Multimodal sensing contact for detecting motor intent

Abstract

A modular sensor system and method for detecting muscle activity using co-located electromyography (EMG) and magnetically encoded force myography (FMG) signals. Each sensor unit comprises an electrode configured to detect EMG signals, a conductive spring mechanically coupled to a magnet, and a magnetic sensing component, such as a Hall-effect sensor, positioned to detect changes in magnetic field strength resulting from mechanical deformation. A signal processing unit, located on the same circuit board, is configured to generate the EMG and FMG signals from a common anatomical location, assess electrode-skin contact quality, suppress motion artifacts, and output a filtered signal. The system supports single-unit or arrayed deployment in wearable or prosthetic applications, and enables scalable, real-time, high-fidelity muscle activity sensing using a compact, low-profile architecture.

Description

MULTIMODAL SENSING CONTACT FOR DETECTING MOTOR INTENTSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0001] This invention was made with government support under OD029571 awarded by the National Institutes of Health, and 2139322 awarded by the National Science Foundation. The government has certain rights in the inventionCROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 634,845 entitled "MULTIMODAL SENSING CONTACT FOR DETECTING MOTOR INTENT" and filed April 16, 2024, which is hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION1. Technical Field

[0003] The present disclosure relates generally to systems and methods for sensing muscle activity, and more particularly to electrode systems that co-locate electromyography (EMG) and force myography (FMG) signal acquisition, including applications in prosthetic control, physiological monitoring, and human-machine interfaces.2. Background and Relevant Art

[0004] Surface electromyography (EMG) is a non-invasive technique for detecting electrical signals generated by muscle tissue during activation. Surface EMG systems typically involve placing one or more electrodes on the skin to measure voltage changes associated with muscle depolarization. Such systems are widely used in clinical diagnostics, physical rehabilitation, prosthetic control, sports science, and human-computer interaction.

[0005] Despite its versatility, surface EMG suffers from several limitations. The signal quality is highly sensitive to the quality of electrode-skin contact, which can degrade due to motion, sweat, or electrode displacement. EMG signals are also susceptible to motion artifacts and electrical noise, especially in mobile or wearable environments. Additionally, surface EMG provides limited information about the magnitude of physical force or deformation associatedwith muscle activity, which can be important in interpreting user intent or understanding neuromuscular control.

[0006] To supplement or enhance EMG, force myography (FMG) has been developed as a complementary technique that detects mechanical deformation— such as muscle bulging or skin movement— typically using force-sensitive resistors (FSRs) or pressure sensors. FMG can provide additional context or robustness to EMG-based systems, but most FMG implementations require separate hardware, are spatially offset from the EMG electrodes, or use bulky sensors with limited resolution and response time.

[0007] In various applications, it may be desirable to detect both electrical and mechanical muscle signals using integrated or co-located sensors. In particular, signal accuracy and system robustness may be influenced by factors such as electrode-skin contact quality, motion artifacts, and sensor footprint. Systems that allow for compact, modular sensing of both EMG and FMG signals from the same anatomical location may be useful in contexts such as prosthetic control, robotics, and wearable technologies.

[0008] The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.BRIEF SUMMARY OF THE INVENTION

[0009] The present disclosure relates to systems, electrode units, and methods for detecting and interpreting muscle activity using co-located acquisition of electromyographic (EMG) signals and magnetically encoded force myography (FMG) signals. In some embodiments, the system may include at least one electrode configured to detect an EMG signal from a user, an electrically conductive force sensing component mechanically coupled to a magnet, and a magnetic sensing component configured to detect changes in magnetic field strength resulting from movement of the magnet.

[0010] The force sensing component may include a conductive spring that deforms in response to muscle activation. Movement of the spring may displace the magnet, and the resulting change in magnetic field may be detected by a magnetic sensing component, such as a Hall-effect sensor, which may be mounted on a circuit board within the electrode unit. Thesystem may be configured such that both the EMG and FMG signals are generated from a common anatomical location, and in some embodiments, both signals may be obtained through the same electrode structure.

[0011] As used herein, "magnetically encoded force myography" refers to a force sensing technique in which mechanical deformation caused by muscle activity is converted into a change in magnetic field strength that is detected by a magnetic sensing component. This indirect encoding of force via magnetic field variation provides an alternative to conventional force myography techniques that rely on resistive or capacitive sensors, and may allow for improved miniaturization, co-location, and signal fidelity.

[0012] The signal processing components may include circuitry configured to generate a magnetically encoded FMG signal, analyze the EMG and FMG signals to determine skin contact quality, detect and remove motion artifacts from the EMG signal, and classify user motor intent, physical activity, or physiological state. In some cases, the signal processing circuitry may convert the analog EMG and FMG signals into digital signals, which can be transmitted over a minimal conductor interface, such as a two-wire bus, to an external processing system. As used herein, a 'two-wire bus' refers to a communication interface that transmits both power and digital signal data over a pair of conductors, optionally within a shared sheath or cable. This architecture enables simplified wiring and modular scalability.

[0013] The electrode unit may be modular and individually configurable as a signal, reference, or ground electrode. A plurality of such units may be positioned at different anatomical sites and used in an array configuration. In certain embodiments, the electrode unit may include a cylindrical housing that facilitates mounting within a prosthetic socket and may be secured with an external fastener. The housing or mounting structure may be formed from a low-friction material, such as a thermoplastic containing PTFE, to reduce frictional disturbances that could otherwise interfere with FMG signal fidelity. The spring may optionally be formed from a ferromagnetic material to help focus the magnetic field and reduce sensitivity to external magnetic interference.

[0014] The systems and methods described herein may be used in a variety of applications including, but not limited to, prosthetic and orthotic control, robotic systems, rehabilitation and physiological monitoring, digital avatars, and smart device interfaces.

[0015] Additional features and advantages of exemplary implementations of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary implementations. The features and advantages of such implementations may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such exemplary implementations as set forth hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In orderto describe the manner in which the above recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0017] Figure 1 depicts an embodiment of an electrode loaded onto a conductive spring, and a printed circuit board with a Hall-effect sensor and signal processing unit;

[0018] Figure 2 depicts another embodiment of three electrode units within a housing, with one electrode being compressed and compressing the spring as a result;

[0019] Figure 3 depicts yet another embodiment of an electrode, displaying a rod shaped magnet attached to a conductive spring being compressed, moving the rod shaped magnet towards a Hall-effect sensor;

[0020] Figure 4 depicts another embodiment of an electrode disposed on a mounting structure that houses any internal components, and a two wire bus within a single sheath extending from the mounting structure; and

[0021] Figure 5 depicts a cross-section of an electrode disposed on a mounting structure, where there is an aperture configured to secure the mounting structure to an external prosthetic or similar device;

[0022] Figure 6 depicts a bottom view of an embodiment of the current disclosure when attached to an external device;

[0023] Figure 7 depicts an embodiment of the current disclosure in use, where signals from each individual electrode unit are sent to an external processing unit;

[0024] Figure 8 depicts yet another embodiment of the current disclosure in use, where signals are processed locally at each unit, and each electrode unit is connected to the next by a joint, making a wearable band-like device;

[0025] Figure 9 depicts yet another embodiment, where electrodes are configured in an array on a wearable wristwatch-like device;

[0026] Figure 10 depicts an algorithm exemplary of the disclosure that may be executed locally or externally.DETAILED DESCRIPTION

[0027] The present invention relates generally to devices, systems, and methods for detecting muscle activity, and more particularly to modular electrode devices that simultaneously acquire electromyographic (EMG) and force-based signals from a co-located anatomical site. The invention further relates to the use of magnetically encoded force myography for improved detection, processing, and interpretation of neuromuscular activity in applications including, but not limited to, prosthetic control, wearable robotics, rehabilitation monitoring, and gesture-based human-machine interfaces.

[0028] As previously described, the present devices and systems comprise, in part, an electrode unit. As used herein, an electrode unit refers to a self-contained module configured to simultaneously acquire electromyographic and force-related signals from a single anatomical site. Each unit typically includes an electrode configured to be operable as a signal, reference, or ground; an electrically conductive force sensing component such as a conductive spring; a magnet and a magnetic sensing component; and one or more signal processing components mounted on a circuit board. The electrode unit may be housed in a compact enclosure and may operate independently or as part of a larger sensing array.

[0029] As used herein, magnetically encoded force myography refers to a technique for sensing mechanical deformation associated with muscle activity by translating displacement into changes in a magnetic field. In this approach, a magnet moves relative to a magnetic sensing component —such as a Hall-effect sensor— in response to pressure or force applied at the skin surface. The resulting changes in magnetic field strength are measured and processed togenerate a signal that correlates with muscle force or motion. This signal provides complementary information to surface EMG and may be used to enhance signal robustness, reduce motion artifacts, and infer user intent in real time.

[0030] In various embodiments, the system includes one or more electrode units configured to detect muscle activity signals using both electrical and mechanical sensing modalities. Each electrode unit may comprise: an electrode configured to detect electromyographic (EMG) signals; a conductive spring or compliant structure mechanically coupled to the electrode; a magnet that moves in response to muscle-induced displacement; a Hall-effect sensor mounted on a circuit board; and a signal processing unit configured to interpret both EMG and mechanical signals.

[0031] As the spring compresses in response to muscle bulging or pressure at the skin surface, the magnet is displaced relative to the Hall-effect sensor. The resulting change in magnetic field strength is detected and processed to generate a magnetically encoded force myography (FMG) signal. This signal captures local mechanical deformation correlated with underlying muscle activity, and is acquired from substantially the same anatomical location as the EMG signal.

[0032] Unlike traditional force myography (FMG), which typically relies on force-sensitive resistors (FSRs) or capacitive sensors to measure mechanical deformation of the skin or underlying tissue, magnetically encoded force myography detects force indirectly by tracking displacement of a magnet relative to a fixed magnetic sensor, such as a Hall-effect sensor. This approach eliminates common issues associated with conventional FMG sensors — such as hysteresis, drift, and sensitivity to surface friction— while enabling tighter integration, improved miniaturization, and true co-location with EMG electrodes. As a result, magnetically encoded FMG provides a more stable and precise force signal, well-suited for wearable applications and embedded prosthetic control systems.

[0033] In certain embodiments, the Hall-effect sensor is miniaturized and integrated directly within the electrode unit, enabling the magnetic sensing component to occupy a very small footprint while maintaining high sensitivity to displacement. This miniaturization allows the sensor to be embedded in close proximity to the electrode and mechanical components without increasing the overall size of the unit. Coupled with local signal processing on the same circuit board, this configuration reduces the need for long signal paths or external processors, therebyminimizing noise susceptibility and improving signal fidelity. Local processing also enables realtime analysis of both electromyographic and force signals within each unit, which enhances modularity, scalability, and compatibility with wearable and prosthetic applications. In at least one embodiment, this architecture allows for compact, co-located signal acquisition that would be difficult to achieve using traditional force sensing technologies or offboard processing configurations.

[0034] The co-located acquisition of electromyographic (EMG) signals and magnetically encoded force myography (FMG) signals within a single electrode unit provides several key advantages over conventional sensing approaches. By capturing both electrical and mechanical signals from the same anatomical location, the system enables more accurate correlation of muscle activity and force output, resulting in improved robustness in signal interpretation. Colocation minimizes spatial discrepancies between modalities, reduces sensor placement complexity, and supports more precise estimation of muscle intent and contraction dynamics.

[0035] In certain embodiments, signal processing is performed locally within each electrode unit by an onboard signal processing component mounted on the same circuit board as the sensing elements. This localized processing architecture minimizes the length of analog signal paths, thereby reducing susceptibility to electrical noise and motion artifacts. Local processing also allows real-time filtering, artifact rejection, and classification of signals before transmission, which decreases the burden on centralized processing systems and enhances responsiveness in time-critical applications, such as prosthetic control or gesture recognition.

[0036] Digitized output signals may be transmitted from each electrode unit via a low- conductor interface, such as a two-wire bus, which reduces wiring complexity and improves mechanical reliability in wearable or embedded systems. The modular nature of the electrode units allows for use as a standalone sensor or in an array of multiple units positioned at various anatomical sites. This flexibility supports a wide range of form factors, including wearable bands, sleeves, or integration into prosthetic sockets. The compact and self-contained nature of each unit also facilitates scalable deployment, simplifies maintenance or replacement, and supports distributed sensing architectures.

[0037] Referring now to FIG. 1, an example embodiment of a modular electrode unit 100 for detecting muscle activity is shown. The electrode unit 100 is designed to simultaneously acquireelectromyography (EMG) signals and magnetically encoded force myography (FMG) signals from a common anatomical location.

[0038] The system includes an electrode 102, which may be configured to function as a signal, reference, or ground electrode, depending on the configuration of the system or array. The electrode 102 is in direct electrical contact with the user's skin and is operable to detect electrical potentials generated by muscle depolarization.

[0039] Mechanically and electrically coupled to the electrode 102 is a conductive spring 104. Spring 104 is configured to deform in response to mechanical force generated by underlying muscle activity. In some embodiments, the spring is composed of an electrically conductive and optionally ferromagnetic material, allowing it to serve both as a compliant mechanical element and as part of the electrical signal path for the EMG signal.

[0040] Positioned beneath the spring assembly is a printed circuit board (PCB) 106, which provides a rigid substrate for mounting sensing and processing components. The PCB 106 supports a magnetic sensing component, such as a Hall-effect sensor 108, which is aligned with the axis of movement of a magnet (not shown in this simplified figure) that is displaced by the deformation of the spring 104. The Hall-effect sensor 108 is configured to detect changes in the strength of the magnetic field resulting from displacement of the magnet, which correlates with force or pressure applied to the electrode.

[0041] Also mounted on the PCB 106 is a signal processing unit 110, which may include one or more analog or digital processing components. The signal processing unit 110 is electrically coupled to both the electrode 102 and the Hall-effect sensor 108, and is configured to execute a signal processing algorithm. In some embodiments, the algorithm includes operations for generating an EMG signal based on electrical activity detected at the electrode, generating a magnetically encoded FMG signal from the Hall-effect sensor output, assessing electrode-skin contact quality, filtering out motion-induced artifacts from the EMG signal, and optionally classifying user motor intent, activity, or physiological state. In some embodiments, the system may classify physical activity or physiological state based on extracted features from the filtered EMG and FMG signals, such as amplitude patterns, contraction timing, or signal frequency, which may be processed using thresholding logic or machine learning classifiers.

[0042] In some implementations, the signal processing unit 110 digitizes the EMG and FMG signals and transmits them via a low-conductor interface, such as a two-wire bus, to an externalprocessing unit. The entire electrode unit may be housed in a compact form factor suitable for integration into prosthetic sockets, wearable bands, or multi-unit sensor arrays.

[0043] As an additional or alternative configuration, an example embodiment of a multimodal device 200 is shown in Figure 2, in which a plurality of electrodes 102 are arranged within a shared plastic housing 212. Figure 2 can include features described in relation to any other embodiment disclosed herein. The illustrated configuration depicts a wearable or embedded form factor suitable for mounting on a prosthetic socket, limb band, or similar anatomical interface. Each electrode 102 may include its own signal acquisition and processing components, allowing for modular and independent operation.

[0044] Conductive springs 104a, 104b, and 104c are mechanically and electrically coupled to the electrodes of each corresponding electrode 102. These springs deform in response to force applied at the skin-contacting surface of the electrode, such as when the underlying muscle contracts or bulges. In the illustrated embodiment, spring 104c is shown in a compressed state relative to springs 104a and 104b, indicating localized mechanical deformation and simulating real-time sensing of muscular activity. The compression of the spring causes a corresponding displacement of an internal magnet (not shown in this view), which alters the magnetic field detected by the Hall-effect sensor.

[0045] Underneath each electrode 102 there is a Hall-effect sensor 108 positioned adjacent to the spring, typically on a rigid printed circuit board, and aligned with the axis of magnet displacement. The Hall-effect sensor 108 is configured to detect changes in magnetic field strength resulting from the spring compression and magnet movement. This magnetic signal is used to generate a magnetically encoded force myography (FMG) signal, indicative of force or pressure at the anatomical site.

[0046] Also shown in FIG. 2 is a signal processing unit 110, electrically coupled to both the Hall-effect sensor 108 and the electrode. The plastic housing 212 serves to mechanically support and align the electrode 102 in a fixed spatial relationship. The housing may be configured to enclose the electrode units partially or fully, and may include apertures, mounting features, or fixation elements to enable integration into prosthetic devices, wearable bands, or other bodymounted systems. The housing may also help to isolate each unit from lateral movement or external disturbance, thereby preserving signal integrity and force resolution.

[0047] FIG. 3 illustrates an internal view of an electrode 102, in which the outer electrode structure has been removed to expose the underlying components involved in mechanical and magnetic signal acquisition, highlighting how muscle-induced deformation results in magnetic field variation.

[0048] A rod-shaped magnet 314 is positioned along the central axis of the assembly and is mechanically coupled to a compliant conductive spring 104. A spring 104 is supported within a housing structure (not shown in this view) and is configured to compress when force is applied to the electrode surface during muscle activation. The magnet 314 is aligned such that its longitudinal axis is oriented in the direction of displacement, indicated by arrow 315, which shows the compression direction corresponding to inward or downward force on the electrode.

[0049] Beneath the spring 104 and magnet 314 is a PCB 106 that provides structural support and electrical interconnection for sensing and processing components. Mounted on the PCB 106 is a Hall-effect sensor 108, positioned directly beneath the magnet 314 and aligned to detect axial changes in magnetic field strength as the magnet moves closer or farther away in response to spring compression. Also shown mounted on the PCB 106 is a signal processing unit 110, electrically coupled to both the Hall-effect sensor 108 and the EMG electrode (not shown in this figure). The configuration illustrated in FIG. 3 demonstrates how compact integration of the spring-magnet mechanism, magnetic sensor, and signal processing circuitry enables precise colocated signal acquisition within a miniaturized modular unit. The use of a rod-shaped magnet aligned with the Hall-effect sensor allows for predictable and sensitive detection of displacement along a single axis, supporting high-resolution force sensing in wearable or prosthetic applications.

[0050] Referring now to FIG. 4, an embodiment of a fully enclosed electrode 102 is shown integrated within a mounting structure 416, which supports mechanical attachment, electrical routing, and modular deployment of the sensing assembly. Figure 4 can include features described in relation to any other embodiment disclosed herein. The mounting structure 416 is configured to house all internal components of the cylindrical body of the electrode, spring mechanism, magnet, magnetic sensing component, and signal processing circuitry, as described in previous figures.

[0051] The mounting structure 416 may be formed from a low-friction material, such as a thermoplastic polymer containing polytetrafluoroethylene (PTFE, commercially known asTeflon). This material selection serves to reduce frictional disturbances between the electrode and the mounting body, thereby improving the fidelity of the force myography signal. The low- friction housing material helps preserve the integrity of the displacement-based signal by minimizing mechanical interference due to sliding or rubbing at the interface between the movable electrode assembly and the surrounding enclosure.

[0052] In addition to friction reduction, the housing may provide structural durability and biocompatibility, and may be shaped to facilitate secure placement within a prosthetic socket, wearable band, or other limb interface. In certain embodiments, the mounting structure includes alignment features or fastening points (not shown) for attachment to the external surface of a prosthetic device or wearable system.

[0053] Extending from the rear or base of the mounting structure 416 is a wire bus 418, which electrically couples the electrode 102 to an external system, such as a host controller or processing module. The wire bus 418 may comprise a two-conductor cable, a shielded twisted pair, or a low-profile flexible cable designed to transmit digitized EMG and FMG signals while minimizing conductor count and wiring complexity. In some embodiments, the wire bus 418 supports both power delivery and bidirectional data transmission, enabling real-time signal communication with minimal hardware overhead.

[0054] The integration of all sensing and processing components within a sealed mounting structure enables reliable, compact deployment of the electrode unit in a variety of environments. This architecture supports robust, co-located acquisition of electromyographic and magnetically encoded force myography signals while providing mechanical durability, modular scalability, and ease of installation into larger systems.

[0055] FIG. 5 shows a cross-sectional view of the electrode unit assembly 500, corresponding to the enclosed configuration previously illustrated in FIG. 4. Figure 5 can include features described in relation to any other embodiment disclosed herein. This view reveals the internal arrangement of components within the housing and highlights both the mechanical sensing mechanism and structural features used for mounting and electrical interfacing.

[0056] The assembly 500 includes an electrode 102 positioned at the upper portion of the device and configured to contact the user's skin. The electrode 102 is mechanically and electrically coupled to a conductive spring 104, which provides compliance and force transmission during muscle activity. Beneath the spring 104 and magnet 314 is a printed circuitboard (PCB) 106, which houses a Hall-effect sensor 108 aligned with the axis of the magnet. As the spring compresses and the magnet 314 moves closer to the sensor, the Hall-effect sensor 108 detects changes in the magnetic field, which are used to generate a magnetically encoded force myography (FMG) signal. PCB 106 may also carry additional signal conditioning and digitization circuitry.

[0057] At the base of the device is a wire bus 418, which serves as the electrical output and communication interface for the electrode unit. The wire bus 418 may comprise a two-conductor cable or other compact connection system that carries power and / or digitized EMG and FMG signals to an external host system or control module.

[0058] Also visible in the cross-sectional view is an aperture 520, positioned near the periphery of the housing. The aperture 520 is configured to receive an external fastener, such as a screw or bolt, enabling the electrode assembly 500 to be secured to a prosthetic socket or wearable interface from the outside. This fastening configuration facilitates quick installation and modular replacement while maintaining alignment and mechanical stability during use.

[0059] The structural layout shown in FIG. 5 demonstrates how the electrode assembly 500 integrates sensing, processing, and mounting features within a compact form factor. The alignment of mechanical and magnetic components, along with the inclusion of integrated fastening and cabling features, supports robust and scalable deployment in various wearable and assistive technologies.

[0060] FIG. 6 illustrates a bottom view of an electrode assembly 500 mounted to an external device 613, such as a prosthetic socket, wearable interface, or structural component of a robotic or assistive system. This view highlights the underside features of the electrode unit and shows the physical configuration by which the unit is secured in place and electrically connected. Figure 6 can include features described in relation to any other embodiment disclosed herein.

[0061] The mounting structure 616 of the electrode assembly 500 is visible from below and is shaped to engage with the external device 613. In the illustrated embodiment, the mounting structure 616 is partially recessed or flush with the external device surface, allowing for stable integration without protrusion. The mounting structure may be formed from a durable, low- friction material— such as thermoplastic containing PTFE (Teflon)— to reduce shear forces and preserve signal quality during use.

[0062] An attachment point 622 is also shown in the bottom view. The attachment point 622 comprises an opening or interface feature configured to receive a fastener, such as a screw, bolt, or mechanical clip. This fastening mechanism enables the electrode unit to be secured from the outside of the external device 613, facilitating straightforward installation, alignment, and removal for maintenance or replacement. The attachment point may be reinforced to ensure mechanical stability and to prevent unintentional movement or detachment during use.

[0063] A wire bus 418 is also shown exiting the electrode unit from the underside. The wire bus 418 provides electrical connectivity between the electrode unit's internal components and an external control system or data acquisition device. The wire bus may include a two-conductor cable for power and data or a more complex harness depending on the signal configuration. In certain embodiments, the cable supports digital signal transmission of both EMG and magnetically encoded FMG signals generated by the unit.

[0064] FIG. 7 illustrates an embodiment in which a plurality of electrode assemblies 500 are deployed along an arm 727, demonstrating the system's application in wearable or prosthetic environments. The figure shows a modular array of four electrode units, each positioned over distinct anatomical sites to detect localized muscle activity. This configuration supports multisite sensing for complex gesture recognition, prosthetic control, or neuromuscular monitoring.

[0065] Each electrode assembly 500 is configured to simultaneously acquire both electromyographic (EMG) signals 728 and magnetically encoded force myography (FMG) signals 730 from its respective anatomical location. The co-located acquisition enables accurate correlation between muscle activation and mechanical deformation at each site, supporting finegrained intent detection and robust control signal generation.

[0066] The EMG signals 728 and FMG signals 730 are transmitted from each electrode assembly 500 to a centralized external processing unit 732. The external processing unit 732 may be configured to receive raw or pre-processed signals from the electrode units and execute higher-level signal fusion, classification, and control algorithms. In some embodiments, each electrode unit may perform preliminary filtering or artifact rejection locally, while the external processor aggregates and interprets the data across multiple units for composite analysis.

[0067] FIG. 8 illustrates an embodiment of a wearable armband configuration in which a plurality of electrode assemblies 500 are arranged in a circumferential array around an arm 727. The electrode assemblies 500 are mechanically joined to one another via a series of joints 826,which permit flexibility and conformability of the armband structure to accommodate the curvature and movement of the limb.

[0068] Each electrode assembly 500 is structurally similar to the modular sensor units described in earlier figures, comprising components for co-located electromyography (EMG) and magnetically encoded force myography (FMG) signal acquisition and processing. The configuration shown in FIG. 8 enables the simultaneous monitoring of muscle activity from multiple anatomical regions around the forearm or upper arm, supporting detailed gesture classification, muscle coordination analysis, or control of multi-degree-of-freedom prosthetic devices.

[0069] The joints 826 between electrode units may include flexible or articulated elements that maintain electrical connectivity while allowing limited movement or rotation between adjacent units. In some embodiments, the joints may house electrical conductors, such as shared bus lines or communication traces, enabling signal transmission along the length of the armband without requiring external cabling. The flexible linkage enhances comfort, wearability, and adaptability for users of varying limb sizes and shapes.

[0070] FIG. 9 illustrates a wearable sensing system 900 in which an array of electrode units 939 is integrated into a compact, wrist-mounted form factor resembling a watch. The electrode units 939 are arranged in a 6x8 diagonal grid beneath a watch face 941, which may serve as a user interface, protective cover, or housing structure. The array is configured such that the lateral spacing between adjacent electrodes is on the order of magnitude of the tendons in the human wrist, allowing for precise anatomical targeting of individual tendons or muscle compartments during use.

[0071] The diagonal orientation of the array is selected to align with the natural angles and anatomical layout of wrist tendons and underlying musculature, improving contact quality and signal selectivity. Each electrode unit in the array may comprise a spring-loaded electrode, a Halleffect sensor, and onboard signal processing circuitry, as described in prior embodiments. The close-packed, anatomically-informed layout enhances the resolution of both electromyographic (EMG) and magnetically encoded force myography (FMG) signals across the surface of the wrist, enabling fine-grained detection of motor intent, gesture classification, or state monitoring.

[0072] FIG. 10 illustrates a flowchart representing an example signal processing algorithm for handling co-located electromyographic (EMG) and magnetically encoded force myography(FMG) signals acquired by the disclosed electrode units. The algorithm may be executed locally within a signal processing unit integrated into the electrode housing, or externally by a host controller or central processing system.

[0073] At block 1038, the system acquires an EMG signal, which corresponds to the electrical activity of muscles detected through the skin-contacting electrode. This signal may be subject to noise, motion artifacts, or variability in skin-electrode contact.

[0074] At block 1040, the system acquires a magnetic signal from a Hall-effect sensor positioned adjacent to a movable magnet within the electrode unit. This signal reflects changes in the local magnetic field resulting from spring compression or mechanical displacement caused by muscle contractions.

[0075] At block 1042, the system generates a magnetically encoded FMG signal based on the acquired magnetic signal. This FMG signal represents local mechanical deformation at the skin surface and serves as a complementary modality to the EMG signal.

[0076] At block 1044, the system assesses the quality of electrode-skin contact using the characteristics of the FMG signal. In some embodiments, changes in signal amplitude, baseline deviation, or other dynamic features may be analyzed to detect poor contact or partial electrode lift-off.

[0077] At block 1046, the system identifies and suppresses motion-induced artifacts present in the EMG signal. This is achieved by comparing the EMG signal to the FMG signal, which serves as a reference for detecting mechanical disturbances unrelated to voluntary muscle activation.

[0078] Finally, at block 948, the algorithm outputs a filtered EMG signal, in which motion artifacts have been removed or suppressed. This filtered signal may be used for downstream classification, control of a prosthetic device, or other signal interpretation tasks.

[0079] Further, the methods may be practiced by a computer system including one or more processors and computer-readable media such as computer memory. In particular, the computer memory may store computer-executable instructions that when executed by one or more processors cause various functions to be performed, such as the acts recited in the embodiments.

[0080] Computing system functionality can be enhanced by a computing systems' ability to be interconnected to other computing systems via network connections. Network connections may include, but are not limited to, connections via wired or wireless Ethernet, cellularconnections, or even computer to computer connections through serial, parallel, USB, or other connections. The connections allow a computing system to access services at other computing systems and to quickly and efficiently receive application data from other computing systems.

[0081] Interconnection of computing systems has facilitated distributed computing systems, such as so-called "cloud" computing systems. In this description, "cloud computing" may be systems or resources for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, services, etc.) that can be provisioned and released with reduced management effort or service provider interaction. A cloud model can be composed of various characteristics (e.g., on-demand self-service, broad network access, resource pooling, rapid elasticity, measured service, etc), service models (e.g., Software as a Service ("SaaS"), Platform as a Service ("PaaS"), Infrastructure as a Service ("laaS"), and deployment models (e.g., private cloud, community cloud, public cloud, hybrid cloud, etc.).

[0082] Cloud and remote based service applications are prevalent. Such applications are hosted on public and private remote systems such as clouds and usually offer a set of web based services for communicating back and forth with clients.

[0083] Many computers are intended to be used by direct user interaction with the computer. As such, computers have input hardware and software user interfaces to facilitate user interaction. For example, a modern general purpose computer may include a keyboard, mouse, touchpad, camera, etc. for allowing a user to input data into the computer. In addition, various software user interfaces may be available.

[0084] Examples of software user interfaces include graphical user interfaces, text command line based user interface, function key or hot key user interfaces, and the like.

[0085] Disclosed embodiments may comprise or utilize a special purpose or general-purpose computer including computer hardware, as discussed in greater detail below. Disclosed embodiments also include physical and other computer-readable media for carrying or storing computer-executable instructions and / or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer-readable media that store computer-executable instructions are physical storage media.

[0086] Physical computer-readable storage media includes RAM, ROM, EEPROM, CD-ROM or other optical disk storage (such as CDs, DVDs, etc), magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

[0087] A "network" is defined as one or more data links that enable the transport of electronic data between computer systems and / or modules and / or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and / or data links which can be used to carry program code in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above are also included within the scope of computer-readable media.

[0088] Further, upon reaching various computer system components, program code means in the form of computer-executable instructions or data structures can be transferred automatically from transmission computer-readable media to physical computer-readable storage media (or vice versa). For example, computer-executable instructions or data structures received over a network or data link can be buffered in RAM within a network interface module (e.g., a "NIC"), and then eventually transferred to computer system RAM and / or to less volatile computer-readable physical storage media at a computer system. Thus, computer-readable physical storage media can be included in computer system components that also (or even primarily) utilize transmission media.

[0089] Computer-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. The computer-executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or actsdescribed above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

[0090] Those skilled in the art will appreciate that the invention may be practiced in network computing environments with many types of computer system configurations, including, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, pagers, routers, switches, and the like. The invention may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

[0091] Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Program-specific Integrated Circuits (ASICs), Program-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0092] The present invention may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

[0093] The disclosed technology is illustrated, for example, according to various features described below. Various examples of features of the disclosed technology are described as numbered features (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the disclosed technology. It is noted that any of the dependent features may be combined in any combination, and placed into a respective independent features. The other features can be presented in a similar manner.

[0094] Feature 1. A system for detecting muscle activity comprising: at least one electrode configured to detect an electromyography signal from a user; an electrically conductive forcesensing component configured to deform in response to muscle activity and mechanically coupled to a magnet; a magnetic sensing component configured to detect changes in a magnetic field resulting from displacement of the magnet due to deformation of the electrically conductive force sensing component; and one or more signal processing components configured to generate a magnetically encoded force myography signal based on the detected changes in the magnetic field, wherein the electromyography signal and the magnetically encoded force myography signal are both generated from a location of the at least one electrode.

[0095] Feature 2. The system of any of the preceding features, wherein the one or more signal processing components are further configured to determine a quality of skin contact at the at least one electrode based on variation in the magnetically encoded force myography signal.

[0096] Feature 3. The system of any of the preceding features, wherein the one or more signal processing components are configured to identify and remove motion-induced artifacts in the electromyography signal by comparing the electromyography signal to the magnetically encoded force myography signal.

[0097] Feature 4. The system of any of the preceding features, wherein the one or more signal processing components are further configured to generate a filtered electromyography signal by removing signal components identified as the motion-induced artifacts using the magnetically encoded force myography signal.

[0098] Feature 5. The system of any of the preceding features, wherein the electromyography signal and the magnetically encoded force myography signal are both obtained through the at least one electrode.

[0099] Feature 6. The system of any of the preceding features, wherein the electrically conductive force sensing component comprises a spring, the spring being electrically conductive.

[0100] Feature 7. The system of any of the preceding features, wherein the magnetic sensing component is a Hall-effect sensor mounted on a substrate adjacent to the electrically conductive force sensing component and is electrically coupled to the one or more signal processing components.

[0101] Feature 8. The system of any of the preceding features, wherein the at least one electrode, the magnet, and the electrically conductive force sensing component are housed together in a single modular sensor unit configured to be used individually or in an array.

[0102] Feature 9. The system of any of the preceding features, wherein the at least one electrode is one of a plurality of electrodes, each independently configurable as a signal, reference, or ground electrode.

[0103] Feature 10. The system of any of the preceding features, wherein the one or more signal processing components are further configured to classify a user's intended gesture or movement based on combined features of the electromyography signal and the magnetically encoded force myography signal.

[0104] Feature 11. The system of any of the preceding features, further comprising a plurality of electrode units positioned at different anatomical sites, each configured to simultaneously collect electromyography and magnetically encoded force myography signals from co-located regions.

[0105] Feature 12. The system of any of the preceding features, wherein the magnet is a rodshaped permanent magnet embedded within a movable electrode cap, the magnet being axially aligned with a Hall-effect sensor when the electrically conductive force sensing component is in a resting state.

[0106] Feature 13. The system of any of the preceding features, wherein the magnetic sensing component is mounted on a rigid substrate and positioned within a recess beneath the magnet such that the magnetic field at the magnetic sensing component varies with displacement of the at least one electrode in a direction perpendicular to a plane of the magnetic sensing component.

[0107] Feature 14. The system of any of the preceding features, comprising: an electrode configured to be operable as a signal, reference, or ground electrode; a conductive spring mechanically and electrically coupled to the electrode; a magnet mechanically coupled to the electrode such that movement of the electrode compresses the spring and displaces the magnet; a circuit board positioned adjacent to the spring, the circuit board comprising: a Hall-effect sensor mounted on the circuit board and positioned to detect changes in magnetic field strength resulting from displacement of the magnet; and a signal processing unit electrically coupled to the electrode and the Hall-effect sensor; wherein the electrode unit is configured to simultaneously generate an electromyography signal based on electrical activity detected by the electrode and a magnetically encoded force myography signal based on the detected changes in magnetic field strength; and wherein the electromyography signal and the magnetically encodedforce myography signal are generated from a common anatomical location on a user; wherein the signal processing unit is further configured to detect one or more of a user's motor intent, physical activity, or physiological state based on the electromyography signal and the magnetically encoded force myography signal.

[0108] Feature 15. The system of any of the preceding features, wherein the signal processing unit is configured to process and transmit the electromyography signal and magnetically encoded force myography signals in real time for use in a external device control system.

[0109] Feature 16. The system of any of the preceding features, wherein the electrode unit comprises a cylindrical body enclosing at least a portion of the circuit board, Hall-effect sensor, conductive spring, and electrode, the cylindrical body being configured to be insertable through a hole in a prosthetic socket and mountable via an external fastener.

[0110] Feature 17. The system of any of the preceding features, wherein a housing that mounts the electrode comprises a low-friction material.

[0111] Feature 18. The system of any of the preceding features, wherein the conductive spring comprises a ferromagnetic material configured to focus a magnetic field generated by the magnet and reduce susceptibility to external magnetic interference.

[0112] Feature 19. The system of any of the preceding features, wherein the circuit board further comprises a digitization circuit configured to convert the electromyography signal and the detected changes in magnetic field strength into digital signals, and further configured to transmit both signals via a two-wire bus to a processing circuit.

[0113] Feature 20. A method for processing muscle activity data using a co-located electrode system, comprising: acquiring an electromyography signal from an electrode, the electrode configured to be in contact with a user's skin; acquiring a magnetic signal from a Hall-effect sensor, the magnetic signal corresponding to changes in magnetic field strength resulting from displacement of a magnet mechanically coupled to the electrode; and generating, from the magnetic signal, a magnetically encoded force myography signal indicative of mechanical deformation at an interface between a user's skin and the electrode; and applying a signal processing algorithm configured to: assess a quality of electrode and skin contact based on characteristics of the magnetically encoded force myography signal, identify one or more motion artifacts in the electromyography signal using the magnetically encoded force myography signalas a reference, suppress or exclude the identified motion artifacts to produce a filtered electromyography signal, and outputting the filtered electromyography signal for use in controlling a prosthetic device.

Claims

CLAIMSWhat is claimed is:

1. A system for detecting muscle activity comprising: at least one electrode configured to detect an electromyography signal from a user; an electrically conductive force sensing component configured to deform in response to muscle activity and mechanically coupled to a magnet; a magnetic sensing component configured to detect changes in a magnetic field resulting from displacement of the magnet due to deformation of the electrically conductive force sensing component; and one or more signal processing components configured to generate a magnetically encoded force myography signal based on the detected changes in the magnetic field, wherein the electromyography signal and the magnetically encoded force myography signal are both generated from a location of the at least one electrode.

2. The system of claim 1, wherein the one or more signal processing components are further configured to determine a quality of skin contact at the at least one electrode based on variation in the magnetically encoded force myography signal.

3. The system of claim 1, wherein the one or more signal processing components are configured to identify and remove motion-induced artifacts in the electromyography signal by comparing the electromyography signal to the magnetically encoded force myography signal.

4. The system of claim 3, wherein the one or more signal processing components are further configured to generate a filtered electromyography signal by removing signal components identified as the motion-induced artifacts using the magnetically encoded force myography signal.

5. The system of claim 1, wherein the electromyography signal and the magnetically encoded force myography signal are both obtained through the at least one electrode.

6. The system of claim 1, wherein the electrically conductive force sensing component comprises a spring, the spring being electrically conductive.

7. The system of claim 1, wherein the magnetic sensing component is a Hall-effect sensor mounted on a substrate adjacent to the electrically conductive force sensing component and is electrically coupled to the one or more signal processing components.

8. The system of claim 1, wherein the at least one electrode, the magnet, and the electrically conductive force sensing component are housed together in a single modular sensor unit configured to be used individually or in an array.

9. The system of claim 1, wherein the at least one electrode is one of a plurality of electrodes, each independently configurable as a signal, reference, or ground electrode.

10. The system of claim 1, wherein the one or more signal processing components are further configured to classify a user's intended gesture or movement based on combined features of the electromyography signal and the magnetically encoded force myography signal.

11. The system of claim 1, further comprising a plurality of electrode units positioned at different anatomical sites, each configured to simultaneously collect electromyography and magnetically encoded force myography signals from co-located regions.

12. The system of claim 1, wherein the magnet is a rod-shaped permanent magnet embedded within a movable electrode cap, the magnet being axially aligned with a Hall-effect sensor when the electrically conductive force sensing component is in a resting state.

13. The system of claim 1, wherein the magnetic sensing component is mounted on a rigid substrate and positioned within a recess beneath the magnet such that the magnetic field at the magnetic sensing component varies with displacement of the at least one electrode in a direction perpendicular to a plane of the magnetic sensing component.

14. An electrode unit for detecting muscle activity, comprising: an electrode configured to be operable as a signal, reference, or ground electrode; a conductive spring mechanically and electrically coupled to the electrode; a magnet mechanically coupled to the electrode such that movement of the electrode compresses the spring and displaces the magnet; a circuit board positioned adjacent to the spring, the circuit board comprising: a Hall-effect sensor mounted on the circuit board and positioned to detect changes in magnetic field strength resulting from displacement of the magnet; anda signal processing unit electrically coupled to the electrode and the Hall-effect sensor; wherein the electrode unit is configured to simultaneously generate an electromyography signal based on electrical activity detected by the electrode and a magnetically encoded force myography signal based on the detected changes in magnetic field strength; and wherein the electromyography signal and the magnetically encoded force myography signal are generated from a common anatomical location on a user; wherein the signal processing unit is further configured to detect one or more of a user's motor intent, physical activity, or physiological state based on the electromyography signal and the magnetically encoded force myography signal.

15. The electrode unit of claim 14, wherein the signal processing unit is configured to process and transmit the electromyography signal and magnetically encoded force myography signals in real time for use in a external device control system.

16. The electrode unit of claim 14, wherein the electrode unit comprises a cylindrical body enclosing at least a portion of the circuit board, Hall-effect sensor, conductive spring, and electrode, the cylindrical body being configured to be insertable through a hole in a prosthetic socket and mountable via an external fastener.

17. The electrode unit of claim 14, wherein a housing that mounts the electrode comprises a low-friction material.

18. The electrode unit of claim 14, wherein the conductive spring comprises a ferromagnetic material configured to focus a magnetic field generated by the magnet and reduce susceptibility to external magnetic interference.

19. The electrode unit of claim 14, wherein the circuit board further comprises a digitization circuit configured to convert the electromyography signal and the detected changes in magnetic field strength into digital signals, and further configured to transmit both signals via a two-wire bus to a processing circuit.

20. A method for processing muscle activity data using a co-located electrode system, comprising: acquiring an electromyography signal from an electrode, the electrode configured to be in contact with a user's skin;acquiring a magnetic signal from a Hall-effect sensor, the magnetic signal corresponding to changes in magnetic field strength resulting from displacement of a magnet mechanically coupled to the electrode; and generating, from the magnetic signal, a magnetically encoded force myography signal indicative of mechanical deformation at an interface between a user's skin and the electrode; and applying a signal processing algorithm configured to: assess a quality of electrode and skin contact based on characteristics of the magnetically encoded force myography signal, identify one or more motion artifacts in the electromyography signal using the magnetically encoded force myography signal as a reference, suppress or exclude the identified motion artifacts to produce a filtered electromyography signal, and outputting the filtered electromyography signal for use in controlling a prosthetic device.

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