U.S. patent application number 13/298185 was filed with the patent office on 2012-03-15 for grooved electrode and wireless microtransponder system.
This patent application is currently assigned to MICROTRANSPONDER, INC.. Invention is credited to Lawrence James Cauller.
Application Number | 20120065701 13/298185 |
Document ID | / |
Family ID | 40137320 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120065701 |
Kind Code |
A1 |
Cauller; Lawrence James |
March 15, 2012 |
Grooved Electrode and Wireless Microtransponder System
Abstract
A grooved electrode adapted for interfacing cellular matter is
provided. The grooved electrode includes grooves adapted for
electrically interfacing the grooved electrode with cellular matter
growing along the body of the grooved electrode. Further, the
grooved electrode includes a wireless transponder adapted to
electrically interface with cellular matter and to relay such
interactions via RF signals. The RF signals received by the
wireless transponder are modulated in response to electrical
signals generated by the cellular matter, which are detected by the
transponder. The grooved electrode may be implanted within
peripheral nerves for treating various neurological conditions,
which may include nerve rehabilitation and prosthetic actuation,
severe pain, obstructive sleep apnea and so forth.
Inventors: |
Cauller; Lawrence James;
(Plano, TX) |
Assignee: |
MICROTRANSPONDER, INC.
Austin
TX
|
Family ID: |
40137320 |
Appl. No.: |
13/298185 |
Filed: |
November 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12624383 |
Nov 23, 2009 |
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13298185 |
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11821678 |
Jun 25, 2007 |
7630771 |
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12624383 |
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Current U.S.
Class: |
607/46 ;
977/742 |
Current CPC
Class: |
A61N 1/0551 20130101;
A61N 1/0536 20130101; A61N 1/0529 20130101; A61N 1/0556
20130101 |
Class at
Publication: |
607/46 ;
977/742 |
International
Class: |
A61N 1/375 20060101
A61N001/375 |
Claims
1. A method for treating pain, comprising: implanting a
neurostimulation device having a housing and an electrode, wherein
the neurostimulation device is implanted so that the electrode is
proximate to a peripheral nerve; transmitting electromagnetic
signals to the implanted neurostimulation device; and generating a
stimulation charge on the electrode to stimulate the peripheral
nerve, thereby causing paresthesia that reduces pain, wherein the
housing is approximately the length of an active current zone of a
peak spike phase of the peripheral nerve.
2. The method of claim 1, wherein the electromagnetic signals are
transmitted inductively.
3. The method of claim 1, wherein the housing is less than two
millimeters long.
4. The method of claim 1, wherein the housing includes a
groove.
5. The method of claim 4, wherein the electrode is within the
groove.
6. The method of claim 1, wherein the housing has an outer surface
formed of a biocompatible material.
7. The method of claim 6, wherein the biocompatible material is
polymethyl-methacrylate (PMMA), polydimethylsiloxane (PDMS),
polytetrafluoroethylene (PTFE), parylene, polyurethane of
polycarbonate, or combinations thereof.
8. The method of claim 4, wherein the groove extends along an outer
portion of the housing.
9. The method of claim 4, wherein the groove extends along an inner
portion of the housing.
10. The method of claim 5, wherein the electrode is disposed along
a recessed floor of the groove, wherein the groove is configured to
facilitate the growth of nerve fibers for electrically interfacing
the electrodes.
11. The method of claim 1, wherein the electrode is formed of
carbon nano-tubes.
12. The method of claim 4, wherein the groove is partially filled
with neurotrophic factors for promoting growth of peripheral nerves
along the electrode.
13. The method of claim 4, wherein wire leads extend from the
housing, and wherein the wire leads are configured to electrically
connect the housing to systems external to the housing.
14. A method comprising: providing instructions to implant a
neurostimulation device having a housing and an electrode into a
person, wherein the neurostimulation device is implanted so that
the electrode is proximate to a peripheral nerve in the person,
wherein the housing is approximately the length of an active
current zone of a peak spike phase of the peripheral nerve, and
wherein the neurostimulation device is configured to receive
electromagnetic signals from an external device and generate a
stimulation charge on the electrode to stimulate the peripheral
nerve, thereby causing paresthesia that reduces pain.
15. The method of claim 14, wherein the electromagnetic signals are
transmitted inductively, wherein the housing is less than two
millimeters long, wherein the housing includes a groove, wherein
the electrode is within the groove, wherein the housing has an
outer surface formed of a biocompatible material comprising
polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS),
polytetrafluoroethylene (PTFE), parylene, polyurethane of
polycarbonate, or combinations thereof, wherein the electrode is
disposed along a recessed floor of the groove, wherein the groove
is configured to facilitate the growth of nerve fibers for
electrically interfacing the electrodes, wherein the electrode is
formed of carbon nano-tubes, wherein the groove is partially filled
with neurotrophic factors for promoting growth of peripheral nerves
along the electrode, wherein wire leads extend from the housing,
and wherein the wire leads are configured to electrically connect
the housing to systems external to the housing.
16. A method comprising: transmitting electromagnetic signals to a
neurostimulation device, wherein the neurostimulation device has a
housing and an electrode, wherein the neurostimulation device is
implanted in a body such that the electrode is proximate to a
peripheral nerve in the body, wherein the housing is approximately
the length of an active current zone of a peak spike phase of the
peripheral nerve, and wherein the neurostimulation device is
configured to receive the electromagnetic signals and generate a
stimulation charge on the electrode to stimulate the peripheral
nerve, thereby causing paresthesia that reduces pain.
17. The method of claim 16, wherein the electromagnetic signals are
transmitted inductively, wherein the housing is less than two
millimeters long, wherein the housing includes a groove, wherein
the electrode is within the groove, wherein the housing has an
outer surface formed of a biocompatible material comprising
polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS),
polytetrafluoroethylene (PTFE), parylene, polyurethane of
polycarbonate, or combinations thereof, wherein the electrode is
disposed along a recessed floor of the groove, wherein the groove
is configured to facilitate the growth of nerve fibers for
electrically interfacing the electrodes, wherein the electrode is
formed of carbon nano-tubes, wherein the groove is partially filled
with neurotrophic factors for promoting growth of peripheral nerves
along the electrode, wherein wire leads extend from the housing,
and wherein the wire leads are configured to electrically connect
the housing to systems external to the housing.
18. A method comprising: receiving, by a stimulation device,
electromagnetic signals from an external device; and generating, by
the stimulation device, a stimulation charge on an electrode to
stimulate a peripheral nerve, thereby causing paresthesia that
reduces pain, wherein the neurostimulation device has a housing and
the electrode, wherein the neurostimulation device is implanted so
that the electrode is proximate to the peripheral nerve, and
wherein the housing is approximately the length of an active
current zone of a peak spike phase of the peripheral nerve.
19. The method of claim 18, wherein the electromagnetic signals are
transmitted inductively, wherein the housing is less than two
millimeters long, wherein the housing includes a groove, wherein
the electrode is within the groove, wherein the housing has an
outer surface formed of a biocompatible material comprising
polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS),
polytetrafluoroethylene (PTFE), parylene, polyurethane of
polycarbonate, or combinations thereof, wherein the electrode is
disposed along a recessed floor of the groove, wherein the groove
is configured to facilitate the growth of nerve fibers for
electrically interfacing the electrodes, wherein the electrode is
formed of carbon nano-tubes, wherein the groove is partially filled
with neurotrophic factors for promoting growth of peripheral nerves
along the electrode, wherein wire leads extend from the housing,
and wherein the wire leads are configured to electrically connect
the housing to systems external to the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/624,383 field Nov. 23, 2009, which is a
divisional of U.S. patent application Ser. No. 11/821,678 filed
Jun. 25, 2007 (now U.S. Pat. No. 7,630,771), all of which are
hereby incorporated by reference in its entirety.
BACKGROUND
[0002] Embodiments of the invention relate generally to systems and
methods for interfacing cellular matter, particularly, to systems
and methods facilitating signal communication between devices
interfacing cellular matter and external systems.
BRIEF DESCRIPTION
[0003] A variety of medical conditions from which people may suffer
involve disorders and/or diseases of neurological system(s) within
the human body. Such disorders may include paralysis due to spinal
cord injury, cerebral palsy, polio, sensory loss, sleep apnea,
acute pain, and so forth. A characterizing feature of the
aforementioned disorders and/or diseases may be, for example, the
inability of the brain to neurologically communicate with
neurological systems dispersed throughout the body. This may be due
to physical disconnections within the neurological system of the
body, and/or to chemical imbalances, which may alter the ability of
the neurological system to receive and/or transmit electrical
signals, such as those propagating between neurons.
[0004] Advances in the medical field have produced techniques aimed
at restoring or rehabilitating, to some extent, neurological
deficiencies leading to some of the above-mentioned conditions.
Further, such techniques may typically be aimed at treating the
central nervous systems and, therefore, are quite invasive. This
may include, for example, implanting devices, such as electrodes,
into the brain and physically connecting, via wires, those devices
to external systems adapted to send and/or receive signals to or
from the implanted devices. In addition, the incorporation of
foreign matter and/or objects into the human body may present
various physiological complications, rendering such techniques very
challenging to implement. For example, the size and extension of
the implanted devices and wires extending therefrom may
substantially restrict patient movement. Moreover, inevitable
patient movement may cause the implanted device to dislodge within
that portion of anatomy in which the device is implanted. This may
result in patient discomfort and may lead to the inoperability of
the implanted device, thus, depriving the patient from treatment.
Consequently, this may require corrective invasive surgical
procedures for repositioning the device within the body, thereby
increasing risks of infection and/or other complications. In
addition, an implanted device typically requires a built-in battery
so that it can operate. If the device is to remain within the body
for prolonged periods of time, such batteries are frequently
replaced, requiring additional surgical procedures that could yet
lead to more complications.
[0005] Hence, there is a need for implantable devices used with
systems and/or methods adapted to address the aforementioned
shortcomings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0007] FIG. 1 illustrates a plurality of grooved electrodes
implanted inside a human body, in accordance with an embodiment of
the present technique;
[0008] FIG. 2 is a perspective view of a grooved electrode, in
accordance with an embodiment of the present technique;
[0009] FIG. 3 is a front cross sectional view of a portion of the
grooved electrode shown in FIG. 2, in accordance with an embodiment
of the present technique;
[0010] FIG. 4 is an exploded perspective view of a grooved
electrode fitted with a neuro-microtransponder, in accordance with
an embodiment of the present technique;
[0011] FIG. 5 is a schematic circuit diagram of the
neuro-microtransponder, in accordance with an embodiment of the
present technique;
[0012] FIG. 6 is a schematic diagram illustrating the manner of
operation of the neuro-microtransponder, in accordance with an
embodiment of the of the present technique;
[0013] FIG. 7 is a perspective view of another embodiment of
grooved electrodes, in accordance with the present technique;
[0014] FIG. 8 is a front view of the grooved electrodes shown in
FIG. 7;
[0015] FIG. 9 is a perspective view of another configuration
showing grooved electrodes, in accordance with an embodiment of the
present technique;
[0016] FIG. 10 is a front view of the configuration shown in FIG.
9, in accordance with an embodiment of the present technique;
and
[0017] FIG. 11 is block diagram of a method for interfacing
cellular matter, in accordance with an embodiment of the present
technique.
DETAILED DESCRIPTION
[0018] Referring to FIG. 1, a grooved electrode 10 is shown as
being implanted inside a human body 12, in accordance with an
embodiment of the present technique. As will be described further
below, the grooved electrode 10 is adapted to be implanted within
the body 12 for interfacing cellular matter. In an exemplary
embodiment, the grooved electrode 10 can be incorporated within the
nervous system of the body 12, more particularly, within peripheral
nerves of the nervous system. A peripheral nerve may be comprised
of multiple nerve fibers, where each fiber includes one axon.
Accordingly, the grooved electrode 10 may comprise biocompatible
materials and/or components, enabling the grooved electrode 10 to
assimilate and become part of the axons of the peripheral nervous
system for extended periods of time. In addition, the grooved
electrode 10 may be physically and/or chemically designed for
promoting growth of cellular mater, such as axons of peripheral
nerves, along portions of the grooved electrode 10 and/or in its
vicinity. This enables the grooved electrode 10 to better mesh with
the cellular matter, i.e., peripheral nerves, thereby enabling
components of the grooved electrode 10 to optimally interact with
the cellular matter. Further, by virtue of its adaptability to
peripheral nerves, the grooved electrode 10 may be implanted within
the body 12 using minimally invasive methods, thereby reducing
risks of infections and/or other complications.
[0019] The grooved electrode 10 may include a wireless
neuro-microtransponder (FIG. 4) configured to interact with certain
portions of the peripheral nervous system. As will be discussed
below, the wireless neuro-microtransponder incorporated within the
grooved electrode 10 is adapted to convey signals, such as
neurological signals, to or from the human body 12. In so doing,
systems external to the body 12 may employ the grooved electrode 10
as an interface for detecting, transmitting, or otherwise
facilitating communication of electrical signals induced by various
physiological processes occurring between various anatomical
structures or communication of signals for actuating biomechanical
devices.
[0020] For example, the grooved electrode 10 can be used with
prosthetics for providing a neural interface between portions of
the body 12, which are naturally anatomical, and portions of the
body 12, which may be artificial, such as artificial limbs. In FIG.
1, arm 14 may include a natural, i.e., non-prosthetic, portion 16
coupled to a prosthetic portion 17 adapted to act as an artificial
extension of the arm 14. As further illustrated, a plurality of the
grooved electrodes 10 may be disposed throughout portions 16 of the
arm 14 and shoulder area of the body 12. As discussed further
below, the grooved electrodes 10 can be used to wirelessly open
neurological pathways between the brain and/or natural anatomical
structures, such as between the portion 16 and the prosthetic 17.
The prosthetic 17 may incorporate biomechanical devices 18 adapted
to receive signals generated by peripheral nerves within portion 16
of the arm 14. The biomechanical devices 18 may include
electromechanical devices some of which may be similar to the
grooved electrode 10.
[0021] In this manner, the prosthetic 17 can be actuated with
sufficient strength, dexterity, and sensitivity, enabling a person
to control the prosthetic 17 as if the prosthetic were a natural
extension of the human body. It should be born in mind that while
the illustrated embodiment may show the grooved electrodes 10 as
being disposed within the arm 14 for accommodating prosthetic
movements, other embodiments may incorporate the grooved electrodes
10 in other portions of the body 12 for other purposes. For
example, the grooved electrode 10 may be used to treat patients
suffering from obstructive sleep apnea. In such instances, the
grooved electrodes 10 may be implanted within the head of the body
12, specifically, within nerves controlling muscles of the soft
palate around the base of the tongue. For example, the grooved
electrode 10 may be used to electrically stimulate a hypoglossal
nerve so as to prevent the aforementioned muscles from obstructing
breathing airways of the patient. Still in other instances, the
grooved electrodes 10 may be used to treat patients suffering of
persistent and/or acute pain by stimulating the peripheral nerves
to cause paresthesia of an area where pain is felt.
[0022] As mentioned, the plurality of grooved electrodes 10, such
as those disposed within the portion 16 of the arm 14, may be
employed as a neurological interface enabling neurological signals
to propagate throughout anatomical regions of the body 12 whose
neurological pathways are compromised or are otherwise absent. To
optimize the grooved electrode 10 for use within the nervous system
of the body 12, those skilled in the art will appreciate the
importance in choosing proper tissue sites within which to
incorporate the grooved electrode 10. For example, peripheral
nerves may include fiber pathways that play an important role in
propagating neurological signals, such as those needed to control
the prosthetic portion 17 of the arm 14. To accommodate such
attributes, grooved electrodes 10 may specifically be designed and
configured to mechanically and electrically interface with such
peripheral nerves. For example, each of the grooved electrodes 10
may be smaller than 1 millimeter, and each may be adapted to detect
axonal spike signals, whose magnitudes are as low as 10 microvolts.
To detect such minute signals, the grooved electrode 10 may
include, for example, bio-synthetic nerve guides with electrically
sensitive carbon nanotubes adaptable to pick up weak electrical
spike signals generated by individual peripheral nerve axons.
Further, the grooved electrode 10 may include neurotrophic factors
adapted for promoting growth and fusion of axons within a mesh of
carbon nanotubes disposed within a nerve guide leading to
components of the grooved electrode.
[0023] To establish wireless neurological pathways, each of the
grooved electrodes 10 incorporates a wireless
neuro-microtransponder enabling each of the grooved electrodes 10
to receive and transmit signals to or from the body 12. In the
illustrated embodiment, a coil 19 may be disposed about portions of
body 12, particularly, about those portions in which the grooved
electrodes are implanted for facilitating wireless communication
between the grooved electrode 10 and external systems. The coil 19
is adapted to generate electromagnetic signals, such as radio
frequency (RF) signals, which can be intercepted by various circuit
components of the transponder. As discussed further below, such
circuit components are adapted to modulate the received RF signals
in response to electrical signals generated by the peripheral
nerves detected by the grooved electrode 10. In other words,
electrical interactions of the transponder with the peripheral
nerves manifest as unique modulations in the RF signals generated
by the coil 19. These modulations are detected by the coil 19 and,
thereafter, undergo further signal processing for identifying the
extent and location of the neurological activity within those
portions of the body 12 where the grooved electrodes 10 are
implanted. In an exemplary embodiment, the grooved electrodes 10
may sense neurological signals, such as those propagating from the
brain via the arm 14, aimed at moving the prosthetic 17.
Accordingly, the transponder senses such signals and, in so doing,
modulates the RF signals generated by the coil 19. The coil 19
receives the modulated RF signals, which could then be analyzed to
determine the nature of the desired movement. Thereafter, the coil
19 may generate RF signals for actuating the biomechanical devices
18, thereby enabling the prosthetic 17 to move according to the
desired movements.
[0024] Further, the RF signals generated by the coil 19 are further
adapted to power the transponder of the grooved electrode 10,
thereby eliminating the incorporation of power supplies, i.e.,
batteries, within the grooved electrode 10. This may simplify
electrical transponder circuitry, which could promote the
miniaturization of the grooved electrode 10 and components thereof.
This may further enable clinicians to implant the grooved electrode
10 within the body 12 with relative ease and accuracy. In addition,
the ability to RF power the grooved electrode 10 may prevent
patients from undergoing repetitive invasive surgical procedures
needed for replacing batteries, such as those used in existing
systems.
[0025] Hence, each of the grooved electrodes 10 may form a single
autonomous wireless unit adapted to independently interact with
peripheral nerves, as well as with other grooved electrodes and/or
other systems disposed in its vicinity. The wireless feature of the
grooved electrodes 10 may replace wire-coupled systems, thereby
unrestricting patient movement.
[0026] FIG. 2 is a perspective view of the grooved electrode 10, in
accordance with an embodiment of the present technique. In the
illustrated embodiment, the grooved electrode 10 includes a hollow
elongated rectangular body 20 forming an encasement through which
electronic components can be inserted and housed. The body 20 has
grooves 22 extending lengthwise throughout the body 20. The grooves
22 are adapted to facilitate growth of cellular matter, i.e.,
peripheral nerves, about the exterior portions of the grooved
electrode 10. To facilitate optimal cellular growth, the grooved
electrode 10 may be shaped to have certain geometrical features and
characteristics corresponding to those portions of anatomies in
which the grooved electrode 10 is implanted. For example, to
facilitate the growth of peripheral nerves, the grooved electrode
10 may be shaped to have a length of less than two millimeters with
the width and the height being much smaller than its length. Such
dimensional characteristics of the grooved electrode 10 may
correspond to the length of an active current zone generated during
a peak spike phase of an active nerve fiber, as may be appreciated
to those skilled in the art. In accordance with the present
technique, this enables the grooved electrode 10 to have sufficient
contact with peripheral nerve fibers growing along the grooved
electrode 10, thereby providing robust signal-sampling capabilities
during the peak spike phase of the nerves. It should be appreciated
that the grooved electrode 10 may attain shapes and sizes other
than the one illustrated by FIG. 1, such as those for accommodating
implantation of the groove electrode through various portions of
the body 12 (FIG. 1).
[0027] Further, the body 20 of the grooved electrode 10 may be
formed of a biocompatible polymer adapted to seal and insulate
components and/or devices, i.e., transponder (FIG. 4), encased
within the body 20. Such a polymer may include FDA-approved polymer
materials, such as polymethylmethacrylate (PMMA),
polydimethylsiloxane (PDMS), polytetraflouroethylene (PTFE),
parylene, as well as biocompatible forms of polyurethane or
polycarbonate. These and other envisioned materials from which the
body 20 may be made are adapted to promote growth and fusion of
axons along the exterior portions of the grooved electrode 10.
[0028] As further illustrated, the grooved electrode 10 includes an
opening 24 disposed at one of the body 20 through which the
microtransponder (FIG. 4) is fitted. Once peripheral nerve fibers
grow lengthwise along the grooves 22, a configuration is achieved
whereby the peripheral nerves encase the transponder disposed
within the body 20. Further, electrode leads 26 disposed along the
grooves 22 are adapted to electrically connect axons of the
peripheral nerves growing along the grooves 22 with the transponder
encased within the body 20. In this manner, the transponder may
form an interface capable of sensing or stimulating those axons
disposed directly in the vicinity of the groove electrode 10. In
addition, the grooved electrode 10 may be coupled to wire leads 30,
configured to electrically couple the grooved electrode 10 to
external devices, such as other grooved electrodes. Accordingly,
the wire leads 30 may be adapted for delivering power to components
disposed within the grooved electrode. The wire leads 30 are also
adapted to transfer electrical signals, such as those generated by
neurons, or those used for stimulating the neurons of a peripheral
nerve. In other exemplary embodiments, the aforementioned
functionalities could also be achieved by using wireless
techniques, as explained further below.
[0029] To optimize the interface between the peripheral nerves and
components disposed within the grooved electrode 10, the grooves 22
may be carved throughout four edges of the grooved electrode 10. As
shown in FIG. 3, which is a front cross-section of FIG. 2 taken
along line 3-3, each of the grooves 22 and the body 20 houses the
electrode lead 26, which extends lengthwise along the grooves 22.
As further illustrated, the electrode lead 26 may be embedded
within the body 20 such that a portion of the electrode lead 26 may
be fully engulfed by the body 20, while a remaining portion of the
electrode lead 26 may be exposed to an opening formed by the groove
22. The electrode leads 26 are adapted to contact those axons 28
growing along the opening of the grooves 22, thereby forming an
electrical connection between the axons and contact leads of a
neural micro-transponder disposed within the grooved electrode 10.
This electrical connection permits electrical current to flow
between the neural axons 28 and the transponder as, for example,
may occur during detection of spike signals. In an exemplary
embodiment, electrode leads 26 may be made from conductive carbon
nanotube or other nano-scale structures having neurotrophic
properties. In other embodiments, electrode leads 26 may be made
from electrically conductive, biocompatible, and
corrosion-resistant materials including metallic alloys, such as
medical-grade stainless steel, gold, platinum, and/or a combination
thereof. Other suitable materials from which the electrode leads 26
may be formed include inert-non-metallic conductors, such as
graphite or polymer composites.
[0030] As illustrated by FIG. 3, the grooves 22 are carved along
the body 20 in a manner permitting proper growth of the axons 28
lengthwise within the groove along the exterior portions of the
grooved electrode 10. In addition, to promote suitable electrical
contacts between the axons 28 and the electrode leads 26, the
grooves 22 may be shaped to have certain dimensional
characteristics. For example, the grooves 22 may be carved so as to
permit healthy maturation of at least one nerve fiber. At the same
time, the grooves 22 may be carved to be small enough for
minimizing the number of fibers exposed to the electrode lead 26.
In an exemplary embodiment, the aforementioned attributes may be
achieved by fabricating the grooves 22 to be approximately 10
micrometers in depth and width.
[0031] As further illustrated by FIG. 3, the opening defined by
each of the grooves 22 may be shaped to have a unique profile. For
example, the opening of the groove 22 may be profiled to have a U,
V, or rectangular shape. For example, the illustrated V-shaped
profile may render the opening of each of the grooves 22 to be
approximately 15 micrometers wide, tapering down to approximately 5
micrometers at the exposed electrode surface at the floor or fundus
of the groove. It should be born in mind that the openings of the
grooves 22 may be shaped to accommodate varying needs, as
prescribed by physiological, anatomical, and/or clinical
constraints.
[0032] Further, in accordance with the above-mentioned
characteristics and profiles of grooves 22, the grooved electrode
10 may be configured to optimally contact and stimulate individual
nerve fibers that grow along the grooves 22. Particularly, the
above-mentioned design of the grooves 22 is adapted to permit
unrestrained fiber growth, thereby eliminating risks of long-term
fiber damage, such as those that are associated with existing
`sieve` designs. Further, the grooves 22 are adapted to isolate
fewer fibers that make contact with each electrode lead 26, thereby
providing finer stimulus resolution and more discrete detection of
fiber activity. In addition, the groove may be filled with
neurotrophic factors or other biochemicals that guide or otherwise
facilitate fiber growth in direct contact with the conductive
electrode lead 26 along recessed portions forming the floor of the
groove.
[0033] FIG. 4 is an exploded perspective view of the grooved
electrode 10 fitted with a wireless neuro-microtransponder 40, in
accordance with an embodiment of the present technique. As
illustrated, the transponder 40 is adapted to fit within the
grooved electrode 10 through the opening 24. The transponder 40 may
be inserted within the grooved electrode 10 together with slow
releasing neurotrophic substances and anti-inflammatory gels for
minimizing aversive tissue reactions and for promoting the proper
implantation of the grooved electrode 10 within the body. In this
manner, the grooved electrode 10 and the transponder 40 make up a
module adapted to physically, electrically, and chemically interact
with peripheral nerves located in the vicinity of the grooved
electrode 10. Specifically, axons of peripheral nerves growing
along exterior portions of the grooved electrode 10, as facilitated
by the grooves 22, may electrically interface with the transponder
40 via the electrode lead 26. This configuration enables signals to
propagate between the transponder 40 and peripheral nerves.
Further, the transponder 40 includes wireless components adapted to
communicate with systems external to the body, thereby enabling
such systems to transmit and receive signals to or from the
peripheral nerves within the body in which the grooved electrode 10
is implanted.
[0034] The transponder 40 includes a magnetic core 42 about which
microcoils 44 are coiled. The microcoils 44 form an inductor
adapted to magnetically interact with electromagnetic fields, such
as those propagating from sources external to the grooved electrode
10. In this manner, the microcoils 44 enable the transponder 40 to
receive and/or transmit signals from or to the external systems
with which the transponder 40 communicates. In addition, the
microcoils 44 are adapted to power the transponder 40 through power
induction. In other words, the microcoils 44 are adapted to
received RF signals and convert those into electrical signals used
to electrically power components of the transponder 40. In this
manner, the transponder 40 may operate while being battery-free for
extended periods of time.
[0035] The core 42 may be fabricated out of nano-crystalline
magnetic alloys, adapted for achieving a high inductance (L) at
radio frequencies. In the illustrated embodiment, the coils 44 may
have an (L) value four orders of magnitude greater than (L) values
achieved by inductors formed of conventional materials. Further,
each coil of the coils 44 may be fabricated to have a diameter that
is as small as 100 micrometers, thereby producing an inductance of
approximately 10 nano-Henry. The core 42 may be fabricated using
laser machining methods of nano-crystalline materials, such as
cobalt. Fabrication of the coils 44 may also involve employing
techniques used in production of micro-electromechanical systems
(MEMS) and nano-electromechanical systems (NEMS).
[0036] The transponder 40 further includes a portion 46 adapted to
encapsulate circuitry of the microtransponder. The portion 46 also
includes contact leads, which connect between the circuitry and the
grooved electrodes 10. As will be discussed further below, the
circuitry encapsulated by the portion 46 includes electrical
components adapted to sense and/or stimulate the peripheral nerves
interfacing with the grooved electrode 10. For example, the portion
46 includes identification (ID) circuitry adapted to generate
unique RF signals in response to the neural spike signals generated
by the peripheral nerves. This Radio Frequency Identification
(RFID) capability of the transponder 40 is configured to relay
neurological activity occurring within the body to systems external
to the body. The ID information may also be used to distinguish
between a plurality of transponders emitting RF signals
simultaneously from their respective grooved electrodes implanted
within the body 12, as shown in FIG. 1.
[0037] Further, the portion 46 may be coated with conductive
materials, such as gold or other biocompatible conductors, to form
the electrical connection between the circuitry encapsulated by the
portion 46 and the electrode leads 26 disposed within the grooves
22 of the grooved electrode 10. The transponder 40 further includes
a capacitor 48 disposed at the rear portion of the transponder 40.
The capacitor 48 may be made from a plurality of nano-tube super
capacitors, adapted to increase the capacitance (C) of the
transponder 40. The capacitor 48 and the coils 44 form an
inductor-capacitor (LC) circuit adapted to modulate received RF
signals for producing the RFID signal of the transponder 40.
[0038] FIG. 5 is a schematic diagram of a circuit 60 disposed
within the neuro-microtransponder 40, in accordance with an
embodiment of the present technique. The circuit 60 includes
electrical components adapted to electrically interface with
neurons of peripheral nerves, such as those disposed along the
grooves 22 of the grooved electrode 10, discussed hereinabove with
relation to FIGS. 2-3. The circuit 60 further includes electrical
components, which enable the transponder 40 to wirelessly interact
with systems external to the transponder 40. Such systems may
include other transponders implanted within the body or external
coils and/or a receiver, such as those shown in FIGS. 1 and 6,
respectively. The wireless capabilities of the circuit 60 enable
the delivery of electrical signals to or from the peripheral
nerves. These include electrical signals indicative of neural spike
signals and/or signals configured to stimulate the peripheral
nerves.
[0039] Accordingly, the circuit 60 includes the coils 44 coiled
about a central axis 62. The coil 44 is coupled in parallel to a
capacitor 61 and to a stimulus trigger demodulator 63, which in
turn is coupled to an RF identity modulator 67 via a switch 65.
Further, the RF identity modulator 67 is coupled to a rectifier 64,
which in turn is coupled to a spike sensor 66 and to a stimulus
drive 70. The rectifier 64 and the spike sensor 66 are both coupled
in parallel to a capacitor 48. In addition, the spike sensor 66 is
coupled to contact lead 68, thereby electrically connecting the
spike sensor 66 to the axon 28. Similarly, contact lead 71 connects
the stimulus driver 70 to the axon 28. The spike sensor 66 is made
up of one or more field effect transistors (FET). As will be
appreciated by those of ordinary skilled in the art, the FET may
include metal oxide semiconductors field effect transistors
(MOSFETS), such as those fabricated using standard small scale or
very large scale integration (VLSI) methods. Further, the spike
sensor 66 is coupled to the RF identity modulator 67, which is
adapted to modulate an in coming/carrier RF signal in response to
neural spike signals detected by the spike sensor 66. The contact
leads 68 and 71 to which the sensor 66 and the stimulus driver 70
are connected, respectively, may be part of the portion 46 (FIG.
4), adapted to interface with the axon 28 of the peripheral nerve
disposed along the grooved electrode 10 (FIG. 2).
[0040] One configuration of the above components depicted by FIG. 5
enables the neuro-microtransponder 40 to operate as an autonomous
wireless unit, capable of detecting spike signals generated by
peripheral nerves, and relaying such signals to external receivers
for further processing. It should be born in mind that the
transponder 40 performs such operations while being powered by the
external RF signals. The above-mentioned capabilities are
facilitated by the fact that magnetic fields are not readily
attenuated by human tissue. This enables the RF signals to
sufficiently penetrate the human body so that signals can be
received and/or transmitted by the transponder 40. In other words,
the coils 44 are adapted to magnetically interact with the RF field
whose magnetic flux fluctuates within the space encompassed by the
coils 44. By virtue of being an inductor, the coils 44 convert the
fluctuations of the magnetic flux of the external RF field into
alternating electrical current, flowing within the coils 44 and the
circuit 60. The alternating current is routed, for example, via the
coils 44 into the rectifier 64, adapted to convert the alternating
current into direct current. The direct current may then be used to
charge the capacitor 48, thereby creating a potential difference
across the FET of the sensor trigger.
[0041] In an exemplary embodiment, a gate of the FET 66 may be
coupled via a contact lead 68 to the axon 28. The gate of the FET
may be chosen to have a threshold voltage that is within a voltage
range of those signals produced by the neural axons. In this
manner, during spike phases of the neural axons, the gate of the
FET 66 becomes open, thereby closing the circuit 60. Once the
circuit 60 closes, the external RF field, the inductor 44, and the
capacitor 48 induce an LC response, which modulates the external RF
field with a unique modulating frequency. The LC characteristic of
the circuit 60, as well as the threshold voltage of the gate of FET
66, can be chosen to determine the unique modulation, thereby
providing a desired ID signal for the transponder 40. Accordingly,
the FET 66 provides the RF identity modulator 67 with a trigger
signal for generating desired RF signal. The ID signal may indicate
the nature of the neural activity in the vicinity of the
transponder 40, as well as the location of the neural activity
within the body. It should be appreciated that the RF capabilities,
as discussed above with respect to the circuit 60, render the
neuro-microtransponder a passive device that reacts to incoming
carrier RF signals. That is, the circuit 60 does not actively emit
any signals, but rather reflects and/or scatters the
electromagnetic signals of the carrier RF wave to provide signals
having specific modulation. In so doing, the circuit 60 draws power
from the carrier RF wave for powering the electrical components
forming the circuit 60.
[0042] While the above-mentioned components illustrated in FIG. 5
may be used to receive signals from the transponder 40 (FIG. 4) in
response, to spike signals generated by peripheral nerves, other
components of the circuit 60 of the transponder 40 may include
components for stimulating the peripheral nerves using the external
RF signals. For example, the RF signals received by the coils 44
may be converted to electrical signals, via the stimulus trigger
modulator 63, so as for providing sufficient current and voltage
for stimulating the peripheral nerves. Hence, the stimulus trigger
demodulator 63 derives power from an RF carrier signal for powering
the stimulus driver 70, which delivers electrical signals suitable
for stimulating the axons 28. This may be used to treat nerves that
are damaged or that are otherwise physiologically deficient.
[0043] FIG. 6 is a schematic diagram of a system 80 used for
interfacing cellular matter, in accordance with an embodiment of
the present technique. The system 80 is adapted to wirelessly
interface with cellular matter, such as peripheral nerves. The
system 80 is further adapted to receive signals, such as neural
spike signals, generated by the peripheral nerves, and analyze
those signals to provide feedback and/or treatment to other
biological and/or biomechanical systems to which the system 80 is
additionally coupled. In the illustrated embodiment, the system 80
includes the neuro-microtransponder 40 interfacing with cellular
matter, such as the axon 28 of a peripheral nerve, in a manner
described and illustrated hereinabove and shown in FIGS. 1-5. While
the present exemplary embodiments may show the single transponder
40 coupled to the axon 28, other embodiments may include the
transponder 40 coupled to more than a single neuron and/or a
plurality transponders coupled to a plurality of neurons, some of
which may or may not be in close proximity to one another.
[0044] The system 80 further includes the coil 19 disposed in the
vicinity of the transponder 40 and the neuron 28. The coil 19 is
coupled to an RF signal generator and receiver (RFGRC) 82, which is
coupled to a spectrum analyzer 84. The spectrum analyzer 84 is
coupled to a processor 86, which is also coupled to the RFGRC 82.
The RFGRC 82 provides an external RF signal, such as 100 MHz, for
powering the transponder 40 and for enabling the transponder 40 to
modulate the external RF signal so as to produce an ID signal. In
an exemplary embodiment, the modulation frequency produced by the
transponder 40 may be two orders of magnitude less than the
original RF signal; however, this may vary depending on the type of
cellular matter interfaced and the type of transponders used. In
embodiments where a plurality of transponders may be employed, a
modulation frequency of approximately 1 MHz provides a relatively
high bandwidth for the ID signal. This enables the system 80 to
distinguish between relatively large amounts of
neural-microtransponders responding to electrical neural signals,
some of which may be closely coincident.
[0045] Further, the RFGRC 82 receives the modulated RF signal and
forwards the signal to the spectrum analyzer 84 for analysis. The
spectrum analyzer is adapted to determine the modulation frequency,
which is then provided to the processor 86 adapted to determine the
ID signal characteristic of the spike signal detected by the
transponder 40. In response to the identified spike signals, the
processor 86 may prompt the RFGRC 82 to generate RE signals adapted
to stimulate other biological and/or biomechanical systems to which
additional transponders may be coupled. For example, the modulated
RF signal received by the RFGRC 82 may originate from neural spike
signals generated by peripheral nerves that are severed or are
otherwise damaged. In response to such signals, the processor 86
may prompt the RFGRC 82 to actuate biomechanical devices, such as
those incorporated into prosthetics, thereby inducing movement. The
capabilities provided by the system 80 for interfacing cellular
matter also facilitate treatment of various neurological conditions
some of which may include acute pain and obstructive sleep
apnea.
[0046] Further, in another exemplary embodiment, the configuration
provided by the system 80 may be adapted to generate load
modulation in the transponder 40 by switching the drain-source
resistance of the FET of the circuit 60. This configures the
circuit 60 to detect the carrier signal. As mentioned above, in
other embodiment the system 80 may be used for stimulating the
peripheral nerves. Hence, the carrier wave emitted by the external
coil 19 may provide the transponder 40 with power for triggering
electrodes adapted to deliver electrical signals to the peripheral
nerves. In this mode of operation, the powering of the transponder
40 and, thereafter, the stimulation of the peripheral nerves may
occur in a periodic sequence in accordance with a specific
frequency.
[0047] FIGS. 7 and 8 are perspective and front views, respectively,
of another exemplary embodiment of grooved electrodes, in
accordance with the present technique. Accordingly, grooved
electrode 100 may be made up from a substrate 102 conformed to a
hollow cylinder populated with grooves 104 extending lengthwise
along the interior portion of the cylinder. As illustrated by FIG.
8, grooved electrode 100 includes electrode leads 106 having a
diameter less than 50 micrometers, disposed within the grooves 104.
Similar to the electrode leads 26 discussed above, the electrodes
106 are adapted to contact axons growing along the grooves 22,
thereby forming an electrical connection between the axons and
neural micro-transponders, which may be exterior to the grooved
electrode 100. The electrode leads 106 may be made from conductive
carbon nanotubes, having neurotrophic properties, or from
electrically conductive, biocompatible, and corrosion-resistant
materials including metallic alloys. Such alloys may include
medical-grade stainless steel, gold, platinum, and/or a combination
thereof. Other suitable materials from which the electrode 106 may
be formed include inert-non-metallic conductors such as graphite or
polymer composites.
[0048] The grooved electrode 100 can be constructed by initially
embedding a layer of the electrodes 106 within a pre-folded flat
substrate 102 formed by casting a biocompatible polymer, such as
sylgard. Thereafter, the grooves 104 are carved through the
substrate 102, thereby exposing a portion of each the electrode
leads 106, as illustrated in FIG. 8. Thereafter, the substrate 102
is rolled into a cylindrical structure forming the grooved
electrode 100. This configuration enables neural fibers to grow and
fuse with the interior portions of the grooved electrode 100. To
maximize likelihood that the fibers growing along the grooves 104
properly contact the electrode leads 106, the grooves 104 may be
filled with biochemical factors promoting fiber growth along the
grooved electrode 100, as well as adhesion thereto. The cylindrical
structure provided by the grooved electrode 100 can further
facilitate formation of artificial fascicles which otherwise form
internal structures of peripheral nerves, as appreciated to those
skilled in the art.
[0049] FIGS. 9 and 10 are perspective and front views,
respectively, of another exemplary embodiment of grooved
electrodes, in accordance with the present technique. Accordingly,
grooved electrode 150 is similar to the grooved electrode 100
discussed hereinabove in that both grooved electrodes 100, 150 may
be formed using similar materials and techniques. The grooved
electrode 150 is fabricated to form a flattened structure that
avoids structural failures which otherwise may result from rolling
or flexing the substrate 102. The flattened structure of the
grooved electrode 150 may be used to force the fibers in fascicles
to grow in contact with the electrode 106. This may be done, for
example, by flattening the grooved electrode 150 to a thickness
less than the fascicles, e.g., <0.3 millimeter.
[0050] Similarly, other embodiments may include grooved electrodes
having various shapes and configurations adapted to promote growth
of cellular matter along the body of the grooved electrodes. For
example, rather than disposing electrodes, such as the electrode
106, along the interior volume of the grooved electrodes (FIG.
710), the electrodes 106 can be disposed along exterior portions of
the grooved electrodes. Such exemplary embodiments may correspond
to, for example, folding the substrate 102 so that the grooves 104
face outward. Thus, the grooves can promote growth of peripheral
nerves along the outer portions of the grooved electrode. In
addition, this configuration may be implemented to produce grooved
electrodes having other geometrical shapes, such as of the grooved
electrodes shown in FIGS. 9 and 10.
[0051] FIG. 11 is a block diagram of a method 200 for interfacing
cellular matter, in accordance with an embodiment of the present
technique. The method 200 may be used to wirelessly interface
peripheral nerves using devices, such as the grooved electrode 10,
transponder 40, and system 80 discussed hereinabove and shown in
FIGS. 2-4 and 6. Accordingly, the method begins at step 202 in
which an RF signal is generated exterior to the cellular matter. At
step 204, the RF signal is received by a transponder implanted
within the cellular matter. The RF signal is adapted to power the
transponder so that it can electrically interface with the cellular
matter. At step 206, electrical signals generated by the cellular
matter are detected by the powered transponder. The electrical
signals generated by the cellular matter may originate from neural
spike signals of peripheral neurons interfacing with the
transponder. As discussed above, the ability to detect such spike
signals is facilitated by powering the transponder via the RF
signal. Thereafter, the method proceeds to step 208, whereby the RF
signal is modulated in response to the detection of the electrical
signal produced by the peripheral nerves. The modulation of the RF
may be unique insofar as it may identify the nature of the signal
generated by the cellular matter and/or indicate its origin. At
step 210, the modulated RF signal is received and, thereafter, at
step 212 the signal is analyzed to determine its ID
characteristics. Thereafter, the modulated signal is processed to
determine whether to generate additional RF signals to provide
additional detection or stimulation of the peripheral nerves,
whereby the method 200 returns to step 202.
[0052] While only certain features of the invention have been
illustrated and described herein, many modifications and changes
will occur to those skilled in the art. It is, therefore, to be
understood that the appended claims are intended to cover all such
modifications and changes as fall within the true spirit of the
invention.
* * * * *