Ultrasound-based protocol for operating implantable device

Abstract

To provide, generally, operating an implantable device and, more specifically, operating the implantable device using ultrasonic waves.SOLUTION: Method and system embodiments for operating a device implantable in a subject using ultrasonic waves are described. In some embodiments, a method is implemented at the implantable device to receive ultrasonic waves including an operating mode command. Then, the implantable device sets an operating mode of the implantable device to one operating mode from a plurality of predetermined operating modes based on the operating mode command.SELECTED DRAWING: None

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 788,390, filed January 4, 2019, which is incorporated by reference herein for all purposes.

[0002] [Technical field] The present disclosure relates generally to operating implantable devices, and more particularly to operating implantable devices using ultrasound. [Background technology]

[0003] Invasive methods have been developed to treat various medical conditions in patients. These methods can include inserting an implantable medical device (IMD), such as a cardiac or neurobiological implant, into the patient's body. Operating such implantable devices in a wireless manner remains a technical challenge for many biomedical applications. This is in part because the traditional approach of using radio frequency (RF) to control wireless devices has many limitations in biomedical settings and may pose health risks to the patient. For example, the RF antennas required to process the RF may have a large form factor, making implantable devices that use RF antennas too large to be safely and comfortably placed in many locations within the body.

[0004] Additionally, biological tissues tend to readily absorb energy from RF carrier frequencies, which may limit the implantable depth of an implantable device. Furthermore, due to the high absorption rate of RF energy, biological tissues may overheat, posing a health risk to the patient.

[0005] The disclosures of all publications, patents, and patent applications referenced herein are each incorporated herein by reference in their entirety. In the event that any reference incorporated by reference conflicts with the present disclosure, the present disclosure shall control. Summary of the Invention

[0006] As discussed above, there is a need for implantable devices with smaller form factors (e.g., mm and sub-mm dimensions) to increase biocompatibility and reduce the invasiveness and discomfort caused by larger implantable devices that are controlled using, for example, RF. In some embodiments, to achieve this smaller form factor, the implantable device can be configured to operate and be powered using ultrasound waves that are receivable by one or more ultrasound transducers of the implantable device.

[0007] In some embodiments, the use of ultrasound to operate and power implantable devices may be advantageous over other approaches because living tissue absorbs ultrasound at a significantly lower rate than other types of waves, such as RF waves. This property of ultrasound not only reduces tissue heating due to energy absorbed by the tissue, but may also allow the device to be implanted deeper within the subject.

[0008] In some embodiments, to address the above-mentioned needs, a device implantable in a subject includes an ultrasound transducer configured to receive ultrasound including an operational mode command, and a controller circuit configured to set an operational mode of the implantable device from a plurality of operational modes to one operational mode based on the operational mode command.

[0009] In some embodiments, the multiple operational modes include one or more of a downlink mode for downloading data from received ultrasound or an uplink mode for uploading data generated at the implantable device using the received ultrasound to an external device, hi some embodiments, the multiple operational modes include a downlink mode and an uplink mode.

[0010] In some embodiments, ultrasound is received from an interrogator.

[0011] In some embodiments, the ultrasound is received from another implantable device.

[0012] In some embodiments, the method includes determining that the operational mode command corresponds to a pattern from among a plurality of predefined patterns, and setting the operational mode based on the determined pattern.

[0013] In some embodiments, determining that the operational mode command corresponds to a pattern includes determining that a first portion of the operational mode command corresponds to the determined pattern.

[0014] In some embodiments, this first portion includes a single pulse indicating the start of an operational mode command, hi some embodiments, this first portion includes a sequence of two or more pulses.

[0015] In some embodiments, the plurality of predetermined patterns comprises a plurality of corresponding pulse durations, a plurality of corresponding amplitudes, or a plurality of corresponding phase or frequency changes.

[0016] In some embodiments, the plurality of predetermined patterns includes a plurality of corresponding pulse durations, one or more of which are set based on a carrier signal period of the received ultrasound.

[0017] In some embodiments, determining that the operational mode command corresponds to a pattern includes converting the ultrasonic wave into an electrical signal that includes a representation of the operational mode command and counting a number of instances where a first portion of the electrical signal exceeds a predetermined voltage level, the number of instances corresponding to the determined pattern.

[0018] In some embodiments, the determined pattern is associated with uploading data, and the operational mode command includes a second portion different from the first portion, and the method includes setting the operational mode to an uplink mode to upload device data associated with the uplink mode, and backscattering ultrasound, the backscattered ultrasound encoding the device data in the backscatter of the second portion of the operational mode command.

[0019] In some embodiments, the uplink mode includes an acknowledgement mode, and the device data includes an acknowledgement that the implantable device successfully extracted the operational command from the second ultrasound received by the implantable device.

[0020] In some embodiments, the uplink mode includes a physiological condition reporting mode and the device data includes information associated with a physiological condition detected by the implantable device in the physiological condition reporting mode.

[0021] In some embodiments, the uplink mode includes a neural activity reporting mode, and the device data includes information associated with electrophysiological signals detected by the implantable device in the neural activity reporting mode.

[0022] In some embodiments, the device data includes information associated with electrical pulses emitted by the implantable device, the electrical pulses configured to modulate activity of a target nerve.

[0023] In some embodiments, the implantable device is configured to emit an electrical pulse in response to an operational command extracted from the second ultrasound received by the implantable device when the operational mode of the implantable device is set to a downlink mode.

[0024] In some embodiments, the determined pattern is associated with downloading data, and the operational mode command includes a second portion different from the first portion, and the method includes setting the operational mode to a downlink mode to extract the data from the second portion of the operational mode command.

[0025] In some embodiments, the extracted data is associated with measuring a physiological condition, and the method includes measuring the physiological condition in response to extracting the data.

[0026] In some embodiments, the physiological condition comprises temperature, pulse rate, blood pressure, pH level, the presence of an analyte, or the concentration of an analyte, hi some embodiments, the physiological condition comprises the concentration of an analyte, and the analyte is oxygen or glucose.

[0027] In some embodiments, the extracted data is associated with recording an electrophysiological signal, and the implantable device comprises two or more electrodes in electrical communication with a nerve of the subject, the two or more electrodes configured to record the electrophysiological signal. In some embodiments, the method includes recording the electrophysiological signal in response to the data extracted from the second portion.

[0028] In some embodiments, the extracted data is associated with stimulating a nerve, and the implantable device comprises two or more electrodes in electrical communication with the nerve of the subject, and the method includes emitting one or more electrical pulses configured to modulate activity of the nerve using the two or more electrodes in response to the data extracted from the second portion.

[0029] In some embodiments, the method includes maintaining a current operational state of the implantable device based on operational logic defining transitions between operational states, where the implantable device is configured to operate in accordance with the current operational state, and transitioning from the current operational state of the operational logic to a next operational state based on an operational mode command, and configuring the implantable device to operate in accordance with the next operational state.

[0030] In some embodiments, the operational logic is implemented by a microprocessor or microcontroller of the implantable device, hi some embodiments, the computational logic is implemented by a finite state machine (FSM).

[0031] In some embodiments, an implantable device that operates using ultrasound comprises an ultrasound transducer configured to receive ultrasound including an operational mode command, and a controller circuit configured to set an operational mode of the implantable device from a plurality of operational modes to one operational mode based on the operational mode command.

[0032] Additionally, various system embodiments are described herein for operating an implantable device using ultrasound according to any of the method embodiments described above. [Brief description of the drawings]

[0033]

[0013] The following detailed description of the embodiments, together with the foregoing summary, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the disclosure, the drawings show exemplary embodiments of the disclosure, but the disclosure is not limited to the specific methods and instrumentalities disclosed.

[0034] [Figure 1] 1 illustrates a system for operating an implantable device using ultrasound, according to some embodiments.

[0035] [Diagram 2]1 illustrates a system including an interrogator configured to operate one or more implantable devices using ultrasound, according to some embodiments.

[0036] [Diagram 3] 13A-13C show panels illustrating portions of ultrasound emitted to operate an implantable device according to some embodiments.

[0037] [Figure 4] 1 shows a panel illustrating how an interrogator processes ultrasonic backscatter received at the interrogator, according to some embodiments.

[0038] [Figure 5A] , [Figure 5B] and [Figure 5C] 1 illustrates a panel showing ultrasound encoding operational mode commands according to some embodiments.

[0039] [Figure 6A] , and [Figure 6B] 1 illustrates a method for operating an implantable device using ultrasound, according to some embodiments.

[0040] [Figure 7] FIG. 2 shows a diagram illustrating exemplary operational logic of an implantable device according to some embodiments.

[0041] [Figure 8] 1 shows a diagram of an implantable device configured to interact with nerves of a subject, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Described herein are systems and methods for operating an implantable device within a subject using ultrasound. As discussed above, the use of ultrasound may enable an implantable device to maintain a small form factor and a greater implantable depth and operate safely. In some embodiments, to enable such an implantable device to operate wirelessly, the implantable device may be configured with an ultrasound transducer configured to receive ultrasound that includes an operational mode command. The implantable device may also include a controller circuit configured to set an operational mode of the implantable device to an operational mode from a plurality of stored operational modes based on the operational mode command.

[0043] In some embodiments, the implantable device may be configured to determine, based on a first portion of the operational mode command, whether the operational mode command corresponds to a pattern from among a plurality of predefined patterns. The implantable device may then set an operational state corresponding to the operational mode based on the determined pattern. In some embodiments, the implantable device may be configured to operate in an uplink mode from the plurality of operational modes or to operate in a downlink mode from the plurality of operational modes in response to the determined pattern.

[0044] In some embodiments, in an uplink mode, the implantable device may be configured to encode device information in the backscatter of the second part of the operational mode command. An exemplary uplink mode may include a mode for uploading sensor data (e.g., device information), such as neural activity, detected temperature, pH level, concentration of an analyte, etc. Another exemplary uplink mode may include a mode for transmitting an acknowledgement of previously received data (e.g., device information). Another exemplary uplink mode may include a mode for transmitting power information generated in the implantable device (e.g., device information).

[0045] In some embodiments, in a downlink mode, the implantable device may be configured to decode data from a second portion of the operational mode command. An exemplary downlink mode may include a mode for downloading device parameters from a received ultrasound. Another exemplary downlink mode may be a mode for selecting a next operational mode based on the decoded data.

[0046] FIG. 1 illustrates a system 100 for operating an implantable device 104 using ultrasound, according to some embodiments. In some embodiments, the implantable device 104 may be wirelessly powered and operated by ultrasound transmitted from an interrogator 102, as described further below with respect to FIG. 2. In some embodiments, the implantable device 104 may be configured to wirelessly communicate with the interrogator 102 via ultrasound communications. In some embodiments, the implantable device 104 may be configured to wirelessly communicate with one or more other implantable devices via ultrasound communications. In some embodiments, the implantable device 104 may be implanted within a subject, such as a patient, and the interrogator 102 may be external to the subject (i.e., not implanted) or may be a separate device that is fully implanted.

[0047] In some embodiments, to enable the embedded modulation device 104 to operate using ultrasound, the embedded modulation device 104 may include the following device components: an ultrasonic transducer circuit 106, a modulation / demodulation circuit 112, a stimulation circuit 114, a detection circuit 116, a controller circuit 120, and a power circuit 130. In some embodiments, one or more of these device components may be implemented as digital circuits, analog circuits, or mixed-signal integrated circuits, depending on their operation. For example, the controller circuit 120 may include a microprocessor, a finite state machine (FSM), a field programmable gate array (FPGA), or a microcontroller.

[0048] In some embodiments, the ultrasonic transducer circuit 106 includes an ultrasonic transducer 108 coupled to a matching network 110. In some embodiments, the ultrasonic transducer circuit 106 does not include a matching network 110. In some embodiments, the ultrasonic transducer 108 may be configured to receive ultrasonic waves from the interrogator 102 and convert energy from the received ultrasonic waves into an electrical signal to power one or more device components of the implantable device 104. In some embodiments, this electrical signal may be generated by the ultrasonic transducer 108 because vibrations of the ultrasonic transducer 108 caused by the received ultrasonic waves induce a voltage across electrical terminals of the ultrasonic transducer 108, causing a current to flow.

[0049] In some embodiments, as described above, power from received ultrasound waves may be used by the implantable device 104 to power its device components, and therefore these ultrasound waves may be referred to herein as powered ultrasound waves. In some embodiments, received ultrasound waves may encode information including operational mode commands for operating the implantable device, and therefore these ultrasound waves may be referred to herein as communicated ultrasound waves. In some embodiments, similar to how powered ultrasound waves may be processed, the communicated ultrasound waves may be received by the ultrasound transducer 108 to generate an electrical signal having a current flowing through the ultrasound transducer 108. In some embodiments, the generated electrical signal encodes the operational mode command in the current. In some embodiments, the same ultrasound waves may be configured to both power the implantable device 104 and encode information for transmission to the implantable device 104. In some embodiments, as further described below with respect to FIG. 3, each operational mode command may include one or more ultrasound pulses, and each ultrasound pulse may include one or more carrier cycles of ultrasound.

[0050] In some embodiments, the ultrasonic transducer circuit 106 includes multiple ultrasonic transducers coupled to multiple corresponding matching networks. According to some embodiments, by including at least two ultrasonic transducers, the implantable device 104 may be configured to be powered by electrical signals generated by the at least two ultrasonic transducers to more efficiently and consistently extract the power provided by the interrogator 102. In some embodiments, the implantable device 104 may be configured to collect power from one or more ultrasonic transducers selected from the multiple ultrasonic transducers. For example, the implantable device 104 may select the ultrasonic transducer that provides the highest power or the most consistent power.

[0051] Many factors, such as, for example, the orientation of the ultrasound transducer or intervening biological material between the ultrasound transducer 108 and the ultrasound source interrogator 102, can significantly reduce the power receivable at the ultrasound transducer 108. By adding one or more additional ultrasound transducers, the reduction in power receivable at a single ultrasound transducer (e.g., ultrasound transducer 108) may be less likely to adversely affect the operation of the implantable device 104.

[0052] In some embodiments, including at least two ultrasound transducers may allow for more reliable control of the implantable device 102 using ultrasound. For example, the implantable device 102 may be configured to compare signal strengths of the at least two ultrasound transducers and select the signal with the highest signal strength to operate the implantable device 102. In some embodiments, the implantable device 102 may use the selected ultrasound transducer to receive communications (i.e., during a downlink) and backscatter information (i.e., during an uplink). In some embodiments, the implantable device 102 may select a first ultrasound transducer from the at least two ultrasound transducers to receive ultrasound communications for downlink ultrasound communications and select a second ultrasound transducer from the at least two ultrasound transducers to backscatter information for uplink ultrasound communications. In some embodiments, the implantable device 102 may be configured to perform beamforming with the at least two ultrasound transducers to improve the signal-to-noise ratio of the uplink and downlink ultrasound communications. In some embodiments, one or more of these ultrasound transducers may be a micromachined ultrasound transducer, such as a capacitive micromachined ultrasound transducer (CMUT) or a piezoelectric micromachined ultrasound transducer (PMUT), or may be a bulk piezoelectric transducer. Further implementations of the ultrasonic transducer 108 are described below with respect to FIG.

[0053] In some embodiments, the matching network 110 may be an electronic circuit configured to select an impedance match between the electrical impedance of the ultrasonic transducer 108 and the electrical impedance of the implantable device 104 (e.g., the power circuit 130) to reduce signal reflections. In some embodiments, the matching network 110 may be implemented with various configurations of one or more circuit elements, such as inductors, capacitors, resistors, diodes, transistors, or any combination thereof. For example, the matching network 110 may be implemented as multiple capacitors connected in parallel and coupled to multiple corresponding switches. By controlling which switches are opened or closed, the matching network 110 may control how the multiple capacitors are charged to select the impedance. In some embodiments, the matching network 110 may be configured to allow the electrical signal generated by the ultrasonic transducer 108 to bypass the multiple capacitors via separate wires controlled by the switches.

[0054] In some embodiments, the power circuit 130 may include a power recovery circuit 132 electrically coupled to the conditioning circuit 138 to enable powering the implantable device 104 using ultrasound. In some embodiments, the power recovery circuit 132 may be configured to receive and process the electrical signal generated by the ultrasound transducer circuit 106. In some embodiments, the power recovery circuit 132 may include a rectifier circuit (e.g., an active rectifier) ​​for converting the electrical signal from an AC form to a DC form, where the converted electrical signal may be related to a first voltage (i.e., a supply voltage of the received ultrasound).

[0055] In some embodiments, government regulations may limit the amount of power provided by the ultrasound transmitted by the interrogator 102 (e.g., 720 mW / cm) due to health hazards in propagating high power waves through a subject's living tissue. 2). Thus, the first voltage derived from the received ultrasound may not be high enough to operate the electronic components of implantable device 104. For example, transistors used in complementary metal oxide semiconductor (CMOS) technology may require a minimum of about 2 volts to operate the transistor.

[0056] In some embodiments, the powered ultrasound may be transmitted as a pulse width modulated (PWM) signal to provide a higher first voltage to operate the electronic implantable device 102. In some embodiments, by transmitting the powered ultrasound as a PWM signal, the interrogator 102 may be configured to provide short, high intensity pulses such that the average intensity remains within regulation limits, and to provide a higher instantaneous power to generate the higher first voltage. In some embodiments, the interrogator may be configured to control the instantaneous intensity and / or pulse width of the PWM signal (e.g., example ultrasound settings) to control the power provided by the powered ultrasound.

[0057] In some embodiments, to allow the implantable device 104 to be powered by these ultrasound waves, the power conveyor circuit 134 may include a charge pump configured to convert a first voltage to a second voltage greater than the first voltage. In some embodiments, the charge pump may include a plurality of coupling capacitors controlled by one or more switches to generate the second voltage. In some embodiments, the charge pump may achieve a conversion gain of at least 1x, 2x, 3x, or 4x. In some embodiments, the magnitude of the second voltage may be controlled based on a switching frequency of one or more switches.

[0058] As discussed above, the power provided by the received ultrasound may be inconsistent due to many factors including, for example, the implantation depth of the implantable device 104 or the intervening biological material between the ultrasound transducer 108 and the ultrasound source, e.g., the interrogator 102. Thus, in some embodiments, to provide more consistent power to the implantable device 104, the power recovery circuit 132 may include an energy storage device 136 coupled to the power conveyor circuit 134. In some embodiments, the energy storage device may include a storage battery or a storage capacitor. In some embodiments, to maintain a small form factor of the implantable device 104, the energy storage device may be configured as a storage capacitor.

[0059] In some embodiments, the storage capacitor can have a capacitance that is at least 0.1 μF, at least 0.25 μF, at least 0.5 μF, at least 1 μF, at least 2 μF, at least 4 μF, or at least 8. In some embodiments, the storage capacitor can have a capacitance that is less than 10 μF, less than 8 μF, less than 4 μF, less than 2 μF, less than 1 μF, less than 0.5 μF, or less than 0.25 μF. For example, the storage capacitor may have a capacitance in the range of 0.1 to 10 μF, such as in the range of 0.5 to 2 μF. In some embodiments, the storage capacitor can have a capacitance that is about 1 μF.

[0060] In some embodiments, the energy storage device 136 can be configured to operate in at least two power modes to allow the implantable device 104 to more efficiently utilize the power of the received ultrasound and provide more consistent power. In some embodiments, the power modes include a charge mode in which a portion of the power of the received ultrasound can be conveyed to the energy storage device 136, which is capable of storing energy. In some embodiments, the power conveyor circuit 134 can be configured to charge the energy storage device 136 based on the generated first voltage. In some embodiments, the power modes include a discharge mode in which a portion of the energy stored in the energy storage device 136 is discharged to convey power from the energy storage device 136 to provide additional power to other device components of the implantable device 104 (e.g., the stimulation circuit 114, the detection circuit 116, or the controller circuit 120, etc.). In some embodiments, the power flow to and from the energy storage device 136 can be run via the power conveyor circuit 134.

[0061] In some embodiments, the conditioning circuit 138 can be configured to adjust the output voltage (e.g., the second voltage) generated by the power conveyor circuit 134 and supply the adjusted voltage to one or more circuit loads of the implantable device 104. In some embodiments in which the power conveyor circuit 134 includes a charge pump, the conditioning circuit 138 can be configured to remove or reduce potential voltage ripple caused by an operating switch of the charge pump. In some embodiments, the conditioning circuit 138 includes a DC voltage regulator (e.g., a low dropout (LDO) regulator) to adjust the voltage supplied to the digital circuit loads of the implantable device 104. In some embodiments, the conditioning circuit 138 includes a DC voltage regulator (e.g., a low dropout (LDO) regulator) to adjust the voltage supplied to the digital circuit loads of the implantable device 104. In some embodiments, the conditioning circuit 138 includes an AC voltage regulator (e.g., a low dropout (LDO) regulator) to adjust the voltage supplied to the analog circuit loads of the implantable device 104.

[0062] In some embodiments, the modulation and demodulation circuitry 112 can include demodulation circuitry configured to demodulate electrical signals generated by the ultrasound transducer circuitry 106 to extract information encoded in the received ultrasound. In some embodiments, the demodulation circuitry can transmit the extracted information, including instructions, to a controller circuitry 120 configured to control how the implantable device 104 operates based on the instructions.

[0063] In some embodiments, the modulation and demodulation circuitry 112 may include modulation circuitry configured to encode information using ultrasonic backscatter to enable the implantable device 104 to wirelessly communicate information with the interrogator 102. This information is generated by the implantable device 104 and, for ease of explanation, may be referred to as device information in the following description.

[0064] Generally, when the implantable device 104 is implanted within a subject, ultrasound waves (including a carrier wave) emitted by the ultrasound transceiver of the interrogator 102 pass through biological tissue before being received by the ultrasound transducer circuitry 106 of the implantable device 104. As described above, the carrier wave induces mechanical vibrations on the ultrasound transducer 108 (e.g., a bulk piezoelectric transducer) to generate a voltage across the ultrasound transducer 108, which then drives a current through the remainder of the implantable device 104. In some embodiments, the current through the ultrasound transducer 108 causes the ultrasound transducer circuitry 106 to emit backscattered ultrasound waves that correspond to the received ultrasound waves.

[0065] In some embodiments, the modulation circuitry can be configured to modulate the current through the ultrasonic transducer 108 to encode device information, thereby causing the resulting ultrasonic backscattered waves to also encode device information. Thus, ultrasonic backscatter emitted from the implantable device 104 can encode device information associated with the implantable device 104. In some embodiments, the modulation circuitry can include one or more switches, such as an on / off switch or a field effect transistor (FET). An exemplary FET that may be used with some embodiments of the implantable device 104 includes a metal oxide semiconductor field effect transistor (MOSFET). In some embodiments, the modulation circuitry can be configured to change the impedance of the current through the ultrasonic transducer 108, such that variations in the current flow encode information.

[0066] 2, according to some embodiments, the ultrasonic backscatter may be received by an interrogator 102 and decoded to extract device information encoded in the ultrasonic backscatter. In some embodiments, the ultrasonic backscatter may be received by an interrogator that may be the same or different from the interrogator 102 that transmitted the ultrasonic waves received by the ultrasonic transducer 108.

[0067] In some embodiments, the detection circuit 116 can be configured to interface with one or more sensors 140A-C to measure or detect one or more physiological conditions of the subject. In some embodiments, the detection circuit 116 can include a driver configured to provide current to the one or more sensors 140A-C and receive signals generated from the one or more sensors 140A-C. In some embodiments, the received signals can include information representative of the detected physiological condition or the measured physiological condition. In some embodiments, the detection circuit 116 can be configured to transmit this information to the controller circuit 120.

[0068] In some embodiments, one or more of sensors 140A-C may be located inside implantable device 104 or may be coupled to the exterior of implantable device 104. In some embodiments, implantable device 104 includes at least two sensors 140A-C In. In some embodiments, the one or more physiological conditions may include temperature, pH, pressure, heart rate, strain, oxygen pressure, the presence of an analyte, or an amount of an analyte. For example, the analyte may be oxygen or glucose.

[0069] In some embodiments, the sensors 140A-C may include an optical sensor. In some embodiments, the optical sensor comprises a light source and a light detector. In some embodiments, the optical sensor detects blood pressure or pulse. In some embodiments, the optical sensor comprises a substrate comprising a fluorophore or luminescent probe, where the fluorescence intensity or fluorescence lifetime of the fluorophore is dependent on the amount of analyte. In some embodiments, the optical sensor is configured to perform near infrared spectroscopy. In some embodiments, the optical sensor detects glucose.

[0070] In some embodiments, sensors 140A-C may include potentiometric or amperometric chemical sensors, hi some embodiments, the sensors detect oxygen, pH, or glucose.

[0071] In some embodiments, the sensors 140A-C may include a temperature sensor, hi some embodiments, the temperature sensor is a thermistor, a thermocouple, or a proportional to absolute temperature (PTAT) circuit.

[0072] In some embodiments, the sensors 140A-C may include a pressure sensor. In some embodiments, the pressure sensor is a micro-electro-mechanical system (MEMS) sensor. In some embodiments, the detection circuit 116 is configured to measure blood pressure or pulse.

[0073] In some embodiments, the sensors 140A-C may include strain sensors.

[0074] In some embodiments, the detection circuit 116 can be configured to interface with, for example, the sensor 140C to detect electrophysiological signals from the nerve or a targeted subset of nerve fibers within the nerve, as described further below with respect to FIG. 8. In some embodiments, the sensor 140C can include electrode pads, which may be the same or different from the electrode pads 142 operated by the stimulation circuit 114. In some embodiments, the detection circuit 116 can be configured to record neural activity of the nerve or the targeted subset of nerve fibers based on the detected electrophysiological signals.

[0075] In some embodiments, one or more techniques such as computational modeling (e.g., finite element models), inverse source estimation, multipolar (e.g., tripolar) neural recording, velocity selective recording, or beamforming may be implemented by the detection circuit 116 (alone or in conjunction with the controller circuit 120) to selectively target a subset of nerve fibers. See, for example, Taylor et al., Multiple-electrode nerve cuffs for low-velocity and velocity selective neural recording, Medical & Biological Engineering & Computing, vol42, pp. 634643 (2004) and Wodlinger et al., Localization and Recovery of Peripheral Neural Sources with Beamforming Algorithms, IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol.17, no. 5, pp. 461-468 (2009).

[0076] In some embodiments, the detection circuit 116 can be configured to operate multiple electrodes of the sensor 140C for targeted detection of electrophysiological signals. For example, the sensor 140C can be a curved member extending from the implantable device 104, as described further below with respect to FIG. 8. In some embodiments, the detection circuit 116 can analyze the electrophysiological signals detected by all or a subset of the electrode pads to determine a subset of nerve fibers in the nerve that are transmitting the electrophysiological signal. A nerve may transmit a composite electrophysiological signal (or compound action potential) that is the sum of electrophysiological signals (or action potentials) transmitted simultaneously by two or more different subsets of nerve fibers. The detection circuit may be capable of determining which subset of nerve fibers transmit which electrophysiological signal based on the electrophysiological signals detected by the multiple electrode pads. In some embodiments, data received from the interrogator 102 (such as body temperature data, or data related to analyte concentration or other physiological condition) is further used to determine which subset of nerve fibers transmit the electrophysiological signal.

[0077] For example, in some embodiments, the detection circuitry 116 may be configured to selectively detect electrophysiological signals from a targeted subset of nerve fibers using rate-selective recording, which may be combined with multipolar (e.g., tripolar) recording (which may include any number of tripolar electrodes within multiple electrodes on one or more curved members).

[0078] Beamforming may additionally or alternatively be used to detect electrophysiological signals from a targeted subset of nerve fibers. Some or all of the electrode pads of the one or more curved members may detect electrophysiological signals from the nerve, and the detection circuitry 116 may determine a cross-sectional location of the conduction signal within the nerve based on the difference in the electrophysiological signals detected by some or all of the electrode pads of the one or more curved members.

[0079] In some embodiments, stimulation of one or more nerves at a location separate from the location of the implantable device 104 can result in modulation of electrophysiological signals at the location of the implantable device 104. Modulation of electrophysiological signals detected at different subsets of nerve fibers in a nerve in electrical communication with an electrode pad (e.g., electrode pad 142) of the implantable device 104 can be the result of stimulation at a different remote nerve. For example, stimulation of the splenic nerve can result in modulation of electrophysiological signals detected from a first subset of nerve fibers in the vagus nerve, and stimulation of the renal nerve can result in modulation of electrophysiological signals detected from a second subset of nerve fibers in the vagus nerve. Thus, an implantable device positioned on the vagus nerve can detect electrophysiological signals from a first subset of nerve fibers to monitor stimulation of the splenic nerve and a second subset of nerve fibers to monitor stimulation of the renal nerve.

[0080] In some embodiments, the stimulation circuit 114 can be configured to emit targeted electrical pulses to a subset of nerve fibers in the nerve by selectively activating one or more electrode pads 142 connected to the subset of nerve fibers. In some embodiments, the implantable device 104 can include one or more curved members that electrically connect the stimulation circuit 114 to the electrode pads 142, as further described below with respect to FIG.

[0081] In some embodiments, the stimulation circuit 114 may be controlled by the controller circuit 120 to operate or selectively activate the electrode pads 142. Selective activation may include, for example, activating a portion of the electrode pads in the plurality of electrode pads 142 of one or more curved members and / or differentially activating all or a portion of the electrode pads in the plurality of electrode pads 142 of one or more curved members. The plurality of electrodes may thus be operated to direct an electrical pulse emitted by the plurality of electrode pads 142 to a targeted subset of nerve fibers. According to some embodiments, techniques such as electric field disturbance and / or multipolar stimulation (e.g., tripolar stimulation) may be used to target an electrical pulse to a subset of nerve fibers in a nerve. See, for example, Grossman et al., Noninvasive Deep Brain Stimulation via Temporally Interfering Electrical Fields, Cell, vol169, pp. 1029-1041 (2017). Electrode pads 142 in one or more of the curved members can be selectively activated by the controller circuit 120 to target emitted electrical pulses to subsets of nerve fibers.

[0082] The subset of nerve fibers targeted by the emitted electrical pulses may be the same as or different from the subset of nerve fibers for which electrophysiological signals are detected by detection circuit 116. The one or more curved members configured to emit the targeted electrical pulses may be the same as or different from the one or more curved members on implantable device 104 configured to detect the electrophysiological signals. The emitted targeted electrical pulses may stimulate nerves at the location of implantable device 104.

[0083] The subset of nerve fibers targeted by the electrical pulses can be the same or a different subset of nerve fibers from which electrophysiological signals are selectively detected. The subset of nerve fibers targeted by the electrical pulses emitted by the implantable device 104 can be, for example, one or more (e.g., 2, 3, 4, or more) fiber bundles in the nerve, or a portion of one or more (e.g., 2, 3, 4, or more) fiber bundles. In some embodiments, the subset of nerve fibers comprises or consists of the afferent nerve fibers in the nerve, or a subset of the afferent nerve fibers in the nerve. In some embodiments, the subset of nerve fibers comprises or consists of the efferent nerve fibers in the nerve, or a subset of the efferent nerve fibers in the nerve. In some embodiments, the subset of nerve fibers comprises or consists of the efferent nerve fibers in two or more fiber bundles in the nerve, or the afferent nerve fibers in two or more bundles in the nerve.

[0084] Targeted stimulation of a subset of nerve fibers by releasing a targeted electrical pulse to the subset of nerve fibers may result in stimulation of a nerve at a location remote from the nerve location. The remote nerve stimulated by the implantable device 104 depends on the subset of nerves at the location of the implantable device 104 that are targeted by the electrical pulse released by the device. In some embodiments, the implantable device 104 is configured to be placed at a first nerve location and stimulate a second nerve location by releasing a targeted electrical pulse to a subset of nerve fibers in the first nerve location associated with the second nerve location. In some embodiments, the first nerve location and the second nerve location are separated by one or more nerve branch points or one or more synapses. In some embodiments, the second nerve location is proximal to the brain relative to the first nerve location, and in some embodiments, the second nerve location is distal to the brain relative to the first nerve location. In some embodiments, the targeted subset of nerve fibers comprises or consists of afferent nerve fibers. In some embodiments, the targeted subset of nerve fibers comprises or consists of efferent nerve fibers.

[0085] In some embodiments, the controller circuit 120 includes a command processor 122, a power monitor 124, a mode detector 126, and a memory 150. In some embodiments, the memory 150 includes a non-transitory storage memory, such as a register memory, a processor cache memory, or a random access memory. In some embodiments, the controller circuit 120 may be a digital circuit, an analog circuit, or a mixed-signal integrated circuit. Examples of the controller circuit 120 may include a microprocessor, a finite state machine (FSM), a field programmable gate array (FPGA), and a microcontroller.

[0086] In some embodiments, the mode detector 126 can be configured to determine an operational mode command from ultrasonic waves received by the ultrasonic transducer 108. In some embodiments, the mode detector 126 can determine the operational mode command by determining a correspondence to a pattern from among a plurality of predefined patterns 156 stored in the memory 150. For example, the pattern can be a sequence of one or more pulses having a particular ultrasonic characteristic, such as ultrasonic pulse duration. In this example, the mode detector 126 can match a portion of the operational mode command with one or more predefined patterns 156 to determine a matching pattern. In another example, the pattern can correspond to an ultrasonic characteristic, such as pulse duration, amplitude, or phase or frequency change. In this example, the mode detector 126 can analyze an ultrasonic characteristic (e.g., pulse duration) of the portion to determine correspondence to the pattern. In some embodiments, the portion of the operational mode command can be a single pulse indicating the start of the operational mode command. In other embodiments, the portion can be a sequence of ultrasonic pulses. In some embodiments, the controller circuit 120 can be configured to perform methods 600A-B of FIGS. 6A-B, respectively, to determine the operational mode command, as described further below.

[0087] In some embodiments, the mode detector 126 can receive the ultrasound as an electrical signal generated (e.g., demodulated) by the modulation and demodulation circuit 112 based on the ultrasound received at the ultrasonic transducer circuit 106. In some embodiments, the mode detector 126 can include one or more detection circuits configured to detect one or more ultrasonic characteristics from the electrical signal. In some embodiments, one of these detection circuits can include a zero-crossing circuit configured to determine a pulse duration of each ultrasonic pulse in the operational mode command. For example, the zero-crossing circuit can be configured to count and store the number of instances where a first portion of the electrical signal exceeds a predetermined voltage level within a predetermined number of clock cycles to determine the pulse duration. In some embodiments, the predetermined voltage level is a voltage close to 0V (e.g., less than 10mV, less than 50mV, less than 100mV, or less than 200mV).

[0088] In some embodiments, command processor 122 may be configured to set the operational mode of implantable device 104 to one of a plurality of predefined operational modes 152 based on the operational mode command determined by mode detector 126, as described further below with respect to FIGS. 6A-B. In some embodiments, command processor 122 may store the received operational mode command and associated instructions in memory 150, such as an instruction register. In some embodiments, command processor 122 may be configured to control implantable device 104 to enter an operational state corresponding to the operational mode based on the stored operational mode command. For example, command processor 122 may be embedded as an FSM or program within a microcontroller that controls the operational state of implantable device 104 based on a current operational state and one or more detected inputs, such as one or more received operational mode commands, one or more sensor values, or a combination thereof.

[0089] In some embodiments, the command processor 122 can be configured to extract information from a portion of the operational mode command to configure various parameters or to select an operational mode. Information encoded in the ultrasound emitted by the interrogator and received by the closed-loop implantable device can include, for example, an instruction to start or stop neuromodulation, one or more calibration instructions, one or more updates to the operational software, and / or one or more templates (such as a template electrophysiological signal, one or more template electrophysiological signals, and / or one or more template stimulation signals). In some embodiments, the command processor 122 can be configured to process and store the received instructions in the memory 150. In some embodiments, the command processor 122 can enter an operational mode from among a plurality of operational modes based on one or more received operational mode commands, as further described below with respect to FIGS. 6A-B. In some embodiments, the plurality of operational modes can include, for example, a mode for stimulating a nerve, a mode for recording neural activity, or a mode for determining one or more physiological conditions, as further described below with respect to FIGS. 7-8. For example, if the operational mode command indicates that the implantable device 104 should enter a neural stimulation mode, the controller circuit 120 may be configured to control the stimulation circuit 114 to stimulate a particular nerve fiber or portion of that nerve.

[0090] In some embodiments, when command processor 122 controls implantable device 104 to enter a neural activity recording mode or a mode for determining one or more physiological conditions, command processor 122 may control detection circuit 116 to retrieve device information (e.g., neural recording or a detected / measured physiological condition). In some embodiments, command processor 122 may be configured to retrieve a command 154 associated with a current operational mode 152 to control operation of implantable device 104. For example, in a neural activity recording mode, command processor 122 may retrieve a command 154 corresponding to the neural activity recording mode and issue the command 154 to control detection circuit 116 to sample neural activity of a nerve (e.g., an example of device information). In some embodiments, as described above, upon retrieving the device information, command processor 122 may be configured to control modulation and demodulation circuit 112 based on command 154 to encode the device information in ultrasound backscatter.

[0091] In some embodiments, to provide power control and calibration for the implantable device 104, the power monitor 124 can be configured to monitor the available power and power consumption of the implantable device 104. In some embodiments, this available power can include a supply of power provided by ultrasound received at the ultrasound transducer 108 and can include accessible power stored in the implantable device 104. For example, this accessible power can include power accessible from an energy storage device 136 that stores excess energy. In some embodiments, the power monitor 124 can determine the power consumption based on an output voltage generated by the power conveyor circuit 134.

[0092] In some embodiments, when the command processor 122 controls the implantable device to enter the power calibration mode, the command processor 122 can be configured to generate information indicating whether more or less power should be transmitted to the implantable device 104 based on the available power and power consumption monitored by the power monitor 124. For example, the command processor 122 can retrieve a command 154 corresponding to an operating mode 152 (e.g., a power calibration mode) that is sent to the power monitor 124 and other components, such as the modulation and demodulation circuitry 112, to generate and transmit power information. In some embodiments, the controller circuitry 120 can be configured to control the modulation and demodulation circuitry 112 according to the command 154 to encode the generated information in the ultrasound backscatter.

[0093] 2 illustrates a system 200 including an interrogator 202 configured to operate one or more implantable devices 240 using ultrasound, according to some embodiments. In some embodiments, the interrogator 202 may be an example of the interrogator 102 as described above with respect to FIG.

[0094] In some embodiments, the interrogator 202 includes a power source 203, a computation circuit 210, a signal generation circuit 220, and an ultrasonic transducer circuit 204. As shown, the power source 203 can be configured to provide power to the computation circuit 210 and the signal generation circuit 220. In some embodiments, the power source 203 can provide 1.8V, although any suitable voltage can be used. For example, the power source 203 can include one or more batteries to provide the 1.8V.

[0095] In some embodiments, the signal generation circuit 220 includes a charge pump 222 configured to power one or more channels 224. In some embodiments, the charge pump 222 can be configured to increase the voltage provided by the power supply 203. For example, the charge pump 222 may increase the 1.8V supplied by the power supply 203 to 32V.

[0096] In some embodiments, each channel 224 is coupled to and controls the operation of a corresponding ultrasonic transducer 208 of the transducer circuitry 204. In some embodiments, the ultrasonic transducer 208 connected to a channel 224 may be configured to only receive ultrasonic waves or only transmit ultrasonic waves, in which case the switch 229 may optionally be omitted from the channel 224. In some embodiments, each channel 224 may include subsequent electronic components: a delay control 226, a level shifter 228, and a switch 229.

[0097] In some embodiments, the delay control 226 can be configured to control the ultrasonic waveform and / or signal transmitted by the ultrasonic transducer 208. In some embodiments, the delay control 226 can control, for example, the phase shift, time delay, pulse frequency, waveform (including amplitude and wavelength), or combinations thereof, based on commands from the controller circuit 212 to generate the transmit waveform. In some embodiments, data representing the waveform and frequency of each channel can be stored in the delay control 226 or in a "wave table" stored in the memory 216. This may allow the transmit waveform of each channel 224 to be different.

[0098] In some embodiments, the delay control 226 may be connected to a level shifter 228 configured to shift the input pulse from the delay control 226 to a higher voltage used by the ultrasonic transducer 208 to transmit ultrasonic waves. In some embodiments, the delay control 226 and the level shifter 228 may be configured to be used to bleed data out into the actual transmit signal to the transducer array 206. In some embodiments, the transmit waveform for each channel 224 may be generated directly by a high speed serial output of a microcontroller or other digital system and sent to the transducer elements (e.g., ultrasonic transducers 208) via the level shifter 228 or high voltage amplifiers.

[0099] In some embodiments, the switch 229 of the channel 224 can configure the corresponding ultrasound transducer 208 to receive ultrasound waves, such as ultrasound backscatter. In some embodiments, the received ultrasound waves are converted to electrical current by the ultrasound transducer 208 (set in receive mode) and transmitted to a data processor 211 for processing data captured with the received ultrasound. Some embodiments may include an amplifier, an analog-to-digital converter (ADC), a variable gain amplifier, or a time-gain controlled variable gain amplifier to compensate for tissue loss, and / or a bandpass filter to process the received ultrasound.

[0100] In some embodiments, the aforementioned channels 224 do not include a T / Rx switch 229, but instead include separate Tx (transmit) and Rx (receive) with a high voltage Rx (receiver circuit) in the form of a low noise amplifier with good saturation recovery. In some embodiments, the T / Rx circuit includes a circulator. In some embodiments, the transducer array 206 includes more transducer elements (e.g., ultrasonic transducers 208) than the processing channels 224, and the interrogator 202 can be configured to include a multiplexer to select a different setting of transmit elements for each pulse. For example, 64 transmit / receive channels can be connected to 192 physical transducer elements via a 3:1 multiplexer, with only 64 transducer elements being active on a given pulse.

[0101] In some embodiments, the computation circuitry 210 may be a digital circuit, an analog circuit, or a mixed-signal integrated circuit. Examples of the computation circuitry 210 may include a microprocessor, a finite state machine (FSM), a field programmable gate array (FPGA), and a microcontroller. In some embodiments, the interrogator 202 may include non-volatile memory that may be accessed by the computation circuitry 210.

[0102] In some embodiments, the computation circuit 210 includes a controller circuit 212, a data processor 211, and a user interface 213. In some embodiments, the controller circuit 212 includes a command generator 214 and a memory 216 that stores ultrasound settings 218.

[0103] In some embodiments, command generator 214 may be configured to generate instructions for controlling operation of delay control 226 to send one or more operational mode commands to one or more implantable devices 240 to operate one or more implantable devices 240. In some embodiments, as described further below with respect to FIGURE 6B, the operational mode commands may instruct an implantable device receiving the operational mode command (e.g., implantable device 242) to upload certain device data or download data encoded in the operational mode command. Examples of such operational mode commands and their waveform formats are described further below with respect to FIGURES 5A-C.

[0104] In some embodiments, the device data received and processed by the data processor 211 may include power information. In these embodiments, the command generator 214 may be configured to set or select an ultrasound setting to control the output power of the transmitted ultrasound, for example, based on the device information received from the implantable device 242. For example, the received device information may indicate that more power should be transmitted to the implantable device 242. In this example, the command generator 214 may select an ultrasound setting 218, such as a higher pulse width or higher instantaneous intensity of the waveform, to increase the power of the ultrasound transmitted by the ultrasound transducer circuitry 204.

[0105] In some embodiments, the transducer circuit 204 includes one or more ultrasound transducers 208 configured to transmit ultrasound waves to an implantable device 240, such as implantable device 242. In some embodiments, as shown in Figure 2, the transducer circuit 204 includes a transducer array 206 having a plurality of ultrasound transducers 208. In some embodiments, the transducer array 206 includes 1 or more, 2 or more, 3 or more, 5 or more, 7 or more, 10 or more, 15 or more, 20 or more, 25 or more, 50 or more, 100 or more, 250 or more, 500 or more, 1000 or more, 2500 or more, 5000 or more, or 10000 or more ultrasound transducers. In some embodiments, the transducer array 206 includes 100,000 or less, 50,000 or less, 25,000 or less, 10,000 or less, 5000 or less, 2500 or less, 1000 or less, 500 or less, 200 or less, 150 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 7 or less, or 5 or less ultrasonic transducers. The transducer array 206 may be a chip with, for example, 50 or more ultrasonic transducer pixels.

[0106] 2, the transducer circuit 204 includes a single transducer array 206, however, according to some embodiments, the transducer circuit 204 may include one or more, two or more, or three or more separate transducer arrays. In some embodiments, the transducer circuit 204 includes ten or fewer transducer arrays (such as nine, eight, seven, six, five, four, three, two, or one transducer arrays). In some embodiments, the separate transducer arrays may be located at different points on the subject and may communicate with the same or different implantable devices 240. In some embodiments, the transducer arrays may be located on opposite sides of an implantable device, such as implantable device 242.

[0107] In some embodiments, the specific design of the transducer array 206 of the interrogator 202 depends on the desired penetration depth, aperture size, and size of the individual ultrasonic transducers 208 in the transducer array 206. The Rayleigh distance R of the transducer array 206 is calculated as follows:

number

[0108] Individual ultrasonic transducers 208 in the transducer array 206 can be adjusted to control the Rayleigh distance and the position of the beam of ultrasound emitted by the transducer array 206 through a process of beamforming or beamsteering. Techniques such as linearly constrained minimum variance (LCMV) beamforming can be used to communicate multiple implantable devices 240 (e.g., implantable device 242) with an external ultrasound transceiver. See, for example, Bertrand et al., Beamforming Approaches for Untethered, Ultrasonic Neural Dust Motes for Cortical Recording (a Simulation Study, IEEE EMBC, August 2014). In some embodiments, beamsteering is performed by adjusting the power or phase of the ultrasound emitted by the ultrasonic transducers 208 in the transducer array 206.

[0109] In some embodiments, the interrogator 202 (e.g., the computational circuitry 210) includes one or more of instructions for beam steering ultrasound using one or more ultrasound transducers 208, instructions for determining the relative position of one or more implantable devices 240, instructions for monitoring the relative movement of one or more implantable devices 240, instructions for recording the relative movement of one or more implantable devices 240, and instructions for deconvolving backscatter from multiple implantable devices 240.

[0110] In some embodiments, user interface 213 may be configured to allow a user (e.g., a physician or patient) to control the operation of interrogator 202 and to power or communicate with implantable device 240. In some embodiments, user interface 213 may include input devices for providing input to interrogator 202, such as a touch screen or monitor, a keyboard, a mouse, or a voice recognition device. In some embodiments, user interface 213 may include output devices, such as a touch screen, a monitor, a printer, a disk drive, or any suitable device for providing output, such as a speaker.

[0111] In some embodiments, the interrogator 202 may be controlled using a separate computer system (not shown), such as a mobile device (e.g., a smartphone or tablet). The computer system may wirelessly communicate with the interrogator 202, for example, via a network connection, a radio frequency (RF) connection, or Bluetooth. The computer system may, for example, turn the interrogator 202 on or off, or analyze information encoded in ultrasound waves received by the interrogator 202.

[0112] In some embodiments, the interrogator 202 communicates with multiple implantable devices 240. This can be done, for example, using multiple-input multiple-output (MIMO) system theory. For example, communication between the interrogator 202 and the multiple implantable devices 240 may be performed using time division multiplexing, spatial multiplexing, or frequency multiplexing. The interrogator 202 can receive combined ultrasound backscatter from the multiple implantable devices 240 that can be deconvoluted, thereby extracting information from each implantable device 242. In some embodiments, the interrogator 202 can be configured to focus transmitted ultrasound from the transducer array 206 to a particular implantable device via beam steering. For example, the interrogator 202 can focus transmitted ultrasound on a first implantable device (e.g., implantable device 242) and receive backscatter from the first implantable device, and focus transmitted ultrasound on a second implantable device and receive backscatter from the second implantable device. In some embodiments, the interrogator 202 transmits ultrasound to multiple implantable devices 240 and then receives ultrasound backscatter from multiple implantable devices 240 .

[0113] In some embodiments, the interrogator 202 or one or more ultrasonic transducers 208 are wearable. For example, the interrogator 202 or one or more ultrasonic transducers 208 may be secured to the subject's body by ties or adhesive. In another example, the interrogator 202 may be a wand and may be held by a user (such as a medical professional). In some embodiments, the interrogator 202 may be held to the body via sutures, simple surface tension, a clothing-based fastening device such as a fabric wrap, sleeve, elastic band, or by subcutaneous fastening. In some embodiments, the one or more ultrasonic transducers 208 or transducer array 206 of the interrogator 202 may be located separately from the remainder of the interrogator 202. For example, the transducer array 206 may be secured to the skin of the subject at a first location (e.g., proximal to one or more implanted devices) and the remainder of the interrogator 202 may be positioned at a second location having a wire-tethered ultrasound transducer 208 or transducer array 206 to the remainder of the interrogator 202.

[0114] Figures 3A-C are diagrams showing panels 3A-C illustrating portions of emitted ultrasound for operating an implantable device, according to some embodiments. For example, the ultrasound shown in panels 3A-C may be emitted by interrogator 102 of Figure 1 or interrogator 202 of Figure 2. In some embodiments, the emitted ultrasound may be configured to be emitted by one or more other implantable devices.

[0115] Panel 3A shows that the emitted ultrasound includes a sequence of ultrasound commands, such as ultrasound commands 302A and 302B. In some embodiments, each of the ultrasound commands may include one or more pulses of ultrasound (i.e., also known as ultrasound pulses). For example, panel 3B shows a zoomed-in view of ultrasound command 302B, which may include a sequence of six ultrasound pulses (e.g., pulses 304A-B). For illustrative purposes only, the amplitude (i.e., pressure amplitude) and pulse width (i.e., also referred to as pulse length or pulse duration) of each pulse in ultrasound command 302B are shown as being the same, although this may not be the case. In some embodiments, the amplitude or pulse width of each ultrasound pulse may be dictated by the ultrasound protocol implemented by the interrogator. Thus, the amplitude and pulse width of the pulses may differ. In some embodiments, each of the ultrasound pulses may include one or more carrier cycles (i.e., also known as oscillations or oscillation cycles). As used in this disclosure, a carrier cycle may correspond to a single oscillation of ultrasound. For example, panel 3C shows a zoomed-in view of ultrasonic pulse 304A, which includes five carrier cycles (eg, ultrasonic periods 306A-B) that make up pulse duration 308 of ultrasonic wave 304A.

[0116] 4 shows panels 4A-E illustrating how an interrogator processes ultrasound backscatter received at the interrogator, according to some embodiments. In some embodiments, an implantable device (e.g., implantable device 104 of FIG. 1) can be configured to emit ultrasound backscatter, as shown in panel 4A, in response to receiving ultrasound as described above with respect to panel 3A of FIG.

[0117] Panel 4A illustrates ultrasound backscatter received from the implantable device. In some embodiments, the ultrasound backscatter can correspond to backscatter of ultrasound transmitted to the implantable device, as shown in Panel 3A of FIG. 3. As shown in Panel 4A, the ultrasound backscatter can include backscatter portions 402A-B, which correspond to backscatter of the operational mode command portion of the transmitted ultrasound in Panel 3A. In some embodiments, at the end of a transmit cycle, the interrogator can be configured to control a switch (e.g., switch 229) to disconnect the transmit module and connect the receive module to receive the ultrasound backscatter.

[0118] Panel 4B shows a close-up view of the backscatter of a single ultrasound pulse 404, which can be analyzed to extract data encoded in the backscatter 404. For example, as shown in Panel 4C, the ultrasound backscatter 404 can be filtered. As shown in Panel 4C, the filtered backscatter can include four distinct regions 406A-D corresponding to reflections arising from mechanical boundaries, where region 406A corresponds to reflections from the biocompatible material encapsulating the implantable device, region 406B corresponds to reflections from the top surface of the miniaturized ultrasound transducer, (3) region 406C corresponds to reflections from the boundary between the printed circuit board and the miniaturized ultrasound transducer, and region 406D corresponds to reflections from the back surface of the printed circuit board of the implantable device. The amplitude of the backscattered wave reflected from the surface of the miniaturized transducer changes as a function of the change in impedance of the current returning to the miniaturized ultrasound transducer, and this region of backscatter can be referred to as "responsive backscatter" since it encodes information generated in the implantable device. For example, Panel 4C shows the difference in amplitude of the filtered backscatter depending on whether the implantable device is in an operational mode for stimulating a nerve. Further analysis of the filtered backscatter may include rectifying the ultrasound backscatter, as shown in Panel 4D, and integrating the rectified signal to decode the data, as shown in Panel 4E.

[0119] 5A-C show panels showing ultrasound encoding operational mode commands according to some embodiments.

[0120] In ultrasound communication, time of flight (TOF) refers to the two-way travel time between the interrogator transmitting the ultrasound and the implantable device receiving the ultrasound. This time of flight may depend on the distance of the interrogator relative to the implantable device. In some embodiments, the time of flight may constrain how the operational mode command is generated since the data uplink is made possible by encoding information in the backscatter of the ultrasound. Thus, if the interrogator transmits a carrier while a previously transmitted ultrasound is being backscattered, there may be crosstalk between the transmitted carrier and the ultrasound backscatter.

[0121] 5A illustrates panels 502-506 illustrating the timing requirements and data structure of operational mode commands associated with a data uplink, according to some embodiments. Panel 502 illustrates an example ultrasound envelope for an operational mode command 502A transmitted by an ultrasound interrogator (e.g., interrogator 102 or interrogator 202). The operational mode command 502A includes a time envelope for the entire time or duration of the T cmd T sync_up The first portion 502B has a pulse duration of T up A second portion 502C having a duration of T power a third portion 502D having a duration of T D The fourth portion 502E may include a fourth portion 502E having a duration of

[0122] The first portion 502B may include a first pulse of the operational mode command 502A, allowing a mode detector of the implantable device to determine the type of operational mode command. In some embodiments, the mode detector may determine that the operational mode command 502A is associated with an uplink by determining that the pulse duration of the first portion 502B is greater than or equal to T sync_upThe uplink pattern may be associated with a carrier frequency of the received ultrasound. For example, sync_up may be a multiple of the carrier frequency.

[0123] In some embodiments, the pulse duration of the first portion 502B may be used to distinguish between the operating mode commands 502A, allowing the implantable device to operate in multiple operating modes, as well as be powered using ultrasound as an adjustable PWM signal. As discussed above with respect to FIG. 1, transmitting ultrasound as a PWM signal may allow the implantable device to be fully powered using ultrasound while controlling the average intensity of the ultrasound to stay within government regulations. However, the use of a PWM signal with a varying pulse width would defeat traditional communication protocol approaches that use a defined timing structure. This is in part because the absence or presence of a carrier wave at a particular time interval does not necessarily indicate any instruction or command, since the pulse width of the PWM signal may be dynamically adjusted based on the power needs of the implantable device. As discussed above, the use of the first portion 502B addresses problems that would be encountered using traditional approaches for communication protocols.

[0124] The second portion 502C may include a communication ultrasound that allows the implantable device to upload device data. u The duration of p corresponds to the time at which the implantable device must modulate the carrier to upload device data. power The third portion 502D corresponds to ultrasound waves that may be used by the implantable device 104 to power various components, such as the power conveyor circuit 134 or the energy storage device 136. Finally, the fourth portion 502E corresponds to ultrasound waves that do not transmit a carrier wave. DDuring the fourth portion 502E, the interrogator can be configured to enter a receive mode to allow reception of ultrasonic backscatter. In some embodiments, the combined duration of the second and third portions 502C-D is configured to stay within the time of flight so that crosstalk does not occur. In some embodiments, this dead time is at least T up , but may be longer depending on how much power needs to be provided by the third portion 502D.

[0125] As described above, the mode detector can be configured to analyze the duration of the third portion to determine whether ultrasound is associated with a power transmission. In some embodiments, the uplink pattern (e.g., T sync_up ) and the downlink pattern (e.g., T sync_down ) can be shown to extract power from the ultrasound.

[0126] Panel 504 illustrates the ultrasound envelope for operational mode command 502A received at the implantable device. As shown, the implantable device can receive operational mode command 502A as operational mode command 504A a period (i.e., half a TOF) after operational mode command 502A was transmitted. Received operational mode command 504A includes portions 504B-E that correspond to portions 502B-E of operational mode command 502A, as described above. Panel 506 illustrates ultrasound backscatter of a second portion 504C received at the interrogator. As shown, the ultrasound backscatter is measured using a time period of 100 ms (T100 ms) for which the interrogator is receiving the ultrasound backscatter. up and needs to be received during the dead time of the fourth portion 502E to ensure that no crosstalk occurs so that the interrogator can successfully extract data from the ultrasonic backscatter.

[0127] 5B illustrates panels 508-512 illustrating the timing requirements and data structure of operational mode commands associated with a data uplink, according to some embodiments. Panel 508 illustrates an example ultrasound envelope for an operational mode command 508A transmitted by an ultrasound interrogator (e.g., interrogator 102 or interrogator 202). The operational mode command 508A includes a time envelope for the entire time or duration of the T cmd T sync_up A first portion 508B having a pulse duration of T up A second portion 508C having a duration of T power a third portion 508D having a duration of T D In contrast to the operational mode command 502A as shown in FIG. 5A, the third portion 508D, which includes powering the ultrasound, may be transmitted after the dead time of the fourth portion 508E. In some embodiments, this configuration may be configured to transmit a fourth portion 508E having a duration of T up This allows the duration of the second and third portions 502C-D (shown in panel 502) to be extended and allows the ultrasound transmission after the first portion 508B to remain within the duration of the time of flight. Thus, the power needs of the implanted device are such that the combined duration of the second and third portions 502C-D (shown in panel 502) exceeds the time of flight. power If a longer duration is required then the powered ultrasound can be configured to be transmitted after a dead time.

[0128] Panel 510 illustrates the ultrasound envelope for operational mode command 508A received at the implantable device. As shown, the implantable device can receive operational mode command 508A as operational mode command 510A a period of time (i.e., half the time of flight) after operational mode command 508A was transmitted. Received operational mode command 510A includes portions 510B-E that correspond to portions 508B-E of operational mode command 508A, as described above. Panel 512 illustrates ultrasound backscatter of a second portion 510C received at the interrogator. As shown, the ultrasound backscatter is T upand needs to be transmitted during the dead time of the fourth portion 508E to ensure that no crosstalk occurs so that the interrogator can successfully extract data from the ultrasonic backscatter.

[0129] 5C illustrates panels 514-516 illustrating the timing requirements and data structure of operational mode commands associated with a data downlink, according to some embodiments. Panel 514 illustrates an example ultrasound envelope for an operational mode command 514A received by an ultrasound interrogator (e.g., interrogator 102 or interrogator 202). The operational mode command 514A includes a time or duration T cmd T sync_down a first portion 514B having a pulse duration of T data_transfer In some embodiments, the mode detector may determine that the pulse duration of the first portion 514B corresponds to a T associated with the data downlink. sync_down In some embodiments, the method may be configured to determine that T sync_down The value of T sync_up may be different from, but T power For example, T sync_down is the first multiple of the carrier frequency (e.g., T sync_down = 5*Tc), and T sync_up is the second multiple of the carrier frequency (e.g., T sync_up = T c ) in some embodiments. sync_down and T sync_up Implantable devices can be configured to extract power from ultrasound (e.g., T power >5*T c ).

[0130] In some embodiments, upon determining that the first portion 514B indicates a downlink mode, the implantable device can be configured to extract data from the second portion 514C. In some embodiments, the data can be encoded in the second portion 514C using a pulse width modulation amplitude shift keying (PWM-ASK) encoding scheme. For example, as shown in panel 516, pulse encoding logic 0 can have a higher amplitude than pulse encoding logic 1. Additionally, pulse encoding logic 0 can have a higher amplitude than pulse encoding logic 1, as shown in panel 516. notch (Example: T notch = 5*T c ) according to period T 0 (Example: T 0 = 10*T c ), whereas pulse coding logic 1 may have a waveform that follows T notch (Example: T notch = 5*T c ) according to period T 1 (Example: T 1 = 15*T c ) The use of PWM-ASK may ensure that sufficient power is transmitted in portion 514C when multiple data values ​​of logic 0 are transmitted in sequence. In some embodiments, data may be encoded in operational mode command 514A using another encoding scheme, such as pulse interval encoding (PIE), frequency shift keying (PSK), or phase shift keying (PSK).

[0131] 6A illustrates a method 600A of operating an implantable device using ultrasound, according to some embodiments. In some embodiments, the implantable device may be an example of implantable device 104 of FIG. 1. For ease of explanation, the various steps below of method 600 may refer to components of implantable device 104 as described with respect to FIG.

[0132] At step 602, the implantable device receives an ultrasound wave including an operational mode command. In some embodiments, an ultrasound transducer (e.g., ultrasound transducer 108) of the implantable device can be configured to receive the ultrasound wave and convert energy from the received ultrasound wave into an electrical signal including an electrical representation of the operational mode command. In some embodiments, the ultrasound wave is transmitted by an interrogator, such as interrogator 102 of FIG. 1 or interrogator 202 of FIG. 2. In some embodiments, the ultrasound wave can be transmitted by another implantable device. In some embodiments, the operational mode command can correspond to one or more pulses of ultrasound, as described above with respect to panel 3B of FIG. 3. In some embodiments, step 602 includes step 602A.

[0133] In step 602A, the implantable device determines that the operational mode command corresponds to a pattern from among a plurality of predefined patterns. In some embodiments, the implantable device may be configured to determine this correspondence by determining a correspondence between a first portion of the operational mode command and the pattern. For example, the implantable device may compare the first portion to one or more patterns from among the plurality of predefined patterns to determine this correspondence. In some embodiments, this first portion may include a single pulse of the operational mode command. For example, this first portion may be an initial pulse of the operational mode command. In some embodiments, this first portion may include a sequence of two or more pulses of the operational mode command.

[0134] In some embodiments, the plurality of predetermined patterns can be a plurality of corresponding pulses having different characteristics. In some embodiments, the plurality of predetermined patterns can be a plurality of corresponding values ​​associated with a characteristic of the pulse. For example, the pulse characteristic may include a pulse duration, a pulse amplitude, or a phase or frequency change. In some embodiments, each predetermined pattern of the plurality of patterns can include a unique set of values ​​corresponding to two or more pulse characteristics. In some embodiments, each predetermined pattern of the plurality of patterns can include a unique pulse sequence.

[0135] In some embodiments, the plurality of predetermined patterns includes a plurality of corresponding pulse durations, as described above with respect to Figure 1. In some embodiments, one or more of the pulse durations are predetermined based on a carrier signal period of the received ultrasound.

[0136] In some embodiments, the implantable device's mode detector (e.g., mode detector 126) can be configured to count the number of instances where the first portion of the electrical signal exceeds a predetermined voltage level to determine if the operational mode command corresponds to a pattern. In some embodiments, the predetermined voltage level may be a voltage value close to 0V (e.g., less than 10 mV, less than 50 mV, less than 100 mV, or less than 200 mV). In some embodiments, the number of instances may correspond to the pulse duration of the operational mode command.

[0137] In some embodiments, the mode detector can be configured to continuously monitor the ultrasound to determine if an operational mode command is received. For example, the mode detector may determine that an operational command is received when a first portion of the operational mode command is determined to correspond to a pattern from among a plurality of predetermined patterns.

[0138] In step 604, the implantable device sets an operational mode of the implantable device to one of a plurality of predefined operational modes based on the operational mode command. In some embodiments, the operational mode may include a stimulation mode, a neurorecording mode, or a sensor mode, as described above with respect to FIGURE 1. In some embodiments, setting the operational mode may include step 604A.

[0139] In step 604A, the implantable device sets an operational state corresponding to the operational mode based on the determined pattern. In some embodiments, the implantable device may be configured to implement and maintain an operational logic including a plurality of operational states and transitions defined between the operational states. In some embodiments, a controller circuit (e.g., controller circuit 120) of the implantable device may be configured to implement and maintain the operational logic to set the operational state based on the determined pattern. In some embodiments, the controller circuit may include a finite state machine (FSM) to implement the operational logic. In some embodiments, the controller circuit may include a microprocessor to implement the operational logic. In other embodiments, the controller circuit may be implemented using a field programmable gate array (FPGA) or a microcontroller.

[0140] In some embodiments, the implantable device may be configured to maintain a current operating state and transition the implantable device from the current operating state i to a next operating state based on an operating mode command. In some embodiments, the implantable device may be configured to operate according to a next operating state that becomes the new current operating state. For example, the implantable device may control one or more of its components based on one or more commands associated with a set operating mode. In some embodiments, an association between a plurality of operating states (e.g., operating modes 152) and a plurality of corresponding commands (e.g., commands 154) may be stored in a memory (e.g., memory 150).

[0141] In some embodiments, the mode detector can be configured to continuously monitor the received ultrasound to determine if an operational mode command has been received, as described above with respect to step 602. In these embodiments, the implantable device can be configured to reset operation based on a detected operational mode command.

[0142] 6B illustrates a method 600B of operating an implantable device using ultrasound, according to some embodiments. In some embodiments, the implantable device may be an example of implantable device 104 of FIG. 1. For ease of explanation, the various steps below of method 600 may refer to components of implantable device 104 as described with respect to FIG.

[0143] In step 612, the implantable device receives an ultrasound wave including an operational mode command. In some embodiments, step 612 corresponds to step 602 described above with respect to Figure 6A. In some embodiments, step 612 includes step 612A, which may correspond to step 602A of Figure 6A.

[0144] In step 612A, the implantable device analyzes a first portion of the operational mode command to determine a correspondence to the pattern from a plurality of predefined patterns. In some embodiments, in response to determining that the first portion corresponds to the determined pattern, the implantable device determines that the operational mode command corresponds to the pattern. For example, as described above with respect to step 602A, this first portion may be a single pulse indicating the start of the operational mode command. In other examples, this first portion may include a sequence of two or more pulses of the operational mode command.

[0145] At step 614, the implantable device sets the operation mode of the implantable device to one of a plurality of predefined operation modes based on the operation mode command. In some embodiments, the plurality of operation modes includes a downlink mode for downloading data from the received ultrasound and an uplink mode for uploading data generated at the implantable device to an external device using the received ultrasound of step 612. In some embodiments, the plurality of operation modes includes a plurality of downlink modes for performing different operations on the downloaded data, as described above with respect to FIG. 1. In some embodiments, the plurality of operation modes includes a plurality of uplink modes for uploading different types of devices to the interrogator, as described above with respect to FIG. 1.

[0146] In some embodiments, step 614 corresponds to step 604 described above with respect to FIG. 6A. In some embodiments, step 614 includes step 614A. In step 614A, the implantable device sets an operational state corresponding to the operational mode based on the analyzed first portion. For example, the implantable device may set the operational state based on the determined pattern of step 612A. In some embodiments in which the implantable device implements an FSM, data representing the correspondence to the determined pattern may be used as an input to the FSM for setting the operational state.

[0147] In some embodiments, the determined response to the pattern may configure the implantable device to set the operational mode to a downlink mode to extract data from the received ultrasound. For example, the implantable device may be configured to extract data from the second portion of the operational mode command. In some embodiments, the determined response to the pattern may configure the implantable device to set the operational mode to an uplink mode to upload device data to the interrogator using the received ultrasound.

[0148] In step 616, the implantable device operates according to the set operating state corresponding to the operating mode. In some embodiments, step 616 includes one or more of steps 616A-D.

[0149] In some embodiments, for an operational state 618A associated with a downlink, step 616 includes steps 616A-B. In step 616A, the implantable device extracts data from a second portion of the operational mode command. In some embodiments, the second portion includes a sequence of one or more pulses of the operational mode command. In some embodiments, the second portion follows the first portion and does not overlap with the first portion. In some embodiments, the implantable device can be configured to decode the second portion to extract data. In some embodiments, the implantable device can be configured to decode the second portion using a pulse width modulation amplitude shift keying (PWM-ASK) encoding scheme. In some embodiments, the extracted data can include instructions to select an operational mode. In some embodiments, the extracted data can include one or more parameters associated with recording neural activity (e.g., PGA gain). In some embodiments, the extracted data can include one or more parameters associated with stimulating a nerve.

[0150] In step 616B, the implantable device configures the implantable device based on the extracted data. In some embodiments, the implantable device may be configured to generate one or more commands for controlling one or more components based on the extracted data. In some embodiments, the one or more commands (e.g., commands 154) are generated based on the current operating state set in step 614A.

[0151] In some embodiments, for an operational state associated with uplink 618B, step 616 includes steps 616C-D. In step 616C, the embeddable device determines device data to transmit based on the operational state. In some embodiments, the device data includes data generated by the embeddable device. In some embodiments, the embeddable device may be configured to retrieve device data from a memory (e.g., memory 150) based on the operational state.

[0152] In some embodiments, the operating state may correspond to a physiological condition reporting mode (i.e., an example of an uplink mode), where the device data may include information associated with a physiological condition detected or measured by the implantable device in the physiological condition reporting mode. For example, the physiological condition may include temperature, pulse rate, blood pressure, pH level, the presence of an analyte, or a concentration of an analyte. In some embodiments, the analyte may include oxygen or glucose.

[0153] In some embodiments, the operating state may correspond to a neural activity reporting mode (i.e., an example of an uplink mode), in which the implantable device may be configured to generate device data including information associated with electrophysiological signals detected by the implantable device in the neural activity reporting mode, as described further below with respect to FIG.

[0154] In some embodiments, this operational state may correspond to an acknowledgement mode (i.e., an example of an uplink mode), where the device data may include an acknowledgement that the implantable device successfully extracted operational commands from a previously received ultrasound.

[0155] In step 616D, the implantable device encodes device data in the backscatter of a second portion of the operational mode command. As described above with respect to step 616A, this second portion may include a sequence of one or more pulses of the operational mode command. In some embodiments, this second portion follows the first portion and does not overlap with the first portion. In some embodiments, the implantable device may be configured to modulate a current generated from the received ultrasound of step 612 to encode the data. In some embodiments, one or more ultrasound transducers of the implantable device may be configured to emit ultrasound backscatter of ultrasound, where the backscattered ultrasound encodes the device data.

[0156] Thus, based on method 600B, the implantable device can be configured to operate in an uplink mode or a downlink mode based on an operational mode command received in ultrasound.

[0157] FIG. 7 illustrates a diagram 700 showing an example operational logic of an implantable device (e.g., implantable device 104) according to some embodiments. As described above, a controller circuit (e.g., controller circuit 120) of the implantable device can be configured to implement a finite state machine (FSM) to control the operation of the implantable device. For example, diagram 700 illustrates a Moore state machine. As shown in diagram 700, the FSM may include a number of operational states 702A-O. In some embodiments, the embeddable device includes a number of operational modes, each of which may correspond to a unique subset of the number of operational states 702A-O. Although the FSM is shown as a Moore machine, the embeddable device can be configured to control the operational logic according to other types of FSMs. For example, instead of a Moore machine, the FSM may be implemented as a Mealy state machine, a Harrell state machine, or a Unified Modeling Language (UML) state machine. In some embodiments, the implantable device can be configured to transition from a current operating state to a next operating state based on an operational mode command in a received ultrasound, as described above with respect to Figures 6A-B.

[0158] In some embodiments, the implantable device may be configured to compare information corresponding to an operational mode command to one or more patterns from a plurality of predefined patterns to set an operational mode and associated operational state within the FSM. For example, as shown in diagram 700, the operational mode command may be configured to compare information corresponding to an uplink pattern (e.g., T sync_up period) or downlink pattern (e.g., T sync_down The ultrasound pulse duration (e.g., T us ) The uplink pattern may be associated with transitioning the implantable device to an operational state for uploading data, and the downlink pattern may be associated with transitioning the implantable device to an operational state for downloading data.

[0159] In some embodiments, the implantable device may be configured to upload and download data via ultrasound communication. Although the following description may be described with respect to an implantable device communicating with an interrogator, it should be understood that according to some embodiments, an implantable device may similarly use ultrasound to communicate with another implantable device. As described above with respect to FIG. 6B, whenever the implantable device transitions to an operational state associated with downlinking data, the implantable device may be configured to decode a portion of the ultrasound received from the interrogator to extract an operational mode command for operating the implantable device. As described above with respect to FIG. 6B, whenever the implantable device transitions to an operational state associated with uplinking data, the implantable device may be configured to encode device data to be transmitted in the backscatter of a portion of the received ultrasound. The interrogator may then be configured to receive the ultrasound backscatter and decode the device data encoded in the ultrasound backscatter.

[0160] In some embodiments, the implantable device can be configured to begin in an operating state 702A corresponding to a power mode of operation. In the operating state 702A, the implantable device can be configured to charge one or more energy storage devices, energy storage device(s) 136, of the implantable device using ultrasound waves received by one or more ultrasound transducers.

[0161] In some embodiments, the implantable device can be configured to continuously monitor received ultrasound to determine if the received ultrasound contains an operational mode command. As shown in diagram 700, an operational mode command is generated in the uplink pattern (i.e., T us = T sync_up), the embeddable device may transition to an operational state 702B, which corresponds to a broadcast mode of operation. In operational state 702B, the embeddable device may transmit its device ID to the interrogator.

[0162] In some embodiments, the implantable device may receive the next operating mode command (e.g., T us =T sync_down ) is detected. The implantable device may then transition to an operational state 702C, which corresponds to a power calibration mode of operation. In operational state 702C, the implantable device may transmit power information to the interrogator. For example, the power information may include available power or power consumption, as described above with respect to FIG. 1. In some embodiments, upon receiving the power information, the interrogator may be configured to adjust one or more ultrasound settings (e.g., power pulse strength or pulse width) based on the power information. Thus, the power provided by the interrogator may be adjusted based on the power information transmitted by the implantable device to the interrogator.

[0163] As shown in diagram 700, the next operating mode command is us = T sync_down ), the embedded device may transition from operating state 702C to operating state 702D, which corresponds to a mode selection mode of operation. In operating state 702D, the embeddable device may extract data from the second part of the received operational mode command. In some embodiments, the extracted data may include information for selecting an operational mode for the embeddable device.

[0164] The next operating mode command is the uplink pattern (i.e., T us = T sync_up), the implantable device may transition from operating state 702D to operating state 702E, which corresponds to a mode confirmation operating mode. In operating state 702E, the implantable device may transmit an acknowledgment to the interrogator indicating that selection information associated with selecting the operating mode was successfully received.

[0165] The next operating mode command is in the uplink pattern (i.e., T us = T sync_up ), the implantable device may determine which of one or more reporting operating modes to enter based on selection information previously received in operating state 702D. For example, the reporting operating modes may be associated with transmitting information related to various physiological conditions, such as temperature, pulse rate, pH level, or the presence or concentration of a particular analyte. For example, as shown in diagram 700, the implantable device may transition to operating state 702N, which corresponds to temperature operating mode 704C. In some embodiments, the amount of information that can be uploaded is limited (e.g., 4 bits of information). Thus, as shown in diagram 700, temperature operating mode 704C may include multiple operating states 702N-O for transmitting the measured temperature. In some embodiments, the next operating mode command is a downlink pattern (i.e., T us = T sync_up ), the embedded device may transition from operating state 702O back to operating state 702C to recalibrate power delivery from the intergator.

[0166] Returning to the operating state 702E, the next operating mode command is us = T sync_down ), the implantable device can determine whether to enter neural activity recording mode 704A or neural stimulation mode 704B based on the selection information previously received in operational state 702D.

[0167] In some embodiments, when the selection information indicates a neural activity recording mode 704A, the implantable device may transition from operating state 702E to operating state 702F in the neural activity recording mode 704A. In the neural activity recording mode 704A, the implantable device may be configured to receive parameters in operating state 702F and transmit neural activity data in operating states 702G-H. For example, the parameters may include a field programmable gate array gain amplifier (PGA) gain that configures the implantable device to control how much to amplify the detected neural activity signal. As discussed above with respect to the temperature operating mode 704C, device data such as a neural activity recording may be too large to transmit in the backscatter of the second part of the operating mode command. Thus, the neural activity recording mode 704A may include multiple operating states 702G-H for transmitting the entire neural activity recording. Further details regarding how neural activity may be sampled and recorded are provided below with respect to FIG. 8. In some embodiments, the next operating mode command may be transmitted in a downlink pattern (i.e., T us = T sync_up ), the embedded device may transition from operating state 702H back to operating state 702C to recalibrate power delivery from the intergator.

[0168] In some embodiments, when the selection information indicates a neural stimulation mode 704B, the implantable device can transition from operating state 702E to operating state 702I in the neural stimulation mode 704B. In the neural stimulation mode 704B, as shown in diagram 700, the implantable device can be configured to receive and stimulate parameters in operating state 702I, and subsequently transmit an acknowledgment of the received parameters in operating state 702J based on the received operational mode command.

[0169] In operating state 702J, a charge detector of the implantable device can be configured to determine whether the stimulation capacitor is sufficiently charged to be used to stimulate a nerve. If the charge detector indicates sufficient charge (i.e., charge indication=1), the implantable device transitions to operating state 702L, otherwise the implantable device remains in operating state 702K and the stimulation capacitor continues to charge based on ultrasound received from the interrogator. In operating state 702L, the implantable device can stimulate one or more selected nerves by emitting electrical pulses to the one or more selected nerves, as further described below with respect to FIG.

[0170] If the operating mode command corresponds to an uplink pattern, the implantable device may transition to an operating state 702M corresponding to an acknowledgment mode of operation to transmit a state of stimulation as performed in operating state 702L. If the operating mode command corresponds to a downlink pattern, the implantable device may return to operating state 702K to repeat stimulation or return to operating state 702C to recalibrate the implantable device to enter another operating mode, depending on the data included in the operating mode command. For example, instructions extracted from the operating mode command may call for repeated stimulation, which transitions the implantable device to operating state 702K to recharge the stimulation capacitor.

[0171] FIG. 8 illustrates a diagram 800 of an implantable device 811 configured to interact with a nerve 814 of a subject, according to some embodiments. In some embodiments, the implantable device 811 may be an exemplary implementation of the implantable device 104 as described above with respect to FIG. 1. As shown in diagram 800, the implantable device 811 may be implanted on the nerve 814 and may include one or more curved members, such as curved member 802, extending from a body 812. The body 812 of the implantable device 811 may include an integrated circuit 824 (e.g., including the modulation and demodulation circuit 112, the stimulation circuit 114, the detection circuit 116, or the controller circuit 120), a non-transitory memory 826 (e.g., memory 180), a power circuit 828 (e.g., the power circuit 130), and an ultrasonic transducer 830 (e.g., the ultrasonic transducer 108 or the ultrasonic transducer circuit 106). In some embodiments, the body 812 includes multiple ultrasonic transducers, including the ultrasonic transducer 830. Thus, it should be understood that ultrasonic transducer 830 may represent multiple ultrasonic transducers as shown in diagram 800.

[0172] In some embodiments, the ultrasonic transducer 830 can be configured to receive ultrasonic waves transmitted by an interrogator (e.g., interrogator 102 of FIG. 1 or interrogator 202 of FIG. 2) and convert the mechanical energy of the ultrasonic waves into an electrical signal having electrical energy. In some embodiments, the ultrasonic waves are detected by the integrated circuit 824 and can include one or more operational mode commands that set an operational mode of the implantable device 811 from a plurality of operational modes to one operational mode. In some embodiments, the electrical signal includes an electrical representation of the one or more operational mode commands.

[0173] In some embodiments, a portion of the electrical signal may be processed by the power circuitry 828 to provide power to components of the implantable device 811. In some embodiments, the power circuitry 828 may include a power conveyor circuit (e.g., power conveyor circuitry 134) configured to convert the electrical signal having a first voltage to a second signal having a second voltage to provide power to various components of the integrated circuit 824. In some embodiments, the power circuitry 828 may include a rectifier circuit (e.g., an active rectifier) ​​to convert the electrical signal from an AC form to a DC form, where the converted electrical signal may be related to the first voltage. In some embodiments, the power conveyor circuitry may include a charge pump to generate a second voltage greater than the first voltage. In some embodiments, the power circuitry 828 may include an energy storage device (e.g., energy storage device 136) configured to store excess energy provided by the electrical signal and act as a secondary power source when the power provided by the interrogator is insufficient. In some embodiments, the power conveyor circuitry can be configured to control whether power is to be conveyed to or from an energy storage device, which effectively charges or discharges, respectively. In some embodiments, the power conveyor circuitry can be configured to control the time (e.g., number of clock cycles) that power is conveyed over in addition to the direction of power flow (e.g., forward or reverse).

[0174] In some embodiments, the integrated circuit 824 includes a controller circuit (e.g., controller circuit 120) configured to set an operational mode of the implantable device 811 based on an operational mode command received via ultrasound, as described above with respect to FIG.

[0175] In some embodiments, the operational mode command may instruct the implantable device 811 to enter a power calibration mode in which the controller circuit may generate information indicative of whether more or less power should be transmitted to the interrogator. In some embodiments, the controller circuit may be configured to generate this power information based on available power provided by the power circuit 828 and power consumed by the integrated circuit 824. In some embodiments, the available power includes the supplied power provided by the ultrasonic transducer 830 and the accessible power provided by the energy storage device of the power circuit 828. In some embodiments, the controller circuit may be configured to control the ultrasonic transducer 830 to transmit the generated power information to the interrogator to cause the interrogator to control the transmitted ultrasonic wave power. In some embodiments, the power consumption may be determined by the controller circuit based on the operational mode of the implantable device 811, as described above with respect to FIG. 1.

[0176] In some embodiments, the operational mode command may instruct the implantable device 811 to enter a neural stimulation mode or a detection mode, each of which may operate electrode pads 818 on the curved member 802. In some embodiments, the detection mode may be an example of an uplink mode associated with transmitting device data to another device, such as an interrogator, as described above with respect to Figures 6B-7.

[0177] In some embodiments, in a detection mode, the electrode pads 818 are configured to detect electrophysiological signals, and detection signals based on the electrophysiological signals are received by the integrated circuit 824. The detection signals received by the integrated circuit 824 may be processed (e.g., amplified, digitized, and / or filtered) by the detection circuit (e.g., by the detection circuit 116) before being received by the controller circuit. In some embodiments, the controller circuit may access a non-transitory memory (e.g., memory 180) to store data related to the detected electrophysiological signals. In some embodiments, in a detection mode, the controller circuit may be configured to operate the ultrasound transducer 830 to emit backscattered ultrasound waves of the received ultrasound waves that encode data related to the detected electrophysiological signals.

[0178] In some embodiments, the operational mode command can instruct the implantable device 811 to enter a neural stimulation mode. In the stimulation mode, the controller circuit can generate a stimulation signal based on the detection signal and operate one or more electrode pads 818 to emit an electrical pulse to the nerve 814 based on the stimulation signal. In some embodiments, the controller circuit can access a non-transitory memory (e.g., memory 180) to store data related to the stimulation signal or electrical pulse to be emitted to the nerve 814. In some embodiments, in the stimulation mode, the controller circuit can be configured to operate the ultrasound transducer 830 to emit backscatter of received ultrasound, where the backscattered ultrasound encodes data related to a state of stimulation.

[0179] The data stored in the non-transitory memory can be wirelessly transmitted via ultrasonic backscatter waves emitted by the ultrasonic transducer 830. As described above with respect to FIG. 1, to transmit data using ultrasonic backscatter, the ultrasonic transducer 830 may first receive ultrasonic waves and generate a current flowing through a modulation circuit. The controller circuit may then access the memory and operate the modulation circuit to modulate the current flowing through the modulation circuit to encode the data. Through such processing, the ultrasonic backscatter waves emitted by the ultrasonic transducer 830 can encode data.

[0180] In some embodiments, as shown in diagram 800, curved member 802 can include a first portion 802a and a second portion 802b bridged by a body 812 at point 816. In some embodiments, first portion 802a and second portion 802b are directly connected and curved member 802 is attached to body 812 via a connecting member. Curved member 802 can include multiple electrode pads 818 on an inner surface of curved member 802, which can be radially arranged about an axis parallel to the length of nerve 814. A space 820 between first portion 202a and second portion 202b exists along curved member 802 (and can exist on other curved members of implantable device 811 as well). In some embodiments, the implantable device 811 can be implanted by bending the first portion 802a and the second portion 802b of the curved member 802 outward, thereby expanding the size of the gap and allowing the nerve 814 or other thread-like tissue to pass through the gap 820 and fit within the cylindrical space formed by the curved member 802. The first portion 802a and the second portion 802b of the curved member 802 can be released, which allows the curved member 802 to wrap around the nerve 814 or other thread-like tissue.

[0181] A number of electrode pads 818 as shown in FIG. 8 are external to the nerve 814 but in direct contact with the epineurium of the nerve 814. The nerve 814 may include several fiber bundles 822. In some embodiments, the electrode pads 818 in the curved member 802 may be operated for targeted emission of electrical pulses to one or more fiber bundles 822 or other subsets of nerve fibers and / or for targeted detection of electrophysiological signals transmitted by one or more fiber bundles 822 or other subsets of nerve fibers. For example, the electrode pads 818 may be selectively activated by a controller circuit in an integrated circuit 824 housed in the body 812 to emit electrical pulses targeted to one or more fiber bundles 822. In another embodiment, the electrode pads 818 are operated by the controller circuit to detect electrophysiological signals transmitted by one or more fiber bundles 822 in the nerve 814. In some embodiments, curved member 802 can be configured to detect electrophysiological signals transmitted by nerve 814 or a subset of nerve fibers, or to emit an electrical pulse to nerve 814 or target a subset of nerve fibers, or to both detect electrophysiological signals transmitted by nerve 814 or a subset of nerve fibers and emit an electrical pulse to nerve 814 or target a subset of nerve fibers. For example, implantable device 811 may include multiple curved members (including curved member 802), where a first curved member can be configured to detect electrophysiological signals transmitted by nerve 814 or a subset of nerve fibers and a second curved member can be configured to emit an electrical pulse to nerve 814 or target a subset of nerve fibers.

[0182] In some embodiments, the curved member 802 can be sized to engage a selected nerve 814 or fibrous tissue encompassing the nerve 814. The nerve 814 can be a spinal or peripheral nerve. In some embodiments, the nerve 814 is an autonomic or somatic nerve. In some embodiments, the nerve 814 is a sympathetic or parasympathetic nerve. In some embodiments, the nerve 814 is a vagus nerve, mesenteric nerve, splenic nerve, sciatic nerve, tibial nerve, pudendal nerve, celiac ganglion, sacral nerve, or any branch thereof.

[0183] The size, shape, and spacing of the curved members 802 on the implantable device 811 may depend on the type and size of tissue that the implantable device 811 engages. In some embodiments, two or more curved members of the implantable device 811 are spaced apart by about 0.25 mm or more (e.g., about 0.5 mm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, about 4 mm or more, about 5 mm or more, about 6 mm or more, or about 7 mm or more). In some embodiments, two or more curved members are spaced apart by about 8 mm or less (e.g., about 7 mm or less, about 6 mm or less, about 5 mm or less, about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, or about 0.5 mm or less). By way of example, two or more curved members may be spaced apart by about 0.25 mm to about 0.5 mm, about 0.5 mm to about 1 mm, about 1 mm to about 2 mm, about 2 mm to about 3 mm, about 3 mm to about 4 mm, about 4 mm to about 5 mm, about 5 mm to about 6 mm, about 5 mm to about 7 mm, or about 7 mm to about 8 mm. The width of the curved members 802 may also vary depending on the application of the implantable device 811 or the tissue to be engaged by the implantable device 811. In some embodiments, the width of the curved members 802 is about 100 μm or more (e.g., about 150 μm or more, about 250 μm or more, about 500 μm or more, about 1 mm or more, or about 1.5 mm or more). In some embodiments, the width of the curved members 502 is about 2 mm or less (e.g., about 1.5 mm or less, about 1 mm or less, about 500 μm or less, about 250 μm or less, or about 150 μm or less). In some embodiments, the width of the curved member 502 is about 100 μm to about 2 mm (e.g., about 100 μm to about 150 μm, about 150 μm to about 250 μm, about 250 μm to about 500 μm, about 500 μm to about 1 mm, about 1 mm to about 1.5 mm, or about 1.5 mm to about 2 mm). The inner surface of the curved member 802 forms a cylindrical space through which the nerve 814 and / or thread-like tissue passes. The diameter of the cylindrical space formed by the curved member 802 depends on the target nerve and / or thread-like tissue that the implantable device 811 engages.In some embodiments, the curved member 802 forms a cylindrical space having a diameter of about 50 μm to about 15 mm (e.g., about 50 μm to about 100 μm, about 100 μm to about 250 μm, about 250 μm to about 500 μm, about 500 μm to about 1 mm, about 1 mm to about 1.5 mm, about 1.5 mm to about 2.5 mm, about 2.5 mm to about 5 mm, about 5 mm to about 10 mm, or about 10 mm to about 15 mm).

[0184] In some embodiments, the implantable device 811 includes one or more additional fixation members configured to fix the implantable device 811 to the threadlike tissue. Such fixation members may include, for example, loops for suturing the implantable device to an anatomical structure (such as a threadlike tissue or nerve, or other tissue surrounding the threadlike tissue or nerve), pins, or clamps. For example, the implantable device 811 may be sutured to the threadlike tissue or nerve 814, or tissue surrounding the threadlike tissue or nerve, to limit movement of the implantable device 811 once implanted.

[0185] In some embodiments, the curved member 802 of the implantable device 811 may comprise a metal, a metal alloy, a ceramic, a silicon, or a non-polymeric material. The curved member 802 may be flexible, and preferably is elastic, such that the curved member 802 may be positioned around the nerve 814 and / or thread-like tissue. In some embodiments, the curved member 802 or a portion of the curved member 802 is coated with an elastomeric or non-elastomeric coating that is preferably bioinert, such as polydimethylsiloxane (PDMS), silicon, a urethane polymer, a poly(p-xylylene) polymer (such as the poly(p-xylylene) polymer sold under the trade name PARYLENE®), or a polyimide. The curved member 802 may comprise a plurality of electrode pads 818 on an inner surface. In some embodiments, the electrode pads 818 on the inner surface of the curved member 802 are not coated with an elastomeric or non-elastomeric polymer coating, but the inner surface may be coated with a conductive material (e.g., may be electroplated with a PEDOT polymer or a metal to improve the electrical properties of the electrode pads). Thus, in some embodiments, only the outer surface of the curved member 802 is coated with the coating. Optionally, the coating further coats the housing of the body 812.

[0186] In some embodiments, the plurality of electrode pads 818 can include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more electrode pads, such as about 3 to about 50 electrode pads, about 3 to about 5 electrode pads, about 5 to about 10 electrode pads, about 10 to about 25 electrode pads, or about 25 to about 50 electrode pads. In some embodiments, the electrode pads in the plurality of electrode pads 818 can be selectively activated by the controller circuitry to enable targeted electrical pulse emission, as further described herein.

[0187] In some embodiments, the electrode pads 818 may include any suitable conductive material, such as one or more of tungsten, platinum, palladium, gold, iridium, niobium, tantalum, or titanium (or an alloy of one or more of them). The materials of the sensing electrode pads and the stimulating electrode pads may be the same or different. The sizes and shapes of the electrode pads 818 may be the same or different. For example, the electrode pads 818 on a given curved member 802 may be the same or different sizes, and the electrode pads on different curved members may be the same or different sizes.

[0188] In some embodiments, the electrode pad 818 of the implantable device 811 is positioned by the curved member 802 in electrical communication with the nerve 814. In some embodiments, the electrode pad 818 is not in direct contact with the nerve 814 (e.g., not indirectly contacting the exterior of the nerve 814), but is in electrical communication with the nerve 814. In some embodiments, the electrode pad 818 is positioned within about 2 mm (e.g., within about 1.8 mm, within about 1.6 mm, within about 1.4 mm, within about 1.2 mm, within about 1.0 mm, within about 0.8 mm, within about 0.6 mm, within about 0.4 mm, or within about 0.2 mm) of the nerve 814. In some embodiments, the electrode pad 818 is configured to pierce the epineurium of the nerve 814 at one or more locations. For example, the electrode pad 818 can be needle-shaped to allow for piercing of the epineurium. In some embodiments, the electrode pad 818 directly contacts the nerve 814, e.g., the epineurium of the nerve 814.

[0189] In some embodiments, the body 812 includes a housing, which may include a base, one or more sidewalls, and a top. The housing may enclose the ultrasonic transducer 830 and the integrated circuit 824. The housing may be hermetically sealed (e.g., by soldering or laser welding) to prevent interstitial fluid from contacting the ultrasonic transducer 830 or the integrated circuit 824. The housing is preferably made from a bioinert material, such as a bioinert metal (e.g., steel or titanium) or a bioinert ceramic (e.g., titania or alumina). The housing (or the top of the housing) may be thin to allow ultrasonic waves to penetrate the housing. In some embodiments, the housing is about 100 μm or less in thickness, such as about 75 micrometers (μm) or less, about 50 μm or less, about 25 μm or less, or about 10 μm or less. In some embodiments, the housing has a thickness of about 5 μm to about 10 μm, about 10 μm to about 25 μm, about 25 μm to about 50 μm, about 50 μm to about 75 μm, or about 75 μm to about 100 μm.

[0190] In some embodiments, the body 812 of the implantable device 811 is relatively small, which allows for comfortable and long-term implantation while limiting tissue irritation often associated with implantable medical devices. In some embodiments, the longest dimension of the body 812 is about 10 mm or less, such as about 5 mm to about 9 mm, or about 6 mm to about 8 mm.

[0191] In some embodiments, the body 812 includes a material, such as a polymer, within the housing that can fill the empty space within the housing to reduce the acoustic impedance mismatch between the tissue outside the housing and the tissue within the housing. Thus, according to some embodiments, the body 812 is preferably air-free or vacuum-free.

[0192] In some embodiments, the ultrasonic transducer 830 may include a micromachined ultrasonic transducer, such as a capacitive micromachined ultrasonic transducer (CMUT) or a piezoelectric micromachined ultrasonic transducer (PMUT), or may include a bulk piezoelectric transducer. A bulk piezoelectric transducer may be any natural or synthetic material, such as a crystal, ceramic, or polymer. Exemplary bulk piezoelectric transducer data is for barium titanate (BaTiO 3 ), lead zirconate titanate (PZT), zinc oxide (ZO), aluminum nitride (AlN), quartz, berlinite (AlPO 4 ), topaz, langasite (La 3 Ga 5 SiO 14 ), gallium orthophosphate (GaPO 4 ), lithium niobate (LiNbO 3 ), lithium tantalate (LiTaO 3 ), potassium niobate (KNbO 3 ), Sodium Tungstate (Na 2 Wo 3 ), bismuth ferrite (BiFeO 3 ), polyvinylidene fluoride (PVDF), and lead magnesium niobate-lead titanate (PMN-PT).

[0193] In some embodiments, the bulk piezoelectric transducer is approximately cubic (i.e., an aspect ratio of about 1:1:1 (length:width:height)). In some embodiments, the piezoelectric transducer is plate-like with an aspect ratio of about 5:5:1 or greater, such as about 7:5:1 or greater, or about 10:10:1 or greater, in either the length or width aspect. In some embodiments, the bulk piezoelectric transducer is long and narrow, with an aspect ratio of about 3:1:1 or greater, with the longest dimension aligned with the direction of the ultrasonic backscattered waves (i.e., the polarization axis). In some embodiments, one dimension of the bulk piezoelectric transducer is equal to ½ of a wavelength (λ) corresponding to the drive frequency or resonant frequency of the transducer. At this resonant frequency, ultrasonic waves impinging on either face of the transducer will undergo a phase shift of 180° to reach an antiphase, causing maximum displacement between the two faces. In some embodiments, the height of the piezoelectric transducer is about 10 μm to about 1000 μm (such as about 40 μm to about 400 μm, about 100 μm to about 250 μm, about 250 μm to about 500 μm, or about 500 μm to about 1000 μm). In some embodiments, the height of the piezoelectric transducer is about 5 mm or less (such as about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 500 μm or less, about 400 μm or less, 250 μm or less, about 100 μm or less, or about 40 μm or less). In some embodiments, the height of the piezoelectric transducer is about 20 μm or more in length (such as about 40 μm or more, about 100 μm or more, about 250 μm or more, about 400 μm or more, about 500 μm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, or about 4 mm or more).

[0194] In some embodiments, the ultrasonic transducer 830 has a length of about 5 mm or less in its longest dimension (such as about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 500 μm or less, about 400 μm or less, 250 μm or less, about 100 μm or less, or about 40 μm or less). In some embodiments, the ultrasonic transducer 830 has a length of about 20 μm or more in its longest dimension (such as about 40 μm or more, about 100 μm or more, about 250 μm or more, about 400 μm or more, about 500 μm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, or about 4 mm or more).

[0195] In some embodiments, the ultrasonic transducer 830 is connected with two electrodes to enable electrical communication with the integrated circuit 824. A first electrode is attached to a first surface of the ultrasonic transducer 830 and a second electrode is attached to a second surface of the ultrasonic transducer 830, the first surface and the second surface being on opposite sides of the ultrasonic transducer 830 along one dimension. In some embodiments, the electrodes include silver, gold, platinum, platinum black, poly(3,4-ethylenedioxythiophene (PEDOT)), a conductive polymer (such as conductive PDMS or polyimide), or nickel. In some embodiments, the axis between the electrodes of the ultrasonic transducer 830 is orthogonal to the motion of the ultrasonic transducer 830.

[0196] The foregoing description sets forth exemplary methods, parameters, and the like. However, it should be recognized that such description is not intended as a limitation on the scope of the present disclosure, but is instead provided as a description of exemplary embodiments. The exemplary embodiments described above are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments have been selected and described in order to best explain the principles of the disclosed technology and their practical applications. In this way, those skilled in the art can best utilize the technology and various embodiments with various modifications as appropriate for the particular use envisioned.

[0197] Although the present disclosure and examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications should be understood as being included within the scope of the disclosure and examples as defined by the claims. In the foregoing description of the present disclosure and embodiments, reference is made to the accompanying drawings, in which are shown, by way of example, specific embodiments that can be implemented. It is understood that other embodiments and examples can be implemented and changes can be made without departing from the scope of the present disclosure.

[0198] Although the above description uses the terms first, second, etc. to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

[0199] As used herein, reference to "about" or "approximately" a value or parameter includes (and describes) a variation directed to the value or parameter itself. For example, a description referring to "about X" includes the description of "X."

[0200] It will be understood that aspects and variations of the invention described herein include those that "consist of" and / or "consist essentially of".

[0201] The terms "implantable" and "implanted" refer to an object that is fully implantable or fully embedded in a subject, such that no part of the object breaks through the body surface of the subject.

[0202] The term "substantially" refers to 90% or more. For example, a curved member that substantially encircles a cross-section of a nerve refers to a curved member that encircles 90% or more of the cross-section of the nerve.

[0203] The terms "subject" and "patient" are used interchangeably herein to refer to a vertebrate animal, such as a human.

[0204] As used herein, the terms "treat," "treating," and "treatment" refer interchangeably to any act that provides a benefit to a subject suffering from a medical condition or disorder, including amelioration of the disorder through the alleviation, inhibition, suppression, or elimination of at least one symptom, slowing the progression of a disease or disorder, slowing the recurrence of a disease or disorder, or inhibiting a disease or disorder.

[0205] When a range of values ​​is provided, it is to be understood that each intervening value between the upper and lower limit of that range, and any other stated or intervening value in that stated range, is encompassed within the scope of the disclosure. Where a stated range includes an upper or lower limit, ranges excluding either of those limits are also included in the disclosure.

[0206] Furthermore, it should be understood that the singular forms "a," "an," and "the," as used in the preceding description, are intended to include the plural forms unless the context clearly dictates otherwise. The term "and / or," as used herein, should also be understood to refer to and include any and all possible combinations of one or more of the associated listed items. Furthermore, it should be understood that the terms "including," "comprising," and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, components, components, and / or units, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, units, and / or groups thereof.

[0207] The term "if" may be interpreted to mean "when" or "at the time" or "upon determining" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "whether determined" or "whether a 'stated condition or event' is detected" may be interpreted to mean "upon determining" or "upon determining" or "upon detecting a 'stated condition or event'" or "in response to detecting a 'stated condition or event'," depending on the context.

[0208] The features and preferences described above in connection with the "embodiments" are separate preferences and are not limited to that particular embodiment, but may be freely combined with features from other embodiments where technically feasible to form preferred combinations of features. This description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

Claims

1. 1. A method of operating an implantable device using ultrasound, comprising:

2. The implantable device according to claim 1, receiving an ultrasonic wave including an operational mode command; setting an operational mode of the embeddable device from a plurality of operational modes to one operational mode based on the operational mode command; A method comprising:

2. 2. The method of claim 1, wherein the multiple operational modes include one or more of a downlink mode for downloading data from the received ultrasound or an uplink mode for uploading data generated at the implantable device using the received ultrasound to an external device.

3. The method of claim 2 , wherein the plurality of operational modes comprises the downlink mode and the uplink mode.

4. The method of claim 1 , wherein the ultrasound is transmitted by an interrogator.

5. The method of claim 1 , wherein the ultrasound is transmitted by another implantable device.

6. determining that the operational mode command corresponds to a pattern from a plurality of predetermined patterns; setting the operation mode based on the determined pattern; The method of any one of claims 1 to 5, comprising:

7. The method of claim 6 , wherein determining that the operational mode command corresponds to the pattern comprises determining that a first portion of the operational mode command corresponds to the determined pattern.

8. The method of claim 7 , wherein the first portion comprises a single pulse indicating the beginning of the operational mode command.

9. The method of claim 7 , wherein the first portion comprises a sequence of two or more pulses.

10. 10. The method of claim 6, wherein the plurality of predetermined patterns comprises a plurality of corresponding pulse durations, a plurality of corresponding amplitudes, or a plurality of corresponding phase or frequency changes.

11. 10. The method of claim 6, wherein the plurality of predetermined patterns includes a plurality of corresponding pulse durations, one or more of the pulse durations being set based on a carrier signal period of the received ultrasound.

12. Determining that the operational mode command corresponds to the pattern includes: converting said ultrasonic waves into electrical signals containing representations of operational mode commands; counting a number of instances where a first portion of the electrical signal exceeds a predetermined voltage level, the number of instances corresponding to the determined pattern; and The method of claim 11 , comprising:

13. the determined pattern is associated with uploading data, and the operational mode command includes a second portion different from the first portion; setting the operation mode to an uplink mode for uploading device data associated with the uplink mode; backscattering the ultrasound, the backscattered ultrasound encoding the device data in the backscatter of the second portion of the operational mode command; The method of claim 7, comprising:

14. 14. The method of claim 13, wherein the uplink mode includes an acknowledgement mode, and the device data includes an acknowledgement that the implantable device successfully extracted an operational command from a second ultrasound wave received by the implantable device.

15. The method of claim 13 , wherein the uplink mode includes a physiological condition reporting mode, and the device data includes information associated with a physiological condition detected by the implantable device in the physiological condition reporting mode.

16. The method of claim 13 , wherein the uplink mode includes a neural activity reporting mode, and the device data includes information associated with electrophysiological signals detected by the implantable device in the neural activity reporting mode.

17. The method of claim 13 , wherein the device data includes information associated with electrical pulses emitted by the implantable device, the electrical pulses configured to modulate activity of a target nerve.

18. 18. The method of claim 17, wherein the implantable device is configured to emit the electrical pulse in response to an operational command extracted from a second ultrasound signal received by the implantable device when the operational mode of the implantable device is set to a downlink mode.

19. the determined pattern is associated with downloading data, and the operational mode command includes a second portion different from the first portion; 8. The method of claim 7, comprising setting the operational mode to a downlink mode to extract data from the second portion of the operational mode command.

20. 20. The method of claim 19, wherein the extracted data is associated with measuring a physiological condition, the method comprising measuring the physiological condition in response to extracting the data.

21. 21. The method of claim 20, wherein the physiological condition comprises temperature, pulse rate, blood pressure, pH level, the presence of an analyte, or the concentration of the analyte.

22. 21. The method of claim 20, wherein the physiological condition comprises a concentration of an analyte, the analyte being oxygen or glucose.

23. 20. The method of claim 19, wherein the extracted data is associated with recording electrophysiological signals, and the implantable device comprises two or more electrodes in electrical communication with nerves of the subject, the two or more electrodes configured to record the electrophysiological signals.

24. 24. The method of claim 23, comprising recording the electrophysiological signal in response to the data extracted from the second portion.

25. the extracted data is associated with stimulating a nerve, the implantable device comprising two or more electrodes in electrical communication with the nerve of the subject; 20. The method of claim 19, comprising emitting one or more electrical pulses configured to modulate activity of the nerve using the two or more electrodes in response to the data extracted from the second portion.

26. maintaining a current operational state of the embeddable device based on operational logic defining transitions between operational states, the embeddable device being configured to operate in accordance with the current operational state; transitioning the operational logic from the current operational state to a next operational state based on the operational mode command; configuring the implantable device to operate according to the next operating state; 26. The method of any one of claims 1 to 25, comprising:

27. 27. The method of claim 26, wherein the operational logic is implemented by a microprocessor, a microcontroller, or a finite state machine (FSM).

28. 1. An implantable device that operates using ultrasound, comprising: an ultrasonic transducer configured to receive ultrasonic waves including an operational mode command; a controller circuit configured to set an operational mode of the implantable device from a plurality of operational modes to one operational mode based on the operational mode command; An implantable device comprising:

29. 30. The device of claim 28, wherein the multiple operational modes include one or more of a downlink mode for downloading data from the received ultrasound or an uplink mode for uploading data generated at the implantable device using the received ultrasound to an external device.

30. 30. The apparatus of claim 29, wherein the plurality of operational modes comprises the downlink mode and the uplink mode.

31. 31. Apparatus according to any one of claims 28 to 30, wherein the ultrasonic transducer is configured to receive the ultrasonic waves from an interrogator.

32. 32. The device of any one of claims 28 to 31, wherein the ultrasound transducer is configured to receive the ultrasound from another implantable device.

33. The controller circuit includes: determining that the operational mode command corresponds to a pattern from a plurality of predetermined patterns; Setting the operation mode based on the determined pattern 33. Apparatus according to any one of claims 28 to 32, configured to:

34. 34. The apparatus of claim 33, wherein to determine that the operational mode command corresponds to the pattern, the controller circuit is configured to determine that a first portion of the operational mode command corresponds to the determined pattern.

35. 35. The apparatus of claim 34, wherein the first portion includes a single pulse indicating the beginning of the operational mode command.

36. 35. The apparatus of claim 34, wherein the first portion comprises a sequence of two or more pulses.

37. 34. The apparatus of claim 33, wherein the plurality of predetermined patterns comprises a plurality of corresponding pulse durations, a plurality of corresponding amplitudes, or a plurality of corresponding phase or frequency changes.

38. 34. The apparatus of claim 33, wherein the plurality of predetermined patterns includes a plurality of corresponding pulse durations, one or more of the pulse durations being set based on a carrier signal period of the received ultrasound.

39. determining that the operational mode command corresponds to the pattern; the ultrasonic transducer is configured to convert the ultrasonic waves into an electrical signal containing a representation of the operational mode command; the controller circuit is configured to count a number of instances where a first portion of the electrical signal exceeds a predetermined voltage level, the number of instances corresponding to the determined pattern.

39. Apparatus according to any one of claims 33 to 38.

40. the determined pattern is associated with uploading data, and the operational mode command includes a second portion different from the first portion; the controller circuitry is configured to set the operational mode to the uplink mode to upload device data associated with the uplink mode; the ultrasonic transducer is configured to backscatter the ultrasonic waves, the backscattered ultrasonic waves encoding the device data in the backscatter of the second portion of the operational mode command.

40. Apparatus according to any one of claims 33 to 39.

41. 41. The device of claim 40, wherein the uplink mode includes an acknowledgement mode, and the device data includes an acknowledgement that the implantable device successfully extracted an operational command from a second ultrasound wave received by the implantable device.

42. 41. The device of claim 40, wherein the uplink mode includes a physiological condition reporting mode, and the device data includes information associated with a physiological condition detected by the implantable device in the physiological condition reporting mode.

43. 41. The device of claim 40, wherein the uplink mode includes a neural activity reporting mode, and the device data includes information associated with electrophysiological signals detected by the implantable device in the neural activity reporting mode.

44. 41. The device of claim 40, wherein the device data includes information associated with electrical pulses emitted by the implantable device, the electrical pulses configured to modulate activity of a target nerve.

45. 45. The device of claim 44, comprising a stimulation circuit configured to emit the electrical pulse in response to an operational command extracted from a second ultrasound signal received by the implantable device when the operational mode of the implantable device is set to a downlink mode.

46. 40. The apparatus of claim 33, wherein the determined pattern is associated with downloading data, the operational mode command includes a second portion different from the first portion, and the controller circuit is configured to set the operational mode to a downlink mode to extract data from the second portion of the operational mode command.

47. 47. The device of claim 46, wherein the extracted data is associated with measuring a physiological condition, the device comprising detection circuitry configured to measure the physiological condition in response to the data being extracted.

48. 48. The apparatus of claim 47, wherein the physiological condition comprises temperature, pulse rate, blood pressure, pH level, the presence of an analyte, or the concentration of the analyte.

49. 48. The apparatus of claim 47, wherein the physiological condition comprises a concentration of an analyte, the analyte being oxygen or glucose.

50. 47. The apparatus of claim 46, wherein the extracted data is associated with recording electrophysiological signals, the apparatus comprising two or more electrodes in electrical communication with nerves of the subject, the two or more electrodes configured to record the electrophysiological signals.

51. 51. The apparatus of claim 50, wherein the two or more electrodes are configured to record the electrophysiological signal in response to the data extracted from the second portion.

52. 47. The apparatus of claim 46, wherein the extracted data is associated with stimulating a nerve, the apparatus comprising two or more electrodes in electrical communication with the nerve of the subject, the two or more electrodes configured to emit one or more electrical pulses configured to modulate activity of the nerve in response to the data extracted from the second portion.

53. The controller circuit includes: maintaining a current operational state of the implantable device configured to operate in accordance with the current operational state based on operational logic defining transitions between operational states; transitioning the operational logic from the current operational state to a next operational state based on the operational mode command; Configuring the implantable device to operate according to the next operating state 53. Apparatus according to any one of claims 28 to 52, configured to:

54. 54. The apparatus of claim 53, wherein the operational logic is implemented by a microprocessor, a microcontroller, or a finite state machine (FSM).

Images