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WO2024130043A2 - Interfaces musculaires à fils fins - Google Patents

Interfaces musculaires à fils fins Download PDF

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Publication number
WO2024130043A2
WO2024130043A2 PCT/US2023/084147 US2023084147W WO2024130043A2 WO 2024130043 A2 WO2024130043 A2 WO 2024130043A2 US 2023084147 W US2023084147 W US 2023084147W WO 2024130043 A2 WO2024130043 A2 WO 2024130043A2
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WIPO (PCT)
Prior art keywords
muscle
wire
implant
fine
wires
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Ceased
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PCT/US2023/084147
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WO2024130043A3 (fr
Inventor
Cameron Roy TAYLOR
Hugh M. Herr
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Massachusetts Institute of Technology
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Massachusetts Institute of Technology
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Priority to EP23904631.1A priority Critical patent/EP4633457A2/fr
Publication of WO2024130043A2 publication Critical patent/WO2024130043A2/fr
Publication of WO2024130043A3 publication Critical patent/WO2024130043A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Measuring devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb
    • A61B5/112—Gait analysis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Measuring devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb
    • A61B5/1107—Measuring contraction of parts of the body, e.g. organ or muscle
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/279—Bioelectric electrodes therefor specially adapted for particular uses
    • A61B5/296—Bioelectric electrodes therefor specially adapted for particular uses for electromyography [EMG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/389—Electromyography [EMG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6813—Specially adapted to be attached to a specific body part
    • A61B5/6828—Leg
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6813—Specially adapted to be attached to a specific body part
    • A61B5/6829—Foot or ankle

Definitions

  • One candidate for measuring muscle motion is image-based ultrasound, which allows non-invasive muscle imaging, but currently has poor muscle fascicle visibility, and thus is difficult to use for muscle fascicle length tracking.
  • Technologies such as sonomicrometry, fluoromicrometry, and magnetomicrometry provide improved accuracy in muscle fascicle length tracking but require an implantation procedure performed by a clinician to place the devices within the muscle. As society progresses forward, it is important for us to be able to have medical sensing solutions which are both minimally-invasive and can be implemented at home.
  • the muscle interface may include an implant comprising a plurality of fine wires configured to be disposed in muscle tissue and to detect an electrical impedance at the muscle tissue; and a processor configured to determine a state of the muscle tissue based on the detected electrical impedance.
  • the implant is configured to detect at least two electrical impedances at the muscle tissue.
  • the implant is configured to detect an electrical impedance between each combination of two fine wires of the plurality of fine wires.
  • the determined state comprises at least one of length, velocity, or deformation of the muscle tissue.
  • the implant is further configured to detect an electromyographic signal at at least one wire of the plurality, at an additional wire of the implant, or at a combination thereof.
  • the processor is further configured to determine an activation level of the muscle tissue based on the detected electromyographic signal.
  • the muscle interface further comprises a controller electrically coupled to the processor.
  • the implant is further configured to electrically stimulate the muscle tissue via at least one wire of the plurality, at an additional wire of the implant, or at a combination thereof.
  • the controller is further configured to generate a muscle stimulation signal for the implant based on the determined state.
  • the controller is further configured to generate a control signal for an actuator of a wearable robotic device based on the determined state.
  • inventive concepts relate to a method of interfacing with a muscle.
  • the method may include detecting an electrical impedance at a muscle tissue with an implant comprising a plurality of fine wires disposed in the muscle tissue; and determining a state of the muscle tissue based on the detected electrical impedance.
  • the method further includes detecting at least two electrical impedances at the muscle tissue.
  • the method further includes detecting an electrical impedance between each combination of two fine wires of the plurality of fine wires.
  • the determined state includes at least one of length, velocity, or deformation of the muscle tissue.
  • the method further includes detecting an electromyographic signal at at least one wire of the plurality, at an additional wire of the implant, or at a combination thereof.
  • the method further includes determining an activation level of the muscle tissue based on the detected electromyographic signal.
  • the method further includes electrically stimulating the muscle tissue via at least one wire of the plurality, at an additional wire of the implant, or at a combination thereof.
  • the method further includes generating a muscle stimulation signal for the implant based on the determined state.
  • the method further includes generating a control signal for an actuator of a wearable robotic device based on the determined state.
  • inventive concepts relate to a method for controlling drop foot.
  • the method may include monitoring a length of a tibialis anterior using a fine wire impedance myography device, the device including fine wires; determining if the length of the tibialis anterior exceeds a reference length; stimulating the tibialis anterior during an early swing phase of gait using the fine wires of the fine wire impedance myography device; and ending the stimulation when the swing phase is more than a given percentage complete.
  • FIG. 1 shows a side view of an example embodiment of a Percutaneous Fine-Wire Impedance Myography device, in accordance with aspects of inventive concepts.
  • FIG. 2 shows an example embodiment of a device for Percutaneous Fine-Wire Impedance Myography (fwIM) and Functional Electrical Stimulation Combined for Correction of Drop foot, in accordance with aspects of inventive concepts.
  • fwIM Percutaneous Fine-Wire Impedance Myography
  • FIG. 3 shows an example embodiment of a device for Transcutaneous Fine-Wire Impedance Myography, in accordance with aspects of inventive concepts.
  • FIG. 4 shows a State Transition Diagram for Drop foot Control via Combined Fine Wire Impedance Myography and Functional Electrical Stimulation, in accordance with aspects of inventive concepts.
  • these wires can be less than 1 mm in diameter, though ideally less than 0.1 mm in diameter. These techniques can be used for tracking the length and velocity of muscle tissue.
  • the implantation of fine wires can be performed simply, for example, by at-home-implantable continuous glucose monitors (CGMs), making the strategy minimally-invasive, or due to the minimally-invasive nature of fine wires, many fine wires can be implanted at once, whether percutaneously or as part of an implanted neural technology (e.g., eOPRA, Ripple or the like). Percutaneous fine wires can be used without discomfort to the patient and can be easily made biocompatible.
  • CGMs at-home-implantable continuous glucose monitors
  • Systems, device, and/or methods described herein can be made portable with wired or wireless transmission and in combination with a computer for prosthetic and exoskeletal control.
  • a motor controller can directly control a robotic joint using muscle motion tracked in each muscle of an agonist-antagonist pair. More generally, inventive concepts described herein have broad implications for human-machine interfacing.
  • the features and usage described in connection with a computer also apply to a processor.
  • the features and usage described in connection with a processor also apply to a computer.
  • Muscle length and velocity signals are different from, and complementary to, muscle activation signals, such as the signals from electromyography (EMG). While EMG provides a measure of muscle activation, which results more directly from neural commands, muscle length and velocity give information on the shape of the muscle, which in turn can refine our understanding of muscle physiology during a given motion task. Indeed, the combination of muscle motion and activation will allow for increased physiological understanding in new contexts and improved human machine interfaces.
  • EMG electromyography
  • Drop foot (also called foot drop) is a sometimes temporary, but more often permanent disability where a patient is unable to lift the front of their foot (i.e., dorsiflex their ankle).
  • Drop foot can be caused by nerve injury, such as a traumatic-injury compression of the peroneal nerve, or injury to the peroneal nerve during a surgery.
  • nerve injury such as a traumatic-injury compression of the peroneal nerve, or injury to the peroneal nerve during a surgery.
  • drop foot can result from a nerve root injury in the spinal cord, or a muscle, brain, or spinal cord disorder causing muscle weakness or neural signaling pathology.
  • Drop foot most typically results from a number of disease conditions such as polio, Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis, and stroke.
  • ALS amyotrophic lateral sclerosis
  • a myoneural interface that measures muscle motion can use an artificial muscle stimulation controller to determine when to stimulate, using the muscle motion sensing as feedback signals for closed-loop control.
  • Such a technological platform can, for example, use gastrocnemius muscle sensing to get toe-off information, combined with sensing and stimulation of the tibialis anterior, and further, optionally, can be combined with the use of an inertial measurement unit, insole pressure measurement device, or other sensing modalities.
  • This strategy for alleviating drop foot can be similarly applied to other neuropathological cases involving different affected muscles to provide increased fidelity in the muscle control via artificial stimulation, whether this artificial stimulation is provided via electrical, optical, electromagnetic, or some other means.
  • Neuropathologies include but are not limited to spinal cord injury, stroke, polio, Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis (ALS), and/or multiple sclerosis.
  • the tracking of muscle motion can also be used for the control of an active or quasi-passive prosthesis, especially in the case of a person who has an osseointegrated connection to their prosthesis. Further, muscle motion can be used to control a powered orthosis or exoskeleton for any of the above diseases or others.
  • Fine-wire muscle tracking can be performed via the insertion of one or more wires into tissue and monitoring a signal that describes the movement of the one or more wires.
  • the techniques described herein will be described from the perspective of tracking the motion of biological tissue, such as animal and human tissue, such as muscle tissue, but can be applied more generally to other tracking applications outside of biology, such as in tracking motion or stress of other natural or artificial materials, such as rock or concrete.
  • Fine-wire muscle tracking works by tracking either the motion or state of each wire, or by tracking the relative motions or states between wires.
  • the distance between the ends of the inserted fine-wires affects the signal that is used for the tracking of the muscle motion.
  • the distance between the wires themselves affects the signal used for tracking.
  • it is the bend of the wires that provides the muscle motion signal.
  • it is the presence or difference in presence of particular chemicals, such as calcium ions, around the one or more wires that is used to determine the muscle motion or muscle activation.
  • fine-wire tissue tracking strategies are designed with the potential to be inserted percutaneously with a method that can allow the patient to insert the fine wires at home, similar to how a CGM device, such as how the Dexcom G6 allows at home insertion of fine wires.
  • a device may then also be attached to the surface of the skin to cover the insertion point and may also have any needed electronics for power and communication embedded within the device.
  • the device may be implanted via palpation, via ultrasound (especially via portable ultrasound), via virtual or augmented reality guidance, via trial and error (such as repeated insertion or via insertion of more wires than necessary and only keeping the relevant wires inserted or only using the relevant wires as signals), or via a combination of any of these or some other guidance, and this guidance may also be informed by other imaging modalities such as magnetic resonance imaging or computed tomography.
  • the insertion may be performed using a needle which is inserted having the fine wire(s) through the bore of the needle, after which the needle is removed, and the fine wire(s) are left inserted.
  • a bend in the fine wire(s) can help with holding the fine wire(s) in place.
  • a rigid or semi-rigid needle can be used to thread the fine wire(s) by piercing the insertion site next to the fine wire(s), after which the needle can be removed, and the fine wire(s) stay in place.
  • a jet of fluid such as water can be used to create the insertion path and push the fine wire(s) into the path at the insertion site.
  • the fine wire(s) can be made of a material which is rigid at the time of insertion and becomes flexible after insertion, using chemical, thermal, optical, electromagnetic, or other means.
  • fine-wires are inserted percutaneously (through skin)
  • the wires can alternatively be wired through a skin port, through bone or prosthesis (such as in the case the use of an e-opra device), or via an implanted device.
  • the implanted wires can be powered transcutaneously via wireless power to remove the need for a percutaneous wire.
  • the fine-wire inventive concepts described herein can be used as a component of an implanted neural system.
  • an osseointegrated implant with fine wires passing through the implant can employ the muscle motion sensing inventive concepts described herein.
  • one or more fine wires can be placed into each muscle of an amputated residuum to measure muscle lengths, velocities, and/or activations for high fidelity external prosthesis joint control. These implanted muscle wires can then pass into a hole within the residual bone and then through the osseointegrated bone implant and finally into the external prosthetic controller.
  • Standard biomedical device materials and coatings can be used that allow the electrical, mechanical, and/or optical properties for the fine-wire devices described herein, such as gold, platinum, parylene and polydimethylsiloxane.
  • the base materials need not be biocompatible, though ideally would be. If the base material is biocompatible and a coating is not needed for the functioning of the device, the device may not use a coating. Fine wires that are currently used for other interfacing strategies, such as fine-wire EMG, can be used for these techniques.
  • impedance myography is used to observe spatial deformations of muscle via surface electrodes and is a type of electrical impedance tomography (EIT).
  • EIT electrical impedance tomography
  • IM can be combined with surface electromyography (EMG) to improve muscle sensing, for instance for prosthetic control via residual muscles.
  • EMG surface electromyography
  • IM typically works by either injecting a current and monitoring voltage or by controlling a voltage and monitoring current, and the relationship between the current and voltage provides information about the impedance of the material through which it travels.
  • implanted electrodes such as those used in fine- wire EMG, can employ the strategy of IM to measure muscle tissue lengths (see FIG. 1).
  • fine-wire impedance myography can use standard frequencies for impedance myography such as 10 kHz or 50 kHz, or can be much lower or higher, from 0 Hz to 5 MHz or more.
  • One or more frequencies can be used simultaneously for the sensing.
  • the amount of intracellular membrane through which the current travels is what affects the signal, while at higher frequencies, the current also travels through the cells.
  • tissue length and velocity can be used to find signals such as tissue length and velocity, but may also be used to find signals such as temperature, pressure, hydration, activation, ion concentrations, stiffness, or force, or other measurable physical quantities of the muscle, which, including the length or velocity, we will refer to here very generally as the “state” of the muscle.
  • signals may be discovered in real-time or over time.
  • the impedance measurements also need not be performed using sine waves, as any other waveform can also be used to determine the complex impedance of the muscle, such an impulse or impulse train, a square, trapezoid, triangle, or sawtooth wave, white noise, and so on.
  • the waves can be balanced or imbalanced (in other words, their integrals may be zero or nonzero). Because the impedance measured is a complex value, the real and/or the imaginary part of the impedance signal can be used to determine the state of the muscle. For instance, the magnitude or phase of the impedance can be used as a signal. In addition, the real and/or imaginary part of the one or more complex impedance frequencies and signals that are derived from these can be used as a single- or multi-dimensional lookup table (for instance, using nearest neighbor search techniques) to determine the actual muscle state signal of interest. Alternatively, a statistical or machine learning tool can be used to create a map or function from the complex impedance values at the one or more frequencies used (likely each driven by a separate oscillator).
  • Examples of algorithms that can be used to perform this mapping include, but are not limited to, linear or logistic regression, decision trees, support vector machines, naive Bayesian models, k- nearest neighbors, k-means, random forests, dimensionality reductions, or gradient boosting algorithms (such as GBM, XGBoost, LightGBM, or CatBoost).
  • a biophysical model of the muscle physiology for instance, of the complex impedance of the intracellular matrix and of the cells, can be utilized in forming informed determination about the deformation of the muscle or other metrics of muscle state.
  • a calibration technique can be employed that involves the person moving their muscle in a way that best mimics how the muscle will be used with the fine-wire muscle interface, ideally while measuring the muscle activity to get a reference for the physical quantity of interest, then creating a mapping that can be used to predict the physical quantity of interest from the complex impedance.
  • ultrasound may be used to get fascicle length or velocity
  • electromyography might be used to get muscle activation.
  • a muscle biophysical model can then be used to estimate muscle-tendon force.
  • IMUs inertial measurement units
  • IMUs may be used to estimate limb kinematics, and a pressure/force insole to get external limb forces.
  • an inverse dynamics calculation might be used to estimate muscle length, speed, or force. Mapping to one or more of these muscle quantities (activation, length, velocity, force) from the complex impedance measurements during a calibration routine can then be performed.
  • FIG. 1 shows a side view of an example embodiment of a Percutaneous Fine-Wire Impedance Myography device 20, in accordance with aspects of inventive concepts.
  • two insulated wires 10a, 10b blue
  • bare conductor tips I la, 11b yellow
  • An electronic patch or electronic chip 12 houses the electronics.
  • the electronics comprises at least one or more of a computer, battery, current-driver, oscillator, voltage-sensor, or communications hardware.
  • the patch or chip 12 also serves to prevent infection at the site or movement of the implanted fine wires 10a, 10b.
  • the chip 12 remains in place due to an adhesive, either between the chip and the skin and/or over the chip to affix it to the skin.
  • the implant can be used short-term or long-term.
  • the device 20 may comprise a different number of insulated wires 10.
  • the computer/processor 40 is at an external location outside of the chip 12.
  • the electronic chip 12 houses the computer/processor 40.
  • the computer/processor 40 communicates with the electronic chip 12 wirelessly.
  • the computer/processor communicates with the electronic chip 12 with a wired connection.
  • Fine-wire IM can be performed using the fine wire electrodes used for fine-wire EMG, which are insulated everywhere except at the tips.
  • the wires used can be bipolar or monopolar (either two wires or one wire inserted at each site), and one of the two bipolar electrodes can be used (for instance, solely inserting one of the two wires or inserting both wires and removing one of them).
  • Fine-wire IM can also be combined with fine-wire EMG, performing both muscle impedance and muscle activation measurements simultaneously. Such a measurement strategy can allow for calculation of muscle force directly via the combined information from, for instance, muscle length, velocity, and activation. This strategy can, for instance, provide highly accurate, minimally invasive control of a prosthesis or control of a robotic exoskeleton to restore natural biomechanics of a neuromechanically- impaired biological limb.
  • the fwIM can be performed with a single pair of electrodes or with many electrodes at once.
  • the most minimally-invasive case for two-wire fwIM is a pair of electrodes implanted similar to how the single wire of a continuous glucose monitor (CGM) wire is implanted, as in the implantation strategy for the Dexcom G6, but implanting two wires at different implantation sites.
  • CGM continuous glucose monitor
  • These wires can be implanted at different times or simultaneously, and they can be implanted with different hardware or with a single piece of hardware, and they can be permanently connected or electrically connected after implantation via wire or wireless connectivity.
  • Examples of systems that can be used or modified for use for fwIM are the MAX30001 Ultra-Low-Power, Single-Channel Integrated Biopotential (ECG, R-to-R, and Pace Detection) and Bioimpedance (BioZ) analog front-end (AFE) solution for wearable applications by Maxim Integrated (Analog Devices), the MAX30002 Ultra-Low Power, Small Package, Single Channel Integrated Bioimpedance (BioZ) AFE for Fitness and Medical Applications by Maxim Integrated (Analog Devices), the MFIA 500 kHz / 5 MHz Digital Impedance Analyzer and Precision LCR Meter by Zurich Instruments, the MFLI 500 kHz / 5 MHz Lock-in Amplifier by Zurich Instruments, the ADUCM350 Configurable Impedance Network Analyzer & Potentiostat with Integrated Cortex M3 Core by Analog Devices, the AD59331 MSPS, 12-Bit Impedance Converter, Network Analyzer by
  • Combined fwIM with functional muscle stimulation can be used to design an electrical or optical muscle stimulation paradigm that controls muscle length, velocity, or force in a closed-loop manner under computer control.
  • at least one of a muscle length, speed, or force can be estimated in real time using fwIM, and used as closed- loop feedback signals for a muscle stimulation controller.
  • optical or electrical muscle stimulations can be applied in an updating manner based upon the at least one measurement of muscle length, velocity, or force in real time.
  • such a combination of fwIM and functional muscle stimulation can minimize muscular fatigue or amplify muscle force and power output (see FIG. 2).
  • fwIM can be used to monitor spatial deformation of the muscle while the source nerve is stimulated.
  • closed-loop control can be enabled by stimulating muscle or nerve either through the fwIM wires or through some other artificial stimulation technique while monitoring the fwIM signals.
  • muscle length setpoint control can be performed via this strategy.
  • muscle force setpoint control can be performed via this strategy.
  • fwIM can measure muscle length, velocity or EMG. These signals can then be used to estimate muscle force using a biophysical muscle model (e.g., Hill muscle model). This measured biological muscle force can then be used to estimate biological joint torque using a joint moment arm estimation.
  • This biological torque can then serve as a setpoint for an exoskeletal controller where exoskeleton torque is functionally related to the biological torque.
  • Any one of these closed-loop control strategies can be combined with a mix of sensing and/or stimulation on multiple muscles simultaneously, where not all muscles are necessarily sensed or stimulated, and this strategy can be combined with other sensing strategies, including but not limited to ultrasound, pressure insoles, IMUs, or nerve cuffs.
  • FIG. 2 shows an example embodiment of a device 20 for Percutaneous Fine-Wire Impedance Myography (fwIM) and Functional Electrical Stimulation Combined for Correction of Drop foot, in accordance with aspects of inventive concepts.
  • the fwIM device 20 (as seen in FIG. 1) is shown affixed to the front of the leg with the fine wires 10a, 10b located in the tibialis anterior muscle.
  • the fwIM technology can also be performed with any number of additional wires to more easily sense multi-modal three-dimensional information about a muscle, looking at the relationship between the wires pairwise or combining voltage and/or current input and voltage and/or current sensing in new combinations between the wires (see FIG. 3).
  • the wires may be inserted in such a way that some wires get farther apart in the muscle while some get closer together during a particular type of muscle contraction.
  • a full-bridge Wheatstone bridge is created, and this can enable a strategy of stimulation and sensing where a constant input voltage is introduced at two leads, which is modulated by the resistances to provide, for instance, a zero output voltage at the two other leads when the muscle is not contracted, a positive (or negative) voltage when the muscle is contracted, and a negative (or positive) voltage when the muscle is stretched.
  • Other configurations can of course be provided, such as, for example, a quarter bridge configuration where two inserted fine wires constitute the active part of the Wheatstone bridge while the remaining leads are passive.
  • many other circuit configurations, such as other bridge configurations can be used, employing multiple passive or quasi-passive circuit elements within or outside the body.
  • FIG. 3 shows an example embodiment of a device 30 for Transcutaneous Fine- Wire Impedance Myography, in accordance with aspects of inventive concepts.
  • electronic chips or patches 32a, 32b are located both outside and inside the body, each having some subset of the electronics that are described in connection with the percutaneous embodiments of inventive concepts, but the power and communications are delivered transcutaneously via magnetic fields, sound or vibration, ultrasound, light, electromagnetic waves, or via some other means.
  • the one or more wires are connected to the chip that is within the body. This setup or one similar to it can be used for fwIM or for any of the other embodiments of inventive concepts described herein.
  • the current driver, oscillator, and voltage sensing can be in the implanted chip, along with a battery, and a computer and battery can be in the externally-mounted chip.
  • the externally mounted chip can be affixed to the skin or can be affixed to clothing, since perfect and consistent alignment is no longer necessary.
  • the computer/processor 40 can be at an external location outside of the chips 32a, 32b. Alternatively, at least one of the electronic chips 32a, 32b can house the computer/processor 40. In various embodiments, the computer/processor 40 communicates with at least one of the electronic chips 32a, 32b wirelessly. In alternative embodiments, the computer/processor communicates with at least one of the electronic chips 32a, 32b with a wired connection. [0062] In the example embodiment shown in FIG. 3, the device 30 comprises seven wires lOa-lOg. In alternative embodiments, the device 30 of FIG. 3 or the device 20 of FIG. 1 may comprise a different number of wires 10.
  • the impedance between each combination of two wires may be measured.
  • device may measure the impedance between the first wire 10a and the second wire 10b, the first wire 10a and the third wire 10c, etc.
  • the device may measure the impedance between the second wire 10b and the third wire 10c, the second wire 10b and the fourth wire lOd, etc.
  • impedance measurements, and/or other types of measurement described herein may be performed for each combination of two wires.
  • impedance measurements, and/or other types of measurement described herein may be performed for a subset of each combination of two wires.
  • the fwIM technique can be performed percutaneously as with fine-wire EMG using fine wires that pass through the skin boundary or via an osseointegrated implant, or the wires can be fully implanted with some electronics and powered and/or communicated across the skin boundary using a wireless signal transmission.
  • the wires may be introduced uninsulated, fully-insulated, or insulated everywhere except for at the tip (such as how the wires for fine-wire EMG are typically constructed). In some example embodiments, only the tip is left exposed, to provide a more direct relationship between the signal and the distance between the tips of the plurality of fine wires implanted in a muscle.
  • the fine wires can be implanted leaving a minimal interface to the electrodes (for instance, solely access to the leads), and modular electronic components may be added.
  • a patch above a pair of inserted fine wires can accommodate a stack where first an impedance sensing electronic chip is placed over the patch, which provides access to the same electrode leads above it, and above it is stacked an EMG sensing electronic chip, which provides access to the same electrode leads above it, and an electrical muscle stimulation chip is stacked above that.
  • each modular component can either access the leads directly through a minimal interface or through one of the other modular components.
  • the minimal component that lies over the inserted fine wires can itself contain electronics that serve one or more of these functions.
  • a modular component can serve to sense impedance at one frequency or more, and multiple modular components sensing impedance at different frequencies can be employed simultaneously.
  • impedance sensing, EMG sensing, and electrical muscle stimulation can occur at different frequencies and perform electrically compatible functions, all of these functions can be performed simultaneously, though temporal switching can be performed so that some functions occur at different times (for instance, sensing EMG at a different time than electrically stimulating the muscle, to minimize the issues which can accompany sensing artificially induced voltages in the muscle).
  • the basic principle of fine-wire muscle interfacing is to use the positions of the tips of the fine-wires, which can be inserted percutaneously, or fully implanted with a wireless transmission, as a signal to determine muscle length, velocity, activation, and/or deformation. To this end, many other strategies can rely on this principle.
  • fiber Bragg gratings can be used to determine the stretch or bending of fine optical fibers.
  • These cables can have multiple fiber Bragg gratings tuned to different optical frequencies along their length to get multiple signals out, and portable optical spectroscopy can be performed to interrogate the signal, after which a computer can interpret the signals out to monitor the state of the muscle. If needed, the optical fibers can be attached to one another to further facilitate bending measurements.
  • Optical fibers can also be used to deliver light to the tip of a wire.
  • light can be delivered to the tip of a wire or along the wire using electrical wiring and one or more small light-emitting diodes.
  • the attenuation of the light can be used as a signal to determine distance.
  • the phase and/or polarization of the light can be used as a signal to determine the state of the muscle.
  • the optical sensor can be a small optical sensor at the end of a fine wire. Similar to the description above, one of more receivers can receive signals from each of one or more transmitters. Multiple frequencies of light from the infrared to ultraviolet wavelengths in the optical spectrum can be employed with embodiments described herein.
  • radio frequency attenuation of an inserted wire can be used to monitor the state of the muscle. For instance, the resonance of an inserted wire can be used to determine information about the muscle state (particularly about hydration, though this would provide some information about muscle deformation and other physical quantities as well).
  • the radio frequency attenuation between two inserted wires can be used.
  • the inserted fine wires can be viewed as monopole antennas, one can act as a transmitter, and the other can act as a receiver.
  • the signals to be sent can be in the super low to super high frequency range (30 Hz to 30 GHz), and depending on the level of attenuation, the wires can be placed closer to one another when needed to ensure sufficient signal gets through.
  • a single wire can act as the transmitter while the remaining wires act as receivers.
  • the receiving wires can also monitor the phase shift from the input signal. Fine wires can also be inserted in a loop, with either a single loop doubling back on itself, or two wires inserted as described in the primary fwIM technique described above can form a loop with the muscle tissue forming part of the loop.
  • sonomicrometry A well-known strategy for tracking muscle tissue deformation is called sonomicrometry.
  • piezoelectric crystals typically ceramic
  • the time delay (and sometimes the phase) of the acoustic signal from one crystal to the next is used to determine the distance between the crystals, using the speed of sound traveling through the muscle tissue.
  • tiny piezoelectric crystals may be used to enable the minimally-invasive percutaneous implantation of the wires and crystals, and the crystals may be set up to either vibrate tangent to the wire that connects to it or may vibrate orthogonal to the wire in one or all directions, to simplify the need for precise placement of the crystals.
  • the wire itself can be used as the medium for sound transduction.
  • a material that is inherently resonant, such as metal can be used, or this can be performed using a wire tube with a resonant cavity (an acoustic waveguide) filled with materials such as a gas, a liquid, a metal, or some other material which can carry an acoustic signal.
  • the signal can be delivered along the wire via, for instance, a transverse or shear wave.
  • the tip of the wires may be coated in something resonant as well, such as ceramic.
  • the transmitting wires may be implanted while the receiving sensors are external (for instance, performing ultrasound measurements while the sounds are emitted in the ultrasound spectrum), or the receiving wires may be implanted while the transmitting acoustic emitters are external.
  • Tiny Sensors Active or Passive
  • a tiny magnetometer(s) inserted at the end of a fine wire can be paired with a magnetic field source, such as an implanted magnet or an externally-applied magnetic field, to track the position of the wire(s).
  • a magnetic field source such as an implanted magnet or an externally-applied magnetic field
  • Other physical quantities can be sensed similarly, such as the use of a temperature sensor, pressure sensor (such as though used in altimeters), or a bend sensor.
  • the one or more tiny sensors can be powered and/or communicated with wirelessly, for instance, via electromagnetic or ultrasound waves.
  • Chemical sensing at the tip of or along the wire can be used to sense ion concentrations in the muscle to determine the action of a muscle as relayed via neural ion signaling. For instance, oxidation or reduction reactions with calcium that convert the presence of calcium into a voltage can be used to determine activation of the muscle. This is similar to the mechanism of operation of a CGM, but can be used for muscle state sensing and can be applied to human-machine interfacing as described earlier.
  • Such a strategy can also provide information about muscle hydration, an important metric, as it modulates the output power of muscle tissue.
  • one or more fine wires implanted may be fully or partially coated in materials that make them each an anode, a cathode, or partially anode and partially cathode.
  • This anode cathode pair may be used to perform pH sensing of the muscle to interrogate the muscle state.
  • sensing and stimulation are combined to minimize device cost, the number of insertion points, and foreign body reaction.
  • sensing and stimulation can be combined is the drop foot case as described earlier (see FIG. 2).
  • a pair of fine wires can be implanted percutaneously and fine-wire impedance myography can be used to sense the length and velocity of the muscle via onboard electronics.
  • muscle EMG can be sensed to estimate muscle activation.
  • muscle force can be estimated.
  • Information about the length, velocity and/or force of the muscle can be used to determine the frequency, timing and magnitude of muscle stimulation via the same pair of fine wires, using a shared electronics board, which can either communicate wirelessly to a computer or house the computer and battery directly at the site at which the wires are inserted through the skin.
  • the length of a dorsiflexing muscle for example the tibialis anterior (TA) can be used to determine the magnitude of stimulation of the that muscle, followed by a time delay that determines when to stop stimulating as a percentage of predicted swing phase time. This modality is shown in the following state transition diagram (FIG. 4).
  • FIG. 4 shows a State Transition Diagram for Drop foot Control via Combined Fine Wire Impedance Myography and Functional Electrical Stimulation in accordance with aspects of inventive concepts.
  • the tibialis anterior (TA) is monitored for length using fine wire impedance myography (fwIM), and when the measured length exceeds a reference length determined by calibration (for instance, observing the gait of a height and weight matched person or observing the movements of an unaffected leg), the TA is then stimulated during the early swing phase of gait using the same fine wires that are inserted into the TA for fwIM.
  • fwIM fine wire impedance myography
  • Such a controller can enable a person with anterior muscle weakness to walk with sufficient dorsiflexion and foot clearance throughout the swing phase of walking.
  • At least one of muscle length, speed or force, estimated using fwIM combined with EMG sensing can serve as sensory inputs into a muscle stimulation controller in an updating, real time manner, for closed-loop muscle stimulation.
  • muscle length and speed can serve as inputs into a muscle stimulation controller to apply electrical stimulations that are updated in real time from these muscle state sensory inputs. If such a controller were applied to a drop foot patient, a biomimetic stretch reflex control can be used on the tibialis anterior during controlled plantar flexion, spanning from heel strike to forefoot strike during early stance, to eliminate forefoot slap against the walking surface.
  • muscle length and speed can be related to (and can serve as an input to a controller for) at least one of muscle stimulation frequency, pulse width or magnitude using linear or non-linear functional relationships.
  • the muscle stimulation controller can apply a positive force feedback reflex control on the soleus muscle for a person with posterior muscle compartment weakness.
  • at least one of muscle stimulation frequency, pulse width or magnitude can be modulated in an updating manner under computer control during the controlled dorsiflexion and powered plantar flexion phases of gait using a positive force feedback reflex control.
  • a positive force feedback function with soleus force as the dominant sensory input, can determine the at least one of muscle stimulation frequency, pulse width or magnitude to achieve monotonically increasing muscle activations with increasing soleus muscle force.
  • any of these control instantiations can be used in other contexts, such as in the case of therapy, recovery, or movement restoration for a person with spinal cord injury or someone who has had a stroke.
  • additional sensing modalities such as inertial measurement by IMUs, can be used to extend upon these control strategies.
  • the central and/or peripheral nervous system can be used as a control signal, where the nervous system provides a control setpoint, the feedback provides information about the state of the muscle, and the stimulation controller modulates either a biological muscle or an exoskeletal synthetic actuator worn by the person in order to produce natural biomechanics.
  • the stimulation controller modulates either a biological muscle or an exoskeletal synthetic actuator worn by the person in order to produce natural biomechanics. For example, if a person suffers from a weak soleus muscle, and this calf muscle weakness does not allow for a normal level of powered plantar flexion during the late stance phase of gait, a stimulation controller can be applied to augment the force and power of the calf muscle, and the biomechanical functionality of the person’s gait.
  • a linear or nonlinear functional relationship can be used to apply an exoskeleton actuator torque about the biological ankle during the powered plantar flexion phase of gait, wherein the exoskeleton torque monotonically increases with increasing calf muscle torque using a powered steering controller that augments calf muscle function.
  • devices, systems, and/or methods described herein may be replaceable. In various embodiments, devices, systems, and/or methods described herein may be configured to be recyclable.
  • devices, systems, and methods described herein may be configured for user removal and/or application.
  • devices, systems, and/or methods described herein may be configured to alert a user when it is appropriately positioned to be applied to the user.
  • devices, systems, and/or methods described herein may use sensors (for example, ultrasound sensors) on the bottom to provide a user with a three-dimensional view of a target muscle on a display, and, in some embodiments, may highlight the projected insertion path of the fine wire strands into the muscle.
  • devices, systems, and/or methods described herein may display arrows to guide a user toward a correct positioning and/or application.
  • devices, systems, and/or methods described herein may alert a user when the tips of the fine wires are aligned so that they would be positioned on opposite ends of a fascicle in the target muscle.
  • devices, systems, and/or methods described herein may automatically insert wires into a user’s muscle through the skin and lay down a small patch filled with electronics, a battery, and a processor.
  • devices, systems, and/or methods described herein may allow a user to view inserted wires using a mixed reality display.
  • devices, systems, and/or methods described herein may be applied to more than one muscle of a user’s body.
  • devices, systems, and/or methods described herein may be configured to be applied by a user in under ten minutes.
  • devices, systems, and/or methods described herein may comprise strands of wires inserted through a user’s skin into muscles for tracking biomechanics.
  • devices, systems, and/or methods described herein may allow a user to interact and receive interactive feedback with a mixed reality operating system during an augmented and/or mixed reality session by tracking muscle lengths and/or allowing stimulation of the muscles.
  • devices, systems, and/or methods described herein may allow a user to control wearable and off-body robots. In various embodiments, devices, systems, and/or methods described herein may allow a user to control wearable and off-body robots via telepresence. [0099] In various embodiments, devices, systems, and/or methods described herein may stimulate muscles to provide feedback for virtually-simulated forces during physical contact between more than one person. In various embodiments, devices, systems, and/or methods described herein may stimulate muscles to provide feedback for virtually-simulated forces during physical contact between shared physical or virtual items. In various embodiments, devices, systems, and/or methods described herein may be configured to be used during exercise.

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Abstract

Des dispositifs, des systèmes et des procédés de l'invention concernent une interface musculaire et des procédés d'utilisation. L'interface musculaire peut comprendre un implant comprenant une pluralité de fils fins conçus pour être disposés dans un tissu musculaire et pour détecter une impédance électrique au niveau du tissu musculaire ; et un processeur conçu pour déterminer un état du tissu musculaire sur la base de l'impédance électrique détectée.
PCT/US2023/084147 2022-12-15 2023-12-14 Interfaces musculaires à fils fins Ceased WO2024130043A2 (fr)

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AU2006261666B2 (en) * 2005-06-28 2011-05-26 Bioness Inc. Improvements to an implant, system and method using implanted passive conductors for routing electrical current
US20090326602A1 (en) * 2008-06-27 2009-12-31 Arkady Glukhovsky Treatment of indications using electrical stimulation
WO2015061453A1 (fr) * 2013-10-22 2015-04-30 Msssachusetts Institute Of Technology Interface périphérique neurale via régénération des nerfs aux tissus distaux

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