Implantable myoelectric sensing node with wireless power and data telemetry capabilities

Abstract

A system for controlling a prosthesis includes a plurality of implantable devices and a base station. Each implantable device is configured to: dynamically tune the implant antenna to wirelessly receive a power signal via magnetic resonance coupling using the implant antenna, and digitize the electromyogram (EMG) signals detected by one or more electrodes. The base station includes a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna wirelessly coupled with the plurality of implant antennas. The base station is configured to: operate the power delivery module to wirelessly supply the power signal to the implantable devices via magnetic resonance coupling; wirelessly receive the digitized EMG signals from the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

Description

IMPLANTABLE MYOELECTRIC SENSING NODE WITH WIRELESS POWER AND DATA TELEMETRY CAPABILITIESCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional App. No. 63 / 615,417, filed December 28, 2023, which is incorporated herein by reference in its entirety for all purposes.GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with government support under Grant No. W81XWH-20-1-0892 awarded by Department of Defense. The government has certain rights in the invention.FIELD

[0003] The present disclosure relates generally to implantable devices. More specifically, the disclosure relates to implantable devices with capabilities to measure biological signal data and to perform wireless powering and data transmission.BACKGROUND

[0004] Myoelectric prostheses use electromyogram (EMG) signals, which are the electrical signals generated during a muscle contraction, from one or two residuallimb muscles to control motorized arm components. Various switching techniques, such as muscle co-contraction, are used to change functions. Currently known prostheses use myoelectric signals (or EMG signals) in order to control functionality. These signals may be retrieved at the surface of the skin, but doing so may lead to poor spatial and temporal resolution. As such, implants have been designed to detect the EMG signals from inside the body of a human.

[0005] However, currently known implants use inductive charging in order to receive power while still being implanted inside the body. Inductive charging is achieved through mutual inductance and is very sensitive to alignment of the implant inside the body. For example, if the implanted device is misaligned with respect to the base station that is facilitating the inductive charging, the efficiency of thecharging drops significantly, thereby slowing the charging and requiring more time to power the implants.

[0006] As such, there is a need for implants and base stations that are designed to reduce such issues.SUMMARY

[0007] Disclosed herein are systems for controlling a prosthesis based on electromyogram (EMG) signals. The system includes a plurality of implantable devices and a base station. Each implantable device is configured to: dynamically tune the implant antenna to wirelessly receive a power signal via magnetic resonance coupling using the implant antenna, and digitize the EMG signals detected by the electrodes. The base station includes a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna wirelessly coupled with the plurality of implant antennas. The base station is configured to: operate the power delivery module to wirelessly supply the power signal to the implantable devices via magnetic resonance coupling; wirelessly receive the digitized EMG signals from the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

[0008] In one example (“Example 1”), an implantable device includes: a hermetically sealed housing; one or more electrodes integrated into the housing and configured to detect EMG signals in a body; an antenna disposed within the housing; and a controller disposed within the housing and operatively coupled with the electrodes and the antenna. The controller is configured to: dynamically tune the antenna to wirelessly receive a power signal via magnetic resonance coupling using the antenna, and digitize the EMG signals detected by the electrodes and wirelessly transmit the digitized EMG signals to an external device.

[0009] In another example (“Example 2”) further to Example 1 , each of the electrodes is configured as a ring and defines a portion of an outer surface of the housing.

[0010] In another example (“Example 3”) further to any preceding Example, the antenna is disposed more distally within the housing than one of the electrodes.

[0011] In another example (“Example 4”) further to any preceding Example, the housing comprises a first portion and a second portion, and the antenna is disposed within the second portion of the housing.

[0012] In another example (“Example 5”) further to Example 4, the first portion has a first permittivity, and the second portion has a second permittivity greater than the first permittivity.

[0013] In another example (“Example 6”) further to any preceding Example, the controller is disposed on a printed circuit board having a longitudinal axis, and the antenna is disposed along a transverse axis that is substantially perpendicular to the longitudinal axis.

[0014] In another example (“Example 7”) further to Example 6, the antenna includes a coil that is wrapped in a direction substantially parallel to the transverse axis.

[0015] In another example (“Example 8”) further to any preceding Example, the controller is configured to generate a unique identifier associated with the device and wirelessly transmit the unique identifier with the digitized EMG signals.

[0016] In another example (“Example 9”) further to any preceding Example, the controller is configured to amplify the EMG signals detected by the electrodes prior to digitizing the EMG signals.

[0017] In another example (“Example 10”) further to any preceding Example, the device includes at least one parameter adjuster. The controller is configured to dynamically tune the antenna by: determining, based upon the power signal received using the antenna, an amount of parameter to adjust; and adjusting, using the parameter adjuster, one or more parameters by the determined amount.

[0018] In another example (“Example 11”) further to Example 10, the at least one parameter adjuster includes at least one capacitor and at least one resistor.

[0019] In another example (“Example 12”) furtherto Example 10, the one or more parameters include a capacitance of the at least one capacitor and a resistance of the at least one resistor.

[0020] In one example (“Example 13”), a base station for detecting EMG signals includes: a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna configured to wirelessly couple with a plurality of receiverantennas of a plurality of implantable devices, wherein the implantable devices are configured to detect the EMG signals; an output bus operatively coupled with a prosthesis; and one or more processing units operatively coupled with the power delivery module and the output bus. The one or more processing units are configured to: operate the power delivery module to wirelessly supply a power signal to the implantable devices via magnetic resonance coupling; wirelessly receive digitized EMG signals transmitted by the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

[0021] In another example (“Example 14”) further to Example 13, the powering antenna includes a coil configured to be wrapped around a plurality of locations in which the implantable devices are implanted.

[0022] In another example (“Example 15”) further to Example 14, the powering antenna is configured to deliver a total energy of no greater than 1 watt.

[0023] In another example (“Example 16”) further to any one of Examples 13-15, the power delivery module further comprises a plurality of capacitors arranged in a parallel configuration, wherein the capacitors are coupled with a plurality of switches configured to separately and individually control operation of the corresponding capacitor coupled therewith. The one or more processing units are configured to: detect a signal that is reflected from the implantable devices in response to supplying the power signal to the implantable devices; and control, based upon the reflected signal, the switches of the capacitors to optimize the power signal supplied to the implantable devices.

[0024] In another example (“Example 17”) furtherto Example 16, the one or more processing units are configured to: calculate a phase relationship between the power signal to the reflected signal; calculate, based upon the phase relationship, a DC level for the power signal; and control, based upon the DC level, the switches of the capacitors to optimize the power signal supplied to the implantable devices.

[0025] In one example (“Example 18”), a system for controlling a prosthesis includes: a plurality of implantable devices, each of the implantable devices comprising: a hermetically sealed housing; one or more electrodes integrated into the housing and configured to detect EMG signals in a body; an implant antennadisposed within the housing; and a controller disposed within the housing and operatively coupled with the electrodes and the implant antenna. The controller is configured to: dynamically tune the implant antenna to wirelessly receive a power signal via magnetic resonance coupling using the implant antenna, and digitize the EMG signals detected by the electrodes. The system further includes a base station wirelessly coupled with the plurality of implantable devices. The base station includes: a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna wirelessly coupled with the plurality of implant antennas; an output bus operatively coupled with the prosthesis; and one or more processing units operatively coupled with the power delivery module and the output bus. The one or more processing units are configured to: operate the power delivery module to wirelessly supply the power signal to the implantable devices via magnetic resonance coupling; wirelessly receive the digitized EMG signals from the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

[0026] In one example (“Example 19”), a method includes: wirelessly receiving, by an antenna of an implantable device, a power signal; generating power using the power signal via magnetic resonance coupling; determining, by a controller of the implantable device based upon the power signal, an amount of parameter to adjust in order to optimize power generation; adjusting, by a parameter adjuster of the implantable device, one or more parameters by the determined amount; detecting, by one or more electrodes of the implantable device, EMG signals in a body; digitizing, by the controller, the EMG signals detected by the electrodes; and wirelessly transmitting the digitized EMG signals to an external device.

[0027] In one example (“Example 20”), a method includes: operating, by a controller of a base station wirelessly coupled with a plurality of implantable devices, a power delivery module of the base station to wirelessly supply a power signal to the plurality of implantable devices via magnetic resonance coupling; detecting a signal that is reflected from the implantable devices in response to supplying the power signal to the implantable devices; controlling, by the controller based upon the reflected signal, a plurality of switches operatively coupled with a plurality of capacitors that are arranged in a parallel configuration on the base station, tooptimize the power signal supplied to the implantable devices; wirelessly receiving digitized electromyogram (EMG) signals in a body from the implantable devices; generating, by the controller, output signals based upon the digitized EMG signals; and transmitting, via an output bus operatively coupled with the base station, the output signals to a prosthesis operatively coupled with the base station.

[0028] The foregoing examples are just that, and should not be read to limit or otherwise narrow the scope of any of the inventive concepts otherwise provided by the instant disclosure. While multiple examples are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature rather than restrictive in nature.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the embodiments of the disclosure and are incorporated in and constitute a part of this specification, illustrate examples, and together with the description serve to explain the principles of the disclosure.

[0030] FIG. 1 is a photographic image of a system for myoelectric sensing and controlling of prosthesis that is strapped to a human body, according to embodiments disclosed herein.

[0031] FIG. 2 is a cross-sectional illustration of the system of FIG. 1 showing the components thereof, according to embodiments disclosed herein.

[0032] FIG. 3 is an angled view of an implantable device as used in the system of FIG. 1 , where the housing is made transparent to show the components therein, according to embodiments disclosed herein.

[0033] FIG. 4 is a side view of the implantable device of FIG. 3, according to embodiments disclosed herein.

[0034] FIG. 5 is a schematic diagram of the system of FIG. 1 , according to embodiments disclosed herein.

[0035] FIG. 6 is a schematic diagram of the base station in the system of FIG. 1 , according to embodiments disclosed herein.

[0036] FIG. 7A is a graph showing the relationship between forward-to-reflected magnitude ratios and the power generated by the implantable device, according to embodiments disclosed herein.

[0037] FIG. 7B is a graph showing the relationship between phase differences and the power generated by the implantable device, according to embodiments disclosed herein.

[0038] FIG. 8 is a schematic diagram of a plurality of capacitors and switches in a parallel configuration and operable to control power signals generated by the base station, according to embodiments disclosed herein.

[0039] FIG. 9 is a flowchart of a process implemented by the implantable device, according to embodiments disclosed herein.

[0040] FIG. 10 is a flowchart of a process implemented by the base station, according to embodiments disclosed herein.

[0041] It should be understood that some of the drawings and replicas of the photographs may not necessarily be shown to scale, unless otherwise indicated. In certain instances, details that are not necessary for an understanding of the disclosure or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the disclosure is not necessarily limited to the particular examples or embodiments illustrated or depicted herein.DETAILED DESCRIPTIONDefinitions and Terminology

[0042] This disclosure is not meant to be read in a restrictive manner. For example, the terminology used in the application should be read broadly in the context of the meaning those in the field would attribute such terminology. Persons skilled in the art will readily appreciate that the various embodiments of the inventive concepts provided in the present disclosure can be realized by any number of methods and apparatuses configured to perform the intended functions. It should also be noted that the accompanying figures referred to herein are not necessarily drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the figures should not be construed as limiting. Some figures do, however, represent anatomy and the positioning of embodiments relativeto that anatomy and such representations should be understood to be scaled and positioned accurately, with some deviation permitted as the anatomical structures depicted will vary in size and position from person to person.

[0043] With respect to terminology of inexactitude, the terms “about” and “approximately” may be used, interchangeably, to refer to a measurement that includes the stated measurement and that also includes any measurements that are reasonably close to the stated measurement. Measurements that are reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount as understood and readily ascertained by individuals having ordinary skill in the relevant arts. Such deviations may be attributable to measurement error, differences in measurement and / or manufacturing equipment calibration, human error in reading and / or setting measurements, minor adjustments made to optimize performance and / or structural parameters in view of differences in measurements associated with other components, particular implementation scenarios, imprecise adjustment and / or manipulation of objects by a person or machine, and / or the like, for example. In the event it is determined that individuals having ordinary skill in the relevant arts would not readily ascertain values for such reasonably small differences, the terms “about” and “approximately” can be understood to mean plus or minus 10% of the stated value.

[0044] The phrases “at least one”, “one or more”, and “and / or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and / or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. When each one of A, B, and C in the above expressions refers to an element, such as X, Y, and Z, or class of elements, such as Xi-Xn, Yi-Ym, and Z1-Z0, the phrase is intended to refer to a single element selected from X, Y, and Z, a combination of elements selected from the same class (e.g., Xi and X2) as well as a combination of elements selected from two or more classes (e.g., Y1 and Zo).

[0045] It should be understood that every maximum numerical limitation given throughout this disclosure is deemed to include each and every lower numerical limitation as an alternative, as if such lower numerical limitations were expresslywritten herein. Every minimum numerical limitation given throughout this disclosure is deemed to include each and every higher numerical limitation as an alternative, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this disclosure is deemed to include each and every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.

[0046] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.Description of Various Embodiments

[0047] The present disclosure relates to systems, devices, and methods for providing implantable devices (nodes) and base stations for myoelectric sensing, that is, sensing for electromyogram (EMG) signals, that also have wireless power and data telemetry capabilities.

[0048] FIGs. 1 and 2 show an example of a system 100 for myoelectric sensing and controlling of prosthesis. The system 100 may be coupled with a residual limb of a human, as shown, and in some examples the system 100 may be attached to the body of the human using one or more straps and / or harnesses. The system 100 includes a base station 200 that is wirelessly coupled with one or more implantable devices 202, which may be referred to herein as nodes, that are capable of sensing EMG signals from inside the body. In the example as shown, the implantable devices 202 are located inside the residual limb of the human. In other examples, the devices 202 may be located inside a chest or torso of the human, as suitable, or any other suitable location in a human body, for sensing the EMG signals.

[0049] The base station 200 is coupled with a controller 204 for a prosthesis 206. The controller 204 may be any suitable controller that is capable of interpreting (or deciphering) the command signals provided by the base station 200 and instructing the prosthesis 206 how to move or function. For example, the controller 204 may be the Complete Control System Gen2 (Coapt, LLC), and the prosthesis 206 may be an Espire Elbow prosthesis (Steeper Group), both of which are matched with the base station 200.

[0050] The controller 204 may be operatively and electrically coupled with the base station 200 via an output bus 208 through which output signals are provided from the base station 200 to the controller 204. The base station 200 may be attached to or coupled with a socket 212 of the prosthesis 206 such that a powering antenna 210, which may be a cord, is wrapped around the locations in which the devices 202 are implanted within the residual limb. In some examples, the powering antenna 210 may be any suitable type and design of antenna, including but not limited to monopole and dipole antennas, as well as loop antennas and coils. In some cases, implementing the antenna 210 as a coil to wrap around the devices 202 that are implanted in the residual limb may be beneficial in allowing more efficient power signal transmission, as compared to a substantially flat loop antenna which may be disposed on one side of the limb such that some of the implants are farther from the antenna than other implants.

[0051] FIGs. 3 and 4 show an example of the implantable device 202 according to embodiments disclosed herein. The device 202 does not contain a battery and does not provide stimulation to the outside tissue when implanted. The device 202 includes a hermetically sealed housing 300, a controller 302, an antenna 304, and one or more electrodes 306. The controller 302 may be a microcontroller. The antenna 304 may also be referred to as a resonator. The antenna 304 may include a coil. The controller 302 and the antenna 304 are contained within the housing 300.

[0052] The implantable device 202 may include a single electrode 306 or a plurality of electrodes 306, such as a pair of electrodes 306A and 306B. The electrodes 306 may be integrated into the housing 300 and may be configured to detect EMG signals in the body while implanted. According to some examples, the housing 300 may be substantially cylindrical or tubular in shape, may resemble acapsule, or assume any other suitable shape or configuration. The housing 300 may have the electrode 306A disposed on one end of the housing 300, and the electrode 306B disposed between the two ends of the housing 300. In some examples, one or more of the electrodes 306 may be ring-shaped. In some examples, one or more of the electrodes 306 may extend circumferentially around the housing 300. In some examples, one or more of the electrodes 306 may be substantially flush with an external or outer surface of the housing 300.

[0053] In an example, the housing 300 may be formed of two portions: a first portion 308 and a second portion 310. The first portion 308 may define the section of the housing 300 between the electrodes 306A and 308B, and the second portion 310 may define the section of the housing 300 that is distal to the electrode 308B or extends beyond the electrode 308B. The first portion 308 and the second portion 310 may be formed using the same biocompatible material, or at least two different materials. For example, the second portion 310 may be made of a material that has a greater permittivity than the material that is used to make the first portion 308. As an example, the material of the first portion 308 may be aluminum, and the material of the second portion 310 may be ceramic, which has a greater permittivity than aluminum.

[0054] The antenna 304 may be disposed at an end of the controller 302 inside the housing 300, for example inside the second portion 310. The controller 302 may include, or may be disposed on, a printed circuit board (PCB) 312 having a longitudinal axis L — L as shown in FIG. 4. The longitudinal axis L — L may also define the longitudinal axis of the housing 300. The PCB 312 may be formed using a substrate with a length, width, and thickness, and the material of the substrate may include but are not limited to: fiberglass, ceramics, and / or any other suitable polymers including epoxy laminate and parylene, for example.

[0055] The antenna 304 may be disposed along or parallel to a transverse axis (T — T) that is substantially perpendicular to the longitudinal axis. For example, if the antenna 304 includes a coil, the coil may be wrapped such that the winding (or wrapping) of the coil is substantially parallel to the transverse axis, or the winding is on a plane that is parallel to the transverse axis or substantially perpendicular to the longitudinal axis. The coil may alternatively be defined such that the coil is woundaround the longitudinal axis, thereby using the longitudinal axis as the central axis of the coil. The device 202 may also include one or more capacitors 318 and resistors 320 (also referred to herein as parameter adjusters 316) that are disposed on the PCB 312 to perform adjustment on one or more parameters (e.g., capacitance and / or resistance) for autotuning the antenna 304, as well as a processing unit 314, for example an integrated circuit (IC) chip or a central processing unit (CPU), disposed on the PCB 312 which determines how much parameter adjustment is to be performed, as further explained herein.

[0056] The controller 302 is operatively and electrically coupled with the electrodes 306 and the antenna 304, such that the controller 302 is capable of dynamically tuning the antenna 304 to wirelessly receive power signals via magnetic resonance coupling using the antenna 304, as well as to digitize the EMG signals that are detected by the electrodes 306 and to wirelessly transmit the digitized EMG signals to an external device, which may be the base station 200. The dynamic tuning of the antenna 304 may be performed by determining, based upon the power signal received using the antenna 304, an amount of one or more parameter(s), e.g., at least one of a capacitance or a resistance of the implantable device 202, to adjust, and then adjusting, using the parameter adjuster(s) 316, the parameter(s) by the determined amount. This is performed, for example, using a variable capacitor (e.g., for voltage tuned capacitance) and / or a variable resistor (e.g., voltage-controlled resistor), which may be electrically adjusted by the controller 302. After each adjustment, the controller 302 may detect the next power signal that is subsequently received, and based on the newly detected power signal, the controller 302 may either adjust the parameter(s) more in the same direction, or in a different direction (such as increasing instead of decreasing, or vice versa) to self-tune the antenna 304, until the controller 302 determines that a desired power level is achieved.

[0057] In some examples, the controller 302 may also generate a unique identifier that is associated with the implantable device 202, and wirelessly transmit, using the antenna 304, the unique identifier, along with the digitized EMG signals, to the external device (e.g., base station 200). With such identifier, each of the multiple implantable devices 202 is capable of distinguishing itself from other devices 202, and the external device such as the base station 200 is also capable of separatingthe EMG signals provided by different implantable devices 202, thereby reducing the risk of mixing up or switching the received EMG signals.

[0058] In some examples, the diameter of the housing 300 may be from 5 mm to 6 mm, and the longitudinal length of the housing 300 may be from 20 mm to 30 mm. Multiple implantable devices 202 are to be implanted in the body so as to detect the EMG signals at various locations. In some examples, multiple devices 202, for example eight (8) such devices, may be implanted into a single limb so as to allow better control of the prosthesis 206. Upon detecting the EMG signals, the device 202 digitizes the detected EMG signals and transmits the digitized EMG signals in a signal using a predetermined frequency within the ISM band, for example 2.4 GHz. Simultaneously, the device 202 may also transmit a unique identifier that is specifically assigned to the device 202 along with the digitized EMG signal, such that the external device, such as the base station 200, that receives the digitized EMG signals from multiple devices 202 can differentiate between the signals provided from the different devices.

[0059] FIG. 5 shows the different components of the base station 200, in an embodiment. The base station 200 includes one or more processing units 500 and a power delivery module 502 operatively coupled with the processing units 500. The module 502 includes a signal generator 504, a signal amplifier 506, a plurality of capacitors 508, and a plurality of switches 510 coupled with or associated with the corresponding capacitors 508. The signal generator 504 may be any suitable power signal generator which facilitates the magnetic resonance coupling with the implantable devices 202 to wirelessly supply power to each of the devices 202. The signal amplifier 506 may be any suitable power signal amplifier which operates with the signal generator 504 and the powering antenna 210 to amplify the power of the signal to be transmitted via the antenna 210. The signal amplifier 506 may additionally or alternatively operate to amplify the signals received by the base station 200 from the implantable devices 202, for example via the powering antenna 210 or another antenna of the base station 200.

[0060] In some examples, the powering antenna 210 may operate to solely transmit the powering signal to the implantable devices 202, in which case an additional antenna (not shown) is also provided in the base station 200 that operatesto receive the EMG signals transmitted from the implantable devices 202. In some examples, the powering antenna 210 may additionally operate to receive the EMG signals transmitted from the implantable devices 202, in which case the additional antenna may not be required in order to receive the EMG signals from the devices 202. In some examples, multiple antennas are provided for redundancy such that even if one antenna fails, the remaining antenna(s) would be capable of substituting for the failed antenna.

[0061] A plurality of capacitors 508 and switches 510 (e.g., radiofrequency or microwave switches) are provided such that each switch is configured to control operation of a corresponding capacitor, and the capacitors are arranged in a parallel configuration with respect to each other, as shown in FIG. 8 for example. Each of the switches 510 is independently operable and can receive control signals from the processing unit(s) 500 in order to switch between a closed circuit and an open circuit, thereby connecting or disconnecting (or isolating) the corresponding capacitor with respect to the remaining capacitors. In the parallel configuration, each of the capacitors 508 is capable of being connected to a common input line, RF(in), and a common output line, RF(out), that is connected to the signal generator 504. In some examples, each of the capacitors 508 has a capacitance that is unique to the capacitor. For example, if there are eight (8) capacitors 508, the capacitance values thereof may be 10 pF, 20 pF, 56 pF, 100 pF, 220 pF, 560 pF, 1000 pF, and 2000 pF. Any other suitable combination of capacitance values may be implemented, such as from 10 pF to 20 pF, from 20 pF to 50 pF, from 50 pF to 100 pF, from 100 pF to 200 pF, from 200 pF to 500 pF, from 500 pF to 1000 pF, from 1000 pF to 2000 pF, or any other range therebetween. Providing a plurality of capacitors, with different values of capacitance, provides the benefit of offering a greater granularity in adjusting the outputted power signal, based upon the signal that is reflected from the implanted devices 202, as further explained herein.

[0062] FIG. 6 shows an example of how the base station 200 may be implemented according to configurations disclosed herein. The base station 200 in this example includes one or more processing units, which in this case are microcontrollers (MCU) 500, each being an IC chip having an independently operating processing unit, memory module (e.g., random access memory and / orflash memory, as well as any other suitable type of volatile or non-volatile memory as known in the art), communication interface(s), and peripheral(s), as known in the art. The MCUs 500 are operatively and electrically coupled with a radiofrequency (RF) generator 600, an auto-tuner 602, a plurality of buses 604, an auxiliary input / output (I / O) interface 606, a plurality of test points 608, a plurality of external connections 610, and a power conditioning module 612. The base station 200 is also provided with a power source (not shown) such as an energy storage device including but are not limited to a battery (for example, a two- to four-cell lithium polymer or lithium ion battery) or a power grid that provides the necessary voltage to operate the base station. The functionality of each component is further explained herein. In some examples, the components of the base station 200 may be attached or affixed to one or more surfaces of one or more PCBs (not shown).

[0063] The MCU 500 may include a single MCU capable of performing all functions as disclosed herein, or may include a plurality of MCUs such that each MCU performs a portion of the functions. As such, hereinafter, any reference to the “MCU” is to be understood as including at least one MCU. In some examples, the functions of the MCU include aggregating data that is received via wireless data transmission, for example with the use of Bluetooth® Low Energy (Bluetooth LE / BLE) chipset(s), into aggregated data to be transmitted to an external device such as the controller 204 of the prosthesis 206 via the output bus 208, which may be one of the buses 604. In some examples, the functions of the MCU include controlling the RF generator 600 by setting the frequency and amplitude of the powering signal that is to be generated. The setting may be performed via an input bus such as a Serial Peripheral Interface (SPI) or a signal pin such as a general-purpose input / output (GPIO) interface, for example. In some examples, the functions of the MCU include communicating with the auto-tuner 602 which may be a coil tuning coprocessor via communication hardware such as a universal asynchronous receiver-transmitter (UART), for example. In some examples, the functions of the MCU include controlling light-emitting diodes (LEDs) which may be installed on the base station 200 for light indication, for example. The light indication may be provided for user notification.

[0064] The RF generator 600 is configured to energize the powering antenna 210 to provide power to the implantable devices 202. In some examples, the RF generator 600 may be operatively coupled with a power amplifier (e.g., the signal amplifier 506) which takes a continuous wave signal generated by the RF generator 600 and amplifies the signal to a predetermined energy level or power. The predetermined power may be at or below 1 W. Beneficially, maintaining the power transmission at or below 1 W may help prevent the system from excessive heating or overheating. In some examples, a low pass filter may be implemented to reduce the harmonics of the continuous wave signal. In some examples, the frequency of the signal that is transmitted may be within the ISM band.

[0065] In some examples, the frequency of the powering signal may range from 5 MHz to 7 MHz, from 7 MHz to 10 MHz, from 10 MHz to 15 MHz, from 15 MHz to 20 MHz, from 20 MHz to 30 MHz, from 30 MHz to 50 MHz, from 50 MHz to 70 MHz, from 70 MHz to 100 MHz, or any other suitable value therebetween or combination of ranges thereof, to facilitate efficient power generation via magnetic resonance coupling with the implantable devices 202. In some examples, the frequency is within one of the ISM frequency bands, such as from 6.765 MHz to 6.975 MHz (center frequency 6.78 MHz), from 13.553 MHz to 13.567 MHz (center frequency 13.56 MHz), from 26.957 MHz to 27.283 MHz (center frequency 27.18 MHz), from 40.66 MHz to 40.7 MHz (center frequency 40.68 MHz), etc. In some examples, the power amplifier has a ground (e.g. metal base) that is connected to the system ground of the base station 200, where the ground is electrically connected via a metal heatsink to a ground of the PCB to which the other components of the base station 200 may be attached. The PCB may have an exposed copper area to allow such connections.

[0066] In some examples, the RF generator 600 may condition the amplitude of the continuous wave signal to a predetermined range. In some examples, the range may be from 10 dBm to 15 dBm, such as at 14 dBm, such that the signal may be fed to the power amplifier to generate a final output having a predetermined range of wattage. In some examples, the range may be from 0.1 W (watt) to 0.3 W, from 0.3 W to 0.5 W, from 0.5 W to 0.7 W, from 0.7 W to 1 W, or any other suitable range therebetween or combination of ranges thereof.

[0067] The auto-tuner 602 is a coprocessor which operates with the MCU 500. The coprocessor may be an individual MCU or IC chip that works in conjunction with the MCU 500 as well as the RF generator 600. In some examples, the functionality of the auto-tuner 602 may be incorporated into the MCU 500. The functions of the auto-tuner 602 may include obtaining a voltage standing wave ratio (VSWR) by reading from an analog- digital converter (ADC) coupled therewith. The functions of the auto-tuner 602 also include detecting the signal that is reflected from the implantable devices 202 after power signal has been transmitted to the devices 202, and based on analyzing the reflected signal, computing an optimal tuning configuration (e.g., adjustment to the impedance by controlling the capacitors 508). The functions of the auto-tuner 602 also include controlling the RF switches 510 to achieve such optimal tuning. In some examples, the optimal tuning is defined as achieving a configuration that achieves the lowest value of VSWR.

[0068] To perform the functions of the auto-tuner 602, there may be one or more coil tuning circuits (for example, a tuning circuit 800 as shown in FIG. 8) implemented therein, or operatively coupled therewith. The auto-tuner 602 automatically senses the forward and reflected RF signals to / from the powering antenna 210. In some examples, the auto-tuner 602 converts the ratio of the forward RF signal power to the reflected RF signal power (i.e. , forward-to-reflected RF power ratio) into a direct- current (DC) value. In some examples, the auto-tuner 602 converts a phase relationship between the forward RF signal and the reflected RF signal, such as a relative phase shift between these signals, into a DC value. Both examples of conversion are explained further with respect to FIGs. 7A and 7B. In response, the auto-tuner 602 determines which of the capacitors 508 to insert into the tuning circuit or to remove from the tuning circuit, by automatically controlling the corresponding switches 510, so as to optimize the subsequent DC value.

[0069] In some examples, the conversion of the forward-to-reflected RF power ratio to a DC value may be facilitated using a directional coupler. For example, the directional coupler may couple a fraction of the forward RF wave and the reflected RF wave to a gain detector. The detector outputs the ratio of the forward RF wave amplitude to the reflected RF wave amplitude as a DC value. In some examples, the conversion of the phase relationship between the forward RF signal and the reflectedRF signal into a DC value may be facilitated using the same directional coupler. For example, the directional coupler may couple a fraction of the forward RF wave and the reflected RF wave to a phase detector. The detector outputs the relative phase difference between the two RF waves as a DC value. In some examples, the gain detector and the phase detector are separate components. In some examples, a single detector is capable of detecting both the gain and the phase.

[0070] The buses 604 may include any one or more types of wired electrical connections. For example, wired connections may include serial cables, fiber optic cables, CAT5 cables, FFC / FPC jumper cables, or any other form of wired connection. In some examples, the buses 604 may include a controller area network (CAN) bus that provides the exchange of signals, information, and / or data. The CAN bus may include any number of wired and wireless connections.

[0071] The auxiliary I / O interface 606 may be used for hardware flow control, or controlling the flow of electrical signals between or within hardware components. For example, one or more of the buses 604 of the base station 200 may not have any built-in hardware for controlling flow of electrical signals therein, thus requiring software flow control to be implemented. An example of such software flow control may include round robin which is used in scheduling algorithms to distribute electrical signals evenly among available resources / components. In some examples, the auxiliary I / O interface 606 may serve as a backup hardware flow control mechanism in case the software flow control is not sufficient or fails to operate.

[0072] In some examples, the auxiliary I / O interface 606 may include two I / O lines, each of which is implemented with suitable transceivers that are configured in half-duplex to provide the system with two pairs of differential lines for flow control. Alternatively, the transceivers may be bypassed such that the two differential pairs are converted into four single-ended signals. In some examples, the auxiliary I / O interface 606 may be configured to operate in single-ended mode. In some examples, the auxiliary I / O interface 606 may be configured to operate in differential mode to improve noise immunity or to reduce the amount of noise in the system. When operating in the differential mode, the auxiliary I / O interface 606 may be treated as additional half-duplex buses. When operating in the single-ended mode, each of the signal lines may be used, for example, as an interrupt request line (IRQ).

[0073] The test points 608 include a plurality of exposed electrically conductive pads, such as copper pads, that can be utilized for debugging or profiling purposes. The test points 608 may be used to test for data transmission (e.g., signal transmission) in communication hardware such as the LIART associated with one or more of the components, such as the MCU or the auto-tuner, or wireless data transmission devices such as the BLE chipset. In some examples, the test points 608 may be used for testing power rails, which may be used to connect the components with the power source to facilitate energy transfer. In some examples, the test points 608 may be used to extract profiling information from the MCU or multiple MCUs, such as a timing code execution path. In some examples, the test points 608 may be used to test for the control signals transmitted via the auxiliary I / O interface 606. Control signal types may include those originating from the MCU(s) and the wireless data transmission devices such as the BLE chipset.

[0074] The external connections 610 include cables or harnesses that are connected to the base station 200 during operation. In some examples, the external connections 610 may include connections for flashing or programming on-board MCUs such as the MCU 500, where flashing refers to the process of moving a computer program into the memory of the MCU. Once flashed, the MCU is capable of executing the flashed program when powered on. In some examples, the external connections 610 may also include connections for the auxiliary I / O interfaces 606 such as for connecting to off-board BLE chipsets, for an RF connector that is configured to energize the powering antenna via a power socket, or a CAN bus.

[0075] The power conditioning module 612 may be implemented as an IC chip that provides the base station 200 with protection against overvoltage, undervoltage, and reverse polarity to ensure that an input voltage is maintained within a predetermined range, such as from 5.23 V to 17.06 V. In some examples, the power conditioning module 612 also provides protection against overcurrent. In some examples, the power condition module 612 also generates voltages (for example, 10 V, 5 V, and 3.3 V) for system rails to provide power to each of the components electrically coupled to the system rails, according to the power demand of the component. For example, the 10 V rail may supply power to the signal amplifier 506. The 5 V rail may supply power to the RF generator 600, the RF detector (such as thegain / phase detector), and an external BLE chipset. The 3.3 V rail may supply power to the MCU 500, an internal BLE chipset, the auto-tuner 602, the transceivers, and the switches 510 as well as the logic control for the switches. In some examples, one or more filter caps may be provided at the outputs to reduce noise on the power rail, and may be removed to allow current measurements to be made on the power rails.

[0076] In some examples, the module 612 includes one or more resettable fuses in order to limit the current of the system to a predetermined value, such as 750 mA. The fuse is configured to reset after the overcurrent condition is removed from a downstream circuit. In some examples, the module 612 includes one or more transient-voltage-suppression (TVS) diodes in order to limit the maximum voltage of the system to a predetermined value, such as 17 V. The TVS diode may be placed downstream of the resettable fuse such that, if the TVS diode fails and becomes a short circuit, the resettable fuse can trip and protect the power source that is upstream. Furthermore, in some examples, the resettable fuse and the TVS diode may work together to protect the system from negative voltage, such as when a battery is plugged in backwards.

[0077] FIG. 7A shows a relationship between magnitude ratio (in dB) and voltage (in mV). The magnitude ratio represents the forward-to-reflected RF power ratio as previously explained herein. The voltage is the amount of voltage generated by magnetic resonance coupling. The relationship shows an increase in the amount of generated voltage in response to an increase in the magnitude ratio. When the magnitude ratio is 0 dB, the forward RF power is equal to the reflected RF power, indicating that the implantable device 202 is not receiving any power. Therefore, increasing the difference between the power of the powering signal sent to the implantable device 202 and the power of the signal reflected from the implantable device 202 in response to receiving the powering signal to be as large as possible would facilitate a greater amount of power being generated forthe implantable device 202.

[0078] FIG. 7B shows a relationship between phase difference (in degrees) and voltage (in mV). The phase difference is the difference in phase between the forward powering signal transmitted to the implantable device 202 and the reflected signalfrom the implantable device 202 in response to receiving the powering signal. The relationship shows a maximum voltage generated when the phase difference is 0. Therefore, adjusting the phase of the forward powering signal to substantially match the phase of the reflected signal from the implantable device 202 would facilitate the greatest amount of power being generated for the implantable device 202.

[0079] FIG. 8 shows an example of a tuning circuit 800 according to embodiments disclosed herein. The tuning circuit 800 includes a plurality of capacitors 508 and switches 510 associated with the capacitors. The switches 510 are controlled using control signals provided by the processing unit 500 in FIG. 5 or the auto-tuner 602 in FIG. 6, in order to insert or remove the corresponding capacitors 508 to or from the tuning circuit 800. The capacitors 508 are connected in a parallel configuration with respect to each other, such that removing or inserting a capacitor changes the overall capacitance of the circuit 800, thereby changing the output power signal that is transmitted by the powering antenna 210. In the illustration of FIG. 8, there are three (3) capacitors 508A, 508B, and 508C and three (3) switches 510A, 510B, and 510C corresponding thereto. It is to be understood that any number of capacitors and switches may be implemented. Furthermore, increasing the number of capacitors would beneficially provide additional granularity to the adjustability of the powering signal.

[0080] Upon receiving the respective control signal (e.g., 508A control signal, 508B control signal, and / or 508C control signal), the switches may change position such that one position creates an open circuit in the switch (denoted by the “X”) and the other position connects the input line RF(in) with the output line RF(out) via the appropriate capacitor. In some examples, the switches 510 may require both a buffered version and an inverted version of the control signals to be provided before feeding to the switches. In such cases, each switch may also be coupled with dual inverters capable of converting the control signal to the buffered version and the inverted version of the control signal to be provided to the switch.

[0081] FIG. 9 shows an example of a process 900 which may be performed by the implantable device 202. In step 902, a power signal is wirelessly received, for example by the antenna 304 of the device 202. In step 904, power is generated using the power signal via magnetic resonance coupling. The generated power isused to activate or power the controller 302, which in step 906 determines, based upon the power that was generated or based upon the power signal that was received, an amount of one or more parameters to adjust, in order to optimize power generation for the device 202. The parameter may include one or more of the capacitance and / or resistance of the capacitor 318 and / or resistor 320 (collectively referred to as the parameter adjuster 316) that is implemented in the device 202. In step 908, the parameter adjuster 316 is controlled so as to adjust the one or more parameters by the determined amount.

[0082] In some examples, the process 900 may return to step 904 after performing step 908 if the controller 302 determines that the amount of power that was generated is too little to adequately perform the operations assigned to the device 202. In some examples, the adjustment may be repeated multiple times before the controller 302 determines that the power generation is adequate, or the amount of power that is generated has reached a predetermined threshold, in which case the process 900 may proceed to step 910. In some examples, the process 900 may continue from step 908 to step 910 regardless of the amount of power generated in step 904.

[0083] In step 910, the electrodes 306 of the implantable device 202 detects the EMG signals in the body. In step 912, the controller 302 digitizes the EMG signals detected by the electrodes 306. In step 914, the digitized EMG signals are wireless transmitted, for example via the antenna 304, to an external device, which may be the base station 200. The process 900 may then return to step 902 when additional power signals are provided, or to step 910 when there is sufficient power for the device 202 to continue its operation.

[0084] FIG. 10 shows an example of a process 1000 which may be performed by the base station 200. In step 1002, the controller or processing unit 500 of the base station 200 operates the power delivery module 502 to wireless supply a power signal to the implantable devices 202 via magnetic resonance coupling. In step 1004, the base station 200 detects a signal that is reflected from the implantable devices 202 in response to supplying the power signal in step 1002. The signal may be detected by any one or more of the antennas that is implemented in the base station 200. In step 1006, the controller 500 controls, based upon the reflected signal, the switches510 associated with the capacitors 508 that are arranged in a parallel configuration, in order to optimize the power signal supplied to the devices 202.

[0085] In some examples, the process 1000 returns to step 1002 for the base station 200 to send the power signal again to the implantable devices 202 to determine whether the power signal optimization was successful. In some examples, steps 1002, 1004, and 1006 may be repeated until the base station 200 determines that the amount of power that is generated by the devices 202 is sufficient for future operation, in response to which the process 1000 proceeds to step 1008. In some examples, the process 1000 may continue from step 1006 to step 1008 regardless of the amount of power generated by the devices 202.

[0086] In step 1008, the base station 200 wirelessly receives the digitized EMG signals in the body from the devices 202, for example via the one or more antennas implemented in the base station 200. In step 1010, the controller 500 generates output signals based upon the digitized EMG signals. In step 1012, the controller 500 transmits, via the output bus 208, the output signals to the prosthesis 206. In some examples, the output signals are transmitted directly to the controller 204 that is located external to the base station 200 and configured to control movements of the prosthesis 206. The controller 204 may receive the output signals (command signals) from the base station 200 and deciphers the signals, after which the controller 204 instructs the prosthesis 206 how to move. The process 1000 may then return to step 1002 when additional power signals are provided, or to step 1008 when there is sufficient power for the device 202 to continue its operation.

[0087] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of this disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.

Claims

CLAIMSWhat is claimed is:1 . An implantable device comprising: a hermetically sealed housing; one or more electrodes integrated into the housing and configured to detect electromyogram (EMG) signals in a body; an antenna disposed within the housing; and a controller disposed within the housing and operatively coupled with the electrodes and the antenna, wherein the controller is configured to: dynamically tune the antenna to wirelessly receive a power signal via magnetic resonance coupling using the antenna, and digitize the EMG signals detected by the electrodes and wirelessly transmit the digitized EMG signals to an external device.

2. The device of claim 1 , wherein each of the electrodes is configured as a ring and defines a portion of an outer surface of the housing.

3. The device of claim 1 , wherein the antenna is disposed more distally within the housing than one of the electrodes.

4. The device of claim 1 , wherein the housing comprises a first portion and a second portion, and the antenna is disposed within the second portion of the housing.

5. The device of claim 4, wherein the first portion has a first permittivity, and the second portion has a second permittivity greater than the first permittivity.

6. The device of claim 1 , wherein the controller is disposed on a printed circuit board having a longitudinal axis, and the antenna is disposed along a transverse axis that is substantially perpendicular to the longitudinal axis.

7. The device of claim 6, wherein the antenna includes a coil that is wrapped in a direction substantially parallel to the transverse axis.

8. The device of claim 1 , wherein the controller is configured to generate a unique identifier associated with the device and wirelessly transmit the unique identifier with the digitized EMG signals.

9. The device of claim 1 , wherein the controller is configured to amplify the EMG signals detected by the electrodes prior to digitizing the EMG signals.

10. The device of any one of the preceding claims, further comprising at least one parameter adjuster, wherein the controller is configured to dynamically tune the antenna by: determining, based upon the power signal received using the antenna, an amount of parameter to adjust; and adjusting, using the parameter adjuster, one or more parameters by the determined amount.11 . The device of claim 10, wherein the at least one parameter adjuster includes at least one capacitor and at least one resistor.

12. The device of claim 11 , wherein the one or more parameters include a capacitance of the at least one capacitor and a resistance of the at least one resistor.

13. A base station for detecting electromyogram (EMG) signals, the base station comprising: a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna configured to wirelessly couple with a plurality of receiver antennas of a plurality of implantable devices, wherein the implantable devices are configured to detect the EMG signals; an output bus operatively coupled with a prosthesis; andone or more processing units operatively coupled with the power delivery module and the output bus, wherein the one or more processing units are configured to: operate the power delivery module to wirelessly supply a power signal to the implantable devices via magnetic resonance coupling; wirelessly receive digitized EMG signals transmitted by the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

14. The base station of claim 13, wherein the powering antenna includes a coil configured to be wrapped around a plurality of locations in which the implantable devices are implanted.

15. The base station of claim 14, wherein the powering antenna is configured to deliver a total energy of no greater than 1 watt.

16. The base station of any one of claims 13-15, wherein the power delivery module further comprises a plurality of capacitors arranged in a parallel configuration, wherein the capacitors are coupled with a plurality of switches configured to separately and individually control operation of the corresponding capacitor coupled therewith, wherein the one or more processing units are configured to: detect a signal that is reflected from the implantable devices in response to supplying the power signal to the implantable devices; and control, based upon the reflected signal, the switches of the capacitors to optimize the power signal supplied to the implantable devices.

17. The base station of claim 16, wherein the one or more processing units are configured to:calculate a phase relationship between the power signal to the reflected signal; calculate, based upon the phase relationship, a DC level for the power signal; and control, based upon the DC level, the switches of the capacitors to optimize the power signal supplied to the implantable devices.

18. A system for controlling a prosthesis, the system comprising: a plurality of implantable devices, each of the implantable devices comprising: a hermetically sealed housing; one or more electrodes integrated into the housing and configured to detect electromyogram (EMG) signals in a body; an implant antenna disposed within the housing; and a controller disposed within the housing and operatively coupled with the electrodes and the implant antenna, wherein the controller is configured to: dynamically tune the implant antenna to wirelessly receive a power signal via magnetic resonance coupling using the implant antenna, and digitize the EMG signals detected by the electrodes; and a base station wirelessly coupled with the plurality of implantable devices, the base station comprising: a power delivery module comprising a signal generator, a signal amplifier, and a powering antenna wirelessly coupled with the plurality of implant antennas; an output bus operatively coupled with the prosthesis; and one or more processing units operatively coupled with the power delivery module and the output bus, wherein the one or more processing units are configured to:operate the power delivery module to wirelessly supply the power signal to the implantable devices via magnetic resonance coupling; wirelessly receive the digitized EMG signals from the implantable devices; generate output signals based upon the digitized EMG signals; and transmit, via the output bus, the output signals to control operation of the prosthesis.

19. A method comprising: wirelessly receiving, by an antenna of an implantable device, a power signal; generating power using the power signal via magnetic resonance coupling; determining, by a controller of the implantable device based upon the power signal, an amount of parameter to adjust in order to optimize power generation; adjusting, by a parameter adjuster of the implantable device, one or more parameters by the determined amount; detecting, by one or more electrodes of the implantable device, electromyogram (EMG) signals in a body; digitizing, by the controller, the EMG signals detected by the electrodes; and wirelessly transmitting the digitized EMG signals to an external device.

20. A method comprising: operating, by a controller of a base station wirelessly coupled with a plurality of implantable devices, a power delivery module of the base station to wirelessly supply a power signal to the plurality of implantable devices via magnetic resonance coupling; detecting a signal that is reflected from the implantable devices in response to supplying the power signal to the implantable devices; controlling, by the controller based upon the reflected signal, a plurality of switches operatively coupled with a plurality of capacitors that are arranged in aparallel configuration on the base station, to optimize the power signal supplied to the implantable devices; wirelessly receiving digitized electromyogram (EMG) signals in a body from the implantable devices; generating, by the controller, output signals based upon the digitized EMG signals; and transmitting, via an output bus operatively coupled with the base station, the output signals to a prosthesis operatively coupled with the base station.

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