IMPLANTS USING ULTRASONIC BACKSCATTER FOR DETECTING ELECTROPHYSIOLOGICAL SIGNALS
Described herein are implantable devices configured to detect an electrophysiological signal. Certain exemplary implantable devices comprise a first electrode and a second electrode configured to engage a tissue and detect an electrophysiological signal; an integrated circuit comprising a multi-transistor circuit and a modulation circuit configured to modulate a current based on the electrophysiological signal; and an ultrasonic transducer configured to emit an ultrasonic backscatter encoding the electrophysiological signal from the tissue based on the modulated current. Also described herein are systems that include one or more implantable devices and an interrogator comprising one or more ultrasonic transducers configured to transit ultrasonic waves to the one or more implantable devices or receive ultrasonic backscatter from the one or more implantable devices. Further described are computer systems for operating one or more implantable devices, and methods of detecting an electrophysiological signal in a tissue.
1 . An implantable device, comprising:
a first electrode and a second electrode configured to engage a tissue and detect an electrophysiological signal;
an integrated circuit comprising a multi-transistor circuit and a modulation circuit configured to modulate a current based on the electrophysiological signal; and
an ultrasonic transducer configured to emit an ultrasonic backscatter encoding the electrophysiological signal from the tissue based on the modulated current.
2 . The implantable device of claim 1 , wherein the multi-transistor circuit is a digital circuit.
3 . The implantable device of claim 1 or 2 , comprising a body that comprises the ultrasonic transducer and the modulation circuit, wherein the body is about 5 mm or less in length in the longest dimension.
4 . The implantable device of any one of claims 1 - 3 , wherein the first electrode and the second electrode are spaced by about 0.5 mm or more.
5 . The implantable device of any one of claims 1 - 4 , comprising a non-responsive reflector.
6 . The implantable device of any one of claims 1 - 5 wherein the tissue is muscular tissue or nervous tissue.
7 . The implantable device of any one of claims 1 - 6 , wherein the tissue is part of the peripheral nervous system or the central nervous system.
8 . The implantable device of any one of claims 1 - 7 , wherein the tissue is brain tissue or a peripheral nerve.
9 . The implantable device of any one of claims 1 - 6 , wherein the tissue is skeletal muscle, cardiac muscle, or smooth muscle.
10 . The implantable device of any one of claims 1 - 9 , comprising three or more electrodes.
11 . The implantable device of any one of claims 2 - 10 , wherein the digital circuit is configured to operate the modulation circuit.
12 . The implantable device of any one of claims 2 - 11 , wherein the digital circuit is configured to transmit a digitized signal to the modulation circuit, wherein the digitized signal is based on the detected electrophysiological signal.
13 . The implantable device of claim 11 , wherein the digitized signal comprises a unique implantable device identifier or a unique electrode pair identifier.
14 . The implantable device of claim 12 or 13 , wherein the digitized signal is compressed by a factor of 5 or more relative to an analog signal.
15 . The implantable device of any one of claims 1 - 14 , wherein the integrated circuit comprises a spike detector.
16 . The implantable device of any one of claims 1 - 15 , wherein the integrated circuit comprises a power circuit.
17 . The implantable device of any one of claims 1 - 16 , wherein the integrated circuit comprises an analog-to-digital converter (ADC).
18 . The implantable device of any one of claims 1 - 17 , wherein the integrated circuit comprises an amplifier chain.
19 . The implantable device of any one of claims 1 - 18 , comprising a body that comprises the ultrasonic transducer and the modulation circuit, wherein the body has a volume of about 5 mm 3 or less.
20 . The implantable device of any one of claims 1 - 19 , wherein the ultrasonic transducer is configured to receive ultrasonic waves that power the implantable device.
21 . The implantable device of any one of claims 1 - 20 , wherein the ultrasonic transducer is configured to receive ultrasonic waves from an interrogator comprising one or more ultrasonic transducers.
22 . The implantable device of any one of claims 1 - 21 , wherein the ultrasonic transducer is a bulk piezoelectric transducer, a piezoelectric micro-machined ultrasonic transducer (PMUT), or a capacitive micro-machined ultrasonic transducer (CMUT).
23 . The implantable device of any one of claims 1 - 22 , wherein the implantable device is implanted in a subject.
24 . The implantable device of claim 23 , wherein the subject is a human
25 . The implantable device of any one of claims 1 - 24 , wherein the implantable device is implanted in the tissue, on the tissue, or near the tissue.
26 . The implantable device of claim 25 , wherein the first electrode and the second electrode are implanted in the tissue or on the tissue.
27 . The implantable device of any one of claims 1 - 26 , wherein the implanted device is at least partially encapsulated by a biocompatible material.
28 . The implantable device of claim 27 , wherein at least a portion of the first electrode and the second electrode are not encapsulated by the biocompatible material.
29 . A system comprising one or more implantable devices according to any one of claims 1 - 28 and an interrogator comprising one or more ultrasonic transducers configured to transit ultrasonic waves to the one or more implantable devices or receive ultrasonic backscatter from the one or more implantable devices.
30 . The system according to claim 29 , wherein the system comprises a plurality of implantable devices.
31 . The system according to claim 30 , wherein the interrogator is configured to beam steer transmitted ultrasonic waves to alternatively focus the transmitted ultrasonic waves on a first portion of the plurality of implantable devices or focus the transmitted ultrasonic waves on a second portion of the plurality of implantable devices.
32 . The system according to claim 30 , wherein the interrogator is configured to simultaneously receive ultrasonic backscatter from at least two implantable devices.
33 . The system of claim 30 , wherein the interrogator is configured to transit ultrasonic waves to the plurality of implantable devices or receive ultrasonic backscatter from the plurality of implantable devices using time division multiplexing, spatial multiplexing, or frequency multiplexing.
34 . The system according to any one of claims 30 - 33 , wherein the interrogator is configured to be wearable by a subject.
35 . A computer system, comprising:
an interrogator comprising one or more ultrasonic transducers;
one or more processors;
non-transitory computer-readable storage medium storing one or more programs configured to be executed by the one or more processors, the one or more programs comprising instructions for:
detecting an electrophysiological signal based on ultrasonic backscatter encoding the electrophysiological pulse emitted from an implantable device; and
determining a location of the implantable device relative to the one or more ultrasonic transducers of the interrogator, or detecting movement of the implantable device, based on ultrasonic backscatter not responsive to the electrophysiological pulse emitted from the implantable device.
36 . The computer system of claim 35 , wherein the one or more programs comprise instructions for determining a location or movement of the implantable device relative to the one or more ultrasonic transducers of the interrogator.
37 . The computer system of claim 35 or 36 , wherein the ultrasonic backscatter responsive to the electrophysiological signal comprises a digitized signal encoding the electrophysiological signal.
38 . The computer system of any one of claims 35 - 37 , wherein the one or more programs comprises instructions for attributing the detected electrophysiological signal to the implantable device that emitted the ultrasonic backscatter encoding the electrophysiological signal from a plurality of implantable devices.
39 . The computer system of claim 38 , wherein the detected electrophysiological signal is attributed to the implantable device using time division multiplexing, spatial multiplexing, or frequency multiplexing.
40 . The computer system of claim 38 , wherein the detected electrophysiological signal is attributed to the implantable device using a unique identifier encoded in the ultrasonic backscatter encoding the electrophysiological pulse.
41 . A method of detecting an electrophysiological signal in a tissue, comprising:
receiving ultrasonic waves at one or more implantable devices;
converting energy from the ultrasonic waves into an electrical current that flows through a modulation circuit;
detecting the electrophysiological signal;
digitizing the electrophysiological signal;
modulating the electrical current based on the digitized electrophysiological signal;
transducing the modulated electrical current into an ultrasonic backscatter that encodes information related to the electrophysiological signal; and
emitting the ultrasonic backscatter to an interrogator comprising one or more transducer configured to receive the ultrasonic backscatter.
42 . A method of detecting an electrophysiological signal in a tissue, comprising:
transmitting ultrasonic waves from an interrogator comprising one or more ultrasonic transducers to one or more implantable devices; and
receiving from the one or more implantable devices ultrasonic backscatter that encodes digitized information related the electrophysiological signal.
43 . The method of claim 41 or 42 , comprising receiving the ultrasonic backscatter using the interrogator.
44 . The method of any one of claims 41 - 43 , wherein the ultrasonic waves power the one or more implantable devices.
45 . The method of any one of claims 41 - 44 , wherein the tissue is muscular tissue or nervous tissue.
46 . The method of any one of claims 41 - 45 , wherein the tissue is part of the peripheral nervous system or the central nervous system.
47 . The method of any one of claims 41 - 46 , wherein the tissue is brain tissue or a peripheral nerve.
48 . The method of any one of claims 41 - 45 , wherein the tissue is skeletal muscle, cardiac muscle, or smooth muscle.
49 . The method of any one of claims 41 - 48 , comprising reconstructing an electromyogram, an electroneurogram, an electrocardiogram, a compound action potential, a multi-unit activity of multiple neurons, a local field potential, or an action potential.
50 . The method of any one of claims 41 - 49 , comprising implanting the one or more implantable devices.
51 . The method of any one of claims 41 - 50 , wherein the subject is a human
52 . The method of any one of claims 41 - 51 , comprising determining a location or movement of the one or more implantable devices.
53 . The method of any one of claims 41 - 52 wherein the digitized signal comprises a unique implantable device identifier or a unique electrode pair identifier.
54 . The method of any one of claims 41 - 54 , wherein the one or more implantable devices comprises a plurality of implantable devices.