U.S. patent application number 16/189862 was filed with the patent office on 2019-05-16 for implantable intra- and trans-body wireless networks for therapies.
The applicant listed for this patent is THE CHARLES STARK DRAPER LABORATORY, INC.. Invention is credited to Caroline K. Bjune, John R. Burns, IV, Andrew Czarnecki, Elliot H. Greenwald, Jake G. Hellman, John Roland Lachapelle, Alejandro J. Miranda, Matthew C. Muresan, Carlos A. Segura, Wes T. Uy, Jesse J. Wheeler.
Application Number | 20190143126 16/189862 |
Document ID | / |
Family ID | 64664406 |
Filed Date | 2019-05-16 |
View All Diagrams
United States Patent
Application |
20190143126 |
Kind Code |
A1 |
Wheeler; Jesse J. ; et
al. |
May 16, 2019 |
IMPLANTABLE INTRA- AND TRANS-BODY WIRELESS NETWORKS FOR
THERAPIES
Abstract
A system of two or more implantable medical devices is
configured to establish a wireless link between the two or more
implantable medical devices and a device external to a body of a
patient while the two or more implantable medical devices are
implanted in the body of the patient.
Inventors: |
Wheeler; Jesse J.; (Revere,
MA) ; Hellman; Jake G.; (Watertown, MA) ;
Segura; Carlos A.; (Ipswich, MA) ; Burns, IV; John
R.; (Boston, MA) ; Miranda; Alejandro J.;
(Winthrop, MA) ; Greenwald; Elliot H.; (Cambridge,
MA) ; Czarnecki; Andrew; (Quincy, MA) ;
Muresan; Matthew C.; (Somerville, MA) ; Uy; Wes
T.; (Quincy, MA) ; Bjune; Caroline K.;
(Arlington, MA) ; Lachapelle; John Roland;
(Princeton, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE CHARLES STARK DRAPER LABORATORY, INC. |
Cambridge |
MA |
US |
|
|
Family ID: |
64664406 |
Appl. No.: |
16/189862 |
Filed: |
November 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62585346 |
Nov 13, 2017 |
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Current U.S.
Class: |
607/60 |
Current CPC
Class: |
A61B 2560/045 20130101;
A61N 1/3787 20130101; A61N 1/0534 20130101; A61N 1/37288 20130101;
A61N 1/0531 20130101; A61N 1/37211 20130101; A61N 1/3758 20130101;
A61B 5/04001 20130101; A61N 1/36064 20130101; A61N 1/37252
20130101; A61N 1/36125 20130101; A61N 1/37217 20130101; A61B 5/0478
20130101; A61B 5/0031 20130101 |
International
Class: |
A61N 1/372 20060101
A61N001/372; A61B 5/04 20060101 A61B005/04; A61N 1/05 20060101
A61N001/05; A61N 1/36 20060101 A61N001/36; A61N 1/378 20060101
A61N001/378 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS
[0002] This invention was made with government support under
contract number is N66001-15-C-4019 awarded by the Defense Advanced
Research Projects Agency (DARPA). The government has certain rights
in the invention.
Claims
1. A system of two or more implantable medical devices configured
to establish a wireless link between the two or more implantable
medical devices and a device external to a body of a patient while
the two or more implantable medical devices are implanted in the
body of the patient.
2. The system of claim 1, wherein the two or more implantable
medical devices are further configured to establish a communication
link between each other while implanted in the body of the patient
utilizing an intra-body wireless communication link.
3. The system of claim 2, wherein the two or more implantable
medical devices are configured to coordinate therapy for the
patient through the communication link between each other.
4. The system of claim 2, wherein the two or more implantable
medical devices are further configured to share data processing
load through the communication link between each other.
5. The system of claim 1, wherein the device external to the body
of the patient is configured to coordinate therapy for the patient
performed by the two or more implantable medical devices.
6. The system of claim 1, wherein the device external to the body
of the patient is configured to coordinate monitoring of one or
more physiological parameters of the patient by the two or more
implantable medical devices.
7. The system of claim 6, wherein coordinating monitoring of the
one or more physiological parameters of the patient includes
aggregating data acquired by the two or more implantable medical
devices to produce aggregated data regarding the one or more
physiological parameters of the patient.
8. The system of claim 7, wherein the device external to the body
of the patient is further configured to coordinate therapy for the
patient performed by the two or more implantable medical devices
based on the aggregated data.
9. The system of claim 7, wherein the device external to the body
of the patient is further configured to provide the aggregated data
to a diagnostic system distinct from the system.
10. The system of claim 7, wherein the device external to the body
of the patient is further configured to provide a recommendation
for treatment of the patient based on the aggregated data.
11. The system of claim 1, wherein the two or more implantable
medical devices are configured to share data processing load
through the wireless communication link with the device external to
the body of the patient.
12. The system of claim 1, wherein at least one of the two or more
implantable medical devices is configured to be one of placed in
one of a plurality of low power modes and brought from the one of
the plurality of low power modes into an active mode based upon a
signal from another of the two or more implantable medical
devices.
13. The system of claim 1, wherein the system is scalable and
includes at least an additional implantable medical device having
at least one communication link with the device external to the
body of the patient.
14. The system of claim 13, where the system automatically adapts
to activation, deactivation, addition, or removal of an implantable
medical device from the system to coordinate monitoring and therapy
of the patient utilizing each active implantable medical device
implanted in the patient.
15. The system of claim 1, wherein the at least one wireless link
includes a wireless power supply link, a high-speed data link, and
a low-speed data link.
16. The system of claim 15, wherein the high-speed data link is an
asymmetrical data link that uplinks data received from sensors in
the body of the patient by the two or more implantable medical
devices to the device external to the body of the patient.
17. The system of claim 15, wherein the low-speed data link is an
asymmetrical data link that downlinks configuration settings from
the device external to the body of the patient to the two or more
implantable medical devices.
18. The system of claim 15, wherein the low-speed data link
comprises signals generated by modulating current passing through
the power supply link.
19. The system of claim 15, wherein the low-speed data link and
high-speed data link are provided in a single signal.
20. The system of claim 15, wherein the device external to the body
of the patient includes a plurality of antennas and is configured
to determine which of the two or more implantable medical devices
transmitted a signal over one of the high-speed data link or the
low-speed data link based on a known location of the two or more
implantable medical devices and a timing of receipt of the signal
at different antennas in the plurality of antennas.
21. The system of claim 1, wherein the two or more implantable
medical devices communicate with the device external to the body of
the patient utilizing a time-division multiplexing protocol.
22. The system of claim 1, wherein each of the two or more
implantable medical devices have different addresses that provide
for the device external to the body of the patient to communicate
separately with each of the two or more implantable medical
devices.
23. The system of claim 1, wherein the system is a closed-loop
system in which the two or more implantable medical devices are
configured to communicate to determine therapy to be applied to the
patient in the absence of communication with an external
device.
24. The system of claim 1, wherein each of the two or more
implantable medical devices have a volume of less than about 4
cm.sup.3.
25. The system of claim 1, wherein each of the two or more
implantable medical devices includes up to 32 different channels to
tissue interfaces configured to one of receive sensor data signals
or transmit stimulation signals.
26. The system of claim 25, wherein the operating parameters of the
channels are reconfigurable, while the two or more implantable
medical devices are implanted in the patient, for each of sensing
and stimulation by transmission of a down link control signal to
the two or more implantable medical devices.
27. The system of claim 1, wherein the two or more implantable
medical devices include communications security algorithms
including authentication requirements.
28. The system of claim 27, wherein the two or more implantable
medical devices include communications security algorithms further
including encryption.
29. The system of claim 1, wherein the two or more implantable
medical devices are operable to read signals from nerve tissue of
the patient and process the signals to provide outputs to control
an electronic device.
30. The system of claim 29, wherein the electronic device includes
a prosthetic device of the patient.
31. The system of claim 29, wherein the electronic device includes
a computer system distinct from the system.
32. The system of claim 31, wherein the device external to the body
of the patient is further configured to receive an input from the
computer system and adjust one or more operating parameters of one
of the device external to the body of the patient or the two or
more implantable medical devices responsive to receiving the input
from the computer system.
33. The system of claim 1, wherein the two or more implantable
medical devices are reconfigurable, while the two or more
implantable medical devices are implanted in the patient, to
operate with mixed monopolar and bipolar stimulation modes by
transmission of a down link control signal to the two or more
implantable medical devices.
34. The system of claim 1, wherein the two or more implantable
medical devices are reconfigurable, while the two or more
implantable medical devices are implanted in the patient, to switch
between performing differential signal recording and performing
single-ended signal recording by transmission of a down link
control signal to the two or more implantable medical devices.
35. The system of claim 1, wherein the two or more implantable
medical devices are further configured to establish a communication
link between each other while implanted in the body of the patient
utilizing a wired communication link.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Patent Application Ser. No. 62/585,346,
titled IMPLANTABLE INTRA- AND TRANS-BODY WIRELESS NETWORKS FOR
THERAPIES, filed Nov. 13, 2017, the contents of which are
incorporated herein in their entirety for all purposes.
SUMMARY
[0003] In accordance with one aspect, there is provided a system of
two or more implantable medical devices configured to establish a
wireless communication link between the medical devices while
implanted in a body of a patient.
[0004] In some embodiments, the medical devices are configured to
coordinate therapy for the patient through the wireless
communication link.
[0005] In some embodiments, the medical devices are configured to
share data processing load through the wireless communication
link.
[0006] In some embodiments, at least one of the medical devices is
configured to be one of placed in a sleep mode and brought from the
sleep mode into an active mode based upon a signal from another at
least one of the medical devices.
[0007] In some embodiments, the system is configured to establish
at least one communication link between at least one of the two or
more implantable medical devices and an external device disposed
outside of the body of the patient.
[0008] In some embodiments, the system is scalable and includes at
least an additional implantable medical device having at least one
communication link with the external device. The at least one
communication link may include a wireless power supply link, a
high-speed data link, and a low-speed data link. The two or more
implantable medical devices may communicate with the external
device utilizing a time-division multiplexing protocol. Each of the
two or more implantable medical devices may have different
addresses that provide for the external device to communicate
separately with each of the two or more implantable medical
devices.
[0009] In some embodiments, the system is a closed-loop system in
which the two or more implantable medical devices are configured to
communicate to determine therapy to be applied to the patient in
the absence of communication with an external device.
[0010] In some embodiments, each of the two or more implantable
medical devices have a volume of less than about 2 cm.sup.3.
[0011] In some embodiments, each of the two or more implantable
medical devices includes up to 32 different communication channels
configured to one of receive sensor data signals or transmit
stimulation signals. The communication channels may be
reconfigurable while the implantable medical devices are implanted
in the patient by transmission of a down link control signal to the
implantable medical devices.
[0012] In some embodiments, the two or more implantable medical
devices include communications security algorithms including user
authentication requirements.
[0013] In some embodiments, the two or more implantable medical
devices are operable to read signals from nerve tissue of the
patient and process the signals to provide outputs to control a
prosthetic device of the patient.
[0014] In some embodiments, the two or more implantable medical
devices are configured to operate with mixed monopolar and bipolar
stimulation modes.
[0015] In accordance with another aspect, there is provided a
system of two or more implantable medical devices configured to
establish a wireless link between the two or more implantable
medical devices and a device external to a body of a patient while
the two or more implantable medical devices are implanted in the
body of the patient.
[0016] In some embodiments, the two or more implantable medical
devices are further configured to establish a communication link
between each other while implanted in the body of the patient
utilizing an intra-body wireless communication link. The two or
more implantable medical devices may be configured to coordinate
therapy for the patient through the communication link between each
other. The two or more implantable medical devices may be further
configured to share data processing load through the communication
link between each other.
[0017] In some embodiments, the device external to the body of the
patient is configured to coordinate therapy for the patient
performed by the two or more implantable medical devices.
[0018] In some embodiments, the device external to the body of the
patient is configured to coordinate monitoring of one or more
physiological parameters of the patient by the two or more
implantable medical devices. Coordinating monitoring of the one or
more physiological parameters of the patient may include
aggregating data acquired by the two or more implantable medical
devices to produce aggregated data regarding the one or more
physiological parameters of the patient. The device external to the
body of the patient may be further configured to coordinate therapy
for the patient performed by the two or more implantable medical
devices based on the aggregated data. The device external to the
body of the patient may be further configured to provide the
aggregated data to a diagnostic system distinct from the system.
The device external to the body of the patient may be further
configured to provide a recommendation for treatment of the patient
based on the aggregated data.
[0019] In some embodiments, the two or more implantable medical
devices are configured to share data processing load through the
wireless communication link with the device external to the body of
the patient.
[0020] In some embodiments, at least one of the two or more
implantable medical devices is configured to be one of placed in
one of a plurality of low power modes and brought from the one of
the plurality of low power modes into an active mode based upon a
signal from another of the two or more implantable medical
devices.
[0021] In some embodiments, the system is scalable and includes at
least an additional implantable medical device having at least one
communication link with the device external to the body of the
patient. The system may automatically adapt to activation,
deactivation, addition, or removal of an implantable medical device
from the system to coordinate monitoring and therapy of the patient
utilizing each active implantable medical device implanted in the
patient.
[0022] In some embodiments, the at least one wireless link includes
a wireless power supply link, a high-speed data link, and a
low-speed data link. The high-speed data link may be an
asymmetrical data link that uplinks data received from sensors in
the body of the patient by the two or more implantable medical
devices to the device external to the body of the patient. The
low-speed data link may be an asymmetrical data link that downlinks
configuration settings from the device external to the body of the
patient to the two or more implantable medical devices.
[0023] In some embodiments, the low-speed data link comprises
signals generated by modulating current passing through the power
supply link. The low-speed data link and the high-speed data link
may be provided in a single signal. The device external to the body
of the patient may include a plurality of antennas and may be
configured to determine which of the two or more implantable
medical devices transmitted a signal over one of the high-speed
data link or the low-speed data link based on a known location of
the two or more implantable medical devices and a timing of receipt
of the signal at different antennas in the plurality of
antennas.
[0024] In some embodiments, the two or more implantable medical
devices communicate with the device external to the body of the
patient utilizing a time-division multiplexing protocol.
[0025] In some embodiments, each of the two or more implantable
medical devices have different addresses that provide for the
device external to the body of the patient to communicate
separately with each of the two or more implantable medical
devices.
[0026] In some embodiments, the system is a closed-loop system in
which the two or more implantable medical devices are configured to
communicate to determine therapy to be applied to the patient in
the absence of communication with an external device.
[0027] In some embodiments, each of the two or more implantable
medical devices have a volume of less than about 4 cm.sup.3.
[0028] In some embodiments, each of the two or more implantable
medical devices includes up to 32 different channels to tissue
interfaces configured to one of receive sensor data signals or
transmit stimulation signals. The operating parameters of the
channels may be reconfigurable, while the two or more implantable
medical devices are implanted in the patient, for each of sensing
and stimulation by transmission of a down link control signal to
the two or more implantable medical devices.
[0029] In some embodiments, the two or more implantable medical
devices include communications security algorithms including
authentication requirements. The two or more implantable medical
devices may include communications security algorithms further
including encryption.
[0030] In some embodiments, the two or more implantable medical
devices are operable to read signals from nerve tissue of the
patient and process the signals to provide outputs to control an
electronic device. The electronic device may include a prosthetic
device of the patient. The electronic device may include a computer
system distinct from the system. The device external to the body of
the patient may be further configured to receive an input from the
computer system and adjust one or more operating parameters of one
of the device external to the body of the patient or the two or
more implantable medical devices responsive to receiving the input
from the computer system.
[0031] In some embodiments, the two or more implantable medical
devices are reconfigurable, while the two or more implantable
medical devices are implanted in the patient, to operate with mixed
monopolar and bipolar stimulation modes by transmission of a down
link control signal to the two or more implantable medical
devices.
[0032] In some embodiments, the two or more implantable medical
devices are reconfigurable, while the two or more implantable
medical devices are implanted in the patient, to switch between
performing differential signal recording and performing
single-ended signal recording by transmission of a down link
control signal to the two or more implantable medical devices.
[0033] In some embodiments, the two or more implantable medical
devices are further configured to establish a communication link
between each other while implanted in the body of the patient
utilizing a wired communication link.
DESCRIPTION OF THE DRAWINGS
[0034] The accompanying drawings are not intended to be drawn to
scale. For purposes of clarity, not every component may be labeled
in the drawings.
[0035] In the drawings:
[0036] FIG. 1 illustrates a system including implanted
therapy/diagnostic devices linked by a communications network with
the body of a patient;
[0037] FIG. 2A illustrates an embodiment of a system including
therapy/diagnostic/control devices implanted in a human patient and
associated external sensors/controllers;
[0038] FIG. 2B illustrates another embodiment of a system including
therapy/diagnostic/control devices implanted in a human patient and
associated external sensors/controllers;
[0039] FIG. 2C illustrates a methodology for communications between
the implants and the external controller of FIG. 2A or FIG. 2B;
[0040] FIG. 2D is a block circuit diagram of an example of an
external controller of the system of FIG. 2A or FIG. 2B;
[0041] FIG. 3A is an exploded view of an example of a wireless
implant;
[0042] FIG. 3B illustrates external electrical connections on an
external surface of the wireless implant of FIG. 3A for electrodes
or sensors;
[0043] FIG. 4A illustrates an amplifier chip that maybe included in
the wireless implant of FIG. 3A;
[0044] FIG. 4B illustrates a stimulator digital-to-analog converter
chip that maybe included in the wireless implant of FIG. 3A;
[0045] FIG. 4C illustrates a switch matrix chip that maybe included
in the wireless implant of FIG. 3A;
[0046] FIG. 4D illustrates a radio chip that maybe included in the
wireless implant of FIG. 3A;
[0047] FIG. 4E illustrates a power supply chip that maybe included
in the wireless implant of FIG. 3A;
[0048] FIG. 4F is a block diagram of circuitry of an example of a
wireless implant;
[0049] FIG. 4G is a block diagram of a power supply circuit of an
example of a wireless implant;
[0050] FIG. 5 illustrates another example of a wireless
implant;
[0051] FIG. 6 illustrates wireless links associated with examples
of wireless implants;
[0052] FIG. 7A illustrates an external power coil disposed about an
arm of a subject having a prosthetic hand in which four wireless
implants are implanted in the arm to read nerve signals and control
the prosthetic hand;
[0053] FIG. 7B is a chart of power transfer efficiency between an
external power coil and wireless implants;
[0054] FIG. 7C is a chart of packet error rate in data
transmissions to and from a wireless implant;
[0055] FIG. 8A illustrates wireless implants disposed in the back
of a subject;
[0056] FIG. 8B illustrates wireless implants disposed in the head
of a subject;
[0057] FIG. 9 illustrates the effect of compression algorithms on
data measurements acquired by an embodiment of a wireless
implant;
[0058] FIG. 10 illustrates an electrode system that may be utilized
with examples of wireless implants;
[0059] FIG. 11A illustrates in act in the electrode system of FIG.
10 being attached to a nerve;
[0060] FIG. 11B illustrates another act in the electrode system of
FIG. 10 being attached to a nerve;
[0061] FIG. 11C illustrates the electrode system of FIG. 10
attached to a nerve and having signal wires connected to bond pads
of the electrode system; and
[0062] FIG. 12 illustrates a graph showing power consumption
associated with different security and safety features of systems
including wireless implants.
DETAILED DESCRIPTION
[0063] Emerging applications in neuromodulation are increasingly
involving responsive closed-loop stimulation that is coordinated
across distributed targets in the body. A driving factor in the
design of new medical implants is the growing awareness that
disease often involves complex interactions between multiple
systems in the body. This networked perspective has led to the
emergence of the fields of networked physiology and networked
medicine. However, most chronic implants today resemble pacemakers
of the past--large, open-loop, and limited to stimulation or
recording at single locations. Key technical challenges overcome by
aspects and embodiments disclosed herein include high-fidelity
stimulation and recording, miniaturized hermetic packaging,
wireless connectivity for power and data, and wireless
security.
[0064] Current state-of-art complex implantable devices for therapy
operate individually or based on input from an external
(non-implanted) device. No system or method exists to allow
implanted therapy devices to coordinate activity or share
information.
[0065] Aspects and embodiments disclosed herein include systems of
one or more wirelessly connected implants capable of providing
electrical stimulation and/or recording of electrical signals in
muscles or nervous tissue in the body. Aspects end embodiments of
the wireless implants disclosed herein may be far smaller than
previously known implants, for example, having a volume of about 4
cm.sup.3, 2 cm.sup.3, 1 cm.sup.3, or less.
[0066] Systems and methods for modulating a physiological process
are provided. The systems and methods may provide a more effective
technique for neurostimulation or neuromodulation therapies than
previously known systems. The systems and methods may be used for
neurostimulation or neuromodulation in spinal cord, vagus nerve,
deep-brain, and retinal applications. The systems and methods may
also be used for sensing and modulating activity of other
biological organs and systems, including, but not limited to,
cardiac muscle, skeletal muscle, bone, and blood vessels. Signals
of interest include electrical, magnetic, optical, chemical, and
mechanical. The systems and methods may provide improved therapy or
treatment than previously known systems by coordinating treatment
or therapy across multiple implanted devices.
[0067] In some embodiments, each implant is wirelessly powered and
equipped with advanced microelectronics (ASICs) that provide 32
channels of recording and stimulation. In other embodiments, each
implant may be provided with greater than 32 channels of recording
and stimulation. Recorded biosignals can be monitored by
distributed implants, processed individually or as aggregates, and
used to trigger coordinated stimulation therapies on-the-fly to
target disease in ways not previously possible. Each implant can
interface with multiple types of tissue interfaces, including
electrodes and optical waveguides, and the number of networked
implants can be varied based upon the patient's clinical needs.
Some embodiments of systems disclosed herein support networking
among as many as four wireless implants for a total of 128
electrodes. Each wireless implant may be fully reconfigurable for
differential and single-ended recording as well as mono- and
multi-polar stimulation with arbitrary waveforms. Embodiments of
wireless implants disclosed herein may operate with mixed monopolar
and bipolar stimulation modes. Custom ASICs, dense printed circuit
board (PCB) design, and miniaturized hermetic packaging enable a
compact implantable volume of about 2 cm.sup.3, 1 cm.sup.3, or
less.
[0068] The small size of the implants disclosed herein provides for
them to easily go where other implants can not--for example, the
head or smaller anatomy. Existing deep brain stimulation (DBS)
systems are large--typically 20 cc--and require implantation in the
chest with an electrode lead tunneled through the neck and head to
access the brain. However, many brain disorders, like
neuropsychiatric illnesses, affect multiple distributed neural
regions that can't all be accessed by existing systems. The network
capability of the implants disclosed herein may provide new
opportunities to restore balance to these brain networks. Potential
peripheral applications that can benefit from distributed systems
include hypertension, diabetes, incontinence, pain, reanimation of
paralyzed limbs, and restoration of limb function for amputees
through neuroprosthetics.
[0069] Features of aspects and embodiments of the wireless medical
implants disclosed herein exhibit small volumes and form factors
that eases surgical implantation into smaller spaces than
previously possible. A single wearable antenna module may
wirelessly power, communicate, and control multiple wireless
implants, for example, up to four different implants or more. Use
of a single wearable antenna to power and control multiple implants
eases the burden of use for patients compared to multiple external
antenna modules. A system including the external antenna module and
wireless implants requires robust power and data links that are
tolerant to antenna misalignment. Data compression enables
low-power real-time streaming of neural data. In some embodiments,
each implant may include up to 32 re-configurable channels (128
re-configurable channels for a system including four networked
implants). In some embodiments, the wireless implants may support
multiple types of electrode types, for example, Micro-, ECoG, DBS,
Cuff, and EMG electrode types. Each implant may include functional
reconfigurability. Every channel can switch between recording and
stimulation on demand while the implants are implanted in a body of
a patient. Recording parameters of the implants that may be
adjusted include bandwidth, sampling rate, and single-ended or
differential recording modes. Stimulation parameters of the
implants that may be adjusted include selection from four
independent current sources, and ability to generate arbitrary
waveforms. Embodiments of the implants disclosed herein may provide
for stimulation artifact suppression. Inherent isolation between
different implants eliminates electrical ground artifacts that are
common when recording during and immediately after stimulation.
Each implant may feature an amplifier with a .+-.20 mV dynamic
input range that avoids saturation ringing and fast-settle
circuitry that permits high-fidelity recording within 400 .mu.s of
stimulation.
[0070] The systems and methods of the present disclosure may be
utilized alone or in combination with a larger system that may be
used for physiological treatment or for diagnostic purposes. The
systems and methods of the present disclosure may be utilized to
gather information, control an external computer interface, or
treat a subject over a predetermined period of time, or may be used
indefinitely to monitor or treat a subject. It may be used to
monitor a subject, or control a physiological condition of a
subject, or induce or block a certain physiological event. One or
more components of the systems and methods of the present
disclosure may be used in a wireless configuration.
[0071] Various aspects and embodiments disclosed herein relate to
networked therapy or diagnostic implants, and potentially external
devices, for example, external sensors or controllers, which can
together allow for better patient therapies.
[0072] The proposed architecture includes two or more implanted
devices which can coordinate activities together. A wireless data
link between the networked implants allows the devices to share
information related to data collected or intended actions.
[0073] One example of the benefit of a network like this is the
ability for the network of intra- and trans-body implants to share
processing responsibility. This means that data collected on one
implant could be processed on another or that data could be shared
and simultaneously processed by both. This system could lead to
more complex or more efficient data processing.
[0074] In addition, the network could use signaling between the
implants to provide therapy across the network. In a closed-loop
network for neuroprosthetics or disease-treating implants, this
would mean that the network of implants would communicate over a
wireless link to coordinate therapy in the relevant areas based on
information collected from any one of the networked implants. In
neuroprosthetics, these devices could be placed either near one
another in a local part of the body and communicate over short
distances or they could be placed globally across the entire body
and relay information across the whole body.
[0075] Another advantage that the proposed intra- and trans-body
networked implants offer is the ability to save power by
coordinating between them which units are required for the relevant
task. Instead of all implants requiring full power at all times,
the networked implants could wake each other up and shut each other
down in a closed-loop mode based on external stimuli. Additionally
or alternatively the different implants in a system may be
activated sequentially in a time-division multiplexing methodology
in accordance with a timer included in the system. A first implant
may transition from a sleep to a wake mode to perform a desired
task during a first time period and then transitions to a sleep
mode and a next of the implants transitions from a sleep to a wake
mode during a second time period (overlapping or non-overlapping
with the first time period) to perform a desired task and then
returns to a sleep mode and a next of the implants transitions from
a sleep to a wake mode during a third time period, and so on.
[0076] Another way to solve this problem without the use of
wirelessly networked implants is to use wired, or leaded,
implantable systems. While this solution does allow the implants to
be networked together, it may be less safe and uncomfortable for
the patient than wireless implementations and may involve more
complex surgery to ensure the leads traverse the body safely. The
addition of wired links and associated connectors further increases
modes of failure for the implantable system, which are avoided with
the wireless network.
[0077] In addition, an external device could handle the
communication to and from each of the active implants thereby
providing a link between the implants. However, in this embodiment,
energy may be wasted transmitting information to an external entity
only to have it be re-transmitted to another implant. In addition,
this embodiment may involve bulky hardware to be worn by the user
as opposed to housing the entire system in the patient.
[0078] Creating an intra- and trans-body wireless networks for
therapies allows the implants to carry out more complex tasks than
when not networked, including distributed processing, collective
triggering, and coordination of therapies.
[0079] In some embodiments, the networked implants act together as
an individual larger unit. In further embodiments, the implanted
networked implants are part of a system having a dual network
topology, allowing communication between the implants and with
external devices as well.
[0080] As illustrated in FIG. 1, a plurality of networked therapy
or diagnostic implants may be implanted with the body of a patient,
for example, a human patient. Although three networked therapy or
diagnostic implants are illustrated in FIG. 1, it is to be
appreciated that aspects and embodiments of therapy or diagnostic
systems disclosed herein are not limited to including three
networked therapy or diagnostic implants. The three networked
therapy or diagnostic implants may have similar or different
functionality. The three networked therapy or diagnostic implants
may include one or more sensors and/or one or more electrodes to
deliver electrical therapy to the patient. Any one or more of the
networked therapy or diagnostic implants may include a controller
to provide control commands to circuitry in the same or others of
the networked therapy or diagnostic implants. Each of the networked
therapy or diagnostic implants may be in communication with another
through an in-body shared network, which may be a wireless network
or, in some embodiments, may include one or more wired
communication links. At least one of, and in some embodiments, each
of the networked therapy or diagnostic implants may also be in
communication with an external controller through an
implant-external network, which may be a wireless communication
network. One or more other external sensors may also be in
communication with the external controller, via a wired or wireless
communication link. One or more other external devices, for example
a distinct diagnostic device or computer system may also be in
communication with the external controller, via a wired or wireless
communication link.
[0081] FIGS. 2A and 2B illustrate embodiments of systems including
wirelessly networked therapy or diagnostic implants (also referred
to herein as implantable medical devices). As illustrated, one or
more active networked therapy or diagnostic implants/controllers
may be electrically coupled to or otherwise in communication with
one or more internal bodily structures of a patient, for example,
to nerves in the arm, leg, or brain of the patient. One or more
active networked therapy or diagnostic implants/controllers may be
in communication with any one or more other of the active networked
therapy or diagnostic implants/controllers via, for example, an
in-body shared network, which may be a wireless network or, in some
embodiments, may include one or more wired communication links. An
external controller located outside the body of the patient, for
example, in an article of clothing, clipped to a belt, or carried
in a holster may be in communication, for example, via a wireless
network with one or more of the active networked therapy or
diagnostic implants/controllers via, for example, implant-external
network, which may be a wireless communication network. One or more
other externals sensors, for example a blood pressure, blood oxygen
level, temperature, or other type of sensor may also be in
communication with the external controller, via a wired or wireless
communication link. The external sensors/wearable devices
illustrated in FIG. 2A and FIG. 2B are located on the wrist of the
patient, but in other embodiments may be located on or proximate
other portions of the body of the patient.
[0082] Command and control of the wireless implants may be
performed over a wireless low-bandwidth RF radio, which could be
implemented with Bluetooth.RTM. Low Energy, or a similar
technology. To establish a hierarchical wireless network, the
external controller is implemented as the master and the implants
are implemented as slaves. Messages are sent from the external
master to each implanted slave to set up allocated time slots for
each implant to transmit data back to the master using a second
high-bandwidth RF radio that operates at a separate frequency that
does not interfere with the low-bandwidth link. While operating as
slaves over the low-bandwidth link, implants listen to
communication from the external device and await messages that are
addressed to them. Each implant may be separately addressed by the
external controller to provide power and/or read or send data to
each implant separately or at different times. To avoid
interference between simultaneous messages sent from implants to
the external device, a time-division multiplexing (TDM) scheme may
be used, where each implant is allocated a unique period of time in
which it can transmit data to the external controller. The relative
ordering and length of each implant's timeslot can be adjusted
based the number of implants in the network and it's data rate in
order to achieve optimal system performance. FIG. 2C illustrates a
method of communication between four implanted devices (referred to
in this figure as "satellites" or "slaves") and an external
controller (referred to in this figure as "master") utilizing
TDM.
[0083] The low-bandwidth radio can be implemented as a
bi-directional link (for example, Bluetooth.RTM. Low Energy, or
similar technology) that permits messages to be passed from
master-to-slave and also slave-to-master. Alternatively, the
low-bandwidth radio can be implemented as a uni-directional link
using modulation of the power signal transmitted to each implant
from the external controller, or as modulation of a backscatter
carrier that may be used to implement the high-bandwidth link. Data
sent from the external controller to the implants may include
configuration messages that can establish allocated time slots for
transmission across the high-bandwidth link, configure recording
settings (for example, electrodes to be recorded from, differential
recording vs single-ended, bandwidth, sampling rate, amplifier
channel shut-down modes), configure stimulation settings (for
example, electrodes to be stimulated on, monopolar vs bipolar vs
multi-polar modes, waveform parameters), trigger pre-loaded
stimulation sequences or adjust thresholds and algorithm parameters
for closed-loop stimulation triggered by internal computation
within each implant, and/or request device status information (for
example, impedances, voltage levels, humidity, data logs).
[0084] The high-bandwidth data link can be implemented as a
uni-directional link to stream large quantities of data (for
example, physiological recordings) from the implants to the
external controller. The high-bandwidth radio can be implemented as
an active radio or as a passive backscatter communication link. In
the latter, the load or impedance on the implant's backscatter
antenna is modulated such that energy that is reflected back the
external controller contains encoded information. Data sent from
the implants to the external device may include device status, data
logs, and detected faults, and recorded data from neurons, muscle,
accelerometers, temperature, pH, and other sensors.
[0085] The external controller may contain wired and wireless links
to other external systems to send control signals (for example, to
prosthetic limbs or computers) or receive input signals (for
example, from diagnostic devices, prosthetic limbs, or computers).
In some implementations, the external controller may be directly
wired to separate computerized systems (for example, over a USB,
optical, or CAN Bus cable). In other implementations, the external
controller may contain a separate wireless link (for example,
RF).
[0086] A block diagram of one embodiment of an external controller
that may interface with wireless implants as disclosed herein
through an arm cuff is illustrated in FIG. 2C.
[0087] The implant provides an interface to biological tissue (for
example, neurons, muscle, and/or bone) via attached electrodes,
optrodes, or other sensing and stimulation interfaces. The implant
interfaces may be electrical in nature and the types of electrodes
that can be used include micro-electrodes, macro-electrodes, cuff,
intrafascicular, EMG, DBS, ECoG, paddle, and cardiac leads. A
cross-point switch matrix inside each implant allows every channel
to be used for recording and stimulation, which can be
re-configured on-the-fly. The cross-point switch matrix also allows
a bi-polar amplifier to be reconfigured for differential and
single-ended recording modalities. Stimulation can be routed to any
electrode from stimulation circuitry that provides stimulation
waveforms. Multiple stimulation sources may be combined on any
electrode to increase the amount of stimulation (for example,
increase current).
[0088] The implant also contains circuitry for receiving wireless
power from the external system. In some cases, a re-chargeable
battery may be included in the implant. In other cases, the implant
receives continuous wireless power without an internal battery.
[0089] The implant also contains logic for processing data and
implementing closed-loop algorithms that may trigger stimulation in
response to data sensed by the implant itself, or in response to
aggregated data received from the larger network of implants.
[0090] The external system provides an interface between the
implanted network, the user (for example, patient or clinician) and
peripheral devices (for example, prosthetics, diagnostics,
computers, or cloud computing). Data from implants (which may be
pre-processed) is aggregated by the external system and algorithms
are implemented to control external systems or to provide
responsive stimulation therapies that may be distributed throughout
the implants.
[0091] FIG. 3A illustrates an example of a wireless implant 300
that may be utilized in networked implant systems as disclosed
herein. The implant 300 is illustrated in an exploded view and a
U.S. dime is included to give an indication of size. The implant
300 includes a lid 305, an antenna board including one or more
antennas 310, which may include, for example, a inductive power
link antenna, a low-bandwidth data link antenna, and a
high-bandwidth data link antenna, a ferrite and conductive shield
layer 315, a PCB layer 320 including a plurality of ASICs that
control operation of the implant, and a feedthrough layer 325. The
lid 305 and feedthrough layer 320 may con formed of a biocompatible
material such as a ceramic, for example, aluminum oxide or other
biocompatible ceramic. The lid 305 and feedthrough layer 325 are
hermetically sealed while allowing for wireless communication to
and from the circuitry internal to the implant 300. The feedthrough
layer 325 may include electrical contacts 330 that provide
electrical communication between sensors or electrodes or other
stimulation devices external to the implant 300 and the circuitry
within the implant 300. The electrical contacts 330 of the
feedthrough layer 320 may be formed of a biocompatible conductive
material, for example, a metal such as gold, or a platinum-iridium
alloy, or any other biocompatible conductive material. Electrical
contact 330 on the outside of the feedthrough layer 325 are
illustrated in FIG. 3B. In some embodiments, the inductive power
link antenna may be a coil disposed within or on the outside of the
lid 305 and sealed against the environment internal to the body by,
for example, a layer of biocompatible polymer, rather than disposed
in the antenna board 310. The wireless implant 300 may be covered
in a biocompatible material, for example, silicone, with access
apertures for the electrical contacts 330.
[0092] Examples of ASICs that may be included in the implant 300,
for example, on the PCB layer 320 include one or more amplifiers
(FIG. 4A). The one or more amplifiers may each support 32 channels
of single ended recording or 16 channels of differential recording.
A second ASIC that may be included in the implant 300 is a
stimulator digital-to-analog converter (FIG. 4B). The stimulator
digital-to-analog converter may include, for example, four channels
and be capable of outputting .+-.10 mA at .+-.10V. A third ASIC
that may be included in the implant 300 is a cross-point switch
matrix (FIG. 4C). The switch matrix may support reconfiguration of
electrodes for recording or stimulation, with a 70.OMEGA. closed
circuit impedance an >1 G.OMEGA. open circuit impedance. The
switch matrix may support the combination of multiple stimulation
channels to increase stimulation output. The switch matrix may
support mapping of multiple references to amplifier inputs for
combinations of differential and single-ended recordings. A third
ASIC that may be included in the implant 300 is a radio circuit
(FIG. 4D) that may be utilized for communication between different
implants in the body of a subject and/or with an external monitor
or controller. The radio circuit may operate at, for example, 915
MHz with a bandwidth of 20 Mbps or more and may operate in
accordance with the BPSK/QPSK modulation schemes. A third ASIC that
may be included in the implant 300 is a power supply (FIG. 4E). The
power supply may receive input power from an inductive power coil
in the antenna board 310 and output power at, for example, .+-.10V,
3.3V, and 1.8V to provide power at appropriate voltages to the
other components of the implant. The implant may further include
additional integrated circuits, discreet active devices and/or
passive devices (for example, capacitors, inductors, and/or
resistors) not specifically illustrated.
[0093] A block diagram of circuitry of an example of a wireless
implant is illustrated in FIG. 4F. A block diagram of a power
supply circuit of an example of a wireless implant is illustrated
in FIG. 4G.
[0094] An alternate form factor for a wireless implant 400 is
illustrated in FIG. 5. The wireless implant 400 may comprise a
microelectronic printed circuit board 430, a housing 420, and a
plurality of feedthroughs 410. The feedthroughs 410 may be
oppositely disposed. The wireless implant 400 may be constructed,
for example, by fusing the housing 420 with the feedthroughs 410,
such that the printed circuit board 430 is encapsulated within the
housing 420. The wireless implant 400 is illustrated with a portion
of the housing 420 omitted to illustrate the internal circuit board
430. The form factor of the wireless implant 400 is illustrated in
FIG. 5 may have a diameter of about 14 mm with a total implantable
volume of about 0.7 cm.sup.3.
[0095] Embodiments of the wireless implant disclosed herein may
include three robust wireless links that are tolerant to
misalignment and rotation. The three wireless links include power,
low-bandwidth (LBW) bi-directional data, and high-bandwidth (HBW)
uni-directional data streaming. The three wireless links are
illustrated schematically in FIG. 6 with a pair of wireless
implants. Power to the wireless implants may be provided from an
external AC power source (which may transmit power in a radio
frequency band that penetrates the body with little attenuation) to
an inductive power coil that may be included in the antenna board
of the wireless implants or as a separate element of the wireless
implants. FIG. 7A illustrates an external power coil 705 disposed
about an arm of a subject having a prosthetic hand in which four
wireless implants 710 are implanted in the arm to read nerve
signals and control the prosthetic hand. The external power coil
may be in electrical communication with an external controller, for
example, an external controller as illustrated in FIG. 2A or FIG.
2B.
[0096] In some implementations it may be desirable to align the
external power coil 705 directly over and in parallel to the power
link antenna and/or data link antennas of a wireless implant. In
other implementations it may be desirable to wind the external
power coil around the body (for example, circumscribing the arm).
As illustrated in FIG. 7B, power transfer efficiency between an
external power coil and wireless implants may decrease with
distance between the external power coil and wireless implants.
While the wireless power efficiency between any single implant and
the external power coil may decrease as more implants are added to
the system, the overall wireless efficiency of the system may
increase. As illustrated in FIG. 7C packet error rate in data
transmissions to and from a wireless implant in the high bandwidth
link may increase with increasing distance between an antenna of an
external controller and a wireless implant and/or with a degree of
offset or misalignment between the data link antennas of the
wireless implant and that of the external controller. Robust data
transmission may be improved by implementing error detection and
correction (for example, cyclic redundancy checks and automatic
repeat requests).
[0097] FIGS. 8A and 8B illustrate alternate examples of placement
of wireless implants disclosed herein, indicated at 810, in the
back and in the head of a subject, respectively.
[0098] The low-bandwidth data link may operate at a bandwidth of,
for example, 100 kbps and may support down-links of on-the-fly
stimulation profile updates, down-links of system firmware updates,
and up-links of system status and safety data. The high-bandwidth
data link may operate at a bandwidth of, for example, 20 Mbps and
may support greater than 1,000 channels of local field potential
(LFP)/electromyography (EMG) data (18 bit, 1,000 kilo samples per
second (kSps)), 55 channels of raw spike data (18 bit, 20 kSps),
and 125 channels of compressed spike data (8 bit, 20 kSps).
[0099] Increased channels of neural data, particularly spike (AP)
data, creates challenges for real-time embedded processing and
wireless data transmission. Embodiments of the wireless implants
disclosed herein may implement low-power compression algorithms
that may reduce data rates in half (16:7) with negligible effects
on spike sorting fidelity. This reduction of wireless data
bandwidth enables power savings and transmission of 2X more
channels than might otherwise be achievable. FIG. 9 illustrates the
effect of the compression algorithms on data measurements acquired
by embodiments of the wireless implants disclosed herein.
[0100] Electrodes that may be electrically connected to embodiments
of the wireless implants disclosed herein may be inserted into, for
example, muscle tissue or nervous tissue of a subject to monitor
the electrical activity of these tissues or apply stimulation to
same. One example of an electrode that may be utilized with
embodiments of the wireless implants disclosed herein is referred
to as a longitudinal intra-fascicular electrode (LIFE) system. The
LIFE electrode system formed of platinum and silicone and include
fine features which are designed to be implanted within the body of
a peripheral nerve of a subject. The LIFE electrode system,
illustrated generally at 1000 in FIG. 10, includes a cuff 1005
having six cuff electrodes 1010 for macro recording, stimulation,
and proving a secure anchoring point around a nerve. The LIFE
electrode system 1000 further includes an interfascicular active
area 1015 including nine intra-neural electrodes 1020 for micro
recording and stimulation for more precise motor control and
sensory perception. A needle 1025 at the tip of the electrode
system 1000 allows for easy and simplified implantation within
individual motor and sensory fascicles for safer and more reliable
access to targeted neurons. Bond pads 1035 on a bonding surface
1030 coupled to the cuff 1005 provide electrical contact to each of
the cuff electrodes 1010 and intra-neural electrodes 1020 which are
in turn electrically connected to electrical contacts 330 or
feedthroughs 410 of embodiments of a wireless implant as disclosed
herein.
[0101] In use, the LIFE electrode system is threaded into the
fibers of the nerves using the suture needle 1025 located at the
end of the active sites, as shown in FIG. 11A. Once the electrode
system is properly placed, the needle is removed (FIG. 11B). The
electrode system is then secured closely to the nerve fibers to
form a selective neural interface and the wires for connection to a
wireless implant are connected to the bond pads 135 (FIG. 11C).
[0102] It should be appreciated that embodiments of the wireless
implants disclosed herein are not limited to sending or receiving
electrical signals from electrodes. In other embodiments other
forms of sensors, for example, blood pressure, blood oxygen,
glucose level, insulin level, or other forms of mechanical or
chemical sensors may be utilized to provide data to embodiments of
the wireless implants. In alternate embodiments, outputs of
embodiments of the wireless implants may be utilized to drive a
chemical dispenser or drug delivery system or to drive a heating,
cooling, or light emitting device or one that applies mechanical
force to one or more portions of a body of a subject.
[0103] In some embodiments, wireless implants as disclosed herein
may be provided with wireless security measures to prevent hacking.
Implantable medical devices are typically more power constrained
than external systems and designs of such systems may include a
trade-off between power and security. FIG. 12 illustrates a graph
showing power consumption associated with different security and
safety features. Embodiments of wireless implants disclosed herein
may include security algorithms requiring authentication, for
example, multi-factor authentication or proximity-based
authentication. Such algorithms may be reprogrammable.
Confidentiality features of embodiments of wireless implants
disclosed herein may include resting data encryption and/or SSL
architecture for transit data. Data integrity features of wireless
implants disclosed herein may include error detection and automatic
repeat request (ARQ). Availability features of embodiments of
wireless implants disclosed herein may include an integrated
network and short-range radio.
PROPHETIC EXAMPLES
Prophetic Example 1: Restoration of Sensorimotor Function in an
Upper Arm Amputee Through a Sensorized Robotic Arm
[0104] An example application of a wirelessly networked implantable
system is to restore sensorimotor function in an upper arm amputee
through a sensorized robotic arm. In this example, control of the
prosthetic arm could be derived from signals recorded from residual
muscle and nerve in the amputated limb. To provide control signals
for movement of the prosthetic, muscle activity could be recorded
from intramuscular or epimysial electromyography (EMG) electrodes.
Control signals for flexion or extension around a joint could be
derived from different muscle groups that are involved in similar
natural movement, which are often located on opposite sides of the
limb. Two implants could be used to record activity from each
group--one located near to the extensors and one located near to
the flexors. Recorded EMG activity could be processed within each
implant. The power of the EMG signals may be estimated using an
envelope detection method that rectifies and low-pass filters the
raw EMG data. Alternatively, control signals could be derived from
motor neurons using cuff or intrafascicular electrodes.
[0105] Targeted nerves are typically more proximal than the muscles
that they innervate and so the location of an implant that
interfaces with nerve would likely be more proximal than implants
that interface with muscles. Neural recording requires a wider
amplifier bandwidth and higher sampling rate than EMG, and which
could be configured via the wireless down-link to an implant.
Neural signals could be processed within an implant, which might
include threshold detection, action potential sorting, and
calculation of spike rates. Depending upon the chosen algorithms,
the power to wirelessly transmit the neural signals to the external
device may be less than the power to perform the processing within
the implant. In such instances, the neural data, which has a
greater sampling rate than EMG, may be compressed and transmitted
to the external device within an allocated time slot that is
proportionally longer in duration than the time slot duration
allocated to an implant that is recording EMG. The pre-processed
signals could then be aggregated by the external device and further
processed to create a movement control signal that is transmitted
(wirelessly or via a wired connection) to the prosthetic.
[0106] To restore sensory function, both muscle and nerve could be
stimulated to create sensory perceptions in response to movement
and touch on the sensorized prosthetic limb. To create a perception
of limb movement, signals from the prosthetic could be received by
the external device, which would then convert the signals to
desired stimulation patterns that would be sent to implants that
are interfacing with the nerve or muscle that are associated with
the intended perception. Natural sensation of limb movement
involves both the contraction of some muscles, while others are
extended on the opposite side of the joint. To replicate this
sensation, stimulation might be provided at multiple locations in
the limb through multiple distributed implants. Stimulation
patterns might be transmitted from the external device to the
implants using the low-bandwidth downlink by sending changes in the
frequency or amplitude of stimulation to be provided. In this way,
the amount of data required for stimulation can be reduced since
not all of the stimulation parameters need to be transmitted for
every stimulus. Implants may receive the stimulation information
that is addressed to them and conduct further processing to create
the full stimulation pattern that is required. The timing and
location of stimulation can be coordinated across multiple implants
to produce a natural sensation.
Prophetic Example 2: Treating Neuropsychiatric Disorders Through
Closed-Loop Neuromodulation in the Brain
[0107] Another example application of a wirelessly networked
implantable system is to treat neuropsychiatric disorders through
closed-loop neuromodulation in the brain. In this example,
coordinated stimulation may be provided at multiple target
locations in the brain in response to estimates of unhealthy
neuropsychiatric states derived from aggregated neural activity
that is distributed throughout the brain. Neuropsychiatric illness
is increasingly understood from a systems neuroscience perspective
involving dynamic changes in network activity. For example, neural
activity that is predictive of neuropsychiatric state may come from
electrocorticographic (ECoG) signals recorded from prefrontal
cortex and cingulate cortex as well as multi-unit signals from
micro-electrode placed deeper within the striatum. In this example,
three implants may be used--one in each area. The implants used for
ECoG recordings would have their amplifiers configured for lower
bandwidth differential recordings, and the implant used for
multi-unit recordings would be configured for higher bandwidth
single-ended recordings. Power spectra from ECoG recordings may be
calculated within specific frequency bands within the implants and
results wirelessly transmitted to the external device. Algorithms
for spike thresholding, sorting, and calculation of spike rates may
be implemented in the implant configured for multi-unit recordings
and transmitted to the external device. This data may be aggregated
and processed to detect the neuropsychiatric state, which may be
subsequently used to trigger coordinated stimulation on multiple
electrodes distributed across all implants. Alternatively, features
of the recorded signals may be transmitted directly between the
implanted network in the absence of the external device and used to
modulate stimulation therapies.
[0108] Having thus described several aspects of at least one
embodiment, it is to be appreciated that various alterations,
modifications, and improvements will readily occur to those skilled
in the art. Such alterations, modifications, and improvements are
intended to be part of this disclosure and are intended to be
within the scope of the invention. Accordingly, the foregoing
description and drawings are by way of example only, and the scope
of the invention should be determined from proper construction of
the appended claims, and their equivalents.
* * * * *