U.S. patent application number 17/543659 was filed with the patent office on 2022-03-24 for implantable thin film devices.
The applicant listed for this patent is Pacesetter, Inc.. Invention is credited to Tommy Cushing, John R. Gonzalez, Jeffrey Urbanski.
Application Number | 20220088375 17/543659 |
Document ID | / |
Family ID | 1000006013155 |
Filed Date | 2022-03-24 |
United States Patent
Application |
20220088375 |
Kind Code |
A1 |
Gonzalez; John R. ; et
al. |
March 24, 2022 |
IMPLANTABLE THIN FILM DEVICES
Abstract
Implementations described and claimed herein provide thin film
devices and methods of manufacturing and implanting the same. In
one implementation, a shaped insulator is formed having an inner
surface, an outer surface, and a profile shaped according to a
selected dielectric use. A layer of conductive traces is fabricated
on the inner surface of the shaped insulator using biocompatible
metallization. An insulating layer is applied over the layer of
conductive traces. An electrode array and a connection array are
fabricated on the outer surface of the shaped insulator and/or the
insulating layer, and the electrode array and the connection array
are in electrical communication with the layer of conductive traces
to form a flexible circuit. The implantable thin film device is
formed from the flexible circuit according to the selected
dialectic use.
Inventors: |
Gonzalez; John R.;
(McKinney, TX) ; Urbanski; Jeffrey; (Frisco,
TX) ; Cushing; Tommy; (Prosper, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pacesetter, Inc. |
Sylmar |
CA |
US |
|
|
Family ID: |
1000006013155 |
Appl. No.: |
17/543659 |
Filed: |
December 6, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16278464 |
Feb 18, 2019 |
11191952 |
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17543659 |
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15265594 |
Sep 14, 2016 |
10207103 |
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16278464 |
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62358428 |
Jul 5, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 1/115 20130101;
H05K 3/4673 20130101; H05K 3/0032 20130101; H05K 3/064 20130101;
H05K 3/18 20130101; H05K 2201/05 20130101; H05K 2203/065 20130101;
A61N 1/0551 20130101; H05K 3/28 20130101; H05K 3/4644 20130101;
H05K 1/09 20130101; H05K 3/184 20130101; H05K 3/0064 20130101; H05K
1/0298 20130101; H05K 3/42 20130101; H05K 1/11 20130101; A61N
1/36071 20130101; H05K 2201/051 20130101; H05K 2201/0338 20130101;
H05K 2201/0141 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05; H05K 3/18 20060101 H05K003/18; H05K 3/28 20060101
H05K003/28; H05K 3/42 20060101 H05K003/42; H05K 3/46 20060101
H05K003/46; H05K 1/11 20060101 H05K001/11; H05K 1/09 20060101
H05K001/09; H05K 3/06 20060101 H05K003/06; H05K 3/00 20060101
H05K003/00; H05K 1/02 20060101 H05K001/02; A61N 1/36 20060101
A61N001/36 |
Claims
1-23. (canceled)
24. An implantable thin film stimulation device formed as a circuit
tip assembly, comprising: a shaped insulator having a first surface
and a second surface and a stimulation end and a terminal end, the
shaped insulator having a non-flat profile; an insulating layer
applied over the layer of conductive traces; a plurality of
electrodes disposed on the second surface of the shaped insulator
and arranged along a length of the stimulation end of the shaped
insulator; a plurality of connection spots disposed at the terminal
end of the shaped insulator; a plurality of conductive traces
positioned between the insulating layer and the first surface of
the shaped insulator, wherein the plurality of conductive traces
are formed using biocompatible metallization; and one or more
conductive vias, wherein each electrode of the plurality of
electrodes corresponds to one of the connection spots of the
plurality of connection spots, and wherein electrical communication
between electrode and connection spot pairs is established using a
particular conductive trace of the plurality of conductive traces,
a particular conductive via of the one or more conductive vias, or
both.
25. The implantable thin film stimulation device of claim 24,
wherein the shaped insulator comprises a body portion, and wherein
a width of the body portion is narrower than a width of the
terminal end and a width of the stimulation end.
26. The implantable thin film stimulation device of claim 24,
wherein the width of the terminal end and the width of the
stimulation end are tapered at a region of the shaped insulator
where the body portion meets the terminal end and the stimulation
end.
27. The implantable thin film stimulation device of claim 25,
wherein the plurality of conductive traces run substantially
parallel along a length of the body portion.
28. The implantable thin film stimulation device of claim 24,
wherein a first set of conductive traces of the plurality of
conductive traces are disposed on a first side of the terminal end
and a second set of conductive traces of the plurality of
conductive traces are disposed on a second side of the terminal
end, the first side of the terminal end and second side of the
terminal end corresponding to longitudinal edges of the terminal
end.
29. The implantable thin film stimulation device of claim 28,
wherein the plurality of connection spots are disposed between the
first side of the terminal end and second side of the terminal
end.
30. The implantable thin film stimulation device of claim 24,
wherein a first set of conductive traces of the plurality of
conductive traces are disposed on a first side of the stimulation
end and a second set of conductive traces of the plurality of
conductive traces are disposed on a second side of the stimulation
end, the first side of the stimulation end and the second side of
the stimulation end corresponding to longitudinal edges of the
stimulation end.
31. The implantable thin film stimulation device of claim 30,
wherein the plurality of electrodes are disposed between the first
side of the stimulation end and second side of the stimulation
end.
32. The implantable thin film stimulation device of claim 24,
wherein the plurality of conductive traces are formed using at
least one of resist printing, laser ablation, etching, and
conductive printing.
33. The implantable thin film stimulation device of claim 24,
further comprising: a second plurality of conductive traces; and
one or more additional conductive vias, wherein the plurality of
conductive traces, the second plurality of conductive traces, the
one or more conductive vias, and the one or more additional
conductive vias form a plurality of conductive layers, wherein each
conductive layer of the plurality of conductive layers from other
conductive layers of the plurality of conductive layers by one of a
plurality of insulating layers, the plurality of insulating layers
including the insulating layer.
34. The implantable thin film stimulation device of claim 24,
wherein the conductive layers are configured to electrically
connect the electrodes to a power source.
35. The implantable thin film stimulation device of claim 24,
wherein the plurality of electrodes comprise three-dimensional
shapes.
36. The implantable thin film stimulation device of claim 24,
wherein the plurality of connection spots comprise
three-dimensional shapes.
37. The implantable thin film stimulation device of claim 24,
wherein the stimulation end has a paddle shape.
38. A method of manufacturing an implantable thin film stimulation
device, the method comprising: forming a shaped insulator having a
first surface and a second surface and a stimulation end and a
terminal end, the shaped insulator having a non-flat profile;
providing a layer of conductive traces formed using biocompatible
metallization on the first surface of the shaped insulator;
applying an insulating layer over the layer of conductive traces
such that the layer of conductive traces are disposed between the
first surface of the shaped insulator and the insulating layer;
providing one or more conductive vias, wherein at least one
conductive via of the one or more conductive vias is disposed
within the shaped insulator; forming an electrode array of one or
more electrodes on the second surface of the shaped insulator at
the stimulation end; and forming a connection array of one or more
connection spots positioned at the terminal end of the shaped
insulator, wherein electrical communication between the electrode
array and the connection array is provided by the layer of
conductive traces and the one or more conductive vias.
39. The method of claim 38, wherein the layer of conductive traces
is provided on the first surface of the shaped insulator using at
least one of resist printing, laser ablation, etching, and
conductive printing.
40. The method of claim 38, wherein the layer of conductive traces
and the one or more conductive vias form a first conductive layer,
the method further comprising: forming one or more additional
conductive layers; and adding each of the one or more additional
conductive layers and one or more additional insulating layers to
the insulating layer, wherein each of the one or more additional
conductive layers is separated from other conductive layers by one
of the one or more additional insulating layers, the insulating
layer, or both.
41. The method of claim 38, wherein the layer of conductive traces
extend parallel along a length of a body portion of the shaped
insulator, the body portion disposed between the terminal end and
the stimulation end of the shaped insulator.
42. The method of claim 38, wherein the stimulation end, the
terminal end, or both has a paddle shaped form factor.
43. The method of claim 38, wherein the plurality of electrodes
comprise three-dimensional shapes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/265,594, filed Sep. 14, 2016, which claims
the benefit of U.S. Provisional Patent Application Ser. No.
62/358,428, filed Jul. 5, 2016, which are incorporated herein in
their entirety.
TECHNICAL FIELD
[0002] Aspects of the present disclosure relate to thin film
devices implantable in a patient for electrical stimulation of
nerve or tissue and more particularly to thin film flexible
circuits for implantable leads and other devices configured for
various dielectric uses and deployment of thin film traces on a
three-dimensional substrate.
BACKGROUND
[0003] Medical conditions may be treated through the application of
electrical stimulation. For example, Spinal Cord Stimulation (SCS)
involves driving an electrical current into particular regions of
the spinal cord to induce paresthesia, which is a subjective
sensation of numbness or tingling in a region of the body
associated with the stimulated spinal cord region. Paresthesia
masks the transmission of chronic pain sensations from the
afflicted regions of the body to the brain, thereby providing pain
relief to the patient. Typically, an SCS system delivers electrical
current through electrodes implanted along the dura layer
surrounding the spinal cord. The electrodes may be carried, for
example, by a paddle lead, which has a paddle-like configuration
with the electrodes arranged in one or more independent columns on
a relatively large surface area, or percutaneous lead, which
includes the electrodes arranged around a tube. Paddle leads are
generally delivered into the affected spinal tissue through a
laminectomy, involving the removal of laminar vertebral tissue to
allow access to the dura layer and positioning of the paddle lead.
Conventional delivery of paddle leads thus generally requires large
incisions and substantial removal of lamina, resulting in trauma to
the patient and longer procedure time. Similar challenges and
disadvantages apply to other forms of leads implanted to treat
other medical conditions through electrical stimulation. For
example, implantable devices for Deep Brain Stimulation (DBS),
catheter ablation, Cardiac Rhythm Management (CRM), Occipital nerve
stimulation (ONS), Peripheral Nerve Stimulation (PNS), and the like
are often plagued by such challenges and disadvantages. Further,
conventional assembly procedures for electrically coupling a body
to a lead and a pulse generator are often cumbersome, expensive,
prone to breakage of conductive couplings, and/or result in pulse
generators or other power sources with a large footprint. It is
with these observations in mind, among others, that various aspects
of the present disclosure were conceived and developed.
SUMMARY
[0004] Implementations described and claimed herein address the
foregoing problems, among others, by providing implantable thin
film devices and methods of manufacturing and implanting the same.
In one implementation, a shaped insulator is formed having an inner
surface and an outer surface. The shaped insulator has a profile
shaped according to a selected dielectric use. A layer of
conductive traces is fabricated on the inner surface of the shaped
insulator using biocompatible metallization and defines a trace
pattern. An insulating layer is applied over the layer of
conductive traces with intimate contact between the inner surface
of the shaped insulator and an inner surface of the insulating
layer outside of the trace pattern. The insulating layer has an
outer surface opposite the inner surface. An electrode array and a
connection array are fabricated on at least one of the outer
surface of the shaped insulator or the outer surface of the
insulating layer, and the electrode array and the connection array
are in electrical communication with the layer of conductive traces
to form a flexible circuit. The implantable thin film device is
formed from the flexible circuit according to the selected
dialectic use.
[0005] In another implementation, an implantable thin film device
for patient treatment comprises a shaped insulator having an inner
surface and an outer surface. The shaped insulator has a profile
shaped according to a selected dielectric use. A layer of
conductive traces is disposed on the inner surface of the shaped
insulator and defines a trace pattern. The layer of conductive
traces is fabricated on the inner surface of the shaped insulator
using biocompatible metallization. An insulating layer has an outer
surface and an inner surface. The insulating layer is applied over
the layer of conductive traces with intimate contact between the
inner surface of the shaped insulator and the inner surface of the
insulating layer outside of the trace pattern. An electrode array
has one or more electrodes disposed on at least one of the outer
surface of the shaped insulator or the outer surface of the
insulating layer. A connection array has one or more connection
spots disposed on at least one of the outer surface of the shaped
insulator or the outer surface of the insulating layer. The
electrode array and the connection array are in electrical
communication with the layer of conductive traces to form a
flexible circuit.
[0006] Other implementations are also described and recited herein.
Further, while multiple implementations are disclosed, still other
implementations of the presently disclosed technology will become
apparent to those skilled in the art from the following detailed
description, which shows and describes illustrative implementations
of the presently disclosed technology. As will be realized, the
presently disclosed technology is capable of modifications in
various aspects, all without departing from the spirit and scope of
the presently disclosed technology. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows a patient with an example thin film lead
implanted for Spinal Cord Stimulation (SCS).
[0008] FIG. 2 shows an example deployment system and method for
implanting a thin film paddle lead for SCS, the deployment system
shown with a needle inserted into epidural space of the
patient.
[0009] FIG. 3 illustrates the deployment system of FIG. 2 with a
guide wire inserted through the needle into the epidural space of
the patient.
[0010] FIG. 4 illustrates the deployment system of FIG. 3 with a
delivery tool inserted over the guide wire into the epidural space
of the patient.
[0011] FIG. 5 shows the deployment system of FIG. 4 with an inner
penetrator being removed from a sheath of the delivery tool.
[0012] FIG. 6 illustrates the deployment system of FIG. 5 with the
thin film paddle lead being inserted through the sheath of the
delivery tool into the epidural space of the patient.
[0013] FIG. 7 illustrates the thin film paddle lead implanted and
the delivery tool of the paddle lead deployment system of FIG. 6
being removed from the epidural space of the patient.
[0014] FIG. 8 is an exploded view of an example thin film lead,
which may be wrapped radially around a mandrel or deployed
flat.
[0015] FIG. 9 is an isometric view of the thin film lead of FIG. 8
shown assembled.
[0016] FIG. 10 is a detailed view of a stimulation end of the thin
film lead of FIG. 9.
[0017] FIG. 11 is a detailed view of a terminal end of the thin
film lead of FIG. 9.
[0018] FIG. 12 shows an isometric view of an example cylindrical
thin film lead, such as the thin film lead of FIG. 9, wrapped
radially around a biocompatible body.
[0019] FIG. 13 is a detailed view of a stimulation end of the thin
film lead of FIG. 12.
[0020] FIG. 14 is another detailed view of the stimulation end of
FIG. 13.
[0021] FIG. 15 is a detailed view of a terminal end of the thin
film lead of FIG. 12.
[0022] FIGS. 16A-16C illustrate a perspective view, a distal view,
and a side perspective view, respectively, of an example
stimulation end of a thin film lead wrapped around a biocompatible
body.
[0023] FIG. 17 shows an exploded view of an example thin film tips
configured to wrap at a stimulation end and a terminal end and coil
at a lead body.
[0024] FIG. 18 is an isometric view of the thin film lead of FIG.
17 shown assembled.
[0025] FIG. 19 is a detailed view of a stimulation end of the thin
film lead of FIG. 18.
[0026] FIG. 20 is a detailed view of a terminal end of the thin
film lead of FIG. 18.
[0027] FIG. 21 shows an isometric view of an example thin film
paddle lead configured for percutaneous insertion.
[0028] FIG. 22 is a detailed view of a stimulation end of the thin
film paddle lead of FIG. 21.
[0029] FIG. 23 is a detailed view of a terminal end of the thin
film paddle lead of FIG. 21.
[0030] FIG. 24 shows an isometric view of an example thin film
paddle lead with a bifurcated terminal end.
[0031] FIG. 25 is a detailed view of a stimulation end of the thin
film paddle lead of FIG. 24.
[0032] FIG. 26 is a detailed view of the bifurcated terminal end of
the thin film paddle lead of FIG. 24.
[0033] FIG. 27 illustrates an example layer of conductive traces
deployed on a three dimensional substrate.
[0034] FIGS. 28A and 28B each show an example layer of conductive
traces and an electrode array deployed on a tube.
[0035] FIGS. 29A-29E show a plated through hole integration process
for forming an implantable thin film device.
[0036] FIGS. 30A-30G depict a sequential metal integration process
for forming an implantable thin film device.
[0037] FIG. 31 illustrates example operations for manufacturing an
implantable thin film device for patient treatment.
[0038] FIG. 32 illustrates example operations for forming a
flexible circuit from a two-dimensional substrate.
[0039] FIG. 33 illustrates example operations for manufacturing an
implantable thin film device from a three-dimensional
substrate.
DETAILED DESCRIPTION
[0040] Aspects of the present disclosure involve thin film devices
and methods of manufacturing and implanting the same. Generally, an
implantable thin film device includes a flexible circuit formed
from one or more layers with biocompatible metallization and a
substrate, which may be two-dimensional (i.e., flat) or
three-dimensional (i.e., non-flat). In one aspect, conductor traces
are fabricated on a first insulating layer with biocompatible
metallization, and a second insulating layer is applied over the
conductor traces with intimate contact between the first insulating
layer and the second insulating layer in contact areas outside of
the conductor traces. After the conductor traces are encapsulated,
vias may be formed in the first insulating layer and/or the second
insulating layer and filled with conductive material. An electrode
array and a connection array are fabricated on the first insulating
layer and/or the second insulating layer and connected to the
conductive material to form a flexible circuit, which may be a full
tip-to-tail flexible circuit or flexible circuit tip assembly
attached to a lead body.
[0041] The implantable thin film device is formed from the flexible
circuit according to a selected dielectric use. Stated differently,
the implantable thin film device may be formed by deploying the
flexible circuit as is, laminating the flexible circuit to a
flexible carrier, wrapping the flexible circuit around a body,
and/or coiling the flexible circuit around a body. The implantable
thin film device may thus be formed for surgical or percutaneous
deployment across a variety of dielectric uses, including, without
limitation, spinal cord stimulation (SCS), deep brain stimulation
(DBS), catheter ablation, cardiac rhythm management (CRM),
occipital nerve stimulation (ONS), peripheral nerve stimulation
(PNS), electrophysiology (EP), atrial fibrillation (AF), vagus
nerve, and the like.
[0042] In one aspect, where the implantable thin film device is
formed for percutaneous deployment into a target location of a
patient, a stylet, guidewire, or similar delivery structure may be
integrated onto the flexible circuit or onto a flexible carrier to
which the flexible circuit is laminated. Similarly, the flexible
circuit may be deployed around such delivery structures, preloaded
into a removable delivery sheath, or pulled to the target location
in the patient with a custom stylet. Alternatively, a stylet may be
loaded into a biocompatible tube around which the flexible circuit
is wrapped or coiled for deployment.
[0043] Thus, the presently disclosed technology provides
flexibility in manufacturing and deploying an implantable thin film
device customized for a selected dielectric use and having a
reduced footprint once implanted, among other advantages.
[0044] As described herein, the implantable thin film device may be
formed for a selected dielectric use from one or more flexible
circuits and implanted into a target area of a patient. To begin a
detailed description of an example of an implantable thin film lead
formed and deployed for SCS treatment, reference is made to FIG. 1.
It will be appreciated that while many of the example
implementations described herein reference SCS treatment, the
presently disclosed technology is applicable to other dielectric
uses and may be customized accordingly.
[0045] Turning to FIG. 1, a patient 10 is treated for a medical
condition through the application of electrical stimulation. In the
example implementation shown in FIG. 1, the patient 10 is treated
for chronic pain through SCS. In the vertebrate spinal column of
the patient 10, the epidural space 20 is positioned at the
outermost part of the spinal canal formed by vertebrae 40, which
have spinous process 30 projecting therefrom and providing a point
of attachment for muscles and ligaments of the patient 10.
Ligamentum flavum 50 connect the laminae of adjacent vertebrae 40.
The lamina covers the spinal canal, which encloses and protects the
spinal cord 60. In one implementation, an implantable stimulation
system 70 includes an implantable thin film device 80 positioned at
a target location in the epidural space 10 to drive an electrical
current from a power source 90 into particular regions of the
spinal cord 60 of the patient 10 to induce paresthesia. In this
case, the implantable thin film device 80 is a thin film lead, and
the power source 90 is an implantable pulse generator (IPG) or an
external pulse generator (EPG). The thin film lead may be formed as
a percutaneous lead or a paddle lead and deployed into the target
location in the epidural space 20 accordingly. As described herein,
the footprint of the implantable stimulation system 70 within the
patient 10 is minimized by customizing the implantable thin film
device 80 according to a selected dielectric use, in this example,
SCS.
[0046] In one implementation, the implantable thin film device 80
has a body extending between a proximal end and a distal end, which
may be configured as a terminal end and a stimulation end,
respectively. The terminal end of implantable thin film device 80
is configured to connect with the power source 90 to deliver power
to the stimulation end, which is implanted in the target location
of the patient 10. The stimulation end of the implantable thin film
device 80 delivers electrical stimulation to the target location of
the patient 10.
[0047] As described herein, the implantable thin film device 80 is
formed from one or more flexible circuits according to the selected
dielectric use, which may be, without limitation, SCS, DBS, CRM,
ONS, PNS, EP, AF, catheter ablation, vagus nerve, or the like.
Further, the implantable thin film device 80 may be formed from the
one or more flexible circuits for percutaneous deployment or
surgical deployment according to the selected dielectric use. For
example, the implantable thin film device 80 may be formed from the
flexible circuit(s) as a neurostimulation percutaneous lead
configured for delivery through the skin of the patient 10 via a
needle or as a neurostimulation paddle lead configured for surgical
delivery, such as through a laminotomy operation in the case of SCS
treatment. Generally, the one or more flexible circuits comprise a
multiple layer design formed through biocompatible metallization
and involving a flexible polymer or inorganic substrate.
[0048] In one implementation, the implantable thin film device 80
includes a full tip-to-tail flexible circuit having a stimulation
end and a terminal end connected by a body. A length of the full
tip-to-tail flexible circuit from which the implantable thin film
device 80 is formed may vary according to the selected dielectric
use. In one implementation, the length of the full tip-to-tail
flexible circuit may range from approximately 12 to 80 inches
depending on the selected dielectric use for the implantable thin
film device 80. For example, the length may be approximately 12 to
36 inches where the implantable thin film device 80 is a
neurostimulation lead and over approximately 72 inches where the
implantable thin film device 80 is an ablation catheter or EP
device. Further, a shape and profile of the implantable thin film
device 80 may be formed from the flexible circuit based on the
selected dielectric use. Where the implantable thin film device 80
is a neuromodulation percutaneous lead, the full tip-to-tail
flexible circuit may be deployed cylindrically or flat, for example
depending on a connection to the power source 90. More
particularly, where the power source 90 is configured for a
cylindrically shaped connector, the full tip-to-tail flexible
circuit may be wrapped or coiled around a tube to form the terminal
end of the implantable thin film device 80 as a cylindrically
shaped connector, such that the terminal end of the implantable
thin film device 80 may be connected directly into the power source
90 without an additional interface.
[0049] It will be appreciated that in alternative to the
implantable thin film device 80 being formed from a full
tip-to-tail flexible circuit, the one or more flexible circuits
from which the implantable thin film device 80 is formed may
include, without limitation, flexible circuit tip assemblies.
Further, the presently disclosed technology is applicable to
non-flexible active tip assemblies, lead connections, as well as
various forms of percutaneous leads, surgical paddle leads, and
other implantable devices.
[0050] To manufacture the implantable thin film device 80, in one
implementation, a shaped insulator is formed from a substrate
comprising one or more layers. The substrate may be made from an
insulating material, including, without limitation, polyimide,
organic thermoplastic polymer (e.g., Polyether ether ketone
(PEEK)), liquid crystal polymer (LCP), flexible glass, flexible
ceramic, rigid ceramic, and/or other insulating materials. The
shaped insulator may be flexible, non-flexible (e.g., rigid), a
combination of flexible and non-flexible, or transitionally stuff
(e.g., transitioning or otherwise varying in stiffness from
flexible to rigid along a length of the implantable thin film
device 80). The shaped insulator of the implantable thin film
device 80 has an inner surface and an outer surface extending along
a length of the shaped insulator between a proximal end and a
distal end. The outer surface is configured for contact with the
tissue of the patient 10.
[0051] In one implementation, a profile of the shaped insulator
defined transverse to a length of the inner surface and outer
surface is shaped according to the selected dielectric use. For
example, the selected dielectric use dictates formation parameters
of the implantable thin film device 80, including, without
limitation, stimulation direction (e.g., unidirectional stimulation
or multi-directional stimulation), stimulation surface area,
migration potential (e.g., extent to which longitudinal and lateral
migration needs to be minimized after implant), deployment method
(e.g., surgical or percutaneous), deployment shape (e.g., flat,
cylindrical, etc.), connection to the power source 90 (e.g., a
shape of the connection to the power source, etc.), and/or the
like. As such, the profile of the shaped insulator is shaped
accordingly, thereby facilitating deployment, minimizing a
footprint of the implantable stimulation system 70 after implant,
and customizing the implantable thin film device 80 for the
selected dielectric use.
[0052] For example, a profile of the shaped insulator may be shaped
for flat or cylindrical percutaneous deployment of the implantable
thin film device 80. In one implementation, the shaped insulator is
two-dimensional with the profile being flat to form the implantable
thin film device 80 for flat percutaneous deployment. Similarly,
the shaped insulator is three-dimensional with the profile being
non-flat to form the implantable thin film device 80 for
cylindrical percutaneous deployment. The non-flat profile may be
curved, angled, and/or irregular. For example, in one
implementation, the shaped insulator is a tube having a curved
profile shape.
[0053] Once the shaped insulator is formed, a layer of conductive
traces is fabricated on the inner surface of the shaped insulator
using biocompatible metallization. The layer of conductive traces
defines a trace pattern. In one implementation, the trace pattern
includes one or more stimulation end traces, terminal end traces,
and body traces. The stimulation end traces may be fabricated on
the inner surface of the shaped insulator at the proximal end, the
terminal end traces may be fabricated on the inner surface of the
shaped insulator at the distal end, and the body traces may connect
the terminal end traces to the stimulation end traces. Such a trace
pattern may be defined, for example, where the flexible circuit is
a full tip-to-tail flexible circuit. In another implementation, the
trace pattern may include stimulation end traces or terminal end
traces configured to connect with a wound lead body. Such a trace
pattern may be defined, for example, where the flexible circuit is
a flexible circuit tip assembly. The trace pattern will further be
defined depending on the selected dielectric use, for example as it
dictates an electrode count and deployment array, as discussed
herein. Further, the trace pattern may include one or sub-patterns
and/or variations between the stimulation end and the terminal end,
thereby providing additional flexibility to the flexible circuit as
defined for the selected dielectric use. For example, the trace
pattern may include zig-zag patterns, linear patterns, angled
patterns, contoured patterns, and/or the like. The trace pattern
may vary along the stimulation end, the body, and the terminal
end.
[0054] In one implementation, the biocompatible metallization
includes metal deposition, foil attachment (e.g., laminated foils),
conductive printing, and/or the like using one or more metals. The
trace pattern may be defined using resist printing, ablation (e.g.,
laser ablation), etching, conductive printing, insulative
impregnation, insulative implantation, and/or the like. For
example, the layer of conductive traces may be fabricated using a
fully biocompatible deposited or etched foil metal scheme. The
metals may include, without limitation, Palladium (Pd), Gold (Au),
Titanium (Ti), Platinum (Pt), Platinum-Iridium (Pt--Ir), metallic
alloys comprising a plurality of these metals, and/or the like. It
will be appreciated, however, that other biocompatible metals or
non-metallic electrically conductive materials may be used. The
biocompatible metallization may thus utilize seed deposition and
plating, thin laminated foils for conductors, printed conductors,
doped polymer traces, and/or the like.
[0055] Once the layer of conductive traces is fabricated on the
shaped insulator, an insulating layer is applied to the shaped
insulator over the layer of conductive traces. In one
implementation, the insulating layer is applied with intimate
contact between the inner surface of the shaped surface and an
inner surface of the insulating layer outside the trace pattern.
Stated differently, after application, there is intimate contact
between the inner surface of the shaped insulator and the inner
surface of the insulating layer where there are no traces, thereby
encapsulating the layer of conductive traces between the shaped
insulator and the insulating layer. The insulating layer may be
made from an insulating material, including, without limitation,
polyimide, organic thermoplastic polymer (e.g., PEEK), LCP, glass,
ceramic, inorganic material, non-conductive oxide, thermoset
polymer, and/or other flexible or rigid insulating materials. The
insulating layer may be applied through extrusion, coating,
casting, deposition, lamination, printing, and/or the like.
[0056] In one implementation, once the insulating layer is applied,
the layer of conducting traces is encapsulated between the inner
layer of the insulating layer and the inner layer of the shaped
insulator, with the outer layer of the shaped insulator and an
outer layer of the insulating layer configured to contact the
tissue of the patient 10. In another implementation, the insulating
layer and the layer of conductive traces are part of a
multiple-layer series of alternating insulating and conducting
layers. Stated differently, the implantable thin film device 80 may
include conductive traces in a plurality of layers separated by
insulating layers. The implantable thin film device 80 may thus
include multiple layer traces and outer layer connections to
support a higher trace count while minimizing the footprint of
implantable stimulation system 70, among other advantages.
[0057] To deliver electrical stimulation to a target area of the
patient 10 using the implantable thin film device 80, an electrode
array having one or more electrodes and a connection array having
one or more connection spots are fabricated on an outer surface of
the shaped insulator and/or the outer surface of the insulating
layer or outer surface of outermost insulating layer in the case of
a multiple-layer series of alternating insulating and conducting
layers. The electrode(s) and the connection spot(s) may be any
two-dimensional shape (i.e., flat) or three-dimensional shape
(i.e., non-flat). The three-dimensional shapes may include, without
limitation, non-uniform spheres, spheres, polygons, and/or other
curved and/or angled shapes.
[0058] In one implementation, the electrode array and the
connection array are in electrical communication with the layer(s)
of conductive traces to form a flexible circuit. Electrical
communication between the layer(s) of conductive traces and the
electrode array and the connection array may be established in a
variety of manners. For example, in one implementation, one or more
vias are formed in the outer surface of the shaped insulator and/or
the insulating layer(s) and filled with conductive material to
establish the electrical communication. The number of electrodes
included in the electrode array and the number of connection spots
in the connection array, and thus the trace pattern, may vary
depending on the selected dielectric use. Stated differently, the
implantable thin film device 80 formed from the one or more
flexible circuits includes configurable traces, electrodes, and
contacts for one or more selected dielectric uses. The flexible
circuit is thus not limited to a printed circuit board or silicon
wafer scheme but can also utilize a roll to roll process, flat
panel display process, and/or the like.
[0059] The flexible circuit may be, for example, a full tip-to-tail
flexible circuit, a flexible circuit tip assembly, and/or the like.
In one implementation, the flexible circuit is a full tip-to-tail
flexible circuit having a stimulation end and a terminal end
connected by body traces. The electrode array is disposed at the
stimulation end and configured to deliver electrical stimulation to
the target location in the patient 10, and the connection array is
disposed at the terminal end and configured to connect to the power
source 90 to supply electrical energy to the electrode array via
the one or more layers of conductive traces. In another
implementation, the flexible circuit is a flexible circuit tip
assembly, for example configured as a stimulation end tip assembly.
Here, the connection array is electrically connected to one or more
conductors of a body (e.g., conductive wires of a lead body) to
deliver electrical energy to the electrode array from the power
source 90.
[0060] More particularly, where the layer of conductive traces is
part of a flexible circuit tip assembly, for example a stimulation
end tip assembly, each connection spot in the connection array may
be aligned with and placed over a respective conductive wire of the
body of the implantable thin film device 80. A laser may be used to
weld each connection spot to the respective conductive wire of the
body of the implantable thin film device 80. The connection array
is in electrical communication with the electrode array through the
layer of conductive traces, such that electrical energy may be
delivered from the power source 90 through the conductive wires of
the body of the implantable thin film device 80 to the target
location of the patient 10. As such, the flexible circuits may be
attached as tips to a wound lead body to form the implantable thin
film device 80.
[0061] The electrode array and the connection array of the
implantable thin film device 80 may be fabricated using
biocompatible metallization, including, but not limited to, metal
deposition, foil attachment (e.g., laminated foils), conductive
printing, and/or the like using one or more metals. The metals may
include, without limitation, Pd, Au, Ti, Pt, and/or Pt--Ir. It will
be appreciated, however, that other biocompatible metals or
electrically conductive materials may be used. In one
implementation, the biocompatible metallization used in fabricating
the electrode array and the connection array is the same as the
biocompatible metallization used in fabricating the one or more
layers of conductive traces.
[0062] In one implementation, the biocompatible metallization of
the layer of conductive traces, the electrode array, and/or the
connection array involves laser ablation in manufacturing the
implantable thin film device 80. A thin layer of biocompatible
conductive metal, such as Pd, Au, Ti, Pt, Pt--Ir, and/or the like,
is adhered or otherwise coupled to a surface of an insulator (e.g.,
the inner surface of the shaped insulator). The trace pattern of
the layer of conductive traces is defined through the formation of
separating trenches using a laser. More specifically, sufficient
power is applied by the laser to ablate a portion of the thin layer
of biocompatible conductive metal until each trace is electrically
isolated from other traces in the trace pattern. The electrode
array and/or the connection array may be similarly fabricated
through laser ablation.
[0063] The implantable thin film device 80 is formed from one or
more flexible circuits according to the selected dielectric use. As
described herein, the implantable thin film device 80 may be a
percutaneous lead having a stimulation end and a terminal end form
from the flexible circuit. The flexible circuit may be a full
tip-to-tail flexible circuit that is deployed flat or otherwise as
is following the fabrication of the electrode array and the
connection array. Similarly, the implantable thin film device 80
may be a paddle lead configured for percutaneous or surgical
deployment and formed from a full tip-to-tail flexible circuit or
from one or more flexible circuit tip assemblies.
[0064] The implantable thin film device 80 may further be formed
from one or more flexible circuits according to the selected
dielectric use by laminating the flexible circuit to a carrier
(e.g., a flexible carrier, a rigid carrier, a transitionally stiff
carrier (e.g., a carrier that transitions in stiffness from
flexible to rigid), etc.), wrapping the flexible circuit around a
biocompatible body, coiling the flexible circuit around a
biocompatible body, and/or the like. The flexible carrier may be
two-dimensional (i.e., flat) or three-dimensional (i.e., non-flat)
and made from a variety of materials, such as a biocompatible
polymer. The biocompatible body may be a tube, mandrel, or
similarly shaped body and made from a biocompatible polymer, such
as Bionate.RTM., Carbosil.RTM., or Optim.RTM., and/or other
polymers and/or biocompatible materials.
[0065] Thus, the implantable thin film device 80 is formed from one
or more flexible circuits according to the selected dielectric use.
For example, the implantable thin film device 80 may be formed into
a neuromodulation eight channel device for SCS, a segmented DBS
device, a single channel CRM device, a multi-channel CRM device, a
cable harness for ablation catheters, and the like.
[0066] In one implementation, the implantable thin film device 80
is formed and deployed into the target location of the patient 10
according to the selected dielectric use. For percutaneous
deployment, a stylet, guide wire, or the like may be integrated
onto the flexible circuit from which the implantable thin film
device 80 is formed or onto a flexible carrier to which the
flexible circuit is laminated. Alternatively, the flexible circuit
from which the implantable thin film device 80 is formed may be:
deployed around a stylet, guide wire, or the like; preloaded into a
removable delivery sheath; pulled to the target location in the
patient 10 with a custom stylet; and/or the like. In one
implementation, a stylet is loaded into a biocompatible body around
which the flexible circuit is wrapped or coiled to form the
implantable thin film device 80. For a non-limiting example of the
implantable thin film device 80 formed from the flexible circuit(s)
as a paddle lead for percutaneous deployment for SCS treatment,
reference is made to FIGS. 2-7.
[0067] Turning first to FIG. 2, in one implementation, a target
location in epidural space 20 of the patient 10 is chosen for
positioning a stimulation end of the implantable thin film device
80 to deliver SCS treatment. The target location may be selected,
for example, using fluoroscopy. Referring to FIG. 2, in one
implementation, a deployment system 100 includes a needle 102,
which is inserted through a small incision, for example, between
the spinous processes 30 of two vertebrae 40. The needle 102 is
advanced through subcutaneous tissue and the ligamentum flavum 50
of the spine into the epidural space 20 along the spinal cord 60.
In one implementation, the needle 102 is inserted at an angle.
Following entry of the needle 102 into the epidural space 20, an
inner portion 106 (e.g., a stylet) is removed from a proximal end
104 of the needle 102.
[0068] Referring to FIG. 3, in one implementation, after removing
the inner portion 106 from the needle 102, a guide wire 108 is
inserted through the needle 102 into the epidural space 20.
Fluoroscopy may be used to verify a position of a distal end 110 of
the guide wire 108 in the target location of the epidural space 20.
Once the distal end 110 of the guide wire 108 is positioned, the
needle 102 is removed.
[0069] As shown in FIG. 4, a delivery tool 112 having a sheath 114
extending from a hub 116 is deployed over the guide wire 108 into
the epidural space 20. The delivery tool 112 may be inserted at an
angle. In one implementation, as can be understood from FIGS. 4-5,
a dilator 118 extends through a distal tip of the sheath 114 from
an inner penetrator 120, permitting the delivery tool 112 to pass
easily over the guide wire 108 without creating a false passage in
an undesirable location of the anatomy of the patient 10. The
dilator 118 may further provide indication to the surgeon of
contact with the ligamentum flavum 50. Once the delivery tool 112
penetrates the ligamentum flavum 50, the guide wire 108 is removed,
leaving the sheath 114 positioned in the epidural space 10. As
shown in FIG. 5, in one implementation, the inner penetrator 120 is
also removed.
[0070] Referring to FIGS. 6 and 7, the implantable thin film device
80 is inserted through a lumen of the sheath 114 into the target
location of the patient 10 in the epidural space 20. The sheath 114
is then removed, leaving the implantable thin film device 80 in the
epidural space 20 to deliver electrical stimulation from the power
source 90. The implantable thin film device 80 may be manipulated
to achieve a desired SCS therapeutic effect. In one implementation,
the implantable thin film device 80 is secured by suturing it to a
spinous process (e.g., one of the spinous processes 30).
[0071] FIGS. 8-26 depict various examples of the implantable thin
film device 80 formed from a flexible circuit, such as a full
tip-to-tail flexible circuit, as described herein according to a
selected dielectric use. It will be appreciated by those of
ordinary skill in the art that such depictions are exemplary only
and not intended to be limiting.
[0072] Turning first to FIGS. 8-11, the implantable thin film
device 80 is formed as a thin film lead 200, which may be wrapped
radially around a biocompatible body or mandrel, or deployed flat.
In one implementation, the thin film lead 200 is formed from a full
tip-to-tail flexible circuit as an eight channel neuromodulation
lead for SCS, DBS, or a similar dielectric use.
[0073] The thin film lead 200 includes a stimulation end 202 and a
terminal end 204 connected by a lead body 206. In one
implementation, the stimulation end 202 includes an electrode array
208 having one or more electrodes, and the terminal end 204
includes a connection array 210 having one or more connection
spots. As shown in FIGS. 8-11, where the thin film lead 200 is
formed from a full tip-to-tail flexible circuit as an eight channel
neuromodulation lead, the electrode array 208 and the connection
array 210 have eight electrodes and eight connection spots,
respectively. In one implementation, the electrodes of the
electrode array 208 have a larger surface area relative to the
connection spots of the connection array 210, as well as a larger
distance between adjacent electrodes of the electrode array 208
relative to a distance between adjacent connection spots of the
connection array 210. The relatively larger size and separation
distance of the electrode array 208 provides a larger surface area
for electrical stimulation delivery in the target location. On the
other hand, a decreased size and separation distance of the
connection array 210 is beneficial to reduce the footprint of the
terminal end 210 and for connection with the power source 90.
[0074] In one implementation, the thin film lead 200 includes a
shaped insulator 212, which may be formed from a variety of
insulating materials, as described herein. In one implementation,
the shaped insulator 212 is made from an LCP. The shaped insulator
212 is formed with a profile shaped for SCS, DBS, or a similar
dielectric use. For example, as shown in FIGS. 8-11, the shaped
insulator 212 may be two-dimensional with a flat profile. Further,
the shaped insulator 212 may have a varying shape along the length.
For example, the stimulator end 202 and the terminal end 204 of the
shaped insulator 212 may each have a larger surface area relative
to the lead body 206 of the shaped insulator 212. As shown in FIGS.
8-11, the stimulation end 202 and the terminal end 204 of the
shaped insulator 212 may each be shaped like a paddle tapering into
the lead body 206. The stimulation end 202 of the shaped insulator
212 may have a larger surface area relative to a surface area of
the terminal end 204, based on a surface area of the electrode
array 208 and the connection array 210, respectively.
[0075] The shaped insulator 212 has an inner surface and an outer
surface. In the example shown in FIGS. 8-11, the electrode array
208 and the connection array 210 are fabricated on the outer
surface of the shaped insulator 212, and a layer of conductive
traces 216 is fabricated on the inner surface of the shaped
insulator 212. In one implementation, an insulating layer 220 is
applied over the layer of conductive traces 216. The insulating
layer 220 may be, for example, an adhesive, such as a low Tg LCP.
Although the thin film lead 200 shows one layer of conductive
traces and one insulating layer, it will be appreciated that these
layers may be part of a multiple-layer series of alternating
insulating and conductive layers, as described herein.
[0076] In one implementation, one or more vias 214 are formed in
the shaped insulator 212 and/or the insulating layer 220 and filled
with conductive material 218 to connect the layer of conductive
traces 216 to the electrode array 208 and the connection array 210,
thereby forming a flexible circuit. A trace pattern is defined by
the layer of conductive traces 216 at the stimulation end 202, and
a trace pattern is defined by the layer of conductive traces 216 at
the terminal end 204 to accommodate the electrode array 208 and the
connection array 210 according to the selected dielectric use. In
the example shown in FIGS. 8-11, the trace pattern defined by the
layer of conductive traces 216 at the stimulation end 202 includes
eight traces spaced and shaped such that each of the traces will
electrically connect a corresponding electrode in the electrode
array 208 with the power source 90. Similarly, the trace pattern
defined by the layer of conductive traces 216 at the terminal end
204 includes eight traces spaced and shaped such that each of the
traces will electrically connect a corresponding connection spot in
the connection array 210 with the lead body 206.
[0077] The thin film lead 200 is formed from the flexible circuit
according to the selected dielectric use, in the example shown in
FIGS. 8-11, SCS, DBS, or the like. In one implementation, the thin
film lead 200 is formed directly from the flexible circuit, such
that the thin film lead 200 is deployed flat, as shown in FIGS.
8-11.
[0078] Turning to FIGS. 12-15, a cylindrical thin film lead 300
having a lead body 306 extending between a stimulation end 302 and
a terminal end 304 may be similarly formed from a flexible circuit
310. As described herein, the flexible circuit 310 includes an
electrode array 314 disposed at the stimulation end 302 and
electrically connected to a connection array 316 disposed at the
terminal end 304 by a layer of conductive traces 312. In one
implementation, the cylindrical thin film lead 300 is formed from
the flexible circuit 310 by radially wrapping the flexible circuit
310 around a biocompatible body 308. Additional views of an example
stimulation end 400 of a flexible circuit 402 wrapped around a
biocompatible body 404 are shown in FIGS. 16A-16C, with the
electrode array 406 disposed on an outer insulating surface 408,
such as an outer surface of a shaped insulator or an outer surface
of an insulating layer, as described herein.
[0079] As shown in FIGS. 17-20, in one implementation, the
implantable thin film device 80 is formed as a thin film lead 500,
which is wrapped at a stimulation end 502 and a terminal end 504
and coiled at a lead body 506. In one implementation, the thin film
lead 500 is formed from a full tip-to-tail flexible circuit as an
eight channel neuromodulation lead for SCS, DBS, or a similar
dielectric use. The stimulation end 502 is oriented at a first
angle to the lead body 506, and the terminal end 504 is oriented at
a second angle to the lead body 506, thereby providing increased
durability of the thin film lead 500 during movement.
[0080] In one implementation, the stimulation end 502 includes an
electrode array 508 having one or more electrodes, and the terminal
end 504 includes a connection array 510 having one or more
connection spots. As shown in FIGS. 17-20, where the thin film lead
500 is formed from a full tip-to-tail flexible circuit as an eight
channel neuromodulation lead, the electrode array 508 and the
connection array 510 have eight electrodes and eight connection
spots, respectively. In one implementation, the electrodes of the
electrode array 508 have a larger surface area relative to the
connection spots of the connection array 510, as well as a larger
distance between adjacent electrodes of the electrode array 508
relative to a distance between adjacent connection spots of the
connection array 510. The relatively larger size and separation
distance of the electrode array 508 provides a larger surface area
for electrical stimulation delivery in the target location. On the
other hand, a decreased size and separation distance of the
connection array 510 is beneficial to reduce the footprint of the
terminal end 510 and for connection with the power source 90.
[0081] In one implementation, the thin film lead 500 includes a
shaped insulator 512, which may be formed from a variety of
insulating materials, as described herein. In one implementation,
the shaped insulator 512 is made from an LCP. The shaped insulator
512 is formed with a profile shaped for SCS, DBS, or a similar
dielectric use. For example, as shown in FIGS. 17-20, the shaped
insulator 512 may be two-dimensional with a flat profile configured
for coiling around the lead body 506. Further, the shaped insulator
512 may have a varying shape along the length. For example, the
stimulator end 502 and the terminal end 504 of the shaped insulator
512 may each have a larger surface area relative to the lead body
506 of the shaped insulator 512. As shown in FIGS. 7-20, the
stimulation end 502 and the terminal end 504 of the shaped
insulator 512 may each be shaped like a paddle tapering into the
lead body 506 for coiling into a spiral or helix. The stimulation
end 502 of the shaped insulator 512 may have a larger surface area
relative to a surface area of the terminal end 504, based on a
surface area of the electrode array 508 and the connection array
510, respectively.
[0082] The shaped insulator 512 has an inner surface and an outer
surface. In the example shown in FIGS. 17-20, the electrode array
508 and the connection array 510 are fabricated on the outer
surface of the shaped insulator 512, and a layer of conductive
traces 516 is fabricated on the inner surface of the shaped
insulator 512. In one implementation, an insulating layer 520 is
applied over the layer of conductive traces 516. The insulating
layer 520 may be, for example, an adhesive, such as a low Tg LCP.
Although the thin film lead 500 shows one layer of conductive
traces and one insulating layer, it will be appreciated that these
layers may be part of a multiple-layer series of alternating
insulating and conductive layers, as described herein.
[0083] In one implementation, one or more vias 514 are formed in
the shaped insulator 512 and/or the insulating layer 520 and filled
with conductive material 518 to connect the layer of conductive
traces 516 to the electrode array 508 and the connection array 510,
thereby forming a flexible circuit. A trace pattern is defined by
the layer of conductive traces 516 at the stimulation end 502, and
a trace pattern is defined by the layer of conductive traces 516 at
the terminal end 504 to accommodate the electrode array 508 and the
connection array 510 according to the selected dielectric use. In
the example shown in FIGS. 17-20, the trace pattern defined by the
layer of conductive traces 516 at the stimulation end 502 includes
eight traces spaced and shaped such that each of the traces will
electrically connect a corresponding electrode in the electrode
array 508 with the power source 90. Similarly, the trace pattern
defined by the layer of conductive traces 516 at the terminal end
504 includes eight traces spaced and shaped such that each of the
traces will electrically connect a corresponding connection spot in
the connection array 510 with the lead body 506.
[0084] The thin film lead 500 is formed from the flexible circuit
according to the selected dielectric use, in the example shown in
FIGS. 17-20, SCS, DBS, or the like. In one implementation, the thin
film lead 500 is formed by wrapping the flexible circuit at the
stimulation end 502 and the terminal end 504 and coiling the
flexible circuit at the lead body 506.
[0085] Referring to FIGS. 21-23, an example thin film paddle lead
600 configured for percutaneous insertion is depicted. In one
implementation, the thin film paddle lead 600 includes a lead body
606 extending between a stimulation end 602 and a terminal end 604.
In the example shown in FIGS. 21-23, the thin film paddle lead 600
is formed from a full tip-to-tail flexible circuit as an eight
channel neuromodulation lead for SCS, DBS, or a similar dielectric
use. The thin film paddle lead 600 is flat and narrow, permitting
percutaneous deployment.
[0086] In one implementation, the stimulation end 602 includes an
electrode array 608 having one or more electrodes, and the terminal
end 604 includes a connection array 610 having one or more
connection spots. As shown in FIGS. 21-23, where the thin film
paddle lead 600 is formed from a full tip-to-tail flexible circuit
as an eight channel neuromodulation lead, the electrode array 608
and the connection array 610 have eight electrodes and eight
connection spots, respectively. In one implementation, the
electrodes of the electrode array 608 have a larger surface area
relative to the connection spots of the connection array 610, as
well as a larger distance between adjacent electrodes of the
electrode array 608 relative to a distance between adjacent
connection spots of the connection array 610. The relatively larger
size and separation distance of the electrode array 608 provides a
larger surface area for electrical stimulation delivery in the
target location. On the other hand, a decreased size and separation
distance of the connection array 610 is beneficial to reduce the
footprint of the terminal end 610 and for connection with the power
source 90.
[0087] In one implementation, the thin film paddle lead 600
includes a shaped insulator 612, which may be formed from a variety
of insulating materials, as described herein. The shaped insulator
612 is formed with a profile shaped for SCS, DBS, or a similar
dielectric use. For example, as shown in FIGS. 21-23, the shaped
insulator 612 may be two-dimensional with a flat, narrow profile
extending along an entirety of a length of the shaped insulator
612. In one implementation, the thin film paddle lead 600 includes
an insulating layer formed over a layer of conductive traces 616,
which are connected to the electrode array 608 and the connection
array 610 using vias 614 filled with conductive material 618, as
described herein to form the flexible circuit.
[0088] The thin film paddle lead 600 is formed from the flexible
circuit according to the selected dielectric use, in the example
shown in FIGS. 21-23, SCS, DBS, or the like. In one implementation,
the thin film paddle lead 600 is formed directly from the flexible
circuit, such that the thin film paddle lead 600 is deployed flat,
as shown in FIGS. 21-23, for percutaneous insertion.
[0089] FIGS. 24-26 show an example thin film paddle lead 700 with a
bifurcated terminal end. In one implementation, the thin film
paddle lead 700 includes a lead body 706 extending between a
stimulation end 702 and a terminal end 704. In the example shown in
FIGS. 24-26, the thin film paddle lead 700 is formed from a full
tip-to-tail flexible circuit as a multiple-column neuromodulation
lead for SCS, DBS, or a similar dielectric use. More particularly,
the thin film paddle lead 700 is configured for multiple columns of
electrodes (e.g., two eight channel columns) while maintaining a
flat, narrow profile to minimize a footprint of the thin film
paddle lead 700 and the power source 90.
[0090] In one implementation, the stimulation end 702 includes an
electrode array 708 having a plurality of columns of electrodes,
and the terminal end 704 is bifurcated with a connection array 710
having a plurality of connection spots disposed on a first
connection tail 720 and a plurality of connection spots disposed on
a second connection tail 722.
[0091] In one implementation, the thin film paddle lead 700
includes a shaped insulator 712, which may be formed from a variety
of insulating materials, as described herein. The shaped insulator
712 is formed with a profile shaped for SCS, DBS, or a similar
dielectric use. For example, as shown in FIGS. 24-26, the shaped
insulator 712 may be two-dimensional with a flat, narrow profile.
Further, the shaped insulator 712 may have a varying shape along
the length. For example, the stimulator end 702 and the terminal
end 704 of the shaped insulator 712 may each have a larger surface
area relative to the lead body 706 of the shaped insulator 712. As
shown in FIGS. 24-26, the stimulation end 702 of the shaped
insulator 712 may be shaped like a paddle tapering into the lead
body 706. In one implementation, the thin film paddle lead 700
includes an insulating layer formed over a layer of conductive
traces 716, which are connected to the electrode array 708 and the
connection array 710 using vias 714 filled with conductive material
718, as described herein to form the flexible circuit.
[0092] The thin film paddle lead 700 is formed from the flexible
circuit according to the selected dielectric use, in the example
shown in FIGS. 24-26, SCS, DBS, or the like. In one implementation,
the thin film paddle lead 700 is formed directly from the flexible
circuit, such that the thin film paddle lead 700 is deployed flat,
as shown in FIGS. 24-26.
[0093] As can be understood from the present disclosure, a thin
film circuit may be formed for a selected dielectric use. Using
such thin film circuits, implantable thin film devices may include
electrodes and contacts in various customized shapes, sizes, and/or
locations on a substrate, which may eliminate the need for
mechanical components to fabricate, connect, and attach to a power
source. Similarly, the thin film circuits may be formed in a
variety of shapes, including, without limitation, circular, spiral,
and the like, to aid in delivery and durability. The thin film
circuit may be further customized with a desired aspect ratio,
width to length, using large format processing, roll to roll
processing, stitching multiple circuits together, and/or the like.
To minimize the invasiveness to a patient, the footprint of the
implantable thin film device is reduced, for example, by shrinking
the volume and/or forming the implantable thin film device for flat
deployment. The implantable thin film devices may also be formed
from a three-dimensional substrate having a shape customized for
the selected dielectric use. Conductive channels are formed on the
three-dimensional substrate.
[0094] These features and advantages provide the ability to deliver
and/or sense location specific signals within the body of a patient
without complex assemblies having multiple bulky mechanical
components being constructed and deployed in for different
dielectric uses. Conventional assemblies, for example, utilize
individual conductors routed through long narrow substrates to
deliver and/or receive signals from a location in the patient to a
remote generator and/or analysis tool. The individual conductors of
such conventional assemblies typically each require a connection to
an electrode or contact at the distal and proximal ends to provide
an interface to the patient and the generator and/or analysis tool.
With the overall length, size, and number of conductors varying
depending on the dielectric use, the assembly process for such
conventional assemblies can be daunting. For example, the
individual conductors in such conventional assemblies are generally
comprised of wire and/or cables that are manually routed through
delivery substrates, such as tubes. The individual conductors then
need to be correctly spaced and joined to an electrode at the
distal end and a contact at the proximal end. Organizing the
spacing of the electrodes and contacts, as well as ensuring that
the appropriate conductor is joined to the appropriate
electrode/contact is thus often tedious and time consuming.
Further, the junction methods for the electrodes/contacts can be
challenging to fixture and to verify the desired characteristics
for delivering and/or receiving signals are consistently achieved.
These challenges are further exacerbated when accounting for the
additional considerations for a particular dielectric use,
including, but not limited to, final dimensions, footprint,
flexibility, durability, biocompatibility, and the like.
[0095] As described herein, the presently disclosed technology
addresses these concerns by utilizing thin film circuits customized
according to a selected dielectric use, thereby providing
simplified fabrication of otherwise complex implantable devices.
The presently discloses technology enables the fabrication of thin,
flexible multilayer circuits with a reduced footprint and increased
function of the assembly, for example, through the integration of
both mechanical and electrical components. For a detailed
description of example thin film circuits customized for a selected
dielectric use and the manufacturing processes associated
therewith, reference is made to FIGS. 27-33.
[0096] Turning first to FIG. 27, an example thin film circuit 800
having a layer of conductive traces 804 deployed on a
three-dimensional substrate 802 is illustrated. As described
herein, the three-dimensional substrate 802 is formed as a shaped
insulator with a profile being non-flat, for example, curved,
angled, and/or irregular. In one implementation, as shown in FIGS.
28A-B, the three-dimensional substrate 802 is a tube having a
curved profile shape. The three-dimensional substrate 802 may be
flexible or rigid, depending on the selected dielectric use, and
may be made from a variety of materials, such as polyimide, glass,
ceramic, and/or other biocompatible insulating materials.
[0097] Once the three-dimensional substrate 802 is formed as the
shaped insulator, the layer of conductive traces 804 is fabricated
on the inner surface of the three-dimensional substrate 802 using
biocompatible metallization. The layer of conductive traces defines
a trace pattern. In one implementation, the trace pattern includes
one or more stimulation end traces, terminal end traces, and body
traces.
[0098] In one implementation, the biocompatible metallization
includes metal deposition, foil attachment (e.g., laminated foils),
conductive printing, and/or the like using one or more metals. The
trace pattern may be defined using resist printing, laser ablation,
etching, conductive printing, and/or the like. For example, the
layer of conductive traces may be fabricated using a fully
biocompatible deposited or etched foil metal scheme. The metals may
include, without limitation, Palladium (Pd), Gold (Au), Titanium
(Ti), Platinum (Pt), and/or Platinum-Iridium (Pt--Ir). It will be
appreciated, however, that other biocompatible metals or
electrically conductive materials may be used.
[0099] Once the layer of conductive traces 804 is fabricated on the
three-dimensional substrate 802, an insulating layer may be applied
to the shaped insulator over the layer of conductive traces. In one
implementation, the insulating layer is applied with intimate
contact between the inner surface of the shaped surface and an
inner surface of the insulating layer outside the trace pattern.
Stated differently, after application, there is intimate contact
between the inner surface of the shaped insulator and the inner
surface of the insulating layer where there are no traces, thereby
encapsulating the layer of conductive traces between the shaped
insulator and the insulating layer. The insulating layer may be
made from an insulating material, including, without limitation,
polyimide, organic thermoplastic polymer (e.g., PEEK), LCP, glass,
ceramic, and/or other flexible or rigid insulating materials. The
insulating layer may be applied through extrusion, coating,
casting, deposition, lamination, printing, and/or the like.
[0100] In one implementation, once the insulating layer is applied,
the layer of conducting traces 804 is encapsulated between the
inner layer of the insulating layer and the inner layer of the
three-dimensional substrate 802. In another implementation, the
insulating layer and the layer of conductive traces are part of a
multiple-layer series of alternating insulating and conducting
layers. An electrode array having one or more electrodes and a
connection array having one or more connection spots are fabricated
on an outer surface of the three-dimensional substrate 802 and/or
the outer surface of the insulating layer. In one implementation,
the electrode array and the connection array are in electrical
communication with the layer of conductive traces 804 to form a
flexible circuit using vias filled with conductive material, for
example.
[0101] In one implementation, the three-dimensional substrate 802
uses fiber optics to print the layer of conductive traces 804
directly onto a substrate shaped for a selected dielectric use. For
example, the three-dimensional substrate 802 may be shaped as a
tube, as shown in FIGS. 28A-28B, to manufactured leads or EP
catheter devices without a bimetallic strip and additional
mechanical or electrical connections with the power source 90.
[0102] For an example of a thin film lead 900 having a
three-dimensional substrate 902 deployed in the form of a tube,
reference is made to FIGS. 28A and 28B. In one implementation, the
thin film lead 900 includes a layer of conductive traces 904 and an
electrode array having one or more electrodes 906 in electrical
communication with the layer of conductive traces 904 fabricated on
the three-dimensional substrate 902.
[0103] Referring generally to FIGS. 29A-33, it will be appreciated
that the implantable thin film devices are manufactured using
materials that prevent the environment of the body at the target
location from impacting the functionality of the implantable thin
film device or adversely affecting the patient over the term of the
therapy. As such, the implantable thin film device is manufactured
using a substrate formed from a material adapted to withstand
processing conditions involved in the application of conductive
arrays and junctions as well as to withstand the biochemistry
within a patient body without causing any adverse reactions. These
materials may include, without limitation, LCP, PEEK, FR-4,
polyimide, polytetrafluoroethylene (PTFE), silicon, flexible glass,
and/or other materials having resilience to high temperatures,
moisture absorption, dimensional stability, and dielectric
strength.
[0104] The substrate is bonded to another substrate with a layer of
conductive traces disposed therebetween. The substrate layers may
be bonded through the addition of an adhesive between the layers,
thermal bonding, coating, and/or the like. In one implementation,
the substrate layers are formed from LCP, which permits the Glass
transition temperature (Tg) of the raw material to be varied,
thereby enabling thermal bonding of the substrate layers together
without distorting the layer of conductive traces deposited on the
substrate with the higher Tg. The substrate may be formed into a
film from the LCP through solvent casting, extrusion, and/or the
like. Extrusion utilizes a counter rotating die in an extruder head
to provide uniform dimensional and physical stability to the
substrate.
[0105] As described herein, the layer of conductive traces is
formed using biocompatible metallization. Selection of the
conductive material thus balances the conductive characteristics of
the material and the ability to pattern and etch traces in the
material with the ability to withstand body chemistry and
environment. For example, copper is conventionally utilized in thin
film technologies due to its excellent conductive properties and
the ability to pattern and etch copper as desired. However, in the
context of a long term implant device, copper is prone to
degradation, corrosion, leaching, and other problems when exposed
to the chemistry and environment of the body. As such, a less
reactive conductive material, such as Titanium, Gold, Platinum, or
similar materials or alloys, may be used for the layer of
conductive traces. The layer of conductive traces comprising one or
more of these conductive materials is thus deposited on the
substrate where it is patterned and etched, for example, through a
plated through hole integration, a sequential metal integration,
and/or the like.
[0106] For a detailed description of plated through hole
integration, reference is made to FIGS. 29A-29E. In one
implementation, a substrate 1000 is formed according to a selected
dielectric use, as described herein. One or more vias 1002 are
formed in the substrate 1000, as shown in FIG. 29A. In one
implementation, the vias are laser drilled. As shown in FIG. 29B, a
conductive seed layer 1004 is deposited on one or more surfaces of
the substrate 1000. The conductive seed layer 1004 may comprise one
or more layers of biocompatible metal. Turning to FIGS. 29C-29D, a
trace pattern 1008 is defined in the conductive seed layer 1004. In
one implementation, resist 1006 is deposited to pattern the
conductive seed layer 1004. The conductive seed layer 1004 is
etched and the resist 1006 is removed, thereby forming the trace
pattern 1008. As can be understood from FIG. 29E, an electroplate
1010 is deposited on the trace pattern 1008.
[0107] Referring to FIGS. 30A-30G, an example sequential metal
integration process is illustrated. Referring first to FIG. 30A, in
one implementation, a first substrate 1100 is formed according to a
selected dielectric use, as described herein, and a first
conductive layer 1102 is deposited on one or more surfaces of the
substrate 1100. The first conductive layer 1102 may comprise one or
more layers of biocompatible metal. As shown in FIG. 30B, the first
conductive layer 1102 is patterned and wet etched to form a trace
pattern with one or more conductive interconnects 1104 and 1106. In
the alternative, a conductive seed layer, through mask plate, and
seed etch may be used. Turning to FIG. 30C, a second substrate 1108
is laminated to the first substrate 1100 over the conductive
interconnects 1104 and 1006, and a second conductive layer 1110 is
deposited on at least one of an outer surface of the first
substrate 1100 or the second substrate 1108. FIG. 30D shows at
least one via 1112 formed in the first substrate 1100 or the second
substrate 1108 depending on the deposition of the second conductive
layer 1110. In one implementation, the via 1112 is laser drilled
through the second conductive layer 1110 and the second substrate
1108 to expose the conductive interconnect 1106 of the trace
pattern. FIG. 30E illustrates the via 1112 plated with a thick
conductive via fill 1114, which may be a thick noble metal, such as
Gold, to electrically connect the second conductive layer 1110 to
the trace pattern. Turning to FIGS. 30F-30G, the second conductive
layer 1110 is patterned and etched to form an electrode array and a
connection array 1116, with an electroplate 1118 deposited
thereon.
[0108] Referring to FIG. 31, example operations 1200 for
manufacturing an implantable thin film device for patient treatment
are shown. In one implementation, an operation 1202 forms a shaped
insulator according to a selected dielectric use, which may be,
without limitation, spinal cord stimulation, deep brain
stimulation, catheter ablation, cardiac rhythm management,
occipital nerve stimulation, peripheral nerve stimulation,
electrophysiology, vagus nerve, atrial fibrillation, and/or the
like.
[0109] The shaped insulator has an inner surface and an outer
surface. In one implementation, the operation 1202 forms the shaped
insulator with a profile shaped according to the selected
dielectric use. For example, the shaped insulator may be
two-dimensional with the profile being flat, or the shaped
insulator may be three-dimensional with the profile being non-flat.
A non-flat profile may be a variety of shapes, including, but not
limited to, curved, angled, and/or irregular. For example, the
non-flat profile may be cylindrical. As described herein, the
operation 1202 may form the shaped insulator from a variety of
materials adapted to withstand processing conditions involved in
the application of conductive arrays and junctions as well as to
withstand the biochemistry within a patient body without causing
any adverse reactions. These materials may include, without
limitation, polyimide, glass, ceramic, LCP, organic thermoplastic
polymer, inorganic material, non-conductive oxide, thermoset
polymer, and/or the like. The shaped insulator may be flexible,
non-flexible, and/or transitionally stiff.
[0110] In one implementation, an operation 1204 fabricates a layer
of conductive traces on the shaped insulator using biocompatible
metallization. The operation 1204 may fabricate the layer of
conductive traces on the inner surface of the shaped insulator. The
layer of conductive traces defines a trace pattern.
[0111] In one implementation, the biocompatible metallization
includes metal deposition, foil attachment, and/or conductive
printing using one or more conductors, such as Palladium, Gold,
Titanium, Platinum, Platinum-Iridium, and/or the like. As detailed
herein, the operation 1204 may define the trace pattern through
ablation, etching, resist printing, conductive printing, insulative
impregnation, insulative implantation, and/or the like.
[0112] An operation 1206 applies an insulating layer having an
inner surface and an outer surface over the layer of conductive
traces. In one implementation, the operation 1206 applies the
insulating layer with intimate contact between the inner surface of
the shaped insulator and the inner surface of the insulating layer
outside the trace pattern. The operation 1206 may apply the
insulating layer through extrusion, coating, casting, deposition,
lamination, printing, and/or the like. The insulating layer and the
layer of conductive traces may be part of a multiple-layer series
of alternating insulating and conducting layers.
[0113] An operation 1208 fabricates an electrode array and a
connection array in electrical communication with the layer of
conductive traces to form a flexible circuit. The electrode array
and the connection array may be formed on at least one of the outer
surface of the shaped insulator or the outer surface of the
insulating layer. In one implementation, the operation 1208 forms
one or more vias in at least one of the outer surface of the shaped
insulator or the outer surface of the insulating layer. The vias
are filled with conductive material to establish electrical
communication between the electrode array and the layer of
conductive traces. The flexible circuit may be a full tip-to-tail
circuit having a stimulation end and a terminal end with the
electrode array disposed at the stimulation end and the connection
array disposed at the terminal end. The flexible circuit may be a
tip assembly with the connection array electrically connected to
one or more conductors of a body.
[0114] An operation 1210 forms an implantable thin film device from
the flexible circuit according to the selected dielectric use. In
one implementation, the operation 1210 forms the implantable thin
film device by laminating the flexible circuit to a carrier,
preparing the flexible circuit for deployment, wrapping the
flexible circuit around a body, coiling the flexible circuit around
a body, and/or the like. The implantable thin film device may be,
for example, a percutaneous lead having a stimulation end and a
terminal end formed from the flexible circuit. In one
implementation, the connection array is configured to connect to an
implantable power source.
[0115] Referring next to FIG. 32, example operations 1300 for
forming a flexible circuit from a two-dimensional substrate are
illustrated. In one implementation, an operation 1302 forms and
textures a substrate. More particularly, in one implementation, the
operation 1302 provides raw material which may be, for example, an
LCP substrate or a substrate with an LCP overlay. The thickness of
the layer of LCP may be approximately 10-100 microns. In one
example, the LCP has a thickness of approximately 25-50 microns.
The operation 1302 then textures the raw material for bonding. The
raw material may be textured, for example, using O.sub.2 plasma
texture, Ar texture, and/or a wet texture.
[0116] In one implementation, an operation 1304 deposits a
conductive seed layer on the substrate. The conductive seed layer
may comprise one or more layers of biocompatible metals. In one
implementation, the operation 1304 vacuum deposits two sequential
layers of Ti/Au with approximately 500-5000 Angstroms of Au over
approximately 100-1000 Angstroms of Ti. An operation 1306 forms a
trace pattern in the conductive seed layer. In one implementation,
the operation 1306 deposits resist for patterning and performs a
two stage etching of wet and/or dry etching. The trace pattern
formed by the operation 1306 may include final line and space from
approximately 10-100 microns with a number of channels ranging from
1 to 256. An operation 1308 plates the trace pattern. In one
implementation, approximately 1-15 microns of Au are plated on top
of the trace pattern.
[0117] In one implementation, an operation 1310 laminates a cover
layer over the plated trace pattern to the substrate. More
particularly, an LCP coverlay is laminated to the trace side (i.e.,
the side of the substrate onto which the conductive seed layer was
deposited in the operation 1304). In one implementation, the
operation 1310 manages the glass transition temperature (Tg) of the
cover layer and varies the Tg of the substrate to enable thermal
bonding of the cover layer to the substrate without distorting the
plated trace pattern.
[0118] An operation 1312 forms one or vias. In one implementation,
the operation 1312 laser etches or otherwise forms the vias in the
cover layer and/or the substrate. The vias may have a diameter
ranging from approximately 50-500 microns. In one implementation,
the operation 1312 fills the vias with a thick noble metal via
fill. For example, the operation 1312 may plate Au in the vias.
[0119] An operation 1316 deposits a second conductive seed layer on
the cover layer and/or the substrate. The second conductive seed
layer is electrically connected to the trace pattern with the
plated vias. An operation 1318 forms an electrode array and a
connection array from the second conductive seed layer(s). An
operation 1318 plates the electrode array and the connection array.
In one implementation, the operation 1318 builds up the electrode
array and the connection array by plating Au from approximately
1-15 microns to form thick Au electrode and connection arrays, and
the operation 1318 plates approximately 0.5 to 5 microns of Pt or
Pt--Ir over the thick Au electrode and connection arrays to form
plated electrode and connection arrays. An operation 1320 excises a
flexible circuit with the plated electrode and connection arrays.
Stated differently, the operations 1302-1320 form a full
tip-to-tail, fully biocompatible flexible circuit lead with in situ
fully formed traces, electrodes, and contacts. The flexible circuit
uses a thick noble metal plate up to form traces that may be
greater than approximately 12 inches or otherwise sized and shaped
for a selected dielectric use. Similarly, the flexible circuit uses
thick noble metal via fill. The flexible circuit includes full
electrodes and contacts adapted for connection with a power source
without further mechanical and/or metal components, such as
attachments, bonds, welds, and/or the like.
[0120] FIG. 33 illustrates example operations 1400 for
manufacturing an implantable thin film device from a
three-dimensional substrate. In one implementation, an operation
1402 forms and texture a three-dimensional substrate attached to a
mandrel. More particularly, the operation 1402 forms or otherwise
provides raw material in the form of a polyimide tube. In one
implementation, the polyimide tube has an outer diameter of
approximately 30-100 thousandths of an inch and a tube wall of
approximately 1-10 thousandths of an inch. The polyimide tube is
attached to the mandrel, which may be a Teflon coated stainless
steel mandrel. The operation 1402 textures the raw material with a
plasma and/or a wet process.
[0121] An operation 1404 deposits a shaped (e.g., cylindrical)
conductive seed layer on the substrate. In one implementation, the
operation 1404 blanket vapor deposits a Ti/Au conductive seed layer
around an entirety of the polyimide tube with approximately
500-5000 Angstroms of Au over approximately 100-1000 Angstroms of
Ti. An operation 1406 forms a trace pattern in the shaped
conductive seed layer. In one implementation, the operation 1406
uses a three-dimensional inject process to print patterned resist
onto the shaped conductive seed layer, and the operation 1406
etches the shaped conductive seed layer using a wet/dry etch
process or a wet/wet etch process. In another implementation, the
operation 1406 laser ablates the shaped conductive seed layer into
the trace pattern. An operation 1408 plates the trace pattern. In
one implementation, the operation 1408 builds up the traces with a
thick Au plate of approximately 1-15 microns.
[0122] An operation 1410 deposits an insulating coating on the
plated trace pattern. In one implementation, the operation 1410 dip
coats or vapor deposits the insulating coating, which may be a
polymer coating, on the plated trace pattern. An operation 1412
forms one or more vias. In one implementation, the operation 1412
laser ablates or otherwise forms the vias in the insulating
coating. In one implementation, the operation 1412 fills the vias
with a thick noble metal via fill. For example, the operation 1412
may plate Au in the vias.
[0123] An operation 1414 deposits a second shaped conductive seed
layer electrically connected to the trace pattern with the vias. In
one implementation, the operation 1414 blanket vapor deposits the
second shaped conductive seed layer of Ti/Au. An operation 1416
forms an electrode array and a connection array from the second
conductive seed layer. In one implementation, the operation 1416
patterns the second shaped conductive seed layer using a
three-dimensional inject process to print patterned resist onto the
second shaped conductive seed layer, and the operation 1416 etches
the second shaped conductive seed layer using a wet/dry or wet/wet
etch process. In another implementation, the operation 1416 laser
ablates the second shaped conductive seed layer into the electrode
array and the connection array. An operation 1418 plates the
electrode array and the connection array, for example, with a thick
noble metal plate, such as an Au plate of approximately 1-15
microns. An operation 1420 releases the three dimensional substrate
from the mandrel providing an implantable thin film device with a
flexible circuit that may be connected directly into a power
source.
[0124] Various other modifications and additions can be made to the
exemplary implementations discussed without departing from the
spirit and scope of the presently disclosed technology. For
example, while the embodiments described above refer to particular
features, the scope of this disclosure also includes
implementations having different combinations of features and
implementations that do not include all of the described features.
Accordingly, the scope of the presently disclosed technology is
intended to embrace all such alternatives, modifications, and
variations together with all equivalents thereof.
* * * * *