U.S. patent application number 17/528853 was filed with the patent office on 2022-03-10 for micro-molded electrodes, arrays, and methods of making the same.
The applicant listed for this patent is University of Utah Research Foundation. Invention is credited to Rajmohan Bhandari, Sandeep Negi.
Application Number | 20220071537 17/528853 |
Document ID | / |
Family ID | 1000005982905 |
Filed Date | 2022-03-10 |
United States Patent
Application |
20220071537 |
Kind Code |
A1 |
Negi; Sandeep ; et
al. |
March 10, 2022 |
MICRO-MOLDED ELECTRODES, ARRAYS, AND METHODS OF MAKING THE SAME
Abstract
A method of manufacturing a micro-molded electrode having
multiple individually addressable sensors along a shaft can include
forming a recess in a mold substrate, depositing a structural
material therein, depositing a conductive material at specific
locations, providing a coating, and removing the mold substrate. A
micro-molded electrode having a base tapering to at least one shaft
can include an electrode substrate, multiple individually
addressable sensors, and a coating.
Inventors: |
Negi; Sandeep; (Salt Lake
City, UT) ; Bhandari; Rajmohan; (Salt Lake City,
UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
University of Utah Research Foundation |
Salt Lake City |
UT |
US |
|
|
Family ID: |
1000005982905 |
Appl. No.: |
17/528853 |
Filed: |
November 17, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15021858 |
Mar 14, 2016 |
11185271 |
|
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PCT/US2014/055515 |
Sep 12, 2014 |
|
|
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17528853 |
|
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61877695 |
Sep 13, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/4029 20130101;
A61B 5/291 20210101; A61B 5/4058 20130101; A61B 5/24 20210101; A61B
5/296 20210101; A61N 1/0551 20130101; A61B 5/389 20210101; A61B
5/685 20130101; A61B 2562/125 20130101 |
International
Class: |
A61B 5/24 20060101
A61B005/24; A61B 5/291 20060101 A61B005/291; A61B 5/296 20060101
A61B005/296; A61B 5/389 20060101 A61B005/389; A61B 5/00 20060101
A61B005/00; A61N 1/05 20060101 A61N001/05 |
Goverment Interests
GOVERNMENT INTEREST
[0002] This invention was made with government support under R43
NS073162 awarded by the National Institutes of Health. The
government has certain rights in the invention.
Claims
1. A method of manufacturing a micro-molded electrode having
multiple individually addressable sensors along a shaft of the
micro-molded electrode, comprising: modifying a mold substrate to
form a recess therein on a first surface of the mold substrate, the
recess defining the perimeter of the micro-molded electrode;
depositing a structural material within the recess to form the
micro-molded electrode; depositing a conductive material at
specific locations on the micro-molded electrode such that the
conductive material forms the multiple individually addressable
sensors along the shaft of each micro-molded electrode, each sensor
comprising a bonding pad at a base of the micro-molded electrode
electrically connected to an active site on the shaft of the
micro-molded electrode via an electrically conductive trace, the
micro-molded electrode having an active site on at least two sides
of the micro-molded electrode; coating a top side of the
micro-molded electrode and at least one trace with a coating
material; and removing the mold substrate outside the
perimeter.
2. The method of claim 1, further comprising depositing a
structural material within the recess after the deposition of the
conductive material.
3. The method of claim 1, further comprising depositing a
structural material within the recess before the deposition of the
conductive material.
4. The method of claim 3, further comprising polishing the first
surface of the mold substrate after deposition of the structural
material.
5. The method of claim 3, wherein the structural material is heated
to form a solid cohesive structural material.
6. The method of claim 3, wherein the structural material is
selected from the group consisting of silicon, aluminum, alumina,
glass, quartz, steel, epoxy-based negative resist materials,
acrylics, silicon on insulator (SOD, and combinations thereof.
7. The method of claim 1, wherein the coating material includes
parylene-C, polyimide, polyurethane, benzocyclobutene (BCB),
polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), glass,
or mixtures thereof.
8. The method of claim 1, further comprising coating surfaces of
the micro-molded electrode exposed by the removal of the substrate
outside the perimeter.
9. The method of claim 1, wherein modifying comprises etching the
mold substrate.
10. The method of claim 9, wherein etching comprises deep reactive
ion etching.
11. The method of claim 1, wherein depositing a conductive material
includes a lithography process to form the bond pads, active sites,
and electrically conductive traces.
12. The method of claim 1, wherein the coating includes a
lithography process using the coating material.
13. The method of claim 1, wherein removing comprises etching the
mold substrate.
14. The method of claim 13, wherein etching comprises deep reactive
ion etching.
15. The method of claim 1, further comprising forming a channel
within the micro-molded electrode adapted to deliver at least one
active agent.
16. The method of claim 1, further comprising forming a channel
within the micro-molded electrode which is adapted to deliver an
electromagnetic radiation.
17. The method of claim 1, further comprising coupling a plurality
of the micro-molded electrodes to a slotted base, the slotted base
having a plurality of slots which receive the micro-molded
electrodes.
18. The method of claim 17, further comprising forming a power
module, a processing module, and a transceiver module on the
slotted base, wherein the power module electrically powers the
processing module, the transceiver module and the sensors.
19. A micro-molded electrode having a base tapering to at least one
shaft, comprising: an electrode substrate; multiple individually
addressable sensors on at least one side of the electrode
substrate, each individually addressable sensor comprising a
bonding pad at the base of the electrode electrically connected to
an active site on the shaft of the electrode via an electrically
conductive trace, the electrode having an active site on at least
two sides of the electrode; and a coating covering a first side of
the electrode including at least one trace.
20. The micro-molded electrode of claim 19, wherein the
micro-molded electrode has a semi-conical shaft.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 15/021,858, filed Mar. 14, 2016 (issued on Nov. 30, 2021 as
U.S. Pat. No. 11,185,271) which is a U.S. national stage
application under 35 U.S.C. 371 of PCT International Application
No. PCT/US2014/055515 filed Sep. 12, 2014, which claims the benefit
of U.S. Provisional Application No. 61/877,695, filed Sep. 13,
2013, which are each incorporated herein by reference.
FIELD OF THE INVENTION
[0003] The present invention relates generally to microelectrodes,
arrays thereof, and methods of fabrication. Accordingly, the
present invention involves the fields of microscale fabrication,
materials science, and process control.
BACKGROUND
[0004] In the last two decades, the field of neuroprosthetics has
gained tremendous momentum through the development of novel
architectures for neural interfaces. However, to date, there is no
device that has been identified as the "gold standard" in the
field. As a result, the research and technology environment for
neural interfaces is still highly limited. This is due to the
constant need and desire to have electrodes and interconnections
designed and developed according to unique specifications suited to
a particular application, physiological approach, animal model, or
variety of other concerns. Hence, the requirements of each
laboratory are typically unique and require a high-level of
customization and integration.
[0005] For example, microelectrode arrays can be used to stimulate
and record electrical neuronal signals in the central nervous
system (CNS) and peripheral nervous system (PNS). Sensory organs
generate electrical signals that are transmitted by nerves to the
brain. Nerves also conduct electrical signals from the brain to
control muscular activity.
[0006] Microelectrodes can be inserted into nerve tissue to record
and stimulate electrical signals in various parts of the nerve
tissue.
[0007] The pursuits of researchers are often limited by
technological limitations, inadequate resources, infrastructure and
insufficient budget. Hence researchers feel handicapped as none of
the micro devices (penetrating or surface) currently in the market
are fully customizable (e.g. with respect to probe geometrical
parameters and substrate material), sufficiently reliable, and,
most importantly, affordable on a cost-conscience budget. Such
limitations hamper a researcher's ability to pursue their
scientific quest to validate their hypothesis and, hence, delay
potential clinical applications. Therefore, there is still a great
need for further research and development of improved neural
interfaces.
SUMMARY OF THE INVENTION
[0008] The present technology is directed to micro-molded
electrodes, arrays thereof, and methods of fabricating such
electrodes and arrays. The present electrodes and devices have
customizable dimensions, e.g., lengths, and can have high aspect
ratios.
[0009] In one embodiment, a method of manufacturing a micro-molded
electrode having multiple individually addressable sensors along a
shaft of the electrode is described. This method can include
modifying a mold substrate to form a recess therein on a first
surface of the mold substrate. The recess defines a perimeter of
the electrode. The method also includes depositing a structural
material within the recess to form the micro-molded electrode.
Further, a conductive material can be deposited at specific
locations on the micro-molded electrode such that the conductive
material forms the multiple individually addressable sensors along
the shaft of each micro-molded electrode. More specifically, each
sensor comprises a bonding pad at a base of the micro-molded
electrode electrically connected to an active site on the shaft of
the electrode via an electrically conductive trace. The
micro-molded electrode has an active site on at least two sides of
the micro-molded electrode. The method also includes coating a top
side of the micro-molded electrode and at least one trace with a
coating material; and removing the mold substrate outside the
perimeter.
[0010] In another embodiment, a micro-molded electrode having a
base tapering to at least one shaft is described. This micro-molded
electrode can include an electrode substrate having multiple
individually addressable sensors on at least one side of the
electrode substrate. Also, each individually addressable sensor can
include a bonding pad at the base of the micro-molded electrode
which is electrically connected to an active site on the shaft of
the micro-molded electrode via an electrically conductive trace.
The micro-molded electrode has an active site on at least two sides
of the micro-molded electrode; and a coating covering a first side
of the micro-molded electrode including at least one trace.
Optionally, a plurality of micro-molded electrodes can be combined
in 2D or 3D arrays.
[0011] There has thus been outlined, rather broadly, the more
important features of the invention so that the detailed
description thereof that follows may be better understood, and so
that the present contribution to the art may be better appreciated.
Other features of the present invention will become clearer from
the following detailed description of the invention, taken with the
accompanying drawings and claims, or may be learned by the practice
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1A is a perspective view of a mold substrate in
accordance with an embodiment of the present disclosure.
[0013] FIG. 1B is a perspective view of a mold substrate modified
to include a recess in accordance with an embodiment of the present
disclosure.
[0014] FIG. 1C is a perspective view of a mold substrate
illustrating the recess of FIG. 1B filled with a structural
material in accordance with an embodiment of the present
disclosure.
[0015] FIG. 1D is a perspective view of a mold substrate and
structural material including the individually addressable sensors
associated with the micro-molded electrode in accordance with an
embodiment of the present disclosure.
[0016] FIG. 1E is a perspective view of the micro-molded electrode
of FIG. 1D with a coating in accordance with an embodiment of the
present disclosure.
[0017] FIG. 1F is a perspective view of a micro-molded electrode
released from the mold in accordance with an embodiment of the
present disclosure.
[0018] FIG. 2 is a perspective view of a micro-molded electrode
with multiple shafts in accordance with an embodiment of the
present disclosure.
[0019] FIG. 3 is a perspective view of a surface micro-molded
electrode in accordance with an embodiment of the present
disclosure.
[0020] FIG. 4 is a perspective view of a micro-molded electrode
adapted for delivery of a fluid agent in accordance with an
embodiment of the present disclosure.
[0021] FIG. 5 is a perspective view of a micro-molded electrode
adapted for delivery of electromagnetic radiation in accordance
with an embodiment of the present disclosure.
[0022] FIG. 6A is a close-up perspective view of a slotted base
used in a 3D micro-molded array in accordance with an embodiment of
the present disclosure.
[0023] FIG. 6B is a perspective view of the 3D micro-molded array
of FIG. 6A.
[0024] FIG. 6C is a perspective view of a 3D micro-molded array
adapted for wireless communication in accordance with an embodiment
of the present disclosure.
[0025] These drawings merely depict exemplary embodiments of the
present invention they are, therefore, not to be considered
limiting of its scope. It will be readily appreciated that the
components of the present invention, as generally described and
illustrated in the figures herein, could be arranged, sized, and
designed in a wide variety of different configurations.
Nonetheless, the invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings.
DETAILED DESCRIPTION
[0026] Before the present invention is disclosed and described, it
is to be understood that this invention is not limited to the
particular structures, process steps, or materials disclosed
herein, but is extended to equivalents thereof as would be
recognized by those ordinarily skilled in the relevant arts. It
should also be understood that terminology employed herein is used
for the purpose of describing particular embodiments only and is
not intended to be limiting.
[0027] It must be noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the" include
plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a channel" includes one or more of
such particles, reference to "layers" includes reference to one or
more of such layers, and reference to "coating" includes one or
more of such steps.
[0028] Definitions
[0029] In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set forth below.
[0030] As used herein, "substantial" when used in reference to a
quantity or amount of a material, or a specific characteristic
thereof, refers to an amount that is sufficient to provide an
effect that the material or characteristic was intended to provide.
Therefore, "substantially free" when used in reference to a
quantity or amount of a material, or a specific characteristic
thereof, refers to the absence of the material or characteristic,
or to the presence of the material or characteristic in an amount
that is insufficient to impart a measurable effect, normally
imparted by such material or characteristic.
[0031] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the
contrary.
[0032] As used herein, "at least one of" is meant to include at
least one member of a referenced group, list, or the like, but can
include more than one member of the group, list, or the like, in
any combination. As a non-limiting example, "at least one of A, B,
and C" can include only A, only B, only C, or any combinations of
A, B, and C, such as A and B only, A and C only, B and C only, or
A, B, and C together.
[0033] As used herein, "micro-molded electrode" refers to an
electrode body or electrode substrate (e.g. electrically insulating
materials) having at least one individually addressable sensor
coupled to, deposited on, or otherwise connected to the electrode
body or electrode substrate. However, a "micro-molded electrode"
may also include numerous additional features as well, such as
protective coatings, multiple sensors or sensor types, a channel or
channels for delivery of a therapeutic agent or agents, a channel
or channels for delivering electromagnetic radiation, other
channels, and any other suitable features contemplated in designing
a "micro-molded electrode."
[0034] Numerical data may be expressed or presented herein in a
range format. It is to be understood that such a range format is
used merely for convenience and brevity and thus should be
interpreted flexibly to include not only the numerical values
explicitly recited as the limits of the range, but also to include
all the individual numerical values or sub-ranges encompassed
within that range as if each numerical value and sub-range is
explicitly recited. As an illustration, a numerical range of "about
0.6 mm to about 0.3 mm" should be interpreted to include not only
the explicitly recited values of about 0.6 mm and about 0.3 mm, but
also include individual values and sub-ranges within the indicated
range. Thus, included in this numerical range are individual values
such as 0.4 mm and 0.5, and sub-ranges such as from 0.5-0.4 mm,
from 0.4-0.35, etc. This same principle applies to ranges reciting
only one numerical value. Furthermore, such an interpretation
should apply regardless of the breadth of the range or the
characteristics being described.
[0035] As used herein, the term "about" means that dimensions,
sizes, formulations, parameters, shapes and other quantities and
characteristics are not and need not be exact, but may be
approximated and/or larger or smaller, as desired, reflecting
tolerances, conversion factors, rounding off, measurement error and
the like and other factors known to those of skill in the art.
Further, unless otherwise stated, the term "about" shall expressly
include "exactly," consistent with the discussion above regarding
ranges and numerical data.
[0036] In the present disclosure, the term "preferably" or
"preferred" is non-exclusive where it is intended to mean
"preferably, but not limited to." Any steps recited in any method
or process claims may be executed in any order and are not limited
to the order presented in the claims. Means-plus-function or
step-plus-function limitations will only be employed where for a
specific claim limitation all of the following conditions are
present in that limitation: a) "means for" or "step for" is
expressly recited; and b) a corresponding function is expressly
recited. The structure, material or acts that support the
means-plus function are expressly recited in the description
herein. Accordingly, the scope of the invention should be
determined solely by the appended claims and their legal
equivalents, rather than by the descriptions and examples given
herein.
EMBODIMENTS OF THE INVENTION
[0037] The present inventors have recognized a need in the
neuroscience community to have technology that can provide
customizable and affordable devices so that statistically relevant
numbers of neural devices are available for engineering and
physiological tests that can allow researchers to generate a pool
of data to validate their hypotheses. Currently there is a wide
range of commercially available microelectrode microsystems for
both acute and chronic applications. However, most devices
currently available on the market have various limitations. For
example, probes provided by Neuronexus Technologies Inc., offer
customization in electrode design to a certain extent, however the
electrodes can (1) be fragile and hence prone to breakage during
handling and insertion, (2) have sharp longitudinal edges along the
probe, which tend to tear the tissue during insertion, (3) have
cumbersome 3D integration of single probes and poor reliability of
the 3D array in chronic use, (4) lack choice of substrate material,
and (5) have a high cost for customized probes (as inherited from a
tedious fabrication process which is a several mask process).
[0038] The mechanical, geometric, and electrical characteristics of
micro-molded electrodes (MME) according to aspect of the invention
are precise and highly reproducible for consistent, high-quality
results. The current MME technology offers high-quality,
high-channel count neural probes for single-unit, multi-unit and
local field potential recording, electrical stimulation. The
current invention can be used to produce both surface and
penetrating electrodes from a wide variety of materials.
Additionally, the shape is highly customizable with the option to
have multiple active sides on both the top and bottom of the
electrode. Furthermore, the electrode can have rounded edges for
safer insertion and can be manufactured at a relatively low cost.
Furthermore, the current technology provides substantial freedom to
design electrodes to explore variables such as electrode material,
shape, size, number, location of the active site, and any other
suitable variables.
[0039] Accordingly, micro-molded electrodes and associated methods
are described herein that can provide a plurality of benefits over
the state of the art. In one embodiment, a method is described for
manufacturing a micro-molded electrode having multiple individually
addressable sensors along a shaft of the micro-molded electrode.
This can include modifying a mold substrate to form a recess
therein on a first surface of the mold substrate, the recess
defining the perimeter of the micro-molded electrode. A structural
material can be deposited within the recess to form the
micro-molded electrode. A conductive material can be deposited at
specific locations on the micro-molded electrode such that the
conductive material forms the multiple individually addressable
sensors along the shaft of each micro-molded electrode, each sensor
including a bonding pad at a base of the micro-molded electrode
electrically connected to an active site on the shaft of the
micro-molded electrode via an electrically conductive trace. The
micro-molded electrode can have an active site on at least two
sides of the micro-molded electrode. A top side of the micro-molded
electrode and at least one trace can be coated with a coating
material. The mold substrate can be removed outside the perimeter.
As used herein, "perimeter" refers to the portion of the substrate
that delineates the deposited and coated materials from the
remainder of the substrate in the horizontal plane but does not
necessarily refer to the portion of the substrate extending in the
vertical plane, viewing the electrode where length of the electrode
(base to tip) is in the horizontal plane. As such, the substrate
material on the bottom of the electrode (viewing the electrode
laying on a surface--horizontal plane) is not necessarily excluded
by the perimeter. However, in one embodiment, such substrate
material can be excluded by the perimeter, or a portion of such
substrate material can be excluded.
[0040] As further illustrated in FIGS. 1A-1F, this embodiment of
fabricating micro-molded electrodes (MME) or micro-molded arrays
(MMA) is based on a platform technology and uses a novel micro
molding technique which allows fabrication of surface and
penetrating electrodes. As illustrated in FIG. 1A, this embodiment
can use a mold substrate, generally depicted as 100. The mold
substrate 100 can include any substrate that is modifiable to form
a recess therein and can be made from any suitable material. In one
aspect, the mold substrate can be made from at least one of
silicon, silicon dioxide, silicon nitride, glass, quartz, aluminum,
molybdenum, gold, chromium, platinum, tantalum, titanium, titanium
nitride, tungsten, gallium arsenide, indium tin oxide, steel,
polymers such as parylene-C, polyimide, PMMA, PDMS, photoresist
materials, any other suitable material, and combinations
thereof.
[0041] Once an appropriate mold substrate 100 is selected, the mold
substrate 100 can be modified in any suitable way to form a recess
110 within the mold substrate as depicted in FIG. 1B. In one
aspect, the mold substrate 100 can be modified to from a recess 110
by compressing, carving, etching, burning, or otherwise modifying
the mold substrate 100. In one aspect, the modification can be made
by any suitable etching technique, such as wet or dry etching,
anisotropic or isotropic etching, or any other etching process. In
one aspect, the recess 110 can be formed using a process selected
from the group consisting of reactive ion etching, deep reactive
ion etching, wet chemical etching using etchants like KOH, HF,
nitric acid, TMAH, EDP, and combinations thereof. In one specific
aspect, deep reactive ion etching is used to produce the recess 110
in the mold substrate 100. Deep reactive ion etching can be a very
desirable etching process in the current embodiment because of its
ability to generate rounded edges for safer insertion of the
micro-molded electrode. In one specific aspect, deep reactive ion
etching can be used to produce a recess 110 of a depth from about
15 .mu.m to about 300 .mu.m deep within a 500 .mu.m thick mold
substrate. Similarly, the recess can be sized to form a particular
shaft and base geometry. Although a wide variety of geometries can
be used, typically the recess can be from about 10 .mu.m to about
150 mm long and about 10 .mu.m to 150 mm wide.
[0042] The recess 110 can have any suitable shapes, geometries, and
dimensions within the confines of the mold substrate 100. For
example, the recess 110 can be configured for production of a
single shaft MME, a multiple shaft MME as shown in FIG. 2, an
insertable MME, a surface MME as shown in FIG. 3, 3D arrays, or any
other suitable configuration.
[0043] Referring back to FIG. 1C, a structural material 120 can be
inserted into the recess 110 of the mold substrate. The structural
material can be deposited in the recess using any suitable
technique such as, but not limited to, powder consolidation,
pouring molten material, spin coating, spray coating, sputtering
deposition, e-beam evaporation deposition, and the like.
[0044] MMEs are defined by the structural material 120 used to
fabricate them. For example, an MME made with glass is designated
Glass MME, or an MME made with glass-polymer is designated Glass-PI
MME. Although Glass MME and Glass-PI MME are commonly used, any
suitable material can be used to produce MMEs. Some example
materials can include, but are not limited to, silicon, aluminum,
alumina, glass, quartz, steel, acrylics, silicon on insulator
materials, polymeric materials such as parylene-C,
polydimethylsiloxane (PDMS), and poly(methyl methacrylate) (PMMA),
epoxy-based negative resist materials, such as SU8, ceramics, such
as silicon carbide and tungsten carbide, and zinc oxide, and
combinations thereof. In one aspect, the MME can be made from a
structural material selected from the group consisting of silicon,
aluminum, alumina, glass, quartz, steel, epoxy-based negative
resist materials, acrylics, silicon on insulator (SOI), and
combinations thereof. In one specific aspect, glass powder can be
used to fill the recess 110 of the mold substrate 100.
Additionally, other materials can be added to the structural
material to provide added mechanical strength. Such materials can
include steel, titanium, glass, quartz, and any other suitable
material. In the case of a Glass-PI MME, a thin layer of glass can
be added as a backbone to provide sufficient mechanical strength
for insertion. This thin support layer can generally range from
about 10 .mu.m to about 500 .mu.m in thickness.
[0045] Once a suitable structural material 120 has been added to
the recess 110, the mold substrate 100 containing the structural
material 120 can be heated, cooled, pressurized, exposed to
electromagnetic radiation, or otherwise manipulated to form a solid
cohesive structural material. Temperatures, pressures, exposure
times, and other considerations for forming a solid cohesive
structural material will vary according to the structural material
selected for a given application, and are generally known by one
skilled in the art. In one specific example, where glass powder is
used as the structural material, the mold substrate 100 containing
the structural material 120 can be placed in the oven at 0 C for 6
hours to produce a solid cohesive structural material. The mold
substrate 100 and solid cohesive structural material 120 can
optionally be lapped and polished.
[0046] As shown in FIGS. 1D-1E, conductive material can be
deposited and patterned as part of the micro-molded electrode. The
deposited conductive materials can form individually addressable
sensors along the shaft 180 of each MME. Each sensor can include a
bonding pad 130 at the base 170 of the MME that is electrically
connected to an active site 140 on the shaft 180 via an
electrically conductive trace 150. The MME can have an active site
140 on at least two sides of the MME.
[0047] The conductive material can be deposited and patterned using
any suitable deposition and patterning techniques. In one aspect,
the conductive material can be DC sputtered and patterned using
lithography. Deposition can be done by e-beam evaporation
deposition, electroplating, electroless plating, and the like.
Patterning can be done by lift-off technique also, or by laser.
[0048] Any suitable conductive material can be used to form the
conductive components of the MME. In one aspect, platinum, gold,
copper, titanium, silver, conductive polymers, iridium, aluminum,
and combinations thereof can be used as the conductive material. In
one specific aspect, platinum can be used.
[0049] As noted previously, the micro-molded electrode can have
active sites on at least two sides of the MME. In one aspect, the
structural material 120 can be deposited within the recess 110
after the deposition of conductive material within the recess 110.
In another aspect, the structural material can be deposited within
the recess 110 before the deposition of the conductive material. In
this case, the conductive material can be deposited after the MME
is removed from the mold substrate 100, or a channel can be formed
within or on the periphery of the MME that allows an electrically
conductive trace 150 to penetrate to or connect with an opposite or
adjacent side.
[0050] A bonding pad 130 can be located on at least one side of the
MME. In one aspect, at least one bonding pad 130 can be connected
to an active site 140 on an opposite or adjacent side of the MME.
This can be accomplished by providing a channel from one side of
the MME to an opposite or adjacent side, the channel containing
sufficient conductive material to form an electrically conductive
trace 150 or segment of an electrically conductive trace that
electrically connects the bonding pad 130 to the active site on the
opposite or adjacent side of the MME. The channel can penetrate
through the MME or it can be formed entirely on the periphery of
the MME. In another aspect, at least one bonding pad 130 can be
deposited on at least two sides of the MME. The bonding pads can be
electrically connected to active sites on the same side or on
opposite or adjacent sides to the sides where the bonding pads are
located.
[0051] Similarly, a channel or channels can be formed within the
MME that are adapted to deliver at least on active agent, as shown
in FIG. 4. Additionally, a channel or channels can be formed within
the MME that are adapted to deliver electromagnetic radiation, as
shown in FIG. 5. Channels can also be made to deliver an electrical
stimulus. Combinations of such channels can also be formed within
the MMEs. These channels can include valves, inlets, outlets,
connections, and other suitable features to control the
introduction and transmission of therapeutic agents, electrical
stimuli, electromagnetic radiation, or other agents or stimuli.
Channels can be formed by using sacrificial material in the shape
of the channel which is oriented within the shaft through
sequential deposition of structural material, sacrificial material,
and additional structural material. Other approaches to forming
such channels can include using lithography and etching the channel
material selectively. Using material such as PEG polymer which can
be dissolved in water to form channels is one example of using a
sacrificial material.
[0052] Referring now to FIG. 1E, an optional coating 190 can be
applied to the top side of the MME and at least one trace 150. The
coating 190 can be applied using any suitable technique such as,
but not limited to, lithography, spin-coating, chemical vapor
deposition, atomic layer deposition, sputtering, e-beam evaporation
technique, and the like. In one aspect the coating 190 is applied
using standard lithography. The coating 190 can act as an
insulative coating and biological barrier to protect the MME.
Hence, any material suitable for insulating the MME, protecting it
from biological fluids, or both can be used for the coating
material. In one aspect, the coating material can include
parylene-C, polyimide, polyurethane, benzocyclobutene (BCB),
polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), glass,
or mixtures thereof. In one specific aspect, the coating material
can include parylene-C.
[0053] As shown in FIG. 1F, the final MME 160 can be removed from
the mold substrate 100. The final MME 160 can be removed by any
suitable method. In one aspect, the final MME can be removed using
a suitable etching technique. The final MME 160 can be removed from
the mold substrate 100 by carving, etching, burning, or any other
suitable technique. In one aspect, the mold substrate can be
flipped and etched away to remove the MME. The wafer can be flipped
and aligned by front to back aligner. In one further aspect, the
etching technique can include deep reactive ion etching. Once
removed from the mold substrate, the final MME 160 can also be
coated on surfaces exposed by the removal of the mold substrate to
further insulate the electrode, protect it from biological fluids,
or both. In one alternative aspect, the coating layer can be
deposited first, then the conductive material can be deposited on
top of the coating, followed by deposition of the structural
material. As described previously, the final MME 160 can have
rounded edges. In one aspect, lower edges can be rounded by
controlling the process parameters during deep reactive ion etching
(DRIE). The upper edges can be rounded by controlling the polishing
and grinding process for structural materials such as glass. With
respect to polymeric structural materials, such rounding of edges
can be done by using etching such as grey lithography.
[0054] In another embodiment, a micro-molded electrode (MME) is
described. A micro-molded electrode having a base tapering to at
least one shaft can include an electrode substrate with multiple
individually addressable sensors on at least one side of the
electrode substrate. Each individually addressable sensor can
include a bonding pad at the base of the electrode electrically
connected to an active site on the shaft of the electrode via an
electrically conductive trace. The electrode can also have an
active site on at least two sides of the electrode; and a coating
covering a first side of the electrode including at least one
trace.
[0055] The electrode substrate is the MME body to which or upon
which the individually addressable sensors are coupled, deposited,
or otherwise connected. The electrode substrate can be made of any
suitable structural material as previously described. Such support
materials can include, but are not limited to, silicon, aluminum,
alumina, glass, quartz, steel, acrylics, silicon on insulator
materials, polymeric materials such as parylene-C,
polydimethylsiloxane (PDMS), and poly(methyl methacrylate) (PMMA),
epoxy-based negative resist materials, such as SU8, ceramics, such
as silicon carbide and tungsten carbide, and zinc oxide, and
combinations thereof. In one specific aspect, the electrode
substrate can be formed from a structural material that includes
glass.
[0056] The MME can further include, as part of the electrode
substrate, a structural support member oriented between the
multiple individually addressable sensors and the substrate. The
structural support member can comprise any materials that allow
stiffening of the MME such that the MME can withstand insertion
into the targeted tissue. In one aspect, the structural support
member can include silicone, glass, steel, quartz, titanium,
polymeric materials such as polypropylene, polyethylene, and other
suitable polymeric materials, any other suitable support material,
and combinations thereof. In one aspect, the structural member can
comprise glass. While the structural support member is generally
present to provide a strengthening of the electrode shaft, in one
embodiment, the structural support member substantially covers the
first side. In one aspect, the structural support member can cover
at least a portion of the first side from the base of the electrode
along the shaft of the electrode to a tip of the electrode. As
such, the structural support material need not cover an entire side
of the electrode but can be selectively placed to provide the
desired strengthening or stiffening of the electrode as needed.
[0057] Generally, the electrode substrate can have various
geometries and dimensions as desired. Specific geometries of the
base, shaft, segments of the base, segments of the shaft, and
combinations thereof can include any desired geometrical shape;
e.g., curved, flat, square, triangular, oval, conical, etc. In one
embodiment, as illustrated in FIG. 1F, the electrode can have a
base 170 with a rectangular segment 172 and a tapering needle shaft
segment 180. The shaft can have a gradually tapered shape to
facilitate insertion of the MME and also having a rounded cross
sectional shape to avoid the problem of sharp edges, providing for
a cleaner, safer insertion of the MME with reduced tissue damage.
In one aspect, the electrode can have a semi-conical shaft. Such
geometries can extend from along the entire shaft or along a
portion thereof Furthermore, the electrodes can have any desired
dimension. In one embodiment, the electrode can have a high aspect
ratio. As used herein, "high aspect ratio" refers to an electrode
having a length that is at least 10 times greater than its width,
and most often from about 2 to about 6 times greater.
[0058] The individually addressable sensors can be any suitable
sensor or sensor type for an MME. For example, the sensor can
measure pH, oxygen, chemicals around the implant, or the like.
Typically, the sensor can measure tissue health. In some aspects,
the device can include a self measuring sensor which can test
whether the MMA (device) is functioning. One such type of sensor is
an impedance measurement sensor using inter-digitated electrodes.
The present MMEs can include individual bonding sites connected to
individual active sites by traces thereby providing an MME having a
plurality of sensors which are individually addressable. The
present MMEs can include active sites which are also in plane with
the bonding pads. However, the bonding pads need not be in plane
with the active sites. Any suitable conductive material can be used
to form an individually addressable sensor of the MME. In one
aspect, platinum, gold, copper, titanium, silver, conductive
polymers, iridium, aluminum, and combinations thereof can be used
as the conductive material. In one specific aspect, platinum can be
used.
[0059] As noted previously, the micro-molded electrode can have
active sites on at least two sides of the MME. Active sites on
either side of the MME can be connected to bonding pads on either
side of the MME through a variety of configurations. However, a
bonding pad can be located on at least one side of the MME. In one
aspect, at least one bonding pad can be connected to an active site
on an opposite or adjacent side of the MME. This can be
accomplished by providing a channel from one side of the MME to an
opposite or adjacent side, the channel containing sufficient
conductive material to form an electrically conductive trace or
segment of an electrically conductive trace that electrically
connects the bonding pad to the active site or conductive trace on
the opposite or adjacent side of the MME. The channel can penetrate
through the MME or it can be formed entirely on the periphery of
the MME. In another aspect, at least one bonding pad can be
deposited on at least two sides of the MME. The bonding pads can be
electrically connected to active sites on the same side or on
opposite or adjacent sides to the sides where the bonding pads are
located.
[0060] The coating of the MME can cover a first side of the MME,
including at least one trace. The coating can include any suitable
material to provide electrical insulation, protection from
biological fluids, combinations thereof, or to meet any other
suitable design considerations. The coating can include a single
layer or multiple layers where each layer can include a single
coating material or a mixture of coating materials. In one aspect,
the coating can include parylene-C, polyimide, polyurethane, BCB,
alumina, hydrogels, or combinations thereof. In one specific
aspect, two coating layers can be used where one layer is alumina
and the second layer is parylene-C. However, each layer could
include mixtures of both alumina and parylene-C. The ratios of each
material in each layer can be the same or they can be adjusted,
depending on the intended use of the MME.
[0061] Parylene C is chemically inert and has a low dielectric
constant (.epsilon..sub.r=3.15). It has low water vapor
transmission rate (WVTR) of 0.2 (gmm)/(m.sup.2day), high
resistivity (.about.10.sup.15 .OMEGA.-cm) and has a USP class VI
biocompatibility. Another attractive characteristic is the ability
to deposit conformal and pin-hole free films at room temperature.
Parylene C is also an excellent ion barrier, which is useful for
implants exposed to physiological environment. This is also likely
to prevent or reduce corrosion since ions have to be transported
during corrosion reactions. Failure of Parylene C coating has been
reported due to moisture permeation and is dramatically exacerbated
by interface contamination. Another well-known issue with Parylene
C is it has poor adhesion to inorganic and metal substrate
materials. Moisture condensation on contaminants at the interface
can also cause delamination of Parylene films. Al.sub.2O.sub.3
films deposited by atomic layer deposited (ALD) can also act as an
excellent moisture barrier with WVTR at the order of
.about.10.sup.-10 (gmm)/(m.sup.2day), for preventing the
degradation of implants. The biocompatibility of Al.sub.2O.sub.3 is
comparable to that of corrosion resistant metals like titanium. ALD
Al.sub.2O.sub.3 is also superior compared with films generated by
other deposition techniques such as sputtered Al.sub.2O.sub.3 in
terms of moisture barrier because it is denser and pin-hole free.
Liquid water is known to slowly corrode Al.sub.2O.sub.3 thin films,
mostly likely due to the incorporation of hydrogen in the form of
OH groups in the film. Therefore, Al.sub.2O.sub.3 alone may not be
suitable for encapsulation of biomedical implants directly exposed
to physiological environment. However, combining Al.sub.2O.sub.3
and Parylene C can be desirable as Al.sub.2O.sub.3 works as an
inner moisture barrier and Parylene works as an external ion
barrier, preventing contact of Al.sub.2O.sub.3 with liquid water,
and slowing the kinetics of alumina corrosion.
[0062] The MMEs disclosed herein generally comprise a single shaft
or multiple shaft configuration having various individual
addressable channels. In one embodiment, the electrode can be a
single shaft electrode, as illustrated in FIG. 1F. In one aspect,
the single shaft electrode can have 1 to 16 channels. In one aspect
the shaft can be adapted for insertion into nervous tissue or other
suitable tissue.
[0063] In another embodiment, the electrode can be a multiple shaft
electrode, as illustrated in FIG. 2. FIG. 2 depicts an MME with a
single base 200 with multiple shafts 210 extended therefrom. Though
FIG. 2 depicts an MME with three shafts 210, there can be more or
less than three. In one aspect, the multiple shaft electrode can
have 4 to 128 channels.
[0064] Although penetrating electrodes can be formed, surface or
planar electrodes can also be used. For example, as illustrated in
FIG. 3, the shaft 310 can extend from the base 300 and can be
adapted to have a disk 320 associated therewith for topical
monitoring of nervous or other suitable tissue. The bonding bads
350 are electrically connected to active sites 330 on the disc 320
via the conductive traces 340. In this case, multiple active sites
can be distributed across the disk to provide increased
two-dimensional coverage. The individual traces track parallel
along a common shaft and then branch out across the disk.
[0065] While the present electrodes can be used in traditional
electrical stimulation applications, the electrodes can be
configured for use in other applications including delivery of an
active agent, an electrical stimulus, electromagnetic radiation,
and combinations thereof. In one embodiment, the electrode can
further comprise a channel from the base of the electrode to a tip
of the electrode. In one aspect, the channel can be adapted to
deliver an active agent, as shown in FIG. 4. FIG. 4 illustrates an
embodiment of an MME that has a base 400 and a shaft 410 extending
therefrom. Bonding pads 420 are located at the base 400 and are
electrically connected to active sites 440 on the shaft 410 via
conductive traces 430. Additionally, a therapeutic agent delivery
conduit 460 is fluidly connected to the base 400 in order to
conduct the agent 450 through an inner channel and out of the tip
of the shaft 410. In one specific aspect, the active agent can be a
medicinal drug. In another aspect, the channel can be configured
for delivery of an electrical stimulus. Thus, in some aspects, the
device can provide active agent delivery contemporaneously with and
spatially adjacent to electrical stimulus.
[0066] In another aspect, the channel can be configured for
delivery of electromagnetic radiation, as shown in FIG. 5. FIG. 5
illustrates an embodiment that has a bonding pads 520 at the base
500 that are electrically connected to active sites 540 on the
shaft 510 via conductive traces 530. Additionally, a source 550 of
electromagnetic radiation 560 is optically connected at the base
500 in order to transmit electromagnetic radiation 560 through the
MME. Further, magnetic stimulation can be applied using these
devices. Given these additional delivery aspects, the present
electrodes can further comprise materials for facilitating such
deliveries. For example, in one aspect, the channel can further
comprise a coating therein for minimizing interactions of the
active agent with materials used to manufacture the electrode. In
another aspect, the channel can include conductive materials for
facilitating the delivery of an electrical stimulus. In another
aspect, the channel can further comprise wave guide materials for
facilitating the transmission of light through the channel. For
example, reflective coatings can be used or structural materials
can be chosen to have internal reflection sufficient to deliver the
electromagnetic radiation. These channels can also include valves,
inlets, outlets, connections, and other suitable features to
control the introduction and transmission of therapeutic agents,
electrical stimuli, electromagnetic radiation, or other agent or
stimulus.
[0067] Multiple sets of the present electrodes can be used in
conjunction to form an array. As such, in one embodiment, a
micro-molded array can comprise a plurality of MMEs as described
herein. The micro-molded array can include a plurality of MMEs
oriented in a 2D array. Additionally, in one embodiment, the
plurality of electrodes can be oriented in a 3D array, as
illustrated in FIGS. 6A-6C. Such an array can comprise a slotted
base, the slotted base having a plurality of slots configured to
receive the bases of the plurality of MMEs or 2D arrays. In one
aspect, the slotted base can be adapted to receive a plurality of
individual MMEs. In another aspect, the slotted base can be adapted
to receive a plurality of 2D arrays.
[0068] As illustrated in FIG. 6A, in one aspect the slotted base
600 can have conductive connections 620 that are adapted to
electrically interact with the bonding pads on the
[0069] MME. This allows the slotted base 600 to receive electrical
signals from each of the MMEs 630 connected to the slotted base
600. The slotted base 600 can have a plurality of slots that are
adapted to receive a plurality of MMEs 630. A conductive connection
620 can include any suitable conductive material. In one aspect,
the conductive connection 620 can include platinum, gold, copper,
titanium, silver, conductive polymers, iridium, aluminum, and
combinations thereof. In one aspect, the conductive connection 620
can include the same conductive material as that used for the MME.
In one specific aspect, the conductive connection 620 can include
platinum.
[0070] Furthermore, as shown in FIG. 6A, the slotted base 600 can
include insulation barriers 610 between the conductive connections
620. The insulation barriers 610 can include any suitable
insulation material. In one aspect, the insulation material can
include parylene-C, polyimide, polyurethane, benzocyclobutene
(BCB), polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS),
glass, or mixtures thereof. However, there are many other
insulators that can be used in the insulation barrier 610 that are
known by those skilled in the art, and any such materials are
contemplated as useful in the current technology.
[0071] As depicted in FIG. 6B, the slotted base 600 can be
connected to a transmission cable 670. The transmission cable can
be coupled to a computer or other electronic device, including a
wearable device that is adapted to store, process, or transmit data
received via the electrode, or combinations thereof. The data can
be stored locally, transmitted to a remote database, provide a
biofeedback signal, signal administration of a therapeutic agent,
electrical stimulus, electromagnetic radiation, combinations
thereof, or other suitable agent or stimulus. In one aspect, as
depicted in FIG. 6C, the slotted base 600 can be adapted to
communicate wirelessly. The wireless communication components can
include a power module 640, a processing module 650, and a
transceiver module 660 coupled to or formed on the slotted base
600. The power module 640 can be adapted to electrically power the
processing module 650, the transceiver module 660, and the sensors
on the MMEs 630.
[0072] General types of electrodes that are contemplated for use
and manufacturing of include barbed electrodes, flexible electrodes
utilizing flexible substrate, surface electrodes, penetrating
electrodes, drug delivering electrodes, light delivering
electrodes, electrical-stimulus delivering electrodes, and any
other suitable electrode.
[0073] It is to be understood that the above-referenced
arrangements are illustrative of the application for the principles
of the present invention. Numerous modifications and alternative
arrangements can be devised without departing from the spirit and
scope of the present invention while the present invention has been
shown in the drawings and described above in connection with the
exemplary embodiment(s) of the invention. It will be apparent to
those of ordinary skill in the art that numerous modifications can
be made without departing from the principles and concepts of the
invention as set forth in the claims.
* * * * *