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Method for Neuromechanical And Neuroelectromagnetic Mitigation Of Limb … — Massachusetts Institute Of Technology (US20240350033A1)

Massachusetts Institute Of Technology · Google Patents

Google Patents · Patents · License: Open Access

hughm.herr massachusettsinstituteoftechnology

patent, google patents, intellectual property, US20240350033A1, Massachusetts Institute Of Technology, Hugh M. Herr, en, 2024

ABSTRACT

Abstract

A physiological feature of a subject is monitored by implanting a plurality of targets, such as magnets, and detecting at least one change in a physical property of the targets, followed by modifying a physiological feature of the subject in response to a change of state detected by the change in physical property detected in the targets. Cutaneous sensory feedback and proprioceptive feedback in a subject, as well as selective stimulation of axons or nerve fascicles of a neuron of a subject are provided.

Description

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 16/754,351, filed Apr. 7, 2020, which is the U.S. National Stage of International Application No. PCT/US2018/055053, filed Oct. 9, 2018, which designates the U.S., published in English, and claims the benefit of U.S. Provisional Application No. 62/570,343, filed on Oct. 10, 2017 and 62/663,596, filed on Apr. 27, 2018. The entire teachings of the above applications are incorporated herein by reference.

BACKGROUND

Volitional control of wearable robotics, such as prostheses, orthoses or exoskeletons, requires sensing of intent from the wearer. Though there are various methods for acquiring signaled intent from the wearer, limitations such as signal-to-noise ratio, level of invasiveness, and limited degrees of freedom, keep high-resolution, high fidelity control from being a reality. Electromyographic (EMG) signals from residual muscles are sometimes limited in signal quality because the target muscles lie deep within the biological limb, and hence cannot be easily accessed, independently isolated, or measured consistently. Consequently, functional control of wearable robotic devices through transdermal recording platforms, such as surface EMG (sEMG), is limited, and users experience frustration due to poor function. As a resolution to these difficulties, implanted electrodes using wired or wireless approaches have been explored for the measurement of EMG muscle signals. Unfortunately, these approaches are sometimes highly invasive, requiring surgery and the placement of complex electronics into the body such as electrodes, connectors and telemetry elements.

The majority of state-of-the-art powered prosthetic systems controlled extrinsically using neural signals are done so via these imperfect EMG measurements. However, EMG alone cannot provide sufficient information to accurately interpret intended movement. Because muscle force production is dependent on muscle activation as well as fascicle length and velocity, access to muscle state (length and speed) measurements are necessary to enable an efferent control modality that replicates biological muscle function with high fidelity. Muscle state information is also essential for precise modulation of muscle state and perceived joint torque via external muscle stimulation. Unfortunately, there currently exists no robust methodology of measuring real-time muscle state in living humans as part of a chronically wearable system.

Therefore, a need exists for a method for mitigation of limb pathology that overcomes or minimizes the above-mentioned problems.

SUMMARY

The invention generally is directed to a method for neuromechanical and neuroelectromagnetic mitigation of limb pathology.

In one embodiment, the invention is a method for detecting a physical property of tissue that includes implanting a plurality of targets at a tissue of a subject and employing an array of sensors to detect at least one state of the targets relative to each other, wherein the state of the targets is indicative of a physical property of the tissue, thereby detecting the physical property of the tissue.

In another embodiment, the invention is a method of modulating feedback. In this embodiment, the method includes affixing at least one magnetic component at a tissue and applying an array of electromagnetic coils to the tissue proximate to the at least one magnetic component, whereby establishing a magnetic field across the array of electromagnetic coils causes an electromagnetic reaction by the at least one magnetic component, thereby modulating feedback.

In another embodiment, the invention is a method for providing proprioceptive feedback to a subject. In this embodiment, the method includes the steps of affixing at least one magnetic target at a pair of muscles in agonist-antagonist relation to each other. A signal representing an applied force is detected, and an electromagnetic field is selectively generated consequent to the detected signal, thereby causing the at least one magnetic target to apply a force to the pair of muscles in agonist-antagonist relation to each other, whereby an afferent signal is generated by the agonist-antagonist muscle pair, thereby providing proprioceptive feedback to the subject.

In another embodiment of a method for providing proprioceptive feedback in a subject of the invention, targets are implanted at the pair of muscles in agonist-antagonist relation to each other. At least one state of a portion of the targets is detected, thereby detecting a state of the agonist-antagonist pair of muscles. An afferent signal is generated consequent to the change of state of the agonist/antagonist pair of muscles, thereby providing proprioceptive feedback in the subject.

In yet another embodiment, the invention is a method for selectively stimulating at least a portion of axons or nerve fascicles of a neuron of a subject comprising the steps of placing a cuff at or proximate to a neuron of a subject, the cuff including one or more antennas at or proximate to the cuff and collectively extending about at least a portion of a circumference of the neuron, thereby forming an array of the antennas about the neuron. Electromagnetic waves are selectively generated at the one or more antennas, whereby the electromagnetic waves are focused at a subset of at least one member of the group consisting of axons and nerve fascicles of the neuron, thereby causing depolarization of the subset and consequent selective stimulation of at least a portion of the axons or nerve fascicles of the neuron of a subject.

Another embodiment of the invention is a method for detecting a state of one or more objects that includes providing one or more targets at each of the one or more objects and positioning an array of sensors proximate to the one or more targets, whereby a signal from the targets at the sensors is detected. The parameters describing the state of each of the one or more targets are then estimated and predicted values of the signal at each of the sensors are calculated given these estimates of the parameters, whereby a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors is computed. A prediction error Jacobian matrix is then calculated by analytically computing elements of the prediction error Jacobian matrix, and the prediction error in combination with the prediction error Jacobian matrix are used to determine a state of the at least one target, whereby the state is indicative of a physical state of the one or more objects.

In yet another embodiment, the invention is a method for detecting a state of one or more objects while compensating for a disturbance field that includes providing one or more targets at each of the one or more objects and positioning an array of sensors proximate to one or more targets, whereby a signal from the targets at the sensors is detected. The parameters describing the state of each of the one or more targets are then estimated, and the parameters of the disturbance field are also estimated, and predicted values of the signal at each of the sensors are calculated given these estimates of the parameters, whereby a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors is computed. A prediction error Jacobian matrix is then calculated, and the prediction error in combination with the prediction error Jacobian matrix are used to determine a state of the one or more targets, whereby the state is indicative of a physical state of the one or more objects.

A method for detecting a state of one or more objects includes the steps of: providing one or more targets at each of the one or more objects; positioning an array of sensors proximate to the one or more targets, whereby a signal from the targets at the sensors is detected; estimating parameters describing the state of each of the one or more targets; calculating, in a cascading calculation, predicted values of the signal at each of the sensors given the estimates of the parameters; computing a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors; calculating a prediction error Jacobian matrix; and determining from the prediction error and the prediction error Jacobian matrix a state of the one or more targets, whereby the state is indicative of a physical state of the one or more objects.

A method for determining one or more of three sensor positions and three sensor orientations for each of the sensors in a sensor array includes the steps of: placing at least one target in at least one known location relative to a sensor array, whereby a signal from the at least one target at the sensors is detected, and recording at least one measurement of the signal at each of the sensors for each placement of the one or more targets; estimating one or more parameters from the group consisting of x-position, y-position, z-position, yaw, pitch, and roll, of each of the sensors; estimating any unknown state parameters of the at least one target; calculating predicted values of the signal at each of the sensors for each of the measurements given the estimates of the sensor parameters and target states; computing a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors; calculating a prediction error Jacobian matrix by analytically computing elements of the prediction error Jacobian matrix with respect to the estimated parameters of the sensors for each measurement; and determining from the prediction error and the prediction error Jacobian matrix a state of the parameters of the sensors.

In an embodiment, the method further includes the steps of: implanting at least one magnet at each of at least one respective tissue of a subject; applying the array of magnetometers to the subject proximate to the at least one magnet, whereby a position of the magnet relative to the array of magnetometers is determined, the position being indicative of a physical property of the tissue of the subject; and modifying a physiological feature of the subject that affects or is affected by the physical property of the tissue of the subject, thereby modulating the physiological feature of the subject.

In an embodiment, the method further includes the steps of: rotating the array of magnetometers about each of three coordinate axes in a uniform magnetic field while collecting a three-axis data stream from each of the magnetometers; calibrating each of the magnetometers in the array by determining hard iron offsets and soft iron distortions; scaling gains of the magnetometers with respect to one another; and determining rotation matrices that map the three-axis data streams from the magnetometers into a common coordinate system, whereby relative sensor orientations are determined.

A device for detecting a physical property of tissue includes an array of sensors to detect a plurality of targets at a tissue, and electronics to determine at least one state of the targets relative to each other and provide an indication of a physical property of the tissue.

This invention has many advantages. For example, in one embodiment, the invention is generally directed to treatment of limb pathology resulting from disease or traumatic injury. In another embodiment, the invention is directed to human augmentation to enhance human physicality beyond normal physiological limits. In the realm of permanent assistance devices, for example, the invention can preserve post-amputation function in a residuum of an amputee, and restore natural muscle control function in paralyzed or weakened limbs due to age-related degeneration, spinal cord injury, or other neuromuscular pathologies.

The invention can employ an implant system with no active electronics within the body, thereby obviating the need for a wired or wireless transmission of power through the skin. The method of the invention eliminates the need for a percutaneous connection in the case of a wired transmission, eliminating the potential for infection, inflammation, or other complications related to percutaneous wire passage. Further, the method eliminates the need for complex implanted electronics that all too often require repeated surgical procedures for maintenance and repair after extended periods of time within the body.

Sensor architecture employed in an embodiment of the invention provides accurate real-time fascicle state information synchronously with reliable, repeatable force data that enables an efferent control paradigm to produce a precise interpretation of intended joint position, torque and impedance. One example of such a control architecture, in its simplest implementation, is a master-slave control paradigm used to control an actuated joint within a wearable robotic system from measured muscle state within the biological limb. In this paradigm, muscle lengths and speeds can be employed as control targets by the wearable robotic device processors wherein, for example, motors are driven to output artificial joint positions and speeds corresponding to targets obtained using an anatomically-derived transformation from the linear muscle space to a rotary joint space of the wearable system.

In another controller implementation employed in an embodiment of the invention, a wearable device that provides robotic joint torque and impedance is controlled in a strategy that first estimates muscle force from EMG and muscle state using a biophysical muscle model. From this force estimate a corresponding biomimetic torque control target is computed using an anatomically-derived transformation from the linear muscle space to a rotary joint space of the wearable device. Biophysical models of muscle, such as the Hill Muscle Model, are able to predict muscle force from measurements of EMG and fascicle state. EMG can be measured using a number of strategies including surface electrodes, wired epimysial electrodes, or wireless intramuscular electrodes. The EMG signal can then be employed to estimate muscle activation through a model of activation dynamics which describe propagation of an electrical signal throughout the muscle and subsequent temporal properties of muscle contraction, primarily related to calcium release dynamics in individual motor units. Activation then serves as the input to a fascicle length and contraction-velocity dependent model of force production. If these parameters are measured directly, the fully characterized model provides an accurate real-time estimate of force production. With these measurements, it is then possible to reproduce those dynamics in an actuated, computer-controlled prosthetic, orthotic or exoskeletal joint.

In yet another controller implementation employed in an embodiment of the invention, muscle force is measured directly, and motors on the wearable device are driven to output artificial joint torques corresponding to targets obtained using an anatomically-derived transformation from the linear muscle space to a rotary joint space of the device.

Fascicle state and force sensing also has the potential to improve fidelity of muscle control using artificial stimulation. With accurate muscle state and force feedback, a closed-loop control of muscle stimulation employed in one embodiment of the invention allows precise modulation of the state or force of a muscle. Muscle stimulators are inherently imprecise, and it is extremely difficult to model physiological response to artificial stimulation, which makes an open-loop stimulation paradigm extreme

RELATED APPLICATIONS

BACKGROUND

Therefore, a need exists for a method for mitigation of limb pathology that overcomes or minimizes the above-mentioned problems.

SUMMARY

The invention generally is directed to a method for neuromechanical and neuroelectromagnetic mitigation of limb pathology.

In another embodiment of the invention, fascicle state and force sensing can be employed to monitor biomechanical tissue function in humans as a means to prevent or mitigate injury in work and athletic applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particular description of example embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments. The same number present in different figures represents the same item.

FIG. 1 A is a schematic representation of magnetic fields of an implanted permanent magnet on a muscle at rest as employed in one embodiment of a method of the invention.

FIG. 1 B is a schematic representation of the magnetic fields shown in FIG. 1 A during muscle contraction that causes translation and rotation of the magnetic field during the same embodiment of the method of the invention.

FIG. 2 is a schematic representation of an alternative arrangement of permanent magnets in a muscle according to another embodiment of the method of the invention.

FIG. 3 is a schematic representation of an arrangement of permanent magnets and a plurality of ferromagnetic materials at a muscle according to still another embodiment of the method of the invention.

FIG. 4 is a schematic representation of yet another embodiment of the method of the invention, wherein transducer groups are located on skin of a subject.

FIG. 5 is a schematic representation of still another embodiment of a method of the invention, wherein electromagnetic coils are mounted external to a body of the subject and magnets are implanted into or sutured onto an ectopic skin graft.

FIG. 6 is an embodiment of a device employed in another embodiment of a method of the invention that provides cutaneous sensory feedback in a subject.

FIG. 7 is another embodiment of a method of the invention, wherein ferromagnetic material instead of the permanent magnets of FIG. 5 are implanted onto or within an ectopic skin graft.

FIG. 8 is a schematic representation of an embodiment of an arrangement of electromagnetic coils, each with a ferromagnetic or permanently-magnetized plunger, to form a solenoid array according to another embodiment of the method of the invention.

FIG. 9 is a three-dimensional representation of an array of electrically-controlled solenoid valves as employed in still another embodiment of a method of the invention.

FIG. 10 is a schematic representation of an embodiment of electromagnetic coils and a permanent magnet on a tendon as employed in a method for the providing of transcutaneous imposition of force onto muscle tissue according to yet another embodiment of the method of the invention.

FIG. 11 is a schematic representation of the arrangement shown in FIG. 10 , but further including muscle-state sensing magnetometers, as employed in another embodiment of the method of the invention.

FIG. 12 is a schematic representation of a version of the embodiment of the method of the invention, wherein ferromagnetic material, instead of permanent magnets, shown in FIG. 11 , are implanted onto or within muscles or tendons, as employed in yet another embodiment of the method of the invention.

FIG. 13 A is a schematic representation of a prior art linear array of antennas that employs phase offsets to cause a wave to change direction by electronically controlling phase differences between electromagnetic wave crests from each antenna.

FIG. 13 B is a prior art arrangement of a linear array of antennas that is employed to cause symmetric phase shifting that results in electronically-focused electromagnetic waves at a focal point.

FIG. 13 C is a prior art arrangement of a circular array of antennas that is employed to create an electromagnetic focal point by phase shifting of electromagnetic wave crests.

FIG. 14 is a three-dimensional illustration of an implantable biocompatible nerve cuff placed on a nerve in combination with a schematic representation of a controller, as employed in another embodiment of the method of the invention.

FIG. 15 is a three-dimensional arrangement of antennas worn in an array on a band around an anatomical extremity of a subject, as is employed in still another embodiment of the method of the invention.

FIG. 16 is a plan view of physical components of an arrangement of a permanent magnet tracking system employed in still another embodiment of the method of the invention.

FIG. 17 is a perspective view of the antenna array shown in FIG. 15 , in combination with a distribution of permanent magnets, as is employed in another embodiment of the method of the invention.

FIG. 18 is a schematic representation of one embodiment of a cascade method employed to calculate elements of the magnetic field prediction error Jacobian matrix according to an embodiment of a method of the invention.

FIG. 19 is another schematic representation of a cascade method employed to calculate elements of the magnetic field prediction error Jacobian matrix according to an embodiment of a method of the invention.

FIG. 20 is yet another schematic representation of a cascade method employed to calculate elements of the magnetic field prediction error Jacobian matrix according to an embodiment of a method of the invention.

FIG. 21 is a flowchart of one embodiment of a method for tracking a magnet in one embodiment of the method of the invention.

FIG. 22 A is a perspective view of one embodiment of an arrangement of permanent magnets employed in a permanent magnet tracking system for dipole strength measurement according to another embodiment of the method of the invention.

FIG. 22 B is a perspective view of the arrangement of the permanent magnets shown in FIG. 22 A , but including a magnet fixed in a magnet-mounting geometry for precise positioning of the magnet by yet another embodiment of the method of the invention.

FIG. 23 is a schematic representation of an algorithm to optimize an estimate of magnetic dipole strength according to an embodiment of the method of the invention.

FIG. 24 is a schematic representation of a flowchart for determining magnetometer biases and any offset angles before permanent magnets are tracked and before a magnetometer position calibration of dipole strength measurement is obtained according to one embodiment of the method of the invention.

FIG. 25 is a perspective view of an array of permanent magnets and rotations that the array can exhibit in three dimensions in one embodiment of the method of the invention.

DETAILED DESCRIPTION

A description of example embodiments follows.

In one embodiment the method includes implanting a plurality of targets at a tissue of a subject and detecting at least one state of the targets relative to each other, wherein the state of the targets is indicative of a physical property, thereby detecting the physical property. As defined herein, a âstateâ of a target, or targets, includes at least one of any of the members of the group consisting of the position, orientation, and strength of the target or targets. Specifically, the âstate of the targets relative to each otherâ includes at least one of any of the members of the group consisting of the relative positions of the targets, the distance between the targets, and the relative orientation between the targets.

In one specific embodiment, the targets are active targets. As defined herein, an âactive targetâ is defined as a target that requires a dedicated power storage element, such as a battery or a capacitor, which is part of or physically connected to the target. A few examples of active targets include battery-driven electromagnets, resonant coils containing capacitors which are charged via a time-varying externally-applied electromagnetic field, battery-driven piezoelectric acoustic transducers, and targets with built-in sensing and communication capability. Alternatively, the targets are passive targets. In yet another embodiment, the targets are implanted in the tissue. In another embodiment, the physical property detected is a change in physical property of the tissue. In still another embodiment, a change in a state of the targets relative to each other is detected, wherein the change in the state of the targets is indicative of yet another physical property, thereby detecting the additional physical property.

In a specific embodiment, a physiological feature of the subject is then modified in response to the detected physical property of the tissue, thereby modulating the physiological feature of the subject.

In a specific embodiment, the tissue is a muscle, and the targets are a pair of targets spaced apart from each other, whereby contraction or relaxation of the muscle causes the targets to move closer to or further from each other, respectively. Examples of suitable targets include those that include a material selected from the group consisting of a permanent magnetic material and a temporarily magnetizable material.

In an embodiment wherein the targets include a temporarily magnetizable material, the method further includes the step of generating a magnetic field via elements which are distinct from the targets, and further includes the step of exposing the targets to the magnetic field. In one such embodiment, the magnetic field is generated by at least one member of the group consisting of a permanent magnet and an electromagnetic coil. In a specific embodiment, the method further includes the step of placing the at least one permanent magnet, or the at least one electromagnetic coil, at a surface of the subject.

In another embodiment, the at least one state is detected by a magnetometer. Examples of suitable magnetometers include a Hall effect sensor, a passive electromagnetic coil, a magnetoresistor, a magneto-inductive sensor, a fluxgate magnetometer, and a superconducting quantum interference device (SQUID) magnetometer.

In another embodiment, the at least one state is detected by at least one member of the group consisting of a three-axis magnetometer, a two-axis magnetometer and the combination of two single-axis magnetometers. In still another embodiment, the targets are permanent magnets and the permanent magnets have five degrees of freedom. Typically, the physical property of the tissue is determined by detecting both the position and the orientation of the permanent magnets relative to each other, such as by use of at least ten single-axis magnetometers, or at least four three-axis magnetometers.

In another embodiment, the at least one change in the at least one physical property of the targets is detected by a magnetometer at a surface of the subject proximate to the targets. Independently, at least one of the targets can be implanted in a surface of the muscle, or can be implanted within the muscle, or both. In still another embodiment, at least one of the targets can be implanted within a tendon of the subject.

In yet another embodiment, the detected physical property includes at least one member of the group consisting of: a contraction or relaxation of skeletal, cardiac, or smooth muscle; a bone bending; a bone stretching; a lung inflation; a peristalsis; a vasoconstriction; a vasodilation; a skin stress; a skin strain; a position of at least one bodily organ; a volume of at least one bodily organ; and a length of at least one bodily organ. For example, the bodily organ can include at least one member of the group consisting of: a liver; a pancreas; a kidney; a bladder; a tooth; a tongue; and a reproductive organ. In yet another embodiment, the detected physical property is monitored over time, whereby a change in the physical property is detected.

In another embodiment, the plurality of targets includes at least one member of the group consisting of a magnetic material and an electrically conductive material. In this embodiment, the plurality of targets are placed at at least one member of the group consisting of a muscle and a tendon. In one version of this embodiment of the invention, the method further includes the step of positioning at least one electromagnetic coil at a surface of the subject, or externally and apart from the subject. In this embodiment, the method of the invention can include the additional step of generating an electromagnetic field by the at least one electromagnetic coil. In this embodiment, the method can also further include the step of detecting the state of the targets by detecting an inductance of the at least one magnetic coil as part of the system composed of the at least one magnetic coil and the targets, such as wherein the inductance is inferred from measurement of electric current through the at least one electromagnetic coil when the electromagnetic coil is driven with a varying voltage signal.

In still another embodiment, the method can further include the step of measuring at least one member of the group consisting of impedance and resonant frequency of the at least one electromagnetic coil, wherein the electromagnetic coil is arranged in parallel with capacitors. In another embodiment, the method further includes the step of detecting at least one state of the targets by detecting an inductive coupling between a pair of electromagnetic coils. Inductive coupling can be sensed, for example, as a consequence of driving one electromagnetic coil of each pair of the electromagnetic coils, wherein the at least one state of the targets is detected by monitoring the voltage or the current in the corresponding coil in each electromagnetic pair.

In yet another embodiment of the invention, the targets have a density distinct from that of the tissue at which they are implanted, and at least one state of the targets is detected by exposing the targets to ultrasound and detecting the latency of one or more echoes reflected by the targets. Examples of suitable targets can include at least one member of the group consisting of titanium, stainless steel, tantalum, and vanadium steel. In one such embodiment, the targets include a coating of a biocompatible material, such as a material that includes at least one member of the group consisting of: a bioceramic; parylene; glass; silicone; titanium; and a biocompatible polymer.

It is to be understood that, in any of these embodiments, the tissue of the subject can be a pair of muscles in agonist-antagonist relationship to each other, whereby the change in state of tissue is a change in the state of the agonist-antagonist pair of muscles.

In another embodiment, the invention is a method of modulating feedback, such as feedback to a subject. In this embodiment, the method includes affixing at least one magnetic component at a tissue, and applying an array of electromagnetic coils to the tissue proximate to the at least one magnetic component, whereby establishing a magnetic field across the array of electromagnetic coils causes an electromagnetic reaction by the at least one magnetic component, thereby modulating feedback.

In one embodiment, the tissue is of a subject, whereby the feedback is to the subject. In another embodiment, the feedback is sensory feedback, such as cutaneous sensory feedback.

In one embodiment, the method further includes the step of manipulating the electromagnetic field of the array of electromagnetic coils, thereby changing the feedback in the subject. In another embodiment, the electromagnetic field is manipulated in response to sensors at the tissue. In still another embodiment, the electromagnetic field is manipulated in response to sensors at a bionic limb.

In one version of this method of the invention, the tissue is a skin graft that is ectopic and the locations of the sensors at the bionic limb correspond to locations of nerves at the ectopic skin graft, whereby the reaction of the at least one permanent magnet simulates sensation of a biological limb to which the ectopic skin graft is native. In another embodiment, innervating nerves of the ectopic skin graft are native to the ectopic skin graft. Also in this embodiment, the method can further include the step of implanting the ectopic skin graft beneath a native skin surface of the subject.

In another embodiment, the skin graft is denervated and at a distal end of a transected cutaneous nerve, whereby the skin graft is reinnervated. In this embodiment, the skin graft can be vascularized, at the time of implantation.

Alternatively, the skin graft is innervated, wherein the skin graft will vascularize after implantation. In still another embodiment, the skin graft revascularizes and reinnervates following implantation.

In another embodiment, the at least one magnetic component includes is an array of magnets, such as an array of magnets wherein each magnet is fixed in position relative to each of the other magnets of the array prior to implantation in the skin graft. The at least one magnetic component can include at least one member of the group consisting of a permanent magnetic material and an electromagnetic material.

Another embodiment for providing cutaneous sensory feedback in a subject by the method of the invention includes the steps of applying a tactile array to a first cutaneous surface of the subject, the tactile array being linked to sensors at a second cutaneous surface of the subject remote from the first cutaneous surface of the subject. Signals are transmitted from the sensors at the second cutaneous surface of the subject to the tactile array at the first cutaneous surface of the subject, thereby providing cutaneous sensory feedback to the subject. In one such embodiment, the tactile array includes at least one member of the group consisting of: solenoids; linear motors; and rotary motors. In the embodiment, wherein the tactile array includes rotary motors, the rotary motors include a transmission component that converts torque produced by the rotary motors into linear force that is applied to the second cutaneous surface. In one such embodiment, the transmission component includes at least one member selected from the group consisting of: a lever arm; a rack and pinion; and a ball screw. In one specific embodiment, the transmission component further includes at least one Bowden cable.

In another embodiment, the tactile array includes at least one member of the group consisting of a pneumatic component and a hydraulic component. Further, an embodiment of the method of the invention includes the step of implanting a sensing component associated with the first cutaneous surface, whereby afferent feedback generated by the tactile array is monitored. In one such embodiment, the sensing component includes a deformation-sensitive array at the first cutaneous surface. In a specific embodiment, the deformation-sensitive array is a magnetic deformation-sensitive array. Alternatively, or additionally, the deformation-sensitive array is an ultrasound array. In still another embodiment, the sensing component includes a nerve cuff placed at an innervating cutaneous nerve associated with the first cutaneous surface of the subject.

In another embodiment, the invention is a method for providing proprioceptive feedback to a subject. In this embodiment, the method includes the steps of implanting at least one magnetic target at a pair of muscles in agonist-antagonist relation to each other. A signal representing an applied force to the subject, or to a bionic component of the subject, is detected, and a selective electromagnetic field consequent to the detected force is generated, thereby causing the magnetic target to apply a force to the pair of muscles in agonist-antagonist relation to each other, whereby an afferent signal is generated by the agonist-antagonist muscle pair, thereby providing proprioceptive feedback to the subject.

In one such embodiment, the selected magnetic field is applied by a plurality of electromagnetic coils. In a specific embodiment, the method further includes the step of fixing the electromagnetic coils to a surface of the subject proximate to the at least one magnetic target. The method can further include the step of affixing a plurality of sensing magnetometers to the subject proximate to the at least one magnetic target, whereby a change in position of the at least one magnetic target caused by an efferent signal generated by the subject is detected, thereby sensing changes in the muscle lengths of the agonist-antagonist muscle pairs. The at least one magnetic target can be, for example, a permanent magnet or an electromagnet.

In still another embodiment of a method for providing proprioceptive feedback in a subject of the invention, targets are implanted at the pair of muscles wherein the muscles are in an agonist-antagonist relation to each other. At least one state of the targets is detected, thereby detecting a physical property of the agonist-antagonist pair of muscles. An afferent signal is generated consequent to the state of the agonist-antagonist pair of muscles, thereby providing proprioceptive feedback to the subject. In at least one such embodiment, at least one passive target includes at least one member of the group consisting of a permanent magnetic material and an electromagnetic material.

In another embodiment the invention is a method for selectively stimulating at least a portion of axons or nerve fascicles of a neuron of a subject comprising the steps of placing a cuff at or proximate to a neuron of a subject, the cuff including one or more antennas at or proximate to the cuff and collectively extending about at least a portion of a circumference of the neuron, thereby forming an array of the antennas about the neuron. In one embodiment, the array is a fixed array, wherein the antennas are fixed in position relative to each other. Electromagnetic waves are selectively generated at the one or more antennas and focused at a subset of at least one member of the group consisting of axons and nerve fascicles of the neuron, thereby causing depolarization of the subset and consequent selective stimulation of at least a portion of the axons or nerve fascicles of the neuron of a subject.

In one embodiment, the electromagnetic wave generated by the one or more antennas includes a carrier component and a signal component, wherein the carrier component has a lower frequency than the signal component. The electromagnetic waves, in one embodiment, are focused by at least one member of the group consisting of reflection and phase shifting of the electromagnetic waves. In the embodiment wherein the electromagnetic waves are focused by reflection, they can be reflected off a parabolic reflector, for example. In another embodiment, the electromagnetic waves are generated at the one or more antennas by a radiofrequency generator, and the electromagnetic waves are focused by a controller. In yet another embodiment, the method includes amplifying electromagnetic waves by a radiofrequency amplifier. In still another embodiment, the method further includes the step of boosting signal strength from the radiofrequency generator by a radiofrequency repeater.

In another version of this embodiment of the invention, the cuff is a nerve cuff that is implanted at the neuron. For example, the nerve cuff can extend about an epineurium of the neuron. In a specific embodiment, the array is a linear array and is sutured tangent to the epineurium.

In yet another version of this embodiment of the method of the invention, the electromagnetic magnetic waves are in a gigahertz range. In still another embodiment, the array of antennas includes at least one member of the group consisting of stainless steel, silver, gold, poly (3,4,-ethylenedioxythiophene), aluminum, copper, tungsten, and zinc. In a specific embodiment, the array of antennas are coated with a biocompatible material, such as a biocompatible polymer. Another example of a biocompatible material is silicone.

In yet another embodiment of this method of the invention, the cuff is fixed to a surface of the subject. The cuff can be either rigid or flexible. Where the cuff is flexible, the method further includes the steps of identifying the position of the one or more antennas of the fixed array relative to the neuron by at least one member of the group consisting of a position sensor and an angle sensor. In this embodiment, at least one of a position sensor and an angle sensor can include at least one member of the group consisting of the potentiometer, an encoder, and a flex sensor. In yet another embodiment, the method further includes the steps of measuring a time delay among pulses of the one or more antennas of the fixed array relative to each other, and calculating a geometry that causes the fixed antenna array to identify a position of the antennas of the array relative to each other and relative to the neuron. In still another embodiment, the antennas of the array are affixed to a skin patch, which is then attached to the skin of the subject, and the method further includes the step of calibrating each antenna by identifying the position of each of the antennas of the fixed array relative to each other and to the neuron contemporaneously with muscle flexion of the subject. In a specific embodiment, the antennas are embedded in a skin patch, and in another embodiment, the method further includes the step of attaching the skin patch on the subject.

Another embodiment of the invention is a method for tracking one or more objects, and includes applying one or more targets to each of the one or more objects and positioning an array of sensors proximate to the at least one target, whereby a signal from the at least one target at the sensors is detected. The parameters describing the state of each of the one or more targets are then estimated and predicted values of the signal at each of the sensors are calculated given these estimates of the parameters, whereby a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors is computed. A prediction error Jacobian matrix is then calculated by analytically computing elements of the prediction error Jacobian matrix, and the prediction error in combination with the prediction error Jacobian matrix are used to determine a state of the at least one target, whereby the state is indicative of a physical state of the at least one object. In one embodiment, the signal is a magnetic field. In another embodiment, the magnetic field prediction error Jacobian matrix is calculated by analytically computing submatrices of the magnetic field prediction error Jacobian matrix and assembling the analytically-computed submatrices into a single matrix. In yet another embodiment, the sensors are magnetometers. In another embodiment, the submatrices of the error Jacobian are computed in a cascading calculation. In yet another embodiment, the prediction errors are also computed in a cascading calculation. In another embodiment, the object is a tissue of a subject, the change in physical state of the object is indicative of a change in a physiological feature of a subject, and a physiological feature of the subject is modified that affects and or is affected by the changes to the subject, the modification being responsive to the change in state of the subject, thereby modulating the physiological feature of the subject.

In one such embodiment, submatrices are calculated simultaneously and before being assembled into the single matrix. In another embodiment, at least one passive target includes a magnet, and the sensors include magnetometers. Examples of suitable magnets include permanent magnets and electromagnets. In yet another embodiment, the method further includes the step of tracking an ambient magnetic field, whereby the ambient magnetic field is tracked as a time-varying magnetic disturbance, thereby causing interference to be removed from the signal from the at least one target. In another embodiment, the at least one passive target is a permanent magnet, and the array of sensors is an array of magnetometers.

A specific version of one embodiment of this method includes a method for detecting a state (e.g., a change in state) of one or more objects while compensating for a disturbance field that includes applying one or more targets to each of the one or more objects and positioning an array of sensors proximate to the at least one target, whereby a signal from the at least one target at the sensors is detected. The parameters describing the state of each of the one or more targets are then estimated, and the parameters of the disturbance field are also estimated, and predicted values of the signal at each of the sensors are calculated given these estimates of the parameters, whereby a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors is computed. A prediction error Jacobian matrix is then calculated, and the prediction error in combination with the prediction error Jacobian matrix are used to determine a state of the at least one target, whereby the state is indicative of a physical state of the at least one object.

In one embodiment of this method, the position of each target is fixed relative to a global coordinate system, whereby a change in position of the array of sensors relative to the passive target is determined. In another embodiment, the at least one target is a permanent magnet, such as a spherical, cylindrical, or cubical permanent magnet.

In an embodiment, a method for determining one or more of three sensor positions and three sensor orientations for each of the sensors in a sensor array includes the steps of: placing at least one target in at least one known location relative to a sensor array, whereby a signal from the at least one target at the sensors is detected, and recording at least one measurement of the signal at each of the sensors for each placement of the one or more targets; estimating one or more parameters from the group consisting of x-position, y-position, z-position, yaw, pitch, and roll, of each of the sensors; estimating any unknown state parameters of the at least one target; calculating predicted values of the signal at each of the sensors for each of the measurements given the estimates of the sensor parameters and target states; computing a prediction error in the predicted values of the signal with reference to the values of the signals detected at the sensors; calculating a pred

CLAIMS

Claims ( 20 )

1 .- 163 . (canceled)

164 . A method for detecting a physical property of tissue, comprising:

implanting targets at an individual tissue; employing an array of sensors to detect a magnetic field at each of the sensors of the array; estimating a position and orientation of at least two of the targets based on the detected magnetic fields; and determining at least one state of the at least two targets relative to each other based upon the estimated position and orientation of each of the at least two targets, wherein the state of the targets is indicative of a physical property.

165 . The method of claim 164 , wherein the individual tissue is a tendon.

166 . The method of claim 164 , wherein the individual tissue is a muscle.

167 . The method of claim 164 , wherein the individual tissue is a ligament.

168 . The method of claim 164 , wherein the individual tissue is a bone.

169 . The method of claim 164 , wherein the estimating a position and orientation of at least two of the targets based on the detected magnetic fields is performed in real-time and the determining at least one state of the at least two targets relative to each other based upon the estimated position and orientation of each of the at least two targets is performed in real-time.

170 . The method of claim 169 , further comprising employing the physical property in closed-loop control of a muscle using artificial muscle stimulation.

171 . The method of claim 169 , wherein the tissue is a muscle-tendon, the method further comprising:

employing at least one sensor to measure electromyographic (EMG) signals synchronously with the determining at least one state of the at least two targets relative to each other; determining a muscle activation based, at least in part, on the measured EMG signals; and estimating, in real-time, muscle contraction and muscle force production based, at least in part, on the at least one state and the muscle activation.

172 . The method of claim 171 , wherein the method is used to control a prosthetic, orthotic, or other rehabilitative device.

173 . The method of claim 171 , wherein the method is used in musculotendinous applications involving wireless tracking of muscle-tendon state in animals.

174 . The method of claim 173 , wherein tracking data from the wireless tracking of muscle-tendon state in animals is used to determine a muscle-tendon dynamics model.

175 . The method of claim 164 , wherein the physical property of the tissue includes at least one member of the group consisting of: a contraction or relaxation of skeletal, cardiac, or smooth muscle; a bone bending; a bone stretching; a lung inflation; a peristalsis; a vasoconstriction; a vasodilation; a skin stress; a skin strain; a position of at least one bodily organ; an orientation of at least one bodily organ; a volume of at least one bodily organ; and a length of at least one bodily organ.

176 . The method of claim 164 , wherein the targets are implanted at a pair of muscles in agonist-antagonist relationship to each other, whereby the physical property is the degree of contraction of the agonist-antagonist pair of muscles relative to each other.

177 . A device for detecting a physical property of tissue, comprising:

an array of sensors configured to detect a magnetic field from targets at an individual tissue; and electronics configured to:

estimate a position and orientation of at least two of the targets based on the detected magnetic fields;

determine at least one state of the at least two targets relative to each other based upon the estimated position and orientation of each of the at least two targets; and

provide an indication of a physical property of the tissue based on the determined at least one state.

178 . The device of claim 177 , wherein the individual tissue is a tendon, a muscle, a ligament, a bone, or cartilage.

179 . The device of claim 177 , wherein the electronics are configured estimate the position and orientation of the at least two of the targets in real-time and determine the at least one state in real-time.

180 . The device of claim 177 , wherein the physical property is employed in closed-loop control of a muscle using artificial muscle stimulation.

181 . A method for calibrating magnetometers, comprising:

generating a magnetic field in proximity to the magnetometers; processing magnetic field signals generated by the magnetometers based, at least in part, on the magnetic field detected by the magnetometers; and calibrating at least one of bias, location, or angle of the magnetometers based, at least in part, on the magnetic field signals.

182 . The method of claim 181 , wherein the method is used to determine the position and location of the magnetometers within a global coordinate system.

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