Patent Publication Number: US-11642232-B2

Title: Sensor system

Description:
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with U.S. Government support under one or more of contract nos. W911NF-17-C-0058, W911NF-15-C-0014, HR0011512791 awarded by Defense Advanced Research Projects Agency and NS067784-01A1 awarded by the National Institutes of Health. The U.S. Government may have certain rights in this invention. 
    
    
     RELATED APPLICATIONS 
     This application claims the benefit of the filing date of U.S. patent application Ser. No. 15/870,362, filed Jan. 12, 2018, and titled “Sensor System,” the disclosure of which is hereby incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     This disclosure relates to systems and methods for obtaining biopotential signals from a plurality of electrodes in communication with existing muscles or nerves of a patient. More particularly, but not exclusively, such systems may be used to control external devices, such as a prosthesis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates one embodiment of an implantable component of a myoelectric sensor system having a plurality of leads and a plurality of electrodes disposed on each lead consistent with embodiments of the present disclosure. 
         FIG.  2 A  illustrates a perspective view of an external transceiver assembly configured to power and communicate with an implantable electrode consistent with embodiments of the present disclosure. 
         FIG.  2 B  illustrates a cross-sectional view of the external transceiver assembly of  FIG.  2 A  taken along line  2 B- 2 B consistent with embodiments of the present disclosure. 
         FIG.  2 C  illustrates a partially exploded view of the transceiver of  FIG.  2 A  consistent with embodiments of the present disclosure. 
         FIG.  3    illustrates a functional block diagram of an implantable sensor system consistent with embodiments of the present disclosure. 
         FIG.  4    illustrates a flow chart of a method of using an implantable myoelectric sensor system consistent with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Disclosed herein are systems and methods for an implantable myoelectric sensor system that may be utilized in a variety of applications. In some embodiments consistent with the present disclosure, the systems and methods disclosed herein may be utilized to control prosthetic devices. A prosthetic device may be controlled using existing muscle groups in the residual limb that the user may be able to voluntarily activate. By connecting sensors to these muscles, the patient may be able to control the prosthetic device by activating the remaining muscles. The sensors may be connected to amplification and acquisition circuitry and a processor to control movement in a prosthetic device. As used in the present disclosure, the term myoelectric prosthesis refers to devices that use biopotential signals or potentials from voluntarily activated muscles to control the movements of a prosthesis. 
     In connection with a myoelectric prosthesis, biopotential signals may be collected via an electrode, lead, or sensor. Leads are structures that contain one or more electrodes or sensors that are individually placed, or placed in conjunction with other leads. Biopotential channels are electrical differences recorded between one or more electrodes. Electrodes/leads/sensors may be placed on or near the surface of the muscle or implanted into the muscle. A biopotential-signal-receiving device may also be implanted and may connect with an external transceiver via a wireless communication channel. 
     According to various embodiments, systems and methods consistent with the present disclosure may include a wireless multichannel myoelectric implant. In some embodiments, a wireless multichannel implant may be used to acquire biopotential signals from implanted electrodes. Representations of the acquired biopotential signals may be transmitted wirelessly to a system outside the body configured to receive, processes, and utilize the signals to control a myoelectric prosthesis. 
     It may be difficult during a surgery to implant an electrode to determine whether the electrode receives a specific biopotential signal. Accordingly, in various embodiments consistent with the present disclosure, an array of electrodes may be implanted on a plurality of leads to ensure broad coverage of the muscles in the implant area. Signals from the array of electrodes may be analyzed following implantation and processed to make one or more “virtual pairs” of electrodes, which may be selected for use in controlling a prosthesis. In other words, the array of electrodes may be utilized in a flexible configuration that allows for selection of one or more “virtual pairs” that best correspond to a desired biopotential signal used to control a prosthesis. 
     The embodiments of the disclosure will be best understood by reference to the drawings, wherein like parts may be designated by like numerals. The components of the disclosed embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the systems and methods of the disclosure is not intended to limit the scope of the disclosure, as claimed, but is merely representative of possible embodiments of the disclosure. In addition, the steps of a method do not necessarily need to be executed in any specific order, or even sequentially, nor need the steps be executed only once, unless otherwise specified. 
       FIG.  1    illustrates one embodiment of an implantable component  100  of a myoelectric sensor system having a plurality of leads  102  and a plurality of electrodes  104  disposed on each lead consistent with embodiments of the present disclosure. The plurality of leads  102  may each connect to a hermetic feedthrough on a housing  114 . In various embodiments, the housing  114  may be formed of a bio-compatible material and may be hermetically sealed to allow for implantation in a patient. In one specific embodiment, the housing  114  may be formed of ceramic. A plurality of suture holes  112  may be disposed on the housing  114  and may allow the housing to be secured to adjacent tissue. As discussed in greater detail below, the housing  114  may comprise electronics to receive signals from the plurality of electrodes  104  and to communicate with an associated device. 
     The plurality of leads  102  may be flexible, and may be independently positioned within one or more muscle groups. The leads may be wire, helically wound wire or of other constructions including a biostable polymer comprising a plurality of distinct conductive particles. In the illustrated embodiment, implantable component  100  includes eight full length leads  102 , each of which includes four electrodes  104 . 
     A reference lead  108  may include a plurality of reference electrodes  110 . A reference electrode  110  may provide a stable electrical potential against which the electrical potential of other electrodes  104  may be amplified and acquired. The system may be referred to as a “single-ended” reference. The “single-ended” reference may allow for the generation of “virtual pairs” in digital signal processing, rather than using analog amplifiers. 
     In additional to creating differential pairs between reference electrodes  110  and electrodes  104 , “virtual pairs” of electrodes may also be generated after acquisition by a comparison the signal from any electrodes  104  to the signal from any other electrode. For example, a “virtual pair” may be created by comparison of the signals received by the two electrodes identified by reference number  116 . In other words, a “virtual pair” may be generated as a difference between one of the plurality of electrodes and any other of the plurality of electrodes. A “virtual pair” may be generated from multiple signals from electrodes located on one lead or on separate leads. The ability to create a “virtual pair” based on two or more electrode signals provides a wide array of possible combinations. The large number of possible combinations may be analyzed to identify the specific combinations to achieve a specific result (e.g., utilization of a muscle group to control a prosthesis). 
     An anchor  106  may be disposed at the end of each lead  102  and reference lead  108 . The anchors may be configured to hold the leads  102 ,  108  in place. In the illustrated embodiment, a plurality of flanges  118  may oppose motion in the direction of the housing  114 . In contrast, when the leads  102 ,  108  are inserted, the flanges may be pressed inward and offer little resistance. 
       FIG.  2 A  illustrates a perspective view of an external transceiver assembly  200  configured to power and communicate with an implantable electronics package consistent with embodiments of the present disclosure. In various embodiments, external transceiver assembly  200  may be used with implantable component  100  illustrated in  FIG.  1   . The external transceiver assembly may be positioned above the implantable component, and in some embodiments, may be housed within a prosthesis controlled by using biopotential signals received from the implantable component. 
     External transceiver assembly  200  may comprise a housing  202  configured to contain electronics for communicating with an implantable component. A connector  206  may provide an interface for controlling a prosthesis or other device. Power may also be provided via connector  206  for both the external transceiver assembly  200  and an associated implanted component. A plurality of light sources  204  may be disposed on the surface of external transceiver assembly  200 . The plurality of light sources  204  may provide information regarding the status of the external transceiver assembly  200  and/or an associated implantable component. In some embodiments, the external transceiver may include switched or buttons to control operation on the device, including turning off power to the implanted device, changing decode processing parameters such as gain, or switching processing algorithms. In some embodiments, the plurality of light sources  204  may be used in connection with a corresponding plurality of buttons that may be used to provide input to the external transceiver assembly  200 . 
     The external transceiver may have a tunable element, such as a trimmable capacitor, to optimize the power transfer efficiency for individual implants or relative placement of the external transceiver and implanted device. 
       FIG.  2 B  illustrates a cross-sectional view of the external transceiver assembly  200  of  FIG.  2 A  taken along line  2 B- 2 B consistent with embodiments of the present disclosure. Housing  202  includes a printed circuit board (PCB)  220  to which a plurality of electronics may be mounted. The electronics may be configured to enable communication with an implantable component via a receiver  228 . In some embodiments, the receiver may comprise an infrared receiver. The electronics may have components to communicate to the implant by means of amplitude modulation of the inductive powering signal. 
     Communication from an implantable component may be performed with a receiver  228 . In some embodiments, the receiver  228  may comprise an infrared receiver. The infrared frequency range may be well suited to transcutaneous transmission; however, the transceiver may operate using other frequencies in the electromagnetic spectrum. A lens  226  may be configured to focus electromagnetic energy received from an implantable component to the receiver  228 . A lens cover  230  may be disposed at the opening of an aperture in which the lens  226  and receiver  228  are disposed. A second electromagnetic shield  234  may be disposed over the receiver to shield the receiver from noise from the power transmitter. In some embodiments, the second electromagnetic shield  234  may be formed of metal. 
     An inductive coil  222  may be disposed about a portion of the outer surface of housing  202  nearest to the implantable component. The inductive coil  222  may be configured to wirelessly provide electrical power to the implantable component. The inductive coil  222  may be inductively coupled with the implantable component to deliver electrical power. In some embodiments, the wireless electrical power delivered to the implant may be amplitude modulated to provide communication from the external transceiver to the implant. 
     A shield  224  may separate the transceiver  226  from the inductive coil  222 . In some embodiments, the shield  224  may be formed of a ferrous material. The shield  224  may be formed in a disk shape around an aperture in which the transceiver  228 , lens  226 , and lens cover  230  are disposed. In some embodiments, the shield  224  may be formed such that the inductive coil  222  may be received within the shield  224 . The shield may be a ferrite designed to shape the electromagnetic field to increase the coupling between the external transceiver and the implanted device. 
       FIG.  2 C  illustrates a partially exploded view of the external transceiver assembly of  FIG.  2 A  consistent with embodiments of the present disclosure. The bottom portion of housing  202  is omitted to avoid obscuring details of the disclosure. The connector  206  and transceiver  228  are disposed on PCB  220 . 
     Shield  224  is formed in a disk shape with an aperture  232  in the center. The aperture  232  may receive the lens  226 . The lens cover  228  may close aperture  232  in the lower portion of the housing. A channel  234  is formed around the lower perimeter of the shield  224 . The coil  222  may be received within the shield  224 . 
       FIG.  3    illustrates a functional block diagram of an implantable sensor system  300  consistent with embodiments of the present disclosure. System  300  includes an electrode array  302 , an implantable component  324 , an external component  326 , and a prosthesis  322  consistent with certain embodiments disclosed herein. According to various embodiments, electrode array  302  and/or housing  328  may be implanted. Housing  328  may have features designed to hold implanted structures in place, including but not limited to: screw points, suture holes, anchor points, and special films. Certain features may be reinforced by supplemental materials such as metal rings or polymer fibers to prevent tearing. The device may have terminal fixation points that may penetrate intramuscularly and be safely left in the body after explantation. 
     Implantable component  324 , for example, may have electronics hermetically sealed in a small implantable enclosure. According to various embodiments, implantable component  324  may comprise an amplifier  304 , which may be capable of multiple channels of bioamplification. Amplifier  304  may exhibit a relatively fast settle time to permit concurrent stimulation and recording with electrodes in close proximity. 
     Implantable component  324  may further comprise an ND converter  306  that is configured to convert the biopotential signals received from amplifier  304  to digital signals. 
     A microcontroller unit (MCU)  308  may perform signal processing operations and/or implement other functions. MCU  308  may comprise a microcontroller, microprocessor, programmable logic device, or any system used to perform signal processing and perform other functions described herein. Additional signal processing capabilities may be performed by external component  326 . As illustrated in  FIG.  3   , external component  326  may also contain an MCU  316 . Still further, additional processing may, according to some embodiments, be implemented using an external device  334  (e.g., a computer, a PDA, a tablet, a phone, or a remote control) connected via wireless communication interface  332 . In one embodiment the wireless communication interface  332  may be embodied as a Bluetooth chipset. 
     Implantable component  324  may comprise an enclosure made of ceramic, metal, epoxy, polymeric material, or any combination thereof. Hermetic enclosures provide gas-tight areas that are created by metal, glass and ceramic enclosures, or epoxy. Implantable component  324  may include a hermetic enclosure to encapsulate portions of the implant components. Additional surgical materials, such as films, screws, etc., may be implanted to improve the tolerance, biocompatibility, or fixture of implantable component and/or health of skin or other tissues over or near implantable component  324 . The device may include features such as tapers or edges to facilitate easier tunneling through tissue during surgical placement. Implantable component  324  may include non-stick or non-adhesive coatings on surfaces to make explantation easier. 
     In certain embodiments, electrode array  302  may be configured to extract biopotential signals from extramuscular and/or intramuscular sites. Electrode array  302  may, for example, be placed in the chest and/or shoulders, arms, hands, pelvic muscle, legs (upper and lower), or any other extramuscular or intramuscular site that may be used along with muscle decoding algorithms for control of prosthetic devices, computers, wheelchairs, robotic exoskeleton, and/or any other internal or external device. 
     A power source  310  may be located internally or externally to implantable component  324 . Power source  310  may be embodied as an inductive device (i.e., an inductive coil for receiving power), such as wireless power receiver  311  or any other suitable system used for providing power to implantable component  324 , or in some embodiments may include a battery and battery charging circuitry. In the illustrated embodiment, power may be provided inductively by the wireless power transmitter  319  in external component  326 . 
     Transceiver  312  may communicate using a variety of technologies. In one embodiment, transceiver  314  may transmit signals by infrared transmission, reflected impedance transmission, amplitude modulation, and/or any applicable data transmission system. According to some embodiments, transmitted or received data may be recorded. 
     External component  326  may be in communication with prosthesis  322  via an interface  320 . Signals received from electrode array  302  may be transmitted to prosthesis  322  to induce a desired action or movement. In some embodiments, external component  326  may be configured to be received within or integrated with prosthesis  322 . 
     A power source  318  may comprise a wireless power transmitter  319  configured to transfer power to a wireless power receiver  311  associated with power source  310 . In one specific embodiment, wireless power transmitter  319  may be embodied as an inductive coil  222 , as illustrated in  FIG.  2 B . In some embodiments, power source  318  may receive power from prosthesis  322  via interface  320 . 
       FIG.  4    illustrates an exemplary flow chart of a method  400  for controlling a prosthetic device using a system consistent with embodiments disclosed herein. At  402 , an electrode array may be implanted. In one specific embodiment, the electrode array be comprised by the implantable component  100  illustrated in  FIG.  1   . In other embodiments, the electrode array may be configured in a variety of ways (e.g., in a grid configuration). 
     At  404 , one or more “virtual pairs” in the electrode array corresponding with a biopotential signal may be identified. In various embodiments the processing of signals from various electrodes may analyze inputs from a plurality of electrodes in the electrode array and identify one or more “virtual pairs” with desirable characteristics (e.g., a high signal-to-noise ratio). As noted above, it may be difficult to place electrodes within living tissue and to acquire desired biopotential signals (i.e., the nerve impulses that cause muscle voluntary muscle contraction or the muscle activity itself). Accordingly, in various embodiments consistent with the present disclosure, an array comprising a plurality of electrodes may be implanted and later analyzed to identify the electrode signals or composite signals from two or more signals that are best situated for a particular task (e.g., use of a muscle group on a residual limb for control of a prosthesis). 
     At  406 , an identified biopotential signal may be associated via signal processing with a voluntary motion. In some embodiments, a signal “virtual pair” signal may be associated with one or more actions. For example, an identified signal may be associated with a motion to grasp an object with a prosthetic hand. The motion of grasping an object may include a plurality of motions associated with each finger, in addition to positioning the thumb. In some embodiments, all the associated motions may be triggered. 
     A plurality of biopotential signals may be associated with a plurality of voluntary motions, and the biopotential signals may be detected using multiple “virtual pairs”. In one example, a first signal associated with a grasping motion may be detected using a first “virtual pair” in the electrode array, and a second signal associated with a pointing motion may be detected using a second “virtual pair”. In some embodiments, the actions at  402 - 406  may be associated with a commissioning or training, while the actions at  408 - 412  may be associated with use of the device. Such training or commissioning may allow for a plurality of motions to be associated with a plurality of biopotential signals. 
     Many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.