U.S. patent application number 14/519583 was filed with the patent office on 2018-12-06 for neural electrode system with a carrier having a tape spring-type shape.
The applicant listed for this patent is NeuroNexus Technologies, Inc.. Invention is credited to Jamille Farraye Hetke, Daryl R. Kipke, David S. Pellinen, Bencharong Suwarato, Rio J. Vetter.
Application Number | 20180345010 14/519583 |
Document ID | / |
Family ID | 51752027 |
Filed Date | 2018-12-06 |
United States Patent
Application |
20180345010 |
Kind Code |
A9 |
Pellinen; David S. ; et
al. |
December 6, 2018 |
NEURAL ELECTRODE SYSTEM WITH A CARRIER HAVING A TAPE SPRING-TYPE
SHAPE
Abstract
A neural probe comprising an array of stimulation and/or
recording electrodes supported on a tape spring-type carrier is
described. The neural probe comprising the tape spring-type carrier
is used to insert flexible electrode arrays straight into tissue,
or to insert them off-axis from the initial penetration of a guide
tube. Importantly, the neural probe is not rigid, but has a degree
of stiffness provided by the tape spring-type carrier that
maintains a desired trajectory into body tissue, but will
subsequently allow the probe to flex and move in unison with
movement of the body tissue.
Inventors: |
Pellinen; David S.; (Ann
Arbor, MI) ; Suwarato; Bencharong; (Ann Arbor,
MI) ; Vetter; Rio J.; (Van Buren Twp, MI) ;
Hetke; Jamille Farraye; (Brooklyn, MI) ; Kipke; Daryl
R.; (Dexter, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NeuroNexus Technologies, Inc. |
Ann Arbor |
MI |
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20150119673 A1 |
April 30, 2015 |
|
|
Family ID: |
51752027 |
Appl. No.: |
14/519583 |
Filed: |
October 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61895109 |
Oct 24, 2013 |
|
|
|
61893603 |
Oct 21, 2013 |
|
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 25/003 20130101;
A61N 1/0534 20130101; A61M 2025/0031 20130101; A61M 25/007
20130101; G03F 7/40 20130101; A61N 1/36017 20130101; A61B 5/04001
20130101; A61N 1/0558 20130101; A61B 5/0478 20130101 |
International
Class: |
A61N 1/05 20060101
A61N001/05; A61B 5/04 20060101 A61B005/04; G03F 7/40 20060101
G03F007/40 |
Claims
1. A neural probe, which comprises: a) a tape spring-type carrier
having a carrier thickness extending along a carrier length between
first and second major carrier surfaces, the carrier extending from
a proximal carrier end to a distal carrier portion having a distal
carrier end, wherein the proximal carrier end is electrically
connectable to a source of electrical energy; and b) at least one
electrode configured for electrical stimulation of body tissue or
recording of biological characteristics supported on the tape
spring-type carrier, wherein the electrode is supported on at least
one of the first and second major carrier surfaces.
2. The neural probe of claim 1 wherein, when in an unstressed
condition extending in a substantially axial direction, the tape
spring-type carrier has a curved cross-section perpendicular to the
carrier length.
3. The neural probe of claim 1 wherein, when in a stressed
condition bent out of alignment with an axial direction, the tape
spring-type carrier has a linear cross-sectional shape
perpendicular to the carrier length.
4. The neural probe of claim 1 wherein, when in an unstressed
condition extending in a substantially axial direction, the first
surface of the tape spring-type carrier has a concave
cross-sectional shape and the opposite second surface of the
carrier has a convex cross-sectional shape.
5. The neural probe of claim 1 wherein, when in an unstressed
condition extending in a substantially axial direction, the first
surface of the tape spring-type carrier has a parabolic
cross-sectional shape and the opposite second surface of the
carrier has a convex cross-sectional shape.
6. The neural probe of claim 1 wherein, when in an unstressed
condition extending in a substantially axial direction, the tape
spring-type carrier has a shape similar to a carpenter's tape for a
tape measure.
7. The neural probe of claim 1 wherein the tape spring-type carrier
is of a metal selected from the group consisting of tungsten,
stainless steel, and platinum-iridium.
8. The neural probe of claim 1 wherein the tape spring-type carrier
is of a polymeric material.
9. The neural probe of claim 1 wherein the tape spring-type carrier
is sandwiched between opposed polymeric layers contacting the first
and second major carrier surfaces.
10. The neural probe of claim 1 wherein the at least one electrode
is sandwiched between opposed dielectric layers, one of the
dielectric layers contacting a polymeric layer supported on one of
the first and second major carrier surfaces.
11. The neural probe of claim 10 wherein the dielectric layers are
selected from the group consisting of polyimide, parylene, silicon
carbide, aluminum oxide, silicon dioxide, and silicon nitride.
12. The neural probe of claim 1 wherein the at least one electrode
is of a metal selected from the group consisting of iridium,
platinum, gold, and alloys thereof.
13. The neural probe of claim 1 wherein the distal carrier end is
pointed.
14. A method for providing a neural probe, comprising the steps of:
a) providing a tape spring-type carrier having a carrier thickness
extending along a carrier length between first and second major
carrier surfaces, the carrier extending from a proximal carrier end
to a distal carrier portion having a distal carrier end, wherein
the proximal carrier end is electrically connectable to a source of
electrical energy; and b) supporting at least one electrode
configured for electrical stimulation of body tissue or recording
of biological characteristics on at least one of the first and
second major carrier surfaces.
15. The method of claim 14 wherein, when in an unstressed condition
extending in a substantially axial direction, the tape spring-type
carrier has a curved cross-section perpendicular to the carrier
length.
16. The method of claim 14 wherein, when in a stressed condition
bent out of alignment with an axial direction, the tape spring-type
carrier has a linear cross-sectional shape perpendicular to the
carrier length.
17. The method of claim 14 wherein, when in an unstressed condition
extending in a substantially axial direction, the first surface of
the tape spring-type carrier has a concave cross-sectional shape
and the opposite second surface of the carrier has a convex
cross-sectional shape.
18. The method of claim 14 wherein, when in an unstressed condition
extending in a substantially axial direction, the first surface of
the tape spring-type carrier has a parabolic cross-sectional shape
and the opposite second surface of the carrier has a convex
cross-sectional shape.
19. The method of claim 14 wherein, when in an unstressed condition
extending in a substantially axial direction, the tape spring-type
carrier has a shape similar to a carpenter's tape for a tape
measure.
20. The method of claim 14 including selecting the tape spring-type
carrier from the group consisting of tungsten, stainless steel, and
platinum-iridium.
21. The method of claim 14 including providing the tape spring-type
carrier of a polymeric material.
22. The method of claim 14 including sandwiching the tape
spring-type carrier between opposed polymeric layers contacting the
first and second major carrier surfaces.
23. The method of claim 14 including sandwiching the at least one
electrode between opposed dielectric layers, one of the dielectric
layers contacting a polymeric layer supported on one of the first
and second major carrier surfaces.
24. The method of claim 23 including selecting the dielectric
layers from the group consisting of polyimide, parylene, silicon
carbide, aluminum oxide, silicon dioxide, and silicon nitride.
25. The method of claim 14 including selecting the at least one
electrode from the group consisting of iridium, platinum, gold, and
alloys thereof.
26. The method of claim 14 including providing the tape spring-type
carrier by one of the group consisting of a photo-resist process, a
micro-stamping process, a thermoplastic nanoimprinting lithography
process, a fluting process, an extrusion process, and an
electrostatic discharge micromachining process.
27. The method of claim 14 including providing the tape spring-type
carrier with at least one fluid channel extending from the proximal
carrier end to the distal carrier portion.
28. A method for providing a neural probe, comprising the steps of:
a) depositing a photo-resist material on a manufacturing substrate;
b) patterning the photo-resist into a shape similar to a tape
spring-type carrier; c) exposing the patterned photo-resist to UV
light; d) developing the exposed photo-resist; e) heating the
photo-resist to thereby cause the photo-resist to flow and form a
curved upper surface to the substrate of a shape similar to that of
the tape spring-type carrier shape; f) subjecting the photo-resist
to a deep reactive ion etching process to duplicate the
photo-resist pattern on the substrate upper surface; g) depositing
a metal or polymeric carrier layer on the upper substrate surface;
h) patterning the carrier layer; i) depositing a polymeric layer on
opposed major sides of the tape spring-type carrier layer; j)
etching the polymeric layer to define a shape of the tape
spring-type carrier; k) releasing the carrier from the
manufacturing substrate; and l) supporting an electrode on at least
one of the polymeric layers supported by the tape spring-type
carrier.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application Ser. Nos. 61/893,603, filed on Oct. 21, 2013 and
61/895,109, filed on Oct. 24, 2013.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to the field of devices and methods
used for neural interventions. More particularly, the present
invention relates to a neural probe comprising an electrode array
of at least one of a stimulation electrode and a recording
electrode. The electrode array is supported on a carrier having a
shape and structure similar to a carpenter's tape spring. The tape
spring-type carrier provides the electrode array with stiffness
along a line of trajectory once deployed into body tissue, but with
a degree of flexibility that allows the electrode array to move
with the tissue.
[0004] 2. Prior Art
[0005] Chronic Deep Brain Stimulation (DBS) devices (brain
pacemakers) have emerged in the last decade as a revolutionary new
approach to the treatment of neurological and psychiatric
disorders. Conventional DBS therapy involves controllable
electrical stimulation through a lead having four relatively large
electrodes that are implanted in the targeted region of the brain.
While conventional DBS therapy is generally safe and effective for
reducing cardinal symptoms of the approved diseases, it often has
significant behavioral and cognitive side effects and limits on
performance. Additionally, the therapeutic effect is highly a
function of electrode position with respect to the targeted volume
of tissue, and more specifically, a function of which neuronal
structures are influenced by the charge being delivered. With
conventional electrodes, there are limitations as to how the charge
is delivered and stimulation fields are limited as all of the
electrode sites involved with stimulation are positioned along a
single axis.
[0006] A neural lead or probe that is useful with DBS among a host
of other interventional procedures is described in U.S. Pat. No.
8,565,894 to Vetter et al. The probe has a carrier of a rigid
three-dimensional shape. An electrode array comprising stimulation
and recording electrodes is supported on the rigid carrier. The
distal end of a guiding element is connected to the proximal end of
the carrier supporting the electrode array. While the carrier
maintains its rigid three-dimensional shape, the guiding element is
maneuverable from a first three-dimensional shape into a second,
different three-dimensional shape. Since the carrier portion of the
neural probe is rigid, as brain tissue and the like move, the
electrode array is incapable of flexing and shifting to accommodate
such movement.
[0007] Thus, there is a need for an improved neural intervention
system for deployment of multiple neural probes to provide fine
electrode positioning, selectivity, precise stimulation patterning,
and precise lead location. However, the desire for such positional
precision should not be so rigid as to be incapable of flexing and
bending to accommodate tissue movement. The present invention
provides such an improved and useful neural intervention system for
placement of multiple neural probes in tissue, particularly brain
tissue. That is done by supporting an electrode array on a tape
spring-type carrier. The carrier provides an improved degree of
stiffness along a line of trajectory once probe is deployed into
body tissue, but allows for a degree of flexibility to accommodate
movement of body tissue surrounding the neural probe.
SUMMARY OF THE INVENTION
[0008] Each thin-film neural probe electrode array according to the
present invention is comprised of multiple metal traces and sites.
As many as 100 conductive traces and electrode sites can be
realized on an array that is as narrow as 30 microns and as thin as
6 microns. In order to be strong enough to be inserted into tissue,
however, these neural probe electrode arrays must be either
integrated during fabrication on a carrier that provides strength,
or attached to a strengthening carrier post-fabrication. If the
strengthening carrier is stiff, the electrode array can be inserted
into tissue along a desired axial direction of a guiding element.
In some cases, however, it is preferable to interface with tissue
along a trajectory that is off-axis to the initial penetration of
the guiding element. This requires a carrier that can deploy from
the guiding element and follow a bend after penetration into body
tissue and then maintain a straight trajectory after bending.
[0009] The use of tape spring-type carriers and the appropriate
deployment device makes such insertion possible. Tape springs are
used in a variety of deployable structures to serve as hinge
mechanisms. An example is a carpenter's tape measure. It has
geometric stiffness when extended, but can be guided around a
corner. This is due to the curved cross-section of the structure.
The normally curved cross-section results in a stiff U-beam
structure that allows controllable one-directional axial motion
(pulling the tape out or in). When the tape is pushed through a
bend, the section of the tape in the bend flattens. As the tape is
pushed past the bend, the spring returns to its curved U-beam
state, again resulting in a stiff beam structure, but pointed
axially in a new direction.
[0010] Accordingly, the present invention relates to a neural probe
comprising an array of stimulation and/or recording electrodes
supported on a tape spring-type carrier. The neural probe
comprising the tape spring-type carrier is used to insert flexible
electrode arrays straight into tissue, or to insert them off-axis
from the initial penetration of a guide tube. Importantly, the
neural probe is not rigid, but has a degree of stiffness provided
by the tape spring-type carrier that maintains a desired trajectory
into body tissue, but will subsequently allow the probe to flex and
move in unison with movement of the body tissue. Additionally, an
assembly is described to allow deployment of multiple thin-film
neural probe electrode arrays from a single guide tube in a
three-dimensional arrangement. Formation of the neural probe with
the tape spring-type carrier, design of the electrode arrays, and
the deployment mechanism are all described herein.
[0011] These and other objects will become apparent to one of
ordinary skill in the art by reference to the following description
and the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a neural intervention system
10 according to the present invention.
[0013] FIG. 1A is a schematic of the neural intervention system 10
residing in body tissue 18.
[0014] FIG. 1B is an enlarged view of the designated area from FIG.
1A.
[0015] FIG. 2 is a schematic of the neural intervention system 10
shown in FIG. 1 including deployment channels 14 and neural leads
16.
[0016] FIG. 2A is an enlarged perspective view, broken away from
FIG. 2, showing outlet ports 22C to 22E at the distal end of the
guide tube 12.
[0017] FIG. 2B is an enlarged view of deployment port 22C shown in
FIG. 2A.
[0018] FIG. 3A is a perspective view of the distal portion of the
guide tube 12 including the deployment channels 14 shown in FIG.
2.
[0019] FIGS. 3B and 3C are schematic views of deployment tubes 14
and 24 showing exemplary paths of their open conduits 22 and 24
with respect to planes C-C and D-D aligned with longitudinal axis
A-A.
[0020] FIG. 4 is a schematic of an exemplary deployment channel
14.
[0021] FIG. 4A is a cross-sectional view taken along line 4A-4A of
FIG. 4.
[0022] FIG. 4B is a cross-sectional view taken along line 4B-4B of
FIG. 4.
[0023] FIG. 5 is a cross-sectional view of neural probe 16 showing
planar electrodes 36 and 38 supported on opposite sides of a tape
spring-type carrier 40 according to the present invention.
[0024] FIG. 5A is a cross-sectional view of a neural probe 16
similar to that shown in FIG. 5, but with electrodes 36 and 38
having a curved shape.
[0025] FIG. 5B is a cross-sectional view of the neural probe 16
shown in FIG. 5A, but with only one electrode 36 supported on the
tape spring-type carrier 40.
[0026] FIG. 6 is a perspective view of a neural intervention system
10A similar to that shown in FIG. 2 but with the plurality of
neural probes 16 directly connected to a plunger 48 and push rod 50
as an actuation mechanism.
[0027] FIG. 7 is a perspective view of an alternate embodiment of a
neural intervention system 10B according to the present invention
connected to an IPG 17.
[0028] FIG. 8 is a side cross-sectional view of a neural
intervention system 10C according to the present invention with
deployment channels 54 and 56 at different elevational levels along
the guide tube 12 and with respective push rods 62 and 64 for
deploying neural probes therefrom.
[0029] FIG. 9 is a side elevational view of a roll 100 of tape
spring material for one manufacturing method according to the
present invention.
[0030] FIG. 10 is a side cross-sectional view of a neural probe 16
built by affixing a thin film electrode arrays 36 and 38 to opposed
side of the tape spring from the roll 100 shown in FIG. 9.
[0031] FIGS. 11 to 17 illustrate another embodiment of a
photo-resist process for manufacturing the tape spring-type carrier
40 of a neural probe 16 according to the present invention.
[0032] FIGS. 18, 18A and 18B illustrate another embodiment of a
process of microstamping, nanoimprinting or fluting of sheet metal
for manufacturing the tape spring-type carrier 40 of a neural probe
16 according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Turning now to the drawings, a general depiction of one
embodiment of a neural intervention system 10 according to the
present invention is illustrated in FIGS. 1 and 1A. The neural
intervention system 10 comprises a guide tube 12 supporting a
plurality of deployment channels 14 that are configured to direct
the delivery of a number of neural probes 16 into body tissue 18.
Among a host of possible interventional procedures, neural
intervention system 10 is designed for use in deep brain
stimulation procedures and more specifically, for interface with
deep brain tissue in a three-dimensional manner. The neural
intervention system 10 may alternatively be used in any suitable
environment such as with the spinal cord, peripheral nerves,
muscles, or any other suitable anatomical location.
[0034] The guide tube 12 is a conduit shaped structure having a
side wall 12A extending along a longitudinal axis A-A from a distal
portion 12B to a proximal end 12C connectable to a chamber 20.
While shown having a cylindrical shape that is by way of example
only. All that is required is that guide tube 12 has a sidewall
defining a lumen. The chamber 20 is configured for attachment to a
skull, preferably in a cranial burr-hole of a patient. Thin-film
ribbon cables 19 run through the guide tube from the neural probes
16 to the chamber 20.
[0035] The chamber 20 is where the ribbon cables 19 connect to an
electronic subsystem (not shown) that serves as an interface to any
one of a number of external devices, such as implantable pulse
generator (IPG) 17. Other electrical subsystems include, but are
not limited to, a printed circuit board with or without on-board
integrated circuits and/or on-chip circuitry for signal
conditioning and/or stimulus generation, an Application Specific
Integrated Circuit (ASIC), a multiplexer chip, a buffer amplifier,
an electronics interface, an implantable rechargeable battery,
integrated electronics for either real-time signal processing of
the input (recorded) or output (stimulation) signals, integrated
electronics for control of the fluidic components, any other
suitable electrical subsystem, or any combination thereof.
Alternatively, the skull chamber 20 is not needed and the ribbon
cables 19 connect directly to any one of the above listed external
devices.
[0036] The guide tube 12 is preferably made of a rigid material
that can be inserted into tissue or other substances without
buckling and can maintain a generally straight trajectory through
the tissue 18. The material may be uniformly rigid, or rigid only
in a particular direction (such as the axial direction). The guide
tube material is preferably plastic (such as a medical grade
plastic) or metallic (such as titanium), but may alternatively be
any suitable material such as metal or a combination of materials.
The distal tube portion 12B includes a rounded or curved tip 12D
designed to prevent undue trauma to body tissue as the guide tube
is inserted therein. FIG. 3A illustrates an alternate embodiment of
a sharpened tip 12D' adapted to penetrate tissue and aid in
insertion of the guide tube therein.
[0037] It is within the scope of the present invention that the
guide tube 12 is maneuverable into the tissue in a
three-dimensional arrangement. Such a maneuverable guide tube 12
may include a system of cables, joints, connections, or robotics
that is controlled by a user to position the guide tube in a
desired position in the tissue. The maneuverable guide tube 12 may
also be guidable remotely and/or wirelessly.
[0038] The distal portion 12B of the guide tube includes at least
one, and preferably a plurality of deployment channels.
[0039] Exemplary deployment channel 14 (FIG. 4) comprises a
proximal channel portion 14A spaced from a distal channel portion
14B. The exemplary deployment channel 14 has a lumen 22 extending
from a proximal open end 22A adjacent to the proximal channel
portion 14A to a distal open end 22B adjacent to the distal channel
portion 14B. As will be described in greater detail hereinafter,
the proximal and distal open ends 22A, 22B are not aligned along a
common axis. Instead, lumen 22 extends from a proximal open end 22A
residing along a plane B-B aligned substantially perpendicular to
the longitudinal axis A-A of the guide tube 12 to a distal open end
22B serving as an open port at the guide tube sidewall 12A.
Although by way of example only, the path from the proximal open
end 22A to the distal open end 22B is substantially a right
angle.
[0040] FIG. 3B illustrates an embodiment where the lumen 22 from
proximal open end 22A to distal open end 22B of channel 14 is
bisected by an imaginary plane C-C aligned along axis A-A. FIG. 3C
illustrates the lumen path 24 of a second exemplary one of the
deployment channels 26 deviating from a proximal open end 26A
bisected by plane D-D aligned along axis A-A to a distal open end
26B angularly deviating from plane D-D. As seen from the
perspective of a plan view looking down on the proximal end 12C of
guide tube 12 and along axis A-A, the angular deviation can be in
either the clockwise or counter-clockwise directions.
[0041] A third exemplary one of the deployment channels 32 has its
proximal open end 32A residing along the imaginary plane B-B
aligned perpendicular to axis A-A and with its distal open end 32B
exiting the guide tube sidewall 12A so that the lumen follows a
path forming a substantially obtuse angle with respect to axis A-A.
A fourth exemplary one of the deployment channels 34 has its
proximal open end 34A residing along the imaginary plane B-B, but
with its distal open end 34B exiting the guide tube sidewall 12A so
that the lumen follows a path forming a substantially acute angle
with respect to axis A-A. Those skilled in the art will readily
understand that a deployment channel can provide a lumen that
follows a path incorporating a combination of those described with
respect to the first to the fourth exemplary channels 14, 26, 32
and 34. According to the present invention, the trajectory of the
distal channel portion defining the distal open end 22B, 32B and
34B ranges from about 10.degree. to 180.degree. with respect to
axis A-A. Moreover, it is noted that distal open end 32B is more
proximal than distal open end 34B. That is even though their
respective proximal open ends 32A, 34A reside along plane B-B.
[0042] Thus, the exemplary deployment channels 14, 26, 32 and 34
can be angled in many different orientations. That is for the
purpose of introducing a plurality of neural probes 16 into a
target body tissue at any one of a number of trajectories off axis
from axis A-A of the guide tube 12. This greatly improves the
footprint of deployed electrodes so that multiple spatially
separate stimulation and recording channels radiate outwardly from
the distal portion 12B of the guide tube. Enhanced deployment of
neural probes 16 makes it possible to spontaneously record neuronal
activity, movement-related activity, or evoked activity as a result
of stimulation from nearby sites. Simultaneously sampled recordings
could be exploited to increase the speed and accuracy by which data
are acquired. With respect to stimulation, this three-dimensional
arrangement of neural probes 16 can be used in either monopolar or
bipolar modes to steer current to desired body tissue
locations.
[0043] FIG. 2A is an enlarged view of the distal end 12D of the
guide tube. This view shows that the distal open ends 22B of
exemplary deployment channel 14 can reside on the distal guide tube
end 12D. That is in addition to or instead of the distal open end
of a channel residing on the cylindrical sidewall 12A as shown in
FIG. 2. While it is preferred that the distal open end of a
deployment channel have an elongate shape with opposed curved
sidewalls, that is not necessary. Open end 22C has a rectangular
shape without curved sidewalls. There is also an open end 22D for a
deployment channel aligned along the longitudinal axis A-A.
[0044] FIGS. 4, 4A, 4B, 5, 5A and 5B illustrate a novel aspect of a
neural probe 16 according to the present invention. The neural
probe 16 comprises opposed first and second electrodes 36 and 38
comprising an electrode array supported by a tape-spring-type
carrier 40. The carrier 40 is of a metal, preferably selected from
tungsten, stainless steel, platinum-iridium, or of a polymeric
material, and in an unstressed condition has a shape similar to a
carpenter's tape for a tape measure. The tape spring-type carrier
40 flexes to permit the neural probe 16 to readily bend, thereby
when in a stressed condition collapsing into a shape having a
linear cross-section 40A (FIG. 4A) perpendicular to the length of
the carrier as the probe moves along a bend in the lumen 22 of
exemplary deployment channel 14. That portion of the tape
spring-type carrier 40 residing in the proximal portion 14A of the
deployment channel 14 adjacent to the proximal open end 22A has the
concave tape spring-type shape 40B (FIG. 4AB). Similarly, that
portion of the carrier 40 residing in the distal portion 14B of the
deployment channel adjacent to the distal open end 22B and
extending out therefrom has re-assumed the tape spring shape. The
tape spring-type shape of the carrier 40 provides the neural probe
16 with a degree of linear rigidity along the trajectory of the
distal channel portion 14B and outwardly therefrom that is not
available with prior art probes.
[0045] FIG. 4B shows that the curved cross-sectional shape of the
tape spring-type carrier 40 can be concave having a focal point 42
residing outside plane E-E extending through the carrier's opposed
ends. The curve cross-sectional shape of the tape spring-type
carrier can also be that of a parabola.
[0046] FIGS. 5, 5A and 5B show the tape spring-type carrier 40
sandwiched between opposed polymeric layers 40A and 40B. If the
carrier 40 is of a polymeric material, then layers 40A and 40 are
of a different polymeric material. Electrode 36 is exemplary of a
stimulation electrode while electrode 38 is exemplary of a recoding
electrode. The stimulation electrode 36 is configured for
electrical stimulation of biological tissue and recording electrode
38 is configured for recording of biological activity from
biological tissue. The stimulation electrode 36 is sandwiched
between opposed dielectric layers 37A and 37B. Likewise, recording
electrode 38 is sandwiched between opposed dielectric layers 39A
and 39B. The electrode sites 36, 38 are preferably metal such as
iridium, platinum, gold, but may alternatively be any other
suitable material. Polyimide, parylene, inorganic dielectrics such
as silicon carbide or aluminum oxide, or a composite stack of
silicon dioxide and silicon nitride is preferably used for the
dielectric layers 39A, 39B.
[0047] The enlarged portions 36A and 38A depict electrical
interconnects running the length of the neural probe. In an
alternate embodiment (not shown) interconnects 36A, 38A are of a
lesser cross-section than the respective electrodes 36, 38. The
conductive interconnects 36A, 38A are preferably metal or
polysilicon, but may alternatively be any other suitable material.
Interconnects 36A and 38A preferably terminate with electrical
contacts or bond pads (not shown) at their proximal ends. That is
for electrical connection of the electrodes 36, 38 to external
instrumentation and/or hybrid chips, such as depicted by IPG 17 in
FIG. 1. For more detail regarding suitable configurations for
electrodes and interconnects for use with neural probes 16,
reference is made to U.S. Pat. No. 7,941,202 to Hetke et al., which
is assigned to the assignee of the present invention and
incorporated herein by reference.
[0048] FIG. 5A shows the entire electrode structure having a curved
shape mimicking that of the tape spring-type carrier. This is
contrast to the electrode structure shown in FIG. 5 having
generally planar electrode faces. FIG. 5B shows an electrode
supported on only one side of the tape spring-type carrier 40.
[0049] In one exemplary embodiment of the neural probe 16 shown in
FIGS. 1, 1A and 1B, the electrode array preferably includes
sixty-four stimulation electrodes 36 and thirty-two recording
electrodes 38 positioned around and along the tape spring-type
carrier 40. Each stimulation electrode site 36 has a surface area
of preferably 0.196 mm.sup.2 (diameter=500 .mu.m), but may
alternatively have any suitable surface area or shape. Each
recording electrode site 38 has a surface area of preferably
0.00196 mm.sup.2 (diameter=50 .mu.m), but may alternatively have
any suitable surface area or shape. Stimulation sites are also
preferably spaced at 750 .mu.m in the axial direction
(center-to-center) and positioned at sixteen successive locations.
Between each row of stimulation electrode sites 36, two recording
electrode sites 38 are preferably positioned on opposite sides of
the tape spring-type carrier 40. The position of each recording
electrode site pair 38 preferably shifts ninety degrees between
successive depths. Alternatively, there may be any suitable number
of stimulation sites 36 and recording electrode sites 38, and the
stimulation electrode sites and recording sites may alternatively
be positioned in any other suitable arrangement.
[0050] Referring back to FIG. 2A, the enlarged views of deployment
opening 22C, 22D and 22E are designed with central axes aligned
along a desired trajectory line. The trajectory lines come out of
the page and are depicted by the respective points 22C', 22D' and
22E'. The respective axes are centered between the opposed major
and minor sidewalls of the opening. FIG. 2B is an enlarged view of
representative deployment opening 22C showing opposed major
sidewalls 23A and 23B and opposed minor sidewalls 23C and 23D. Axis
22C' is centered therein and represents the trajectory a neural
probe 16 comprising the tape spring-type carrier 40 of the present
invention would take after having been deployed out from the
opening 22C. Representative trajectories 22B', 22C' and 22D' are
also shown in FIG. 2.
[0051] With further reference to FIG. 2, the neural probes 16 are
connected to a manifold 44. Thin-film ribbon cables 19, which
connect from the manifolds 44 to an electronic subsystem (not
shown), serve as an interface to any one of a number of external
devices, such as implantable pulse generator (IPG) 17 (FIGS. 1 and
7). The probes 16 comprising the tape spring-type carrier 40 extend
distally from the manifold 44 and are spaced at even or uneven
intervals from each other. Moreover, the guide tube 12 can support
more than one manifold/neural probe assembly. Two such assemblies
46, 48 are illustrated, but that is by way of example. In any
event, the neural intervention system 10 is constructed with the
probes pre-registered with their respective channels. As previously
discussed, FIG. 3A, which is similar to FIG. 2, illustrates that
the proximal open ends of the plurality of deployment channels are
located along common plane B-B, substantially perpendicular to axis
A-A. The respective proximal open channel ends are arranged in
concentric circles, the outer circle 50 corresponding to the first
manifold/neural probe assembly 44 and the inner circle 52
corresponding to the second manifold/neural probe assembly 46. The
respective distal ends of the probes 16 are received in the
proximal open ends of the channels 14.
[0052] FIG. 2 further shows an actuation mechanism for deploying
the plurality of neural probes 16. The actuation mechanism includes
a plunger 48 connected to the first and second manifold/neural
probe assembly 44, 48. The distal face of plunger 48 has grooves
(not shown) that are sized and configured to receive the upper
edges of the respective manifolds 44 therein. The opposite face of
the plunger 48 supports a push rod 50. The push rod extends to the
proximal end 12C of the guide tube and has a length that is
sufficient for a user to grasp and manipulate to move the plurality
of probes 16 through their respective deployment channels and out
the open ends thereof. The neural probes 16 are of a sufficient
length that with the plunger 48 moved distally along the tube 12
until the manifolds 44 are adjacent to the proximal open ends of
the deployment channels, the probes extend through the exemplary
deployment channels 14, 26, 32 and 34 and out the distal open ends
thereof to penetrate tissue at distances sufficient to provide
effective stimulation or recording capability. While two
manifold/neural probe assemblies are shown in FIG. 2, it is within
the scope of the present invention that three or more such
assemblies can be fitted into a single guide tube 12.
[0053] FIGS. 1A and 1B illustrate the guide tube 12 inserted into
tissue 18 with a plurality of neural probes 16 deployed in a
three-dimensional arrangement into the tissue. The tape spring-type
carrier 40 of the present invention shuttles the neural probes 16
into tissue or other substances in a straight-line or radial
direction once the probe has exited the distal open end of its
deployment channel. Moreover, the carrier 40 may include a
sharpened end 16A adapted to penetrate tissue and aid in insertion
of the neural probe 16 including the carrier 40 into tissue at
trajectories off axis from that of the penetrating guide tube 12.
Importantly, the carrier 40 is not a rigid structure. Instead, the
carrier has sufficient stiffness to follow a desired trajectory
dictated by the trajectory axis of one of previously described
exemplary opens 22C, 22D and 22E, but that will move in response to
movement of the tissue into which the probe 16 has been deployed.
That helps to prevent undue trauma to the body tissue while
maintaining a desired degree of stimulation and recording
efficacy.
[0054] FIG. 6 illustrates another embodiment of a neural
intervention system 10A according to the present invention. System
10A is similar to that shown in FIG. 2 except that the actuation
mechanism for deploying the plurality of neural probes 16 does not
include a manifold. Instead, the neural probes 16 are individually
directly connected to the plunger 48 connected to the push rod 50.
A thin-film ribbon cable 19, which connects from the manifolds 48
to an electronic subsystem (not shown), serves as an interface to
any one of a number of external devices, such as implantable pulse
generator (IPG) 17 (FIGS. 1 and 7).
[0055] FIG. 7 illustrates another embodiment of a neural
intervention system 10B according to the present invention. System
10B is similar to the system 10 shown in FIG. 1 except that the
guide tube 12 has a branched portion 12E extending from the
proximal guide tube end 12C. The branched tube portion 12E houses
the ribbon cables (not shown, but similar to those designated as 19
in FIG. 1A) connected to IPG 17 as an exemplary electronic
subsystem. There is also an open port 52 where the proximal guide
tube portion 12C meets the branched tube portion 12E. Port 52
provides an exit for push rod 50 of the actuation mechanism for
deploying the plurality of neural probes 16 into tissue 18.
[0056] FIG. 8 illustrates a further embodiment of a neural
intervention system 10C. This embodiment shows that it is within
the scope of the present invention that guide tube 12 can support a
first, and preferably a plurality of first deployment channels 54
at a more distal location than a second, and preferably a plurality
of second deployment channels 56. The first deployment channels 54
have their proximal ends 54A supported by plate 58 connected to an
inner surface of the guide tube sidewall 12A. The distal open ends
54B provide a port in the guide tube sidewall 12A adjacent to the
distal tube portion 12D. The proximal ends 56A of the second
deployment channels 56 are likewise supported by a second plate 60
connected to the inner guide tube sidewall. Their distal open ends
56B provide a port in the guide tube sidewall 12A adjacent to the
proximal tube end 12C.
[0057] A firsts push rod 62 serving as an actuation mechanism
extends through an opening 60A in the second plate 60 and is
connected to the proximal ends of neural probes 16 in registry with
the first deployment channels 54. A second push rod 64 serves as an
actuation mechanism for deploying neural probes 16 in registry with
the second deployment channels 56. It is noted that the proximal
ends of first deployment channels 54 are radially closer to the
longitudinal axis A-A than the proximal ends of the second
deployment channels 56. That is to provide clearance so that the
first push rod 62 does not interfere with the second push rod
64.
[0058] It will be understood by those skilled in the art that the
structure of push rods 62 and 64 is for the purpose of illustration
only. Other structural configurations are within the scope of the
present invention. Moreover, while first and second sets of
deployment channels 54, 56 are shown, it is within the scope of the
present invention that there can be two, three or more deployment
channels delineated from each other not by where their respective
distal open ends exit the guide tube sidewall 12A, but where their
proximal open ends reside inside the guide tube with respect to
each other.
[0059] FIGS. 9 and 10 illustrate one method of making a neural
probe according to the present invention. A metal or composite tape
spring 40 is provided in a roll. The tape spring material is rolled
out and fabricated to a desired shape. The electrode structures 36
and 38 shown in FIGS. 5, 5A and 5B are then affixed, such as with a
suitable medical grade adhesive, to one or both sided of the tape
spring-type carrier 40.
[0060] FIGS. 11 to 17 illustrate the steps for forming a neural
probe 16 incorporating a tape spring-type carrier 40 according to a
second embodiment of the present invention.
[0061] FIG. 11 shows a photo-resist material 102 is deposited on a
manufacturing substrate 104. The photo-resist 102 is patterned in a
shape similar to that desired for the product tape spring-type
carrier 40. The substrate 104 is preferably made of glass or
silicon, but may alternatively be made from any other suitable
material. The substrate 104 may be flexible, rigid, or semi rigid
depending on the microfabrication tooling (organic electronics
equipment can increasingly use flexible substrates such as in
roll-to-roll manufacturing, whereas IC and MEMS microfabrication
equipment use a rigid silicon substrate). The substrate 104 has a
thickness ranging from about 200 microns to about 925 microns,
preferably greater than 500 microns.
[0062] The photo-resist material 102 is preferably a thin film of
gel, photoresist, or other transparent or semi-transparent organic
medium that can be patterned onto the substrate 104. The
photo-resist film 102 is preferably at least semi-transparent to
allow passage of light from a UV light source through the
photoresist material. For positive photoresists, the area that is
exposed to the UV light can be developed away in a developer. For
negative photoresist, polymer at the area that is exposed to the UV
light forms strong chemical bonds that can withstand a developer,
while the unexposed area can be developed away in a developer. The
photo-resist film 102 can be deposited, patterned, exposed to UV
light, and developed in any suitable thin film technique.
[0063] FIG. 12 illustrates that the photoresist 102 is subjected to
heat so that it flows and forms a curved or parabolic upper surface
102A to the substrate 104 of a shape approximating the final tape
spring-type carrier shape. Then, the heated photoresist is
subjected to a Deep Reactive Ion Etching (DRIE) 106 process to
duplicate the photoresist pattern 102A on the substrate upper
surface 104A. After the DRIE process, the resulting structure will
be cleaned by oxygen plasma or standard organic and inorganic wet
cleaning process.
[0064] FIG. 13 shows that after cleaning, a metal or polymeric
carrier layer 110 is deposited on the upper or outer surface 104A
of the substrate. The carrier layer 110 can be deposited using any
suitable thin film, semiconductor, microelectromechanical systems
(MEMS) manufacturing technique or other microfabrication process,
such as physical vapor deposition. Exemplary techniques and
processes include evaporation and sputtering deposition. The
carrier layer 110 preferably includes thermal conductive or
electrical conductive material such as of platinum (Pt) or
platinum-iridium, iridium oxide, titanium nitride, or any other
metal, metal oxide, shape memory alloy, or conductive polymer
having suitable electrically conductive properties. The carrier
layer 110 can also be of a polymeric material, such as of
polyimide, but may alternatively be made from any other suitable
material. Moreover, the carrier layer 110 can be of a resorbable
material, which is resorbed into tissue after a period of time.
With the carrier supporting an electrode array, upon resorption,
the electrode array is left to float freely in the brain or other
suitable tissue or material. The bioresorbable polymer is
preferably polyglycolide or polylactide, but may alternatively be
made from any suitable bioresorbable material.
[0065] The carrier layer 110 is shown as a continuous layer and can
be patterned (FIG. 14) using any suitable wet etch or dry etch
technique. The mask (not shown) is a photodefined resist or any
other masking material patterned directly or indirectly using
standard photolithography techniques. After the carrier layer 110
is patterned, excess metal or polymeric layer is etched away,
leaving the pattern of the tape spring behind. A lift-off process,
as is well known to those skilled in the art, can also be used to
leave the tape spring pattern.
[0066] FIG. 15 illustrates that polydimethylsilisane (PDMS) as an
exemplary transfer material 112 is spun onto the carrier patterns
110 followed by mounting a second manufacturing substrate 114
thereon. Polyimide can be used at this step instead of PDMS. In
this case, electrodes can be fabricated on the polyimide film
before undergoing the layer transfer onto a new carrier.
[0067] The original manufacturing substrate 104/108 is removed
exposing curved inner surfaces 110A of the patterned tape
spring-shaped material. This can be achieved by wet or dry etching
technique.
[0068] FIG. 16 shows that the second manufacturing substrate 114 is
flipped upside down, and a polyimide material 116 is spun coated
onto the exposed curved inner surfaces 110A.
[0069] FIG. 17 illustrates that a photolithography process is used
to define the shape of the thusly fabricated tape spring-type
carrier 40 with polyimide layers 40A and 40B coated on both sides.
The result is the tape spring-type carrier 40 sandwiched between
polymeric layers 40A, 40B shown in FIGS. 5, 5A and 5B.
[0070] FIGS. 18, 18A and 18B illustrate the steps for forming a
neural probe 16 incorporating a tape spring-type carrier 40
according to a third embodiment of the present invention.
[0071] FIG. 18 shows a sheet of metal 200 including patterned
carrier 40 and registration patterns 202. The registration patterns
202 provide for registering the carrier sheet 200 to the electrode
manufacturing substrate as shown in FIGS. 5, 5A and 5B. Subsequent
photolithographic processes will embed the carriers 40 between
polymer electrodes. Microstamping is one exemplary process using a
laser to engrave the sheet 200 with a patterned shape of the tape
spring-type carrier.
[0072] Thermoplastic nanoimprint lithography (T-NIL) is another
suitable process. Thermoplastic nanoimprint lithography uses a thin
layer of imprint resist thermoplastic polymer spun-coated onto a
substrate (not shown). Then the substrate, which has topological
patterns of the tape spring shape, is brought into contact with the
polymeric sheet 200 and the mold and sheet are pressed together
under pressure. When heated up above the glass transition
temperature of the polymer sheet 200, the pattern on the mold is
pressed into the softened polymer. After cooling, the mold is
separated from the sheet 200 and the tape spring pattern resist is
left on the sheet 200. A pattern transfer process (reactive ion
etching, normally) is used to transfer the pattern in the resist to
the underneath sheet 200.
[0073] Alternatively, cold welding between two metal surfaces can
be used to transfer low-dimensional nanostructured metal without
heating (especially for critical sizes less than -10 nm) onto sheet
200. Because the cold welding approach does not require heating, it
has the advantage of reducing surface contact contamination or
defect due normally attendant heating-related processes.
[0074] Other methods for shaping metal into a concave/convex
structure suitable for manufacturing a tape spring-type carrier
according to the present invention include fluting, extrusion, and
electrostatic discharge micromachining (ESD).
[0075] The plurality of thusly produced tape spring-type carriers
40 connected to a manifold 44 (four shown carrier are shown in the
subassembly designated 204 in FIG. 18A) are built into neural
probes 16 according to one of the exemplary structures shown in
FIGS. 5, 5A and 5B. The manifolds 40 are similar to those depicted
in FIG. 2.
[0076] The tape spring-type carrier 40 may further extend the
functionality of the system 10 by providing fluidic channels
through which therapeutic drugs, drugs to inhibit biologic response
to the implant, or any other suitable fluid may be transmitted.
This provides for the precise delivery of specific pharmaceutical
compounds to localized regions of the body, such as the nervous
system, and could facilitate, for example, intraoperative mapping
procedures or long-term therapeutic implant devices. The fluidic
channels may also provide a location through which a stiffener or
stylet may be inserted to aid with implantation. Alternatively, the
carrier may further include a separate lumen through which the
stiffener or stylet may be inserted.
[0077] Thus, a plurality of neural probes 16 constructed with a
tape spring-type carrier 40 according to the present invention and
deployed from an exemplary guide tube 12 increases the effective
site area to allow increased charge injection while maintaining
safe electrochemical and biological limits. This will enable, for
example, precise current steering to selectively stimulate neural
structures. The thusly deployed neural probes can be used to
establish one or more tunable neural interface region for the
device. Multiple neural interface regions can be overlapping or
non-overlapping. Additionally, at least two electrode sites from
each probe 16 may be grouped to form a larger composite site that
enables tuning the neural interface region for recording and/or
stimulation. This grouping of sites can be through intrinsic
connection of the site traces, or it can be through external
connections for real-time tuning.
[0078] While this invention has been described in conjunction with
preferred embodiments thereof, it is evident that many
alternatives, modifications, and variations will be apparent to
those skilled in the art. Accordingly, the present invention is
intended to embrace all such alternatives, modifications and
variations that fall within the broad scope of the appended
claims.
* * * * *