A multi-channel electromyography and strain dual-modal electronic skin and neural signal decomposition method

Abstract

The present invention provides a multi-channel electromyographic strain dual-modal electronic skin and a neural signal decomposition method, belonging to the field of sensor technology. The multi-channel electromyographic strain dual-modal electronic skin includes a six-layer composite structure, which is sequentially: a stretchable flexible base layer, a multi-channel strain sensing layer, a dielectric isolation layer, a stretchable circuit, a multi-channel electromyographic sensing layer, and a sticky packaging layer. The present invention has flexible and stretchable characteristics, can ensure reliable contact between the electronic skin and the skin when performing large-scale movements, can perform dual-mode detection of human electromyographic signal-resistance stress changes, and also provides a motion artifact-free fusion signal processing algorithm based on multi-channel dual-modal signals to obtain a motion artifact-free multi-modal fusion signal.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a multi-channel myoelectric strain dual-modal electronic skin and a neural signal decomposition method. Background Art

[0002] Surface electromyography (sEMG) is a bioelectric signal guided and recorded by electrodes placed on the surface of muscles. It reflects the electrophysiological characteristics of the neuromuscular system during activity and is closely linked to muscle activity and functional status. It is a key tool for tracking neuromuscular activity in the fields of health monitoring and disease treatment.

[0003] As the core component for measuring electromyographic signals, the development of electromyographic electrodes is of vital importance. Traditional sEMG acquisition equipment usually uses commercial silver / silver chloride electrodes. However, this type of electrode has many limitations and cannot achieve long-term high-fidelity sEMG signal acquisition. Moreover, due to its non-stretchable nature, when the skin is deformed due to human activities, interface delamination is likely to occur between the electrode and the skin due to the significant difference in modulus, making it difficult to meet the high requirements of practical applications. In recent years, electromyographic electrodes have gradually developed in the direction of arraying and flexibility, but even so, during movements that produce large deformations, existing electromyographic electrodes are still easily interfered by motion artifacts, affecting the accuracy of the signal. Patent CN118319315A discloses a honeycomb multi-channel flexible electromyographic electrode, in which the electrode is made of PI and metal, and the honeycomb geometric design gives it a certain plane bending and stretching ability, but it cannot meet the needs of large deformation movements, and the electrode has no viscosity and poor adhesion to the skin. In addition, the myoelectric electrode can only collect a single-modal signal, electromyography, and cannot directly provide information on skin strain caused by muscle contraction. Relying solely on electromyographic signals often has problems such as insufficient information, susceptibility to motion artifacts, or inaccurate intention recognition, which limits the depth and breadth of its application.

[0004] In the cutting-edge field of flexible electronic skin, electrophysiological and strain dual-modal sensing technology is of great significance. It can simultaneously capture human bioelectric signals and mechanical deformation information, providing strong data support for the precise control of intelligent prostheses and scientific evaluation of sports rehabilitation. The present invention focuses on the shortcomings of existing electronic skin in terms of stretchability and dual-modal integration, and proposes an innovative modular layered preparation strategy. Through key process breakthroughs such as the construction of a stretchable flexible substrate, the step-by-step preparation of a multi-channel electromyography / strain sensing layer, and the optimization of a sticky packaging layer, the independent transmission of multi-channel dual-modal signals has been successfully achieved, and a reliable connection with the end pluggable interface through a stretchable interconnect circuit has been achieved to achieve a low-impedance connection with an external acquisition device, opening up a new path for the dual-modal integration of flexible electronic skin and strongly promoting the development of fields such as intelligent prostheses and sports rehabilitation. Summary of the Invention

[0005] In order to solve the problem that traditional high-density myoelectric electronic skin can only detect a single signal, this invention invented a multi-channel myoelectric strain dual-modal electronic skin and neural signal decomposition method, aiming to solve the dual-modal detection of the wearer's physiological electrical signals and muscle strain.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A multi-channel electromyographic strain dual-modal electronic skin, which includes a six-layer composite structure, which is: a stretchable flexible base layer 7, a multi-channel strain sensing layer 5, a dielectric isolation layer 4, a stretchable circuit 3, a multi-channel electromyographic sensing layer 2, and a sticky packaging layer 1.

[0008] The stretchable flexible base layer 7 is made of highly cross-linked polydimethylsiloxane elastomer and is used to support the other five layers.

[0009] Furthermore, the stretchable flexible base layer 7 has a thickness of 50 μm-100 μm, an elongation at break of 100%-120%, and a Young's modulus that is the same as that of human skin, and can fit the human skin and effectively prevent interface peeling.

[0010] Furthermore, a method for preparing a highly cross-linked polydimethylsiloxane elastomer is provided: a polydimethylsiloxane (PDMS) prepolymer is mixed with a curing agent, the mixture is fully stirred and then defoamed, and then spin-coated on the surface of a polyethylene terephthalate (PET) support layer. After heat curing, the mixture is peeled off to obtain a highly cross-linked polydimethylsiloxane elastomer; furthermore, the mass ratio of the polydimethylsiloxane (PDMS) prepolymer to the curing agent is 10-20:1, the heat curing temperature is 80°C-100°C, and the heat curing time is 0.5 hour-1 hour.

[0011] Preferably, the polydimethylsiloxane (PDMS) prepolymer and the curing agent are both Dow Corning SYLGARD 184.

[0012] Furthermore, the surface of the stretchable flexible substrate layer 7 needs to be treated with oxygen plasma to convert the hydrophobic surface of the stretchable flexible substrate layer 7 into a hydrophilic surface, thereby effectively enhancing the stability of the conductive ink in the stretchable flexible substrate layer 7 and allowing the conductive ink to adhere more firmly. At the same time, it can also effectively prevent interlayer separation when the six-layer composite structure is stacked, thereby ensuring the stability of the multi-layer structure.

[0013] The multi-channel strain sensing layer 5 is used to convert skin deformation signals into resistance signals, and includes a stretchable interconnect circuit 6 and a strain sensitive unit array.

[0014] The stretchable interconnect circuit 6 is a conductor structure formed by dispensing and printing conductive ink with a liquid metal content of 60wt%-80wt%.

[0015] Furthermore, the thickness of the stretchable interconnect circuit 6 is 30 μm-50 μm; the line width of the conductor structure is 50 μm-200 μm, the resistance change rate is 2%-10% under a 40% tensile strain rate, and the resistance change rate is 2%-5% under a 20% cyclic stretching (strain rate 10% / s), and the fatigue life is at least 10 4 Second-rate.

[0016] The strain-sensitive unit array is composed of identical strain-sensitive units, which are formed by dispensing and printing conductive ink with a liquid metal content of 20wt%-40wt%; the strain-sensitive units are elongated rectangles, and the two ends of each strain-sensitive unit in the length direction are connected to the pluggable interface at the end of the electrode through a stretchable interconnect circuit 6.

[0017] Furthermore, the strain sensitive unit array includes 8 to 64 strain sensitive units, each of which has a width of 50μm-100μm and a thickness of 30μm-50μm; the strain sensitive unit has dynamic detection performance, can detect planar displacement of 0.1mm-5mm, a resolution of 10μm-50μm, a minimum sensitivity of 10Ω / mm, and can achieve 50 millisecond synchronization with the electromyographic signal.

[0018] Furthermore, the conductive ink in the stretchable interconnect circuit 6 and the strain-sensitive unit array adopts a mixed system of conductive silver paste and gallium-indium liquid metal alloy. The conductive ink with a liquid metal content of 60wt%-80wt% means that the proportion of gallium-indium liquid metal alloy in the conductive ink is 60wt%-80wt%; the conductive ink with a liquid metal content of 20wt%-40wt% means that the proportion of gallium-indium liquid metal alloy in the conductive ink is 60wt%-80wt%; the mass ratio of gallium to indium in the gallium-indium liquid metal alloy used is 3-4:1.

[0019] The dielectric isolation layer 4 is used to achieve electrical isolation and mechanical decoupling between the multi-channel electromyographic sensing layer 2 and the multi-channel strain sensing layer 5 , and is made of highly cross-linked polydimethylsiloxane elastomer.

[0020] Furthermore, the thickness of the dielectric isolation layer 4 is 20 μm-30 μm.

[0021] Furthermore, the preparation method of the highly cross-linked polydimethylsiloxane elastomer is the same as the preparation method of the stretchable flexible base layer 7 .

[0022] The stretchable circuit 3 is prepared using the same process and materials as the stretchable interconnect circuit 6 of the multi-channel strain sensing layer 5. However, its shape is different from that of the stretchable interconnect circuit 6 of the multi-channel strain sensing layer 5. The stretchable circuit 3 includes a circuit array and a wire structure connecting the circuit array to the pluggable interface at the electrode end.

[0023] Furthermore, the thickness of the stretchable circuit 3 is 30 μm-50 μm.

[0024] The multi-channel electromyographic sensing layer 2 is used to collect electromyographic signals on the skin surface and is an electrode array composed of identical electrode units; the electrode array is connected to the pluggable interface at the electrode end through a stretchable circuit 3 to achieve a low-impedance connection with an external acquisition device.

[0025] Furthermore, the preparation method of the electrode unit is as follows: polydimethylsiloxane (PDMS) prepolymer and curing agent are mixed in a mass ratio of 30-50:1, 1μm-10μm silver powder is added to form a mixed liquid, and the mass ratio of silver powder to polydimethylsiloxane (PDMS) prepolymer is 2.5-3.5:1; the mixed liquid is dispensing-printed to form the electrode unit.

[0026] Furthermore, the spacing between electrode units in the electrode array is 5 mm to 10 mm, the equivalent diameter of each electrode unit is 3 mm to 5 mm, the number of electrode units is 8 to 64, and the relationship between the skin contact impedance of the electrode unit and the AC frequency is 4.4 kΩ to 5 kΩ at 1 kHz. The thickness of the electrode array is 50 μm to 80 μm.

[0027] Furthermore, the spatial mapping relationship between the stretchable circuit 3 and the multi-channel electromyographic sensing layer 2 is as follows: the circuit array of the stretchable circuit 3 and the electrode array in the multi-channel electromyographic sensing layer 2 have the same size and position.

[0028] Furthermore, the spatial mapping relationship between the multi-channel electromyographic sensing layer 2 and the multi-channel strain sensing layer 5 is as follows: the centers of the two ends of the length direction of each strain sensitive unit in the multi-channel strain sensing layer 5 correspond to the center positions of two adjacent electrode units in the multi-channel electromyographic sensing layer 2.

[0029] The adhesive packaging layer 1 is used to adhere the multi-channel electromyographic strain dual-modal electronic skin to the skin and is composed of a low-cross-linked polydimethylsiloxane elastomer.

[0030] Furthermore, the adhesive encapsulation layer 1 has an adhesive strength of 0.6 N / cm-0.7 N / cm and a thickness of 20 μm-30 μm;

[0031] Furthermore, a method for preparing a low-crosslinked polydimethylsiloxane elastomer includes mixing a polydimethylsiloxane (PDMS) prepolymer with a curing agent, thoroughly stirring, defoaming the mixture, spin-coating the mixture onto the multi-channel electromyographic sensing layer 2, and thermally curing the mixture. Preferably, the mass ratio of the polydimethylsiloxane (PDMS) prepolymer to the curing agent is 30-50:1. The thermal curing temperature is 80°C-100°C, and the thermal curing time is 0.5-1 hour.

[0032] The neural signal decomposition method of the multi-channel electromyography and strain dual-modal electronic skin is based on a motion artifact-free fusion signal processing method of the multi-channel dual-modal signal, which is specifically as follows:

[0033] The multi-channel myoelectric strain dual-modal electronic skin is attached to human skin and connected to a multi-channel myoelectric acquisition device and a multi-channel resistance signal acquisition device via a pluggable interface at the end of the electrode. The sampling frequency of the myoelectric signal is 1kHz-2kHz, and the sampling frequency of the resistance signal is 200Hz-400Hz. The resistance signal is then divided by the sensitivity to obtain the skin strain signal, and finally the myoelectric strain dual-modal signal of human muscle activity is obtained. The myoelectric strain dual-modal signal of human muscle activity is then processed according to the following steps:

[0034] 1) Signal preprocessing: Bandpass filtering and power frequency notch filtering are performed on the electromyographic signal; Kalman filtering is performed on the strain signal.

[0035] 2) Motor unit localization: The preprocessed EMG signal is decomposed using a blind source separation algorithm to obtain a motor unit activity sequence. The spike-triggered averaging method is then used to analyze the motor unit activity sequence to obtain the initial motor unit position and waveform, thereby achieving motor unit localization.

[0036] 3) Motion artifact elimination: Based on the preprocessed strain signal, a motion artifact spatial distribution map is constructed. The motion artifact spatial distribution map is used to correct the position of the motor unit, thereby eliminating the motion noise component related to the strain signal in the electromyographic signal and thus eliminating the motion artifact.

[0037] 4) Multimodal fusion output: The motor unit activity sequence, motor unit waveform, and corrected motor unit position are time-domain aligned with the strain signal to output a multimodal fusion signal consisting of the electromyographic signal, motor unit activity sequence, corrected motor unit position, motor unit waveform, and strain signal.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) The present invention has flexible and stretchable properties, and the encapsulation layer is sticky, which not only allows it to better fit the skin, but also ensures reliable contact between the electrode and the skin when performing large movements.

[0040] 2) The present invention can not only detect multi-channel human electromyographic signals, but also achieve dual-mode detection of human electromyographic signal-resistive stress changes. In addition, the present invention also includes a motion artifact-free fusion signal processing algorithm based on multi-channel dual-modal signals, which can obtain motion artifact-free multi-modal fusion signals while achieving dual-mode detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0042] Figure 1 Schematic diagram of the overall structure of the multi-channel myoelectric strain dual-modal electronic skin in the embodiment;

[0043] Figure 2 Schematic diagram of the layered structure of a multi-channel myoelectric strain dual-modal electronic skin according to an embodiment;

[0044] Figure 3 This is a curve showing the change in resistance of the conductor structure of the stretchable interconnect circuit of the multi-channel myoelectric strain dual-modal electronic skin as a function of stretching rate;

[0045] Figure 4 This is a curve showing the change of the resistance value of the strain-sensitive unit of the multi-channel myoelectric strain dual-modal electronic skin as a function of the stretching rate;

[0046] Figure 5 This is a diagram showing a skin contact impedance test of an electrode unit of a multi-channel myoelectric strain dual-modal electronic skin according to an embodiment;

[0047] Figure 6 This is a graph showing the adhesion strength test of the adhesive packaging layer of the multi-channel myoelectric strain dual-modal electronic skin of the embodiment;

[0048] Figure 7 Flowchart of a multimodal biosignal data processing method for a multi-channel myoelectric strain dual-modal electronic skin according to an embodiment;

[0049] Figure 8 The electromyographic signals collected from 16 channels of the embodiment;

[0050] Figure 9 The strain signal collected by 14 channels in the embodiment;

[0051] Figure 10 is the pre-processed electromyographic signal of the embodiment;

[0052] Figure 11 is the strain signal after preprocessing in the embodiment;

[0053] Figure 12 All motion unit activity sequences decomposed using the blind source separation algorithm of the embodiment;

[0054] Figure 13 In the embodiment, the spike-triggered averaging method is used to obtain the motor unit waveform of one of the motor units;

[0055] Figure 14 In an embodiment, the initial position of one of the motor units is obtained using a spike-triggered averaging method;

[0056] Figure 15 is a spatial distribution diagram of motion artifacts in an embodiment;

[0057] Figure 16 for Figure 14 The corrected position of the moving unit.

[0058] In the figure: 1 adhesive packaging layer, 2 multi-channel electromyography sensing layer, 3 stretchable circuit, 4 dielectric isolation layer, 5 multi-channel strain sensing layer, 6 stretchable interconnect circuit, 7 stretchable flexible substrate layer. DETAILED DESCRIPTION

[0059] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0060] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0061] Example 1:

[0062] In this embodiment, a multi-channel myoelectric strain dual-modal electronic skin is disclosed, such as Figure 1 and Figure 2 As shown, the multi-channel myoelectric strain dual-modal electronic skin comprises a six-layer composite structure arranged in order from bottom to top, which is: a stretchable flexible base layer 7, a multi-channel strain sensing layer 5, a dielectric isolation layer 4, a stretchable circuit 3, a multi-channel myoelectric sensing layer 2, and an adhesive encapsulation layer 1. The preparation steps are as follows:

[0063] Step 1: Preparation of the stretchable flexible substrate layer 7:

[0064] Dow Corning SYLGARD 184 polydimethylsiloxane (PDMS) prepolymer and curing agent were mixed in a mass ratio of 10:1, stirred thoroughly, and then defoamed. The mixture was then spin-coated on the surface of a polyethylene terephthalate (PET) support layer at a spin coating speed of 1000 rpm and thermally cured at 80°C for 0.5 h to obtain a stretchable flexible base layer 7 having a thickness of 100 μm, an elongation at break of 100%, and a Young's modulus of 2.5 MPa.

[0065] Step 2: Preparation of the multi-channel strain sensing layer 5:

[0066] S2.1. Mix the conductive silver paste and the gallium-indium liquid metal alloy in a mass ratio of 3:7, wherein the mass ratio of gallium to indium in the gallium-indium liquid metal alloy is 75.5:24.5. After mixing, mechanically stir at a speed of 500 rpm for 30 minutes to obtain a conductive ink for the stretchable interconnect circuit 6.

[0067] S2.2. The surface of the stretchable flexible substrate layer 7 is subjected to oxygen plasma treatment for 70 seconds at a radio frequency power of 30 W.

[0068] S2.3, printing a stretchable interconnect circuit 6 on the stretchable flexible substrate 7 by dispensing glue, wherein the line width of the conductor structure of the stretchable interconnect circuit 6 is 200 μm, the resistance change rate is 10% under a 40% tensile strain rate, the resistance change rate is 5% under a 20% cyclic stretching (strain rate 10% / s), and the fatigue life is 10 4 The resistance value of the conductor structure of the stretchable interconnect circuit 6 changes with the stretching rate as shown in the following figure: Figure 3 As shown, it can be observed that the resistance of the conductor structure of the stretchable interconnect circuit 6 changes very little when stretched, and can be stretched by more than 45%, showing excellent performance.

[0069] S2.4. Mix the conductive silver paste and the gallium-indium liquid metal alloy in a mass ratio of 6:4, wherein the mass ratio of gallium to indium in the gallium-indium liquid metal alloy is 75.5:24.5. After mixing, mechanically stir at a speed of 500 rpm for 30 minutes to obtain a conductive ink for the strain sensitive unit.

[0070] S2.5. Use dispensing printing to connect the ends of the stretchable interconnect circuit 6 in pairs using the conductive ink of the strain sensitive unit to manufacture 14 7×2 strain sensitive units to form a strain sensitive unit array, and obtain a multi-channel strain sensing layer 5; the strain sensitive unit is an elongated rectangle with a width of 100μm and a thickness of 50μm; the strain sensitive unit has dynamic detection performance, can detect planar displacement of 0.1mm-5mm, with a resolution of 50μm and a sensitivity of 11.6Ω / mm. Figure 4The variation of the resistance value of the strain-sensitive unit with the stretching rate is shown. It can be clearly observed that the resistance value varies greatly under continuous stretching, demonstrating the extremely high sensitivity of the multi-channel strain sensing layer 5 to tensile strain.

[0071] Step 3: Preparation of dielectric isolation layer 4, stretchable circuit 3, and multi-channel electromyographic sensing layer 2:

[0072] S3.1. Mix Dow Corning SYLGARD 184 polydimethylsiloxane (PDMS) prepolymer and curing agent in a mass ratio of 10:1, stir thoroughly and then defoam. Spin-coat the mixture on the surface of the multi-channel strain sensing layer 5 at a speed of 3000 rpm. Use a silicone mask to protect the connection position between the interconnected stretchable interconnect circuit 6 and the pluggable interface at the end of the electrode during spin coating. Heat-cure the mixture at 80°C for 0.5 hours to obtain a dielectric isolation layer 4 with a thickness of 30 μm.

[0073] S3.2. The surface of the dielectric isolation layer 4 is treated with oxygen plasma for 70 seconds at a radio frequency power of 30 W.

[0074] S3.3. Prepare a stretchable circuit 3 using the same materials and processes as the stretchable interconnect circuit 6 of the multi-channel strain sensing layer 5. This circuit includes a circuit array and a wire structure connecting the circuit array to the pluggable interface at the electrode end. The thickness of the stretchable circuit 3 is 50 μm.

[0075] S3.4, Multi-channel EMG Sensing Layer 2: Mix polydimethylsiloxane (PDMS) prepolymer and curing agent in a 50:1 mass ratio. Add 5μm flake silver powder to the mixture, with a mass ratio of silver powder to polydimethylsiloxane (PDMS) prepolymer of 3:1. The mixture is then dispensed and printed to form electrode units. The electrode units are 10mm apart and 3mm-diameter circular. Sixteen of these units form an 8×2 electrode array with a thickness of 80μm. Figure 5 The relationship between the impedance of the electrode units and the AC frequency is shown, with a contact impedance of 4.4 kΩ at 1 kHz. The spatial mapping relationship between the stretchable circuit 3 and the multi-channel electromyographic sensing layer 2 is shown: The circuit array of the stretchable circuit 3 and the electrode array in the multi-channel electromyographic sensing layer 2 are identical in size and position. The spatial mapping relationship between the multi-channel electromyographic sensing layer 2 and the multi-channel strain sensing layer 5 is shown: The centers of the two ends of the lengthwise direction of each strain-sensitive unit in the multi-channel strain sensing layer 5 correspond to the centers of two adjacent electrode units in the multi-channel electromyographic sensing layer 2.

[0076] Step 4: Preparation of adhesive encapsulation layer 1:

[0077] S4.1. Use a silicone mask to protect the connection position between the stretchable circuit 3 and the pluggable interface at the end of the electrode and the electrode array.

[0078] S4.2. Mix polydimethylsiloxane (PDMS) prepolymer and curing agent in a mass ratio of 40:1, stir thoroughly and defoam, then spin-coat it on the multi-channel electromyography sensing layer 2 at a spin-coating speed of 3000 rpm. Heat-cure it at 80°C for 0.5 h, remove the silicone mask, and obtain a viscous encapsulation layer 1 with a thickness of 30 μm. Figure 6 The peel force of the adhesive encapsulation layer 24mm wide and 100mm long was demonstrated, and the adhesion strength was calculated to be 0.71N / cm.

[0079] Example 2:

[0080] The pluggable interface at the end of the electrode is glued to the stretchable flexible base layer 7 of the multi-channel electromyography strain dual-modal electronic skin prepared in Example 1 using silicone glue, and is connected to the stretchable circuit 3 and the stretchable interconnect circuit 6.

[0081] The multi-channel myoelectric strain dual-modal electronic skin is attached to human skin and connected to a multi-channel myoelectric acquisition device (the multi-channel myoelectric acquisition device can adopt a wireless high-density EEG and myoelectric hybrid synchronous acquisition and monitoring system provided by patent CN119679431A to collect myoelectric signals) and a multi-channel resistance signal acquisition device through a pluggable interface at the electrode end. Myoelectric signals and resistance signals are collected. The sampling frequency of the myoelectric signal is set to 2 kHz and the sampling frequency of the resistance signal is set to 200 Hz. The resistance signal is then divided by the sensitivity to obtain the skin strain signal, and finally the myoelectric-strain dual-modal signal of human muscle activity is obtained. The myoelectric-strain dual-modal signal of human muscle activity is then processed according to the following steps:

[0082] 1) Signal preprocessing: Bandpass filtering (20Hz-500Hz) and power frequency notch filtering are performed on the electromyographic signal; Kalman filtering is performed on the strain signal to extract the 0Hz-100Hz dynamic deformation.

[0083] 2) Motor unit localization: Use the blind source separation algorithm to decompose the preprocessed electromyographic signal to obtain the motor unit activity sequence, and use the spike potential triggered averaging method to analyze the motor unit activity sequence to obtain the initial motor unit position and motor unit waveform to achieve the purpose of motor unit localization; Preferably, the blind source separation algorithm can recover the original independent signal from the mixed signal without any prior knowledge about the mixing process or source signal; The spike potential triggered averaging method is a classic method for analyzing the relationship between neuronal discharges (spikes) and external stimuli or behavioral signals. Its core idea is to extract potential patterns or characteristics related to neuronal activity by multiple alignment and averaging of specific signals before and after the occurrence of spikes (action potentials); The motor unit is the "minimum functional unit" of muscle contraction, including a motor neuron and all the skeletal muscle fibers it controls; The motor unit activity sequence contains the firing information of the motor unit, directly showing the moment when the neural command is issued and transmitted, and is represented as a 0-1 firing sequence of the motor unit. 3) Motion artifact elimination: Based on the preprocessed strain signal, a motion artifact spatial distribution map is constructed. The motion artifact spatial distribution map is used to correct the position of the motor unit, thereby eliminating the motion noise component related to the strain signal in the electromyographic signal and thus eliminating the motion artifact.

[0084] 4) Multimodal fusion output: The motor unit activity sequence, motor unit waveform, and corrected motor unit position are time-domain aligned with the strain signal to output a multimodal fusion signal consisting of the electromyographic signal, motor unit activity sequence, corrected motor unit position, motor unit waveform, and strain signal.

[0085] Figures 7 to 16 The flow chart of the neural signal decomposition method of multi-channel electromyography and strain dual-modal electronic skin and the effect diagram during the process are displayed.

Claims

1. A multi-channel myoelectric strain dual-modal electronic skin, characterized in that: The multi-channel electromyography and strain dual-mode electronic skin comprises a six-layer composite structure, which comprises: a stretchable flexible base layer (7), a multi-channel strain sensing layer (5), a dielectric isolation layer (4), a stretchable circuit (3), a multi-channel electromyography sensing layer (2), and a viscous packaging layer (1); The stretchable flexible base layer (7) is made of highly cross-linked polydimethylsiloxane elastomer and is used to support the other five layers; The multi-channel strain sensing layer (5) is used to convert skin deformation signals into resistance signals, and includes a stretchable interconnect circuit (6) and a strain sensitive unit array; The stretchable interconnect circuit (6) is a conductor structure formed by dispensing and printing conductive ink with a liquid metal content of 60wt%-80wt%; The strain sensitive unit array is composed of identical strain sensitive units, which are formed by dispensing conductive ink with a liquid metal content of 20wt%-40wt%; the strain sensitive unit is in the form of an elongated rectangle, and both ends of each strain sensitive unit in the length direction are connected to the pluggable interface at the end of the electrode through a stretchable interconnect circuit (6); The dielectric isolation layer (4) is used to achieve electrical isolation and mechanical decoupling between the multi-channel electromyographic sensing layer (2) and the multi-channel strain sensing layer (5), and is composed of a highly cross-linked polydimethylsiloxane elastomer; The preparation process and materials of the stretchable circuit (3) are the same as those of the stretchable interconnect circuit (6) of the multi-channel strain sensing layer (5); however, the shape is different from that of the stretchable interconnect circuit (6) of the multi-channel strain sensing layer (5). The stretchable circuit (3) includes a circuit array and a wire structure connecting the circuit array to a pluggable interface at the end of the electrode; The multi-channel electromyographic sensing layer (2) is used to collect electromyographic signals on the skin surface, and is an electrode array composed of identical electrode units; the electrode array is connected to a pluggable interface at the end of the electrode via a stretchable circuit (3) to achieve a low-impedance connection with an external collection device; The adhesive packaging layer (1) is used to attach the multi-channel electromyographic strain dual-modal electronic skin to the skin and is composed of a low-crosslinked polydimethylsiloxane elastomer.

2. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The stretchable flexible base layer (7) has a thickness of 50 μm-100 μm, an elongation at break of 100%-120%, and a Young's modulus that is the same as that of human skin; the surface of the stretchable flexible base layer (7) needs to be treated with oxygen plasma to convert the hydrophobic surface of the stretchable flexible base layer (7) into a hydrophilic surface; The invention relates to a method for preparing a highly cross-linked polydimethylsiloxane elastomer. The method comprises mixing a polydimethylsiloxane (PDMS) prepolymer and a curing agent, stirring the mixture thoroughly, performing a defoaming treatment, and then spin-coating the mixture on the surface of a polyethylene terephthalate (PET) support layer. The mixture is thermally cured and then peeled off to obtain the highly cross-linked polydimethylsiloxane elastomer. The mass ratio of the polydimethylsiloxane (PDMS) prepolymer to the curing agent is 10-20:1, the thermal curing temperature is 80°C-100°C, and the thermal curing time is 0.5 hour-1 hour.

3. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The thickness of the stretchable interconnect circuit (6) is 30μm-50μm; the line width of the conductor structure is 50μm-200μm, the resistance change rate is 2%-10% under 40% tensile strain rate, the resistance change rate is 2%-5% under 20% cyclic stretching, and the minimum fatigue life is 10 4 times; the strain sensitive unit array contains 8-64 strain sensitive units, each strain sensitive unit has a width of 50μm-100μm and a thickness of 30μm-50μm; the strain sensitive unit has dynamic detection performance, can detect planar displacement of 0.1mm-5mm, a resolution of 10μm-50μm, a minimum sensitivity of 10Ω / mm, and achieves 50 millisecond synchronization with the electromyographic signal.

4. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The conductive ink in the stretchable interconnect circuit (6) and the strain-sensitive unit array adopts a mixed system of conductive silver paste and gallium-indium liquid metal alloy. The conductive ink with a liquid metal content of 60wt%-80wt% means that the proportion of gallium-indium liquid metal alloy in the conductive ink is 60wt%-80wt%; the conductive ink with a liquid metal content of 20wt%-40wt% means that the proportion of gallium-indium liquid metal alloy in the conductive ink is 60wt%-80wt%; the mass ratio of gallium to indium in the gallium-indium liquid metal alloy used is 3-4:

1.

5. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The thickness of the dielectric isolation layer (4) is 20 μm-30 μm; the preparation method of the highly cross-linked polydimethylsiloxane elastomer is the same as the preparation method of the stretchable flexible base layer (7).

6. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The thickness of the stretchable circuit (3) is 30 μm-50 μm; the spacing between the electrode units in the electrode array is 5 mm-10 mm, the equivalent diameter of each electrode unit is 3 mm-5 mm, the number of electrode units is 8-64, and the relationship between the skin contact impedance of the electrode unit and the AC frequency is that the contact impedance is 4.4 kΩ-5 kΩ at 1 kHz; the thickness of the electrode array is 50 μm-80 μm.

7. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The electrode unit is prepared by mixing polydimethylsiloxane (PDMS) prepolymer and curing agent in a mass ratio of 30-50:1, adding 1-10 μm silver powder to form a mixed solution, wherein the mass ratio of silver powder to polydimethylsiloxane (PDMS) prepolymer is 2.5-3.5:1; and dispensing and printing the mixed solution to form the electrode unit.

8. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The spatial mapping relationship between the stretchable circuit (3) and the multi-channel electromyographic sensing layer (2) is as follows: the circuit array of the stretchable circuit (3) and the electrode array in the multi-channel electromyographic sensing layer (2) are the same in size and position; the spatial mapping relationship between the multi-channel electromyographic sensing layer (2) and the multi-channel strain sensing layer (5) is as follows: the centers of the two ends of the length direction of each strain sensitive unit in the multi-channel strain sensing layer (5) correspond to the center positions of two adjacent electrode units in the multi-channel electromyographic sensing layer (2).

9. The multi-channel myoelectric strain dual-modal electronic skin according to claim 1, characterized in that: The adhesive encapsulation layer (1) has an adhesive strength of 0.6N / cm-0.7N / cm and a thickness of 20μm-30μm; a method for preparing a low-crosslinked polydimethylsiloxane elastomer comprises mixing a polydimethylsiloxane (PDMS) prepolymer with a curing agent, stirring the mixture thoroughly and then performing a defoaming treatment, and then applying the mixture on a multi-channel electromyographic sensing layer (2) by spin coating, and then performing a heat curing treatment; the mass ratio of the polydimethylsiloxane (PDMS) prepolymer to the curing agent is 30-50:1; the heat curing treatment temperature is 80°C-100°C, and the heat curing treatment time is 0.5 hour-1 hour.

10. The neural signal decomposition method of a multi-channel myoelectric strain dual-modal electronic skin according to any one of claims 1 to 9, characterized in that: The details are as follows: The multi-channel myoelectric strain dual-modal electronic skin is attached to human skin and connected to a multi-channel myoelectric acquisition device and a multi-channel resistance signal acquisition device via a pluggable interface at the end of the electrode. The sampling frequency of the myoelectric signal is 1kHz-2kHz, and the sampling frequency of the resistance signal is 200Hz-400Hz. The resistance signal is then divided by the sensitivity to obtain the skin strain signal, and finally the myoelectric strain dual-modal signal of human muscle activity is obtained. The myoelectric strain dual-modal signal of human muscle activity is then processed according to the following steps: 1) Signal preprocessing: bandpass filtering and power frequency notch filtering are performed on the electromyographic signal; Kalman filtering is performed on the strain signal; 2) Motor unit localization: The preprocessed EMG signal is decomposed using a blind source separation algorithm to obtain a motor unit activity sequence. The spike-triggered averaging method is then used to analyze the motor unit activity sequence to obtain the initial motor unit position and waveform, thereby achieving motor unit localization. 3) Motion artifact elimination: Based on the preprocessed strain signal, a motion artifact spatial distribution map is constructed. The motion artifact spatial distribution map is used to correct the position of the motor unit, thereby eliminating the motion noise component related to the strain signal in the electromyographic signal and thus eliminating the motion artifact; 4) Multimodal fusion output: The motor unit activity sequence, motor unit waveform, and corrected motor unit position are time-domain aligned with the strain signal to output a multimodal fusion signal consisting of the electromyographic signal, motor unit activity sequence, corrected motor unit position, motor unit waveform, and strain signal.

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