A1 (en) * | 2006-08-29 | 2008-03-06 | Victhom Human Bionics Inc. | Nerve cuff injection mold and method of making a nerve cuff |
| WO2016209171A1 (en) * | 2015-06-25 | 2016-12-29 | Agency For Science, Technology And Research | Neuroprosthetics devices and methods for providing a neuroprosthetics device |
| US10231736B2 (en) | 2015-06-11 | 2019-03-19 | The Regents Of The University Of California | System and method for soft tissue gripping |
-
1999
- 1999-03-26 CA CA 2266999 patent/CA2266999A1/en not_active Abandoned
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007140597A1 (en) | 2006-06-02 | 2007-12-13 | Victhom Human Bionics Inc. | Nerve cuff, method and apparatus for manufacturing same |
| EP2024026A1 (en) * | 2006-06-02 | 2009-02-18 | Victhom Human Bionics Inc. | Nerve cuff, method and apparatus for manufacturing same |
| EP2024026A4 (en) * | 2006-06-02 | 2010-04-28 | Neurostream Technologies Gener | Nerve cuff, method and apparatus for manufacturing same |
| US8214056B2 (en) | 2006-06-02 | 2012-07-03 | Neurostream Technologies General Partnership | Nerve cuff, method and apparatus for manufacturing same |
| US8428749B2 (en) | 2006-06-02 | 2013-04-23 | Neurostream Technologies General Partnership | Nerve cuff, method and apparatus for manufacturing same |
| WO2008025155A1 (en) * | 2006-08-29 | 2008-03-06 | Victhom Human Bionics Inc. | Nerve cuff injection mold and method of making a nerve cuff |
| EP2059377A1 (en) * | 2006-08-29 | 2009-05-20 | Victhom Human Bionics Inc. | Nerve cuff injection mold and method of making a nerve cuff |
| EP2059377A4 (en) * | 2006-08-29 | 2011-04-13 | Neurostream Technologies General Partnership | Nerve cuff injection mold and method of making a nerve cuff |
| US10231736B2 (en) | 2015-06-11 | 2019-03-19 | The Regents Of The University Of California | System and method for soft tissue gripping |
| WO2016209171A1 (en) * | 2015-06-25 | 2016-12-29 | Agency For Science, Technology And Research | Neuroprosthetics devices and methods for providing a neuroprosthetics device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2024026B1 (en) | Nerve cuff and method for manufacturing same | |
| US6757970B1 (en) | Method of making multi-contact electrode array | |
| JP6925467B2 (en) | Deep brain stimulation lead | |
| US7650184B2 (en) | Cylindrical multi-contact electrode lead for neural stimulation and method of making same | |
| US6265691B1 (en) | Method of making implantable lead including laser wire stripping | |
| RU2452529C2 (en) | Method for making neurostimulation chain and neurostimulation chain | |
| US5524338A (en) | Method of making implantable microelectrode | |
| US9263172B2 (en) | Wire constructs | |
| US7039470B1 (en) | Medical lead and method for medical lead manufacture | |
| EP0812575A2 (en) | RF ablation catheter and manufacturing process | |
| US20050256557A1 (en) | Medical lead and method for medical lead manufacture | |
| WO2000001300A1 (en) | Subdural electrode arrays for monitoring cortical electrical activity | |
| WO1997006760A1 (en) | Multi-electrode cochlear implant | |
| CA2447239A1 (en) | Endocardial mapping system | |
| US11890100B2 (en) | Deflectable mapping guide sheath for his bundle pacing | |
| CA2266999A1 (en) | Implantable interfaces with embedded signal carriers and methods for fabricating same | |
| US4923469A (en) | Prothesis and electrode for the electrical stimulation of the inner ear, and method for producing said electrode | |
| CN106310514B (en) | Feedthrough connector | |
| JP3802756B2 (en) | Electronic scanning ultrasonic probe | |
| EP2772183A1 (en) | Electronic endoscope and method of manufacturing electronic endoscope | |
| JP4914094B2 (en) | Shielded distance telemetry pin wiring for active implantable medical devices | |
| WO2022182765A1 (en) | Implant strain relief | |
| WO2023198672A1 (en) | Sensor housing for improved accuracy and electrical reliability | |
| AU2020358125A1 (en) | Lead for an active implantable medical device | |
| Kuo et al. | ARRAYED 3D PARYLENE SHEATH PROBES FOR NEURAL RECORDINGS |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 20040326 |