U.S. patent application number 10/623639 was filed with the patent office on 2005-01-27 for implantable electrical cable and method of making.
This patent application is currently assigned to Epic Biosonics Inc.. Invention is credited to Bluger, Henry.
Application Number | 20050016657 10/623639 |
Document ID | / |
Family ID | 33565189 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016657 |
Kind Code |
A1 |
Bluger, Henry |
January 27, 2005 |
IMPLANTABLE ELECTRICAL CABLE AND METHOD OF MAKING
Abstract
The present invention is an implantable cable and a process to
manufacture said implantable cable. The cable is composed of a
biocompatible fluoropolymer, in which biocompatible conductor wires
are embedded. The entire cable is heat treated at various stages to
ensure the wires are securely embedded. The cable is then undulated
to enhance its pliability and flexibility. Further treatment
activates the outer surface of the cable, following which it may be
encapsulated in silicone.
Inventors: |
Bluger, Henry; (Victoria,
CA) |
Correspondence
Address: |
Paul Smith Intellectual Property Law
330-1508 West Broadway
Vancouver
BC
V6JIW8
CA
|
Assignee: |
Epic Biosonics Inc.
|
Family ID: |
33565189 |
Appl. No.: |
10/623639 |
Filed: |
July 22, 2003 |
Current U.S.
Class: |
156/50 ;
156/206 |
Current CPC
Class: |
Y10T 156/1018 20150115;
H01B 13/0009 20130101; H01B 13/0013 20130101; A61N 1/05
20130101 |
Class at
Publication: |
156/050 ;
156/206 |
International
Class: |
H01B 013/00 |
Claims
I claim:
1. A process to manufacture an implantable cable, said process
comprising the steps of: establishing a plurality of grooves on a
first fluoropolymer film layer; positioning biocompatible conductor
wires into one or more of said grooves; applying heat to confine
said wires into said grooves; depositing a second fluoropolymer
layer to form a first structure; creating a second structure with
outer surfaces by encapsulating said first structure through
application of heat; undulating said second structure; activating
said outer surfaces of the said second structure to form a final
structure; and encapsulating said final structure with silicone to
form said implantable cable.
2. The process of claim 1, wherein said first and second
fluoropolymer film layers are comprised of FEP or PFA.
3. The process of claim 1, wherein said conductor wires are
comprised of Pt or Pt/Ir.
4. The process of claim 1, wherein the first and second
fluoropolymer layers are removed from an end portion of said
implantable cable to partially expose one or more conductor
wires.
5. The process of claim 4, wherein said end portion is removed
through laser cutting.
6. The process of claim 3, wherein said conductor wires have round,
oval or rectangular cross sections.
7. An implantable cable comprising: a plurality of conductor wires
embedded within a fluoropolymer film; said fluoropolymer film
comprising outer surfaces and at least one tip; said fluoropolymer
film being overall undulated; said fluoropolymer film being removed
at a tip of said implantable cable;
8. The implantable cable of claim 7, wherein said fluoropolymer is
activated.
9. The implantable cable of claim 7, wherein said fluoropolymer is
activated by sodium treatment of said implantable cable.
10. The implantable cable of claim 7 wherein said fluoropolymer is
activated by plasma treatment of said implantable cable.
11. The implantable cable of claim 8, 9 or 10 wherein said cable is
encased with silicone after activating said fluoropolymer.
12. The implantable cable of claim 7, wherein said biocompatible
film is comprised of FEP or PFA.
13. The implantable cable of claim 7, wherein said conductor wires
are comprised of Pt or Pt/Ir.
14. The implantable cable of claim 13, wherein said conductor wires
have round, oval or rectangular cross sections.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This present invention relates generally to the field of
implantable medical cables and conductor wires, particularly to
implantable medical cable for use with various implantable
electrical devices such as cochlear implants and other
neurostimulation and recording applications, and to a method of
fabricating such cables.
BACKGROUND OF THE INVENTION
[0002] The human body is a hostile environment to implanted medical
devices and materials, particularly to chronically implanted
electrical cables and leads. For example, implantable cardiac
cables are typically coupled at their proximal ends with implanted
pacemaker and pacemaker/cardioverter/defibrillator pulse
generators. Over the years of implantation, the cables and
insulation are subjected to cumulative mechanical stresses that can
result in degradation of the insulation or fractures of the lead
conductors with untoward effects on device performance and patient
well-being.
[0003] The traditional tubular insulation is most commonly composed
of an elastomeric material such as silicone or polyurethane. The
combination of a helically wound conductor with elastomeric outer
insulation provides conventional construction with the potential
for a substantial amount of elastic deformation in the direction of
the length of the lead.
[0004] An implantable electrical cable must also be completely
biocompatible, in that the exterior of the cable is preferably made
of biocompatible materials which are strong and flexible enough
that the constant flexure caused by movement of the patient or his
organs does not cause the cable to rupture. The exterior of the
cable is also preferably smooth to avoid abrasion of surrounding
tissue and other discomfort to the patient. The cable is also
preferably compliant and supple, to avoid damage to surrounding
tissue by being so stiff that it resists movement as the
surrounding tissues move. A stiff and inflexible cable would apply
a bias force, which would resist movement of the patient, and which
would cause discomfort to the patient.
[0005] U.S. Pat. No. 4,000,745 discloses the electrical leads for
cardiac stimulators comprising an insulated electrical conductive
section and a lead-in securing section including a helical member
which may be screwed into the heart muscle.
[0006] U.S. Pat. No. 6,374,141 discloses a bioelectrical stimulus
cable in which the insulated electrical lead includes at least one
fibril having a coating of rigid insulating, low friction material.
A coating of shock dampening elastomeric, insulating material is
tightly set about the rigid, insulating, low friction material. In
one preferred embodiment, the cable includes a braided sheath
encompassing a portion of the cable and increasing the tensile
strength of the cable.
[0007] Notwithstanding the variety of the implantable cable designs
that have been proposed, there is still a desire to improve the
mechanical characteristics and the product capability of the
implantable electrical cables.
[0008] An implantable cable is preferably thin. Cables that have
many wires will become stiffer as the numbers of parallel
conductors increases. A cable should be readily interconnectable
with other devices, that is, having a grouping or arrangement of
conductors that are dimensionally controlled and predictably
located for reliable fastening to other devices.
[0009] It is thus an object of the present invention to provide an
implantable cable which can withstand constant flexure during long
term chronic implantation.
[0010] A still further object of the present invention is to
provide an implantable cable which is encased with fluoropolymer
such as FEP or PFA
[0011] A further object of the present invention is to provide an
implantable cable having improved mechanical characteristics and
improved manufacturability.
[0012] A still further object of the invention is to provide a
manufacturing process for an implantable cable which can be
manufactured in a simple and reliable way.
[0013] These and other objects of the invention will be appreciated
by reference to the summary of the invention and to the detailed
description of the preferred embodiment that follow. It will be
appreciated that all of the foregoing objectives may not be
satisfied simultaneously by the preferred embodiment or by each of
the claims.
SUMMARY OF THE INVENTION
[0014] In accordance with one aspect of the present invention, a
process to manufacture an implantable cable comprises the steps of:
a) establishing a number of grooves on a first fluoropolymer film
layer; b) positioning biocompatible wires into said grooves; c)
applying heat to confine said wires into said grooves; d) deposing
a second fluoropolymer layer; e) encapsulating a resulting
structure by applying heat; f) undulating a further resulting
structure; g) activating the surface of the fluoropolymer film
layer; and h) encapsulating a final structure with silicone.
[0015] The first and second fluoropolymer layers are preferably
comprised of FEP or PFA. The conductor wire is preferably comprised
of Pt or Pt /Ir. The tip portion of the implantable cable may be
cut away to establish lead through laser cutting. The conductor
wires may have a flat, round, oval or rectangular cross
section.
[0016] The foregoing was intended as a broad summary only and of
only some of the aspects of the invention. It was not intended to
define the limits or requirements of the invention. Other aspects
of the invention will be appreciated by reference to the detailed
description of the preferred embodiment and to the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1A is a sectional view of a fluoropolymer film used to
manufacture an implantable cable according to the present
invention.
[0018] FIG. 1B is a sectional view of a fluoropolymer film having
grooves to manufacture an implantable cable according to the
present invention.
[0019] FIG. 2A is a sectional view of a fluoropolymer film within
which a conductor wire is placed in each groove.
[0020] FIG. 2B is a sectional view of a fluoropolymer film having
conductor wires after a thermal treatment.
[0021] FIG. 3A is a sectional view of a fluoropolymer film having
conductor wires on which another fluoropolymer film is
deposited.
[0022] FIG. 3B is a sectional view of the final structure of an
implantable cable according to the present invention.
[0023] FIG. 4A shows one method of undulating an implantable cable
according to the present invention.
[0024] FIG. 4B shows another method of undulating an implantable
cable according to the present invention.
[0025] FIG. 5A is a perspective view of an undulated implantable
cable according to the present invention.
[0026] FIG. 5B is perspective view of an undulated implantable
cable with the fluoropolymer material removed from the tip.
[0027] FIG. 6 is a sectional view of an undulated implantable cable
undergoing plasma treatment.
[0028] FIG. 7A shows an undulated implantable cable encapsulated
with silicone.
[0029] FIG. 7B shows a method of encapsulating an undulated
implantable cable with silicone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0030] The following describes the best mode presently contemplated
for carrying out the invention. This description is not to be taken
in a limiting sense, but is made merely for describing the general
principles of the invention. The scope of the invention should be
determined with reference to the claims.
[0031] FIG. 1A is a sectional view of a fluoropolymer film 2 used
to manufacture an implantable cable according to the present
invention. FEP or PFA film 2 is used in the preferred embodiment of
the present invention. However, it is possible to use other melt
processable biomaterials such as fluorocarbons PVDF, PCTFE, ECTFE,
ETFE, MFA (a copolymer of TFE and PVE), polyethylene's and
polypropylenes. The thickness of the film 2 is preferably about
20-100 .mu.m.
[0032] FIG. 1B is a sectional view of a fluoropolymer film 2 having
grooves 4 to manufacture an implantable cable according to the
present invention. A plurality of grooves 4 are established within
the FEP film 2 through laser cutting or other method such as
thermal forming and sawing.
[0033] Grooves 4 may be used to locate the conductor wires used to
deliver electrical signals. FIG. 2A is a sectional view of a
fluoropolymer film as in FIG. 1B with a conductor wire 6 placed in
each groove 4 in the FEP film 2. Conductor wire 6 may be made of Pt
or a Pt/Ir alloy. The conductor wires 6 may preferably have round,
oval or rectangular cross sections. Instead of Pt or Pt/Ir, well
known to those skilled in the art, titanium (and some alloys
thereof), platinum, tantalum, or gold may be used.
[0034] FIG. 2B is a sectional view of a fluoropolymer film as in
FIG. 2A after a thermal treatment. After locating wires 6 into
grooves 4 shaped on film 2, heat and pressure are applied to
overall structure to confine the wires within the film 2. This
thermal treatment ensures the wire conductors 6 are retained within
the film 2. Usually, in the case of FEP film, a thermal treatment
at 240-350.degree. C. is applied to the structure.
[0035] FIG. 3A is a sectional view of a fluoropolymer film as in
FIG. 2B on which another fluoropolymer film 8 is deposited. To
further encapsulate the wires 6, and to ensure the wires 6 will be
held tightly within the structure, another film 8 is deposited on
the film 2 in which the conductor wires are located. Film 8 is
preferably FEP, but, as with film 2, may be PFA or other melt
processable biomaterials such as fluorocarbons PVDF, PCTFE, ECTFE,
ETFE, MFA (a copolymer of TFE and PVE), polyethylenes and
polypropylenes.
[0036] FIG. 3B is a sectional view of the final structure of an
implantable cable according to the present invention. After
depositing film 8, another thermal treatment is applied, forming a
relatively flat implantable cable 300. The conductor wires 6 are
thus tightly encapsulated within the fluoropolymer film forming
implantable cable 300.
[0037] To increase cable flexibility and pliability, by allowing
ready expansion or contraction of the cable, it is preferred that
the cable 300 be undulated. FIGS. 4A and 4B show possible methods
of undulating an implantable cable 300 according to the present
invention. As shown in FIG. 4A, two opposing drums 10 may be used.
The drums 10 preferably have fine teeth 12 or other meshing
projections which roll over the surface of implantable cable 300,
thereby undulating the implantable cable 300 and forming undulated
cable 302. The drums 10 revolve at a certain speed and press the
implantable cable 300 from both sides. This is a very efficient
method of manufacturing undulated cable 302.
[0038] FIG. 4B shows an alternative method of undulating an
implantable cable 300 according to the present invention. There are
provided a number of pins 14, which revolve at a certain speed. The
pins 14 are positioned in a zigzag formation. Then, the implantable
cable 300 is undulated, forming undulated cable 302, by feeding it
through the pins 14. The undulation process preferably takes place
at an elevated temperature.
[0039] FIG. 5A is a perspective view of an undulated implantable
cable 302 according to the present invention. As shown in FIG. 5B,
the film on the tip of the undulated implantable cable 302 is then
partly cut away to expose the conductor wires 6. While any suitable
method to strip the cable tip without damaging the wires may be
used, laser cutting is the preferred method. The exposed wires may
then be welded to either a connector or an exposed junction, in
order to connect undulated implantable cable 302 to another
device.
[0040] The undulated implantable cable 302 needs additional plasma
treatment or sodium treatment to be activated. FIG. 6 is a
sectional view of an undulated implantable cable 302 undergoing a
plasma treatment. The cable is treated on both sides, as shown by
the arrows. This treatment facilitates the adhesion of an
encapsulating layer of silicone to the implantable cable 302.
[0041] After undulating the cable, it is preferred to encapsulate
the implantable cable 302 with silicone. Silicone is preferred as
it is highly elastic and is therefore capable of being elongated
with an elastic recovery to its initial shape. FIG. 7A shows an
undulated implantable cable 302 encased with a silicone coating 16
by an injection molding method. FIG. 7B shows another method in
which the undulated implantable cable 302 is fed through a bottle
shaped tool 20 through which liquid silicone 18 is flowing, thereby
encapsulating the undulated implantable cable 302. A heat coil or
some other heat source (not shown) may be used to provide heat to
keep the silicone 18 warm and flowable, to ensure good uniform
contact and coverage over all sides of the undulated implantable
cable 302.
[0042] It will be understood that in general these implantable
medical cables have extremely wide application in the medical
device field.
[0043] Moreover, as described above, it is seen that the
implantable cable described herein may be manufactured using low
cost technology and simple-to-implement manufacturing techniques
for mass production.
[0044] Finally, it is seen that the implantable cable of the
present invention may be safely and reliably used in various
medical devices.
[0045] The above descriptions are intended to illustrate the
preferred and alternative embodiments of the invention. For
example, the process for stripping out the undulated cable can be
done in the last stage after encasing the cable with silicone. It
will be appreciated that modifications and adaptations to such
embodiments may be practiced without departing from the scope of
the invention, such scope being most properly defined by reference
to this specification as a whole and to the following claims.
* * * * *