Breathable liquid metal-fabric electrode with durable interface and preparation method thereof

Abstract

The invention belongs to the technical field of wearable electronic devices, and particularly relates to a breathable liquid metal-fabric electrode with a durable interface and a preparation method of the breathable liquid metal-fabric electrode. Comprising the following steps that an interface modifier solution is added into liquid metal, and modified liquid metal slurry is obtained in an ice-bath ultrasonic mode; coating a fabric substrate with the modified liquid metal slurry, and drying at room temperature until the modified liquid metal slurry is cured to obtain an electrode precursor; and applying external force to the electrode precursor to obtain the liquid metal-fabric electrode. The liquid metal micro / nano particles are subjected to interface modification through the interface modifier, the interface modifier and the fabric substrate are subjected to interface interaction, the liquid metal is anchored to the fabric substrate, meanwhile, the modified liquid metal particles are promoted to be fused through external force, and a continuous conductive network is formed; the gel electrode shows excellent tolerance under water washing, air exposure and mechanical deformation, and has good skin compatibility and interface impedance lower than that of a commercial gel electrode.

Description

Technical Field

[0001] This invention belongs to the field of wearable electronic device technology, specifically relating to a breathable and durable liquid metal-fabric electrode and its preparation method. Background Technology

[0002] Monitoring various electrophysiological signals in the human body, such as ECG, EMG, EEG, and EOG, requires long-term, high-fidelity signal acquisition for several hours or more without interfering with normal behavior. Traditional multi-channel clinical electrode systems are bulky, complex to deploy, and unsuitable for long-term home monitoring. Wearable electrodes should possess low skin-electrode interface impedance, good conformability, sweat / wash resistance, mechanical deformation resistance, and high breathability to ensure comfort and stability during extended wear in daily life, at night, and during exercise.

[0003] Liquid metals (LMs, such as GaIn alloys and EGaIn) are widely regarded as preferred materials for manufacturing flexible conductors and epidermal electrodes due to their liquid state at room temperature, high conductivity, and good ductility. Epidermal electrodes based on highly conductive liquid metals can effectively collect and transmit bioelectrical signals. LMs are liquid at room temperature, and their fluidity and ductility allow them to closely conform to the skin and adapt to complex deformations, avoiding some limitations faced by dry electrodes based on solid fillers (such as graphene, MXene, and carbon nanotubes). Compared to microneedle electrodes, liquid metal epidermal electrodes can achieve low-resistance interfaces without minimally invasive punctures, and gallium-based LMs have low cytotoxicity, making them suitable for long-term wear and biomedical applications. However, the low viscosity and high surface tension of liquid metals can hinder their uniform spread on substrates, and the weak physical interface is prone to aggregation, peeling, and leakage under contact and friction. To address these issues, existing studies have employed methods such as metal particle doping, hydrochloric acid vapor treatment, and hydrogen bonding to reduce surface tension, anchor LM (metal luminescent membrane), and suppress leakage. However, these methods suffer from weak interfacial bonding, and the interfacial robustness still needs further improvement when faced with complex usage conditions such as sweat, water, and mechanical deformation. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a breathable and durable liquid metal-fabric electrode and its preparation method. The method involves surface modification of liquid metal micro / nano particles using an interface modifier, and anchoring the liquid metal onto the fabric substrate through interfacial interaction between the interface modifier and the fabric substrate. Simultaneously, external mechanical activation ruptures the oxide film of the liquid metal, causing the modified liquid metal particles to physically link on a macroscopic scale, forming a continuous conductive network. This electrode exhibits excellent stability and biocompatibility under conditions of sweat exposure, mechanical deformation, and long-term wear. Even after undergoing extensive mechanical deformation, high-speed washing, and sweat / water immersion, it maintains low interfacial impedance and a high signal-to-noise ratio, enabling continuous and stable electrophysiological signal acquisition during prolonged static and dynamic states.

[0005] To achieve the above objectives, the specific technical solution provided by the present invention is as follows: The first objective of this invention is to provide a method for preparing a breathable and interfacially durable liquid metal-fabric electrode, comprising the following steps: S1. Add an interface modifier to the liquid metal, disperse the liquid metal into micro / nano particles by ultrasound, and perform coordination modification on their surface to obtain a modified liquid metal slurry.

[0006] S2. The modified liquid metal material is coated onto the fabric substrate and dried at room temperature until cured, so that the interface modifier and the fabric substrate interact with each other, anchoring the liquid metal on the fabric substrate to obtain the electrode precursor.

[0007] S3. Apply an external force to the electrode precursor, and the oxide film on the surface of the liquid metal particles will break, causing the liquid metal particles to form a continuous conductive network structure between the fibers, thus obtaining a liquid metal fabric electrode.

[0008] Furthermore, the interface modifier is (3-mercaptopropyl)triethoxysilane, phytic acid, or glucose.

[0009] Furthermore, when the interface modifier is (3-mercaptopropyl)triethoxysilane, the mass ratio of liquid metal to (3-mercaptopropyl)triethoxysilane is 1:0.05–0.2; when the interface modifier is phytic acid, the mass ratio of liquid metal to phytic acid is 1:0.5–2.5; and when the interface modifier is glucose, the mass ratio of liquid metal to glucose is 1:1–5.

[0010] Furthermore, the liquid metal is a gallium-indium alloy, with a gallium to indium mass ratio of 3:1.

[0011] Furthermore, the ultrasound was performed under ice bath conditions, with a power of 400W to 800W and a duration of 30s to 90s. After ultrasound, the cells were allowed to settle for 4h to 8h.

[0012] Furthermore, the fabric base is polyester fiber / fabric, polyamide fiber / fabric, polyurethane fiber / fabric, or cotton fiber / fabric.

[0013] Furthermore, when an external force is applied to rupture the oxide film on the surface of the liquid metal particles, the color of the coated area changes.

[0014] A second objective of this invention is to provide a breathable and durable liquid metal-fabric electrode, which is prepared using the above-described preparation method.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a mechanochemical interface coupling strategy. Using ultrasound, liquid metal is cavitated and split into micro / nanoparticles through high-energy ultrasonication, exposing metal sites. An interface modifier acts as a molecular bridge, coordinating and modifying the exposed metal sites of the liquid metal micro / nanoparticles to form coordination bonds. Simultaneously, it interacts with the fabric substrate, anchoring the liquid metal between the interface modifier and the fabric substrate. Under applied mechanical pressure, the oxide film on the surface of the liquid metal particles ruptures, forming a continuous conductive network structure between the liquid metal particles and fibers, resulting in a liquid metal-fabric electrode. This electrode retains the porous structure and breathability of the textile substrate and maintains stable electrical performance under various mechanical and chemical stresses. It exhibits excellent stability and biocompatibility in sweat exposure, mechanical deformation, and long-term wear scenarios. Even after undergoing extensive mechanical deformation, high-speed washing, and extreme conditions such as sweat / water immersion, it maintains low interfacial impedance and high signal-to-noise ratio, achieving continuous and stable acquisition of human electrophysiological signals over long periods and in dynamic scenarios. Attached Figure Description

[0016] Figure 1 This diagram illustrates the interaction mechanism between the liquid metal of this invention and (3-mercaptopropyl)triethoxysilane.

[0017] Figure 2 This diagram illustrates the interaction mechanism between the liquid metal and phytic acid in this invention.

[0018] Figure 3 This diagram illustrates the interaction mechanism between the liquid metal and glucose in this invention.

[0019] Figure 4 This is a scanning electron microscope image of the morphology of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 4 In the diagram, a represents the morphological structure of S-GIP before activation, and b represents the morphological structure of S-GIP after activation.

[0020] Figure 5 The X-ray diffraction pattern of the liquid metal-fabric electrode prepared in Example 1 of this invention is shown.

[0021] Figure 6 The total reflectance infrared spectrum of the liquid metal-fabric electrode prepared in Example 1 of this invention.

[0022] Figure 7 The image shows the X-ray photoelectron spectrum of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 7 In the image, (a) is the O 1s spectrum and (b) is the S 2p spectrum.

[0023] Figure 8 The figures show the electrical properties and stability characterization of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 8 In the diagram, a represents the resistance before and after activation, b represents the resistance stability during the mechanical cycle, and c represents the environmental resistance stability.

[0024] Figure 9 This is a customizable pattern and interface stability diagram of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 9 In the diagram, a represents a custom pattern, and b represents the surface resistance distribution spectrum before and after pattern activation and after tape peeling.

[0025] Figure 10 This is a biocompatibility test image of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 10 In the figures, a is the blank control, b is the PET substrate, c is EGaIn, and d is the S-GIPE prepared in the example.

[0026] Figure 11 The air permeability of the liquid metal-fabric electrode prepared in Example 1 of this invention, Figure 11 In the figure, a represents the water weight retention rate, and b represents the water vapor transmission rate.

[0027] Figure 12 This is a digital photograph of the skin-friendly properties of the liquid metal-fabric electrode prepared in Example 1 of the present invention.

[0028] Figure 13 Frequency-impedance curves of the electrode-skin interface of the liquid metal-fabric electrode prepared in Example 1 of the present invention compared with those of a commercial gel electrode.

[0029] Figure 14 The above describes the EEG signals of the liquid metal-fabric electrode prepared in Example 1 of this invention under three environmental exposures. Figure 14 In the figures, a represents 7 days of air exposure, b represents 7 days of water exposure, and c represents 7 days of sweat exposure.

[0030] Figure 15 The time-domain and time-frequency plots of the EEG signals from the liquid metal-fabric electrode prepared in Example 1 of this invention for sleep EEG monitoring are shown. Figure 15 In the diagram, a is the time-domain plot of the EEG signal, and b is the time-frequency plot.

[0031] Figure 16 The energy spectral density diagrams of EEG signals from four random time intervals for sleep EEG monitoring using the liquid metal-fabric electrode prepared in Example 1 of this invention.

[0032] Figure 17 The EEG signals collected by the liquid metal-fabric electrodes prepared in Examples 2 and 3 of this invention. Figure 17 In the text, a represents Example 2, and b represents Example 3.

[0033] Figure 18 This is a scanning electron microscope image of the morphology of the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 18 In the diagram, a is a morphological structure diagram of LMC in Comparative Example 2, b is an enlarged view of the box in a, c is an LMPC of Example 4, and d is an enlarged view of the box in c.

[0034] Figure 19 The total reflectance infrared spectrum of the liquid metal-fabric electrode prepared in Example 4 of this invention.

[0035] Figure 20 To assess the resistance stability of the liquid metal-fabric electrode prepared in Example 4 of this invention, Figure 20 In the figure, a represents the resistance stability under mechanical deformation, b represents the resistance stability after 7 days of immersion, and c represents the resistance stability after water washing.

[0036] Figure 21 This is a biocompatibility test image of the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 21 In the diagram, a is a cotton fabric substrate, b is liquid metal, c is Example 4, and d is a commercial gel electrode.

[0037] Figure 22 The air permeability of the liquid metal-fabric electrode prepared in Example 4 of this invention is discussed. Figure 22 In the figure, a represents the water weight retention rate, and b represents the water vapor transmission rate.

[0038] Figure 23 The ECG images and signal-to-noise ratios of the liquid metal-fabric electrode prepared in Example 4 of this invention under different extreme treatments are shown. Figure 23 In the diagram, a represents the ECG signal and corresponding signal-to-noise ratio after 7 wear-to-desorption cycles, b represents the ECG signal and corresponding signal-to-noise ratio after 7 days of air exposure, and c represents the ECG signal and corresponding signal-to-noise ratio after dust adhesion.

[0039] Figure 24The image shows a comparison of the SNR of the liquid metal-fabric electrode prepared in Example 4 of this invention under different treatments.

[0040] Figure 25 This is an ECG electrophysiological signal image collected by the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 25 In the diagram, a represents the overall electrophysiological signal, while b and c represent electrophysiological signal at different stages.

[0041] Figure 26 This is an EMG electrophysiological signal image collected by the liquid metal-fabric electrode prepared in Example 4 of this invention. Figure 26 In the diagram, a represents the overall electrophysiological signal, while b, c, and d represent electrophysiological signal diagrams at different stages.

[0042] Figure 27 The XPS spectrum of the liquid metal-fabric electrode prepared in Example 5 of this invention.

[0043] Figure 28 Digital photographs showing the surface adhesion of the liquid metal to the liquid metal-fabric electrode prepared in Example 5 of this invention before and after tape peeling.

[0044] Figure 29 This is an ECG signal data diagram of the liquid metal-fabric electrode prepared in Example 5 of the present invention.

[0045] Figure 30 This is a flowchart of the liquid metal-fabric electrode prepared according to the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] This invention provides a method for preparing a breathable and interfacially durable liquid metal-fabric electrode, such as... Figure 30 As shown, it includes the following steps: S1. Add an interface modifier solution to liquid metal (LM), disperse the liquid metal into micro / nano particles using ice bath ultrasound, and perform coordination modification of the liquid metal micro / nano particles using the interface modifier. After static sedimentation, a modified liquid metal slurry is obtained.

[0049] S2. The modified liquid metal slurry is coated onto the fabric substrate and dried at room temperature until cured, so that the interface modifier and the fabric substrate interact at the interface, and the liquid metal is encapsulated on the fabric substrate to obtain the electrode precursor.

[0050] S3. Apply an external force to the electrode precursor. The oxide film on the surface of the liquid metal particles breaks, causing the liquid metal particles to form a continuous conductive network structure between the fibers, thus obtaining a liquid metal-fabric electrode.

[0051] This invention provides a mechanochemical interface coupling strategy using ultrasound. The metal luminescent electrode (LM) is split into micro / nanoparticles through high-energy ultrasonic cavitation, exposing metal sites. An interface modifier acts as a bimodal molecular bridge, coordinating and modifying the exposed metal sites of the LM micro / nanoparticles to form coordination bonds. Simultaneously, it interacts with the fabric substrate, anchoring the LM between the interface modifier and the fabric substrate. Under external mechanical pressure, the oxide film on the surface of the LM particles ruptures, forming a continuous conductive network structure between the fibers, resulting in an LM-fabric electrode. This electrode retains the porous structure and breathability of the textile substrate and maintains stable electrical performance under various mechanical and chemical stresses. It exhibits excellent stability and biocompatibility in sweat exposure, mechanical deformation, and long-term wear scenarios. Even after undergoing extensive mechanical deformation, high-speed washing, and extreme conditions such as sweat / water immersion, it maintains low interfacial impedance and high signal-to-noise ratio, achieving continuous and stable acquisition of human electrophysiological signals in both static and dynamic scenarios over extended periods.

[0052] In some embodiments, the interface modifier is (3-mercaptopropyl)triethoxysilane (KH-580), phytic acid or glucose (Glu), the liquid metal is gallium-indium alloy (EGaIn), the mass ratio of gallium (Ga) to indium (In) is 3:1, and the fabric substrate is polyester (PET) fiber / fabric, polyamide (PA) fiber / fabric, polyurethane (PU) fiber / fabric or cotton fiber / fabric.

[0053] When the interface modifier is KH-580, the mass ratio of LM to KH-580 is 1:0.05-0.2, and the KH-580 solution is prepared by mixing KH-580, deionized water, and ethanol in a mass ratio of 0.05-0.2:1:0.2. Figure 1As shown, under ultrasonic treatment, the EGaIn alloy is sheared and fractured into micro / nanoparticles, exposing Ga-In sites. Thiol groups chelate with these sites, resulting in surface-functionalized LM particles. After settling, the supernatant is discarded, yielding a surface-modified LM slurry. During the drying and curing process at room temperature after coating, thiol-silane undergoes dehydration condensation, forming a polymer network entangled with the fiber substrate and encapsulating the LM droplets.

[0054] When the interface modifier is phytic acid, the mass ratio of LM to phytic acid is 1:0.5–2.5, and the phytic acid solution is prepared by mixing phytic acid and deionized water at a mass ratio of 1:1. Figure 2 As shown, phytic acid forms coordinate bonds with exposed metal sites through its polyhydroxy phosphate groups, and hydrogen bonds with a small amount of metal oxides on the surface. At the same time, it interacts with the hydroxyl groups of the fiber through hydrogen bonding / electrostatic interaction, thereby forming a functionalized molecular layer on the particle surface, which enhances the anchoring of LM to the fiber at the molecular / nanoscale.

[0055] When the interface modifier is Glu, the mass ratio of LM to Glu is 1:1 to 5, and the Glu solution is prepared by mixing Glu and deionized water at a mass ratio of 1:10. For example... Figure 3 As shown, the abundant hydroxyl and carboxyl hydroxyl groups on the Glu molecule form coordination bonds with the metal sites exposed by the LM, and hydrogen bonds with a small amount of metal oxides on the surface. At the same time, they interact with the hydroxyl groups of the fiber through hydrogen bonding / electrostatic interaction, thereby forming a functionalized molecular layer on the particle surface, which enhances the anchoring of the LM to the fiber at the molecular / nanoscale.

[0056] In some embodiments, the ultrasonic power is 400W to 800W, the duration is 30s to 90s, and the settling time is 4h to 8h. In this invention, LM particles with a submicron / nanometer dispersion are obtained by shear dispersion in an aqueous phase containing an interface modifier using ultrasonic probe.

[0057] In some embodiments, the color of the coated area changes when an external force is applied to rupture the oxide film on the surface of the liquid metal particles. In this invention, the applied mechanical pressure is used to apply localized mechanical fracturing (e.g., rolling or needle pressure) to the coated area. This invention does not limit the magnitude of the applied external force, but when the applied external force ruptures the oxide film on the surface of the liquid metal particles, the color of the coated area changes from grayish-black to a bright silver with a metallic luster. At this time, the rupture of the oxide film on the surface of the LM particles causes the LM particles to form a continuous conductive network structure between the fibers, resulting in an LM-fabric electrode. This electrode retains the porous structure and breathability of the textile substrate and maintains stable electrical performance under various mechanical and chemical stresses, exhibiting excellent stability and biocompatibility in sweat exposure, mechanical deformation, and long-term wear scenarios.

[0058] The following specific examples will provide further explanation.

[0059] Example 1 A method for preparing a breathable and interfacially durable liquid metal-fabric electrode includes the following steps: S1. Add 1.25g of KH-580 solution to 1g of LM (EGaIn, Ga and In mass ratio of 3:1). The KH-580 solution system is prepared by mixing KH-580, deionized water and ethanol in a mass ratio of 0.05:1:0.2. Under ice bath conditions, use a 3mm diameter ultrasonic probe to sonicate at 600W power for 1min (ultrasonic power density approximately 8500W / cm³). 2 Then, let it stand for 8 hours to allow the LM particles to settle, discard the supernatant, and obtain the surface-modified LM slurry.

[0060] S2. Apply LM slurry evenly to the PET fiber substrate using a template, and let it dry completely at room temperature for 12 hours to obtain the preform of the liquid metal-fabric electrode, named S-GIP. Apply an external load to the coated area of ​​S-GIP until the coated area changes from gray-black to a bright silver state with metallic luster to obtain the liquid metal-fabric electrode, named S-GIPE.

[0061] Example 2 A method for preparing a breathable and interfacially durable LM-fabric electrode differs from Example 1 in that: S1, 1.3g of KH-580 is added to 1g of LM (EGaIn, Ga and In mass ratio of 3:1). The mass ratio of KH-580, deionized water, and ethanol in the KH-580 solution system is 0.1:1:0.2. Under ice bath conditions, ultrasonication is performed for 0.5min using a 3mm diameter ultrasonic probe at 800W power (ultrasonic power density approximately 8500W / cm²). 2 Then, let it stand for 6 hours to allow the LM particles to settle, discard the supernatant, and obtain the surface-modified LM slurry.

[0062] Example 3 A method for preparing a breathable and interface-durable liquid metal-fabric electrode differs from Example 1 in that: S1, 1.4g of KH-580 is added to 1g of LM (EGaIn, Ga and In mass ratio of 3:1). The mass ratio of KH-580, deionized water, and ethanol in the KH-580 solution system is 0.2:1:0.2. Under ice bath conditions, ultrasonication is performed for 1.5min using a 3mm diameter ultrasonic probe at 400W power (ultrasonic power density approximately 8500W / cm²). 2 Then, let it stand for 4 hours to allow the LM particles to settle, discard the supernatant, and obtain the surface-modified LM slurry.

[0063] The liquid metal-fabric electrodes of Examples 1 to 3 were subjected to structural and performance tests, and the results are as follows: Figure 4 This is a morphological structure diagram of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 4 In the diagram, a represents the morphological structure of the S-GIP before activation, and b represents the morphological structure of the S-GIP after activation. Figure 4 The small image in the upper right corner of image a is an S-GIP digital image. Figure 4 The small image in the upper right corner of image b is an S-GIPE digital image, such as... Figure 4 As shown, due to the insulating nature of the polymer shell, external force is required to activate it and expose the conductive LM surface to obtain S-GIPE. Scanning electron microscopy revealed significant changes in surface morphology before and after activation: before activation, the surface was uniformly covered with a functionalized LM layer while maintaining the PET fiber morphology; at high magnification, protrusions or capsules formed by the encapsulated LM were visible. After activation, the polymer film exhibited numerous cavities, indicating that the LM had leaked out of the shell. Elemental distribution mapping confirmed the uniform presence of the thionyl coupling agent and EGaIn in the activation electrode.

[0064] Figure 5 The image shows the X-ray diffraction pattern of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 5 As shown, the characteristic diffraction peaks of PET are significantly weakened in S-GIPE, while the characteristics associated with EGaIn are enhanced, indicating the influence of the silane network and EGaIn released from the microcapsules on the diffraction characteristics.

[0065] Figure 6 The total reflectance infrared spectrum of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 6 The small image in the lower left corner shows the wavenumber at 600cm. -1 ~675cm -1 The total reflectance infrared spectrum. For example... Figure 6 As shown, the intensity of the C=O and COC vibrational bands associated with PET is significantly weakened in S-GIPE, and vibrational peaks at low wavenumbers are attributed to Ga-S and In-S. The weakening of the -SH characteristic peak indicates that thiols are largely consumed and participate in coordination.

[0066] Figure 7 The image shows the X-ray photoelectron spectrum of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 7 In the image, (a) is the O 1s spectrum and (b) is the S 2p spectrum. Figure 7 As shown, the formation of the Si-OC / Si-O-Si component and the Ga-S component at 163.1 eV in the S 2p spectrum were further confirmed, confirming the thiol-gallium coordination and the formation of the polymer network by silane condensation.

[0067] Resistance was measured in a coated circular area with a diameter of 20 mm. Figure 8 The figures show the electrical properties and stability characterization of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 8 In the diagram, a represents the resistance before and after activation, b represents the resistance stability during the mechanical cycle, and c represents the environmental resistance stability. For example... Figure 8 As shown, due to the protective properties of the silane network, S-GIP maintained its electrical insulation state after standing, 7 days of water washing (100 rpm), and 7 days of sweat immersion. Upon pressure activation, S-GIPE exhibited low resistance (approximately 2 Ω), indicating that the internal EGaIn was not damaged by the environment and could be successfully released and made conductive. The resistance of S-GIPE remained stable after 1000 bending and torsion cycles, and its conductivity remained relatively constant after 7 days of air exposure, 7 days of water immersion, and 7 days of sweat immersion (slight fluctuations are attributed to oxide layer formation and impurity adsorption).

[0068] Figure 9 This is a customizable pattern and interface stability diagram of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 9 In the diagram, 'a' represents a custom pattern, and 'b' shows the surface resistance distribution spectrum before and after pattern activation, and after tape peeling. (Example:) Figure 9 As shown, a 20mm×20mm sample was divided into 100 stations. A specific station was activated with a rigid needle with a diameter of 1mm to form an "X" shaped conductive pattern. After all stations were activated, 500 tape peel tests were performed. The conductive array still maintained its intrinsic electrical properties, indicating that a solid interconnect was formed between the LM and the substrate.

[0069] The skin compatibility and breathability of the liquid metal-fabric electrode prepared in Example 1 were tested, specifically including the following steps: Human umbilical vein endothelial cells (HUVECs) were seeded in a culture medium containing PET fiber substrate, EGaIn, or S-GIPE (5mm × 5mm) under the following conditions: 37°C, 95% humidity, and 5% CO2 (volume concentration). After 24 hours, the cells were washed and stained with Calcein AM and propidium iodide. Cell viability was observed using a confocal laser microscope.

[0070] Figure 10 This is a biocompatibility test image of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 10 In the diagram, a represents a blank control, b represents a PET substrate, c represents EGaIn, and d represents S-GIPE prepared in the example. Figure 10As shown, the 24-hour HUVEC cell culture results showed that the cell viability of blank control, PET substrate, EGaIn and final S-GIPE were 100%, 99.34%, 99.90% and 97.09%, respectively, indicating that S-GIPE has almost no cytotoxicity and is suitable for long-term skin contact.

[0071] Figure 11 The air permeability of the liquid metal-fabric electrode prepared in Example 1 of this invention, Figure 11 In the figure, 'a' represents the water weight retention rate, and 'b' represents the water vapor transmission rate. The water vapor transmission rate (WVTR) test is conducted at 28°C and 45% relative humidity. Figure 11 As shown, the WVTR of S-GIPE is >1500 g·m⁻¹. -2 ·day -1 Significantly higher than commercial patch electrodes (490 g·m -2 ·day -1 (The commercial patch electrodes are from Jingdian Yikang and Ledemei Sanhe Medical Technology Co., Ltd.), indicating that S-GIPE has better breathability and can significantly reduce skin moisture accumulation and irritation.

[0072] Figure 12 This is a digital photograph illustrating the skin-friendly properties of the liquid metal-fabric electrode prepared in Example 1 of this invention. Figure 12 As shown in the comparison experiment after 6 hours of wear, the S-GIPE left no obvious pressure marks on the skin, while the commercial gel electrode left obvious marks and sticky residue.

[0073] Figure 13 This is the frequency-impedance curve of the electrode-skin interface of the liquid metal-fabric electrode prepared in Example 1 of the present invention. Figure 13 As shown, the skin impedance of S-GIPE and commercial electrodes was compared at different frequencies, demonstrating that S-GIPE has advantages across the entire frequency band.

[0074] Figure 14 The above describes the EEG signals of the liquid metal-fabric electrode prepared in Example 1 of this invention under three environmental exposures. Figure 14 In the diagram, a represents 7 days of air exposure, b represents 7 days of water exposure, and c represents 7 days of sweat exposure. Figure 14 As shown, comparing the EEG waveforms after the initial state, 7 days of air exposure, 7 days of water exposure, and 7 days of sweat exposure, S-GIPE can still output high-fidelity EEG signals after these harsh treatments.

[0075] The liquid metal-fabric electrode prepared in Example 1 was used for sleep EEG monitoring to achieve non-invasive, long-term sleep EEG monitoring. Figure 15The images show the time-domain and time-frequency plots of EEG signals from a liquid metal-fabric electrode used for sleep EEG monitoring in Embodiment 1 of the present invention. Figure 15 In the diagram, a is the time-domain plot of the EEG signal, and b is the time-frequency plot. Figure 16 This is an energy spectral density diagram of EEG signals from four random time intervals in Embodiment 1 of the present invention, using a liquid metal-fabric electrode for sleep EEG monitoring. Figure 15 and Figure 16 As shown, in a 6-hour continuous sleep recording, both the time-domain and frequency-domain spectra indicate continuous and stable signals, directly identifying transient high-amplitude events such as electromyographic bursts and eye movement artifacts. The spectrograms present the frequency band energy distribution (δ, θ, α, σ / spindle wave, β) corresponding to different sleep stages, and more than three complete sleep cycles can be observed. PSD analysis of four 30-second artifact-free video segments reveals the following: In the early sleep stage (815s–845s), the PSD is widely distributed between 3Hz and 27Hz, with the θ band (3Hz–9Hz) dominating, indicating N1 / N2; subsequently, a segment (1285s–1315s) is dominated by 3Hz–4Hz, indicating deep sleep (N3). The middle stage (7825s–7855s) is dominated by the δ band, while the late stage (19385s–19415s) shows energy concentration around 11Hz, consistent with N2 characteristics. These results demonstrate that S-GIPE can reliably acquire high-fidelity sleep EEG and support professional quantitative analysis.

[0076] Figure 17 The EEG signals collected by the liquid metal-fabric electrodes prepared in Examples 2 and 3 of this invention. Figure 17 In the text, a represents Example 2, and b represents Example 3. For example... Figure 17 As shown, the EEG signals collected from the epidermal electrodes prepared with two different component ratios exhibit a high degree of consistency in amplitude and waveform, proving that the electrodes prepared within the provided material ratio range maintain applicability and stable, excellent electrical properties.

[0077] Example 4 A method for preparing a breathable and interfacially durable liquid metal-fabric electrode includes the following steps: S1. Add 0.5g of phytic acid solution to 1g of LM (EGaIn, Ga and In mass ratio of 3:1). The phytic acid solution has a phytic acid to deionized water mass ratio of 1:1. Under ice bath conditions, use a 3mm diameter ultrasonic probe at 600W power for 1min (ultrasonic power density approximately 8500W / cm³). 2 Then, let it stand for 4 hours to allow the LM particles to settle, discard the supernatant, and obtain the surface-modified LM slurry.

[0078] S2. Apply the LM slurry evenly to the cotton fabric substrate using a template, and let it dry completely at room temperature for 12 hours to obtain the liquid metal-fabric electrode precursor. Apply an external load to the coated area until the coated area changes from gray-black to a bright silver state with metallic luster to obtain the liquid metal-fabric electrode, named LMPC.

[0079] Comparative Example 2 A method for preparing a breathable and durable liquid metal-fabric electrode, which differs from Example 4 in that phytic acid is not added, and a liquid metal-fabric electrode is obtained, named LMC.

[0080] The liquid metal-fabric electrodes prepared in Example 4 and Comparative Example 2 were subjected to structural and performance tests. The structures are as follows: Figure 18 This is a morphological structure diagram of the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 18 In the diagram, a is a morphological structure diagram of LMC in Comparative Example 2, b is an enlarged view of the box in a, c is an enlarged view of LMPC in Example 4, and d is an enlarged view of the box in c. Figure 18 As shown, unmodified LMC exhibits obvious blocky or aggregated structures, while the phytic acid-modified sample shows a more uniform coating layer, with fiber bundles wrapped in a continuous metal / composite layer, and the pore structure partially preserved.

[0081] Figure 19 The image shows the infrared spectrum of the liquid metal-fabric electrode prepared in Example 4 of this invention. Figure 19 As shown, at approximately 2700cm -1 P-OH stretching vibrations associated with phytic acid were observed nearby, and at 950 cm⁻¹ -1 ~980cm -1 An absorption peak that may be attributed to POC or PO-Ga / In was detected, suggesting that phytic acid interacts with both the fiber and LM.

[0082] To simulate sports usage scenarios, the liquid metal-fabric electrode prepared in Example 4 was subjected to cyclic mechanical fatigue tests including stretching, bending, and torsion (>5000 cycles), as well as accelerated aging treatments such as soaking in artificial sweat or deionized water for 7 days, or high-speed rotation washing (120 min, 1000 rpm). Figure 20 To assess the resistance stability of the liquid metal-fabric electrode prepared in Example 4 of this invention, Figure 20 In the diagram, a represents the resistive stability under mechanical deformation, b represents the resistive stability after 7 days of immersion, and c represents the resistive stability after water washing. For example... Figure 20As shown, the LMPC electrode maintains a continuous conductive network and low impedance after the above treatment, while the unmodified LMC shows a significant decrease in conductivity or LM detachment under fewer cycles or milder washing conditions. The authors attribute this to the bimodal binding (coordination + hydrogen bonding) formed by phytic acid molecules at the interface and the inherent mobility of LM, thereby synergistically improving interfacial robustness at both the particle level and the macroscopic scale.

[0083] HUVEC cells were cultured in vitro and subjected to fluorescence imaging to assess cell viability and toxicity; skin compatibility tests were also performed to evaluate skin comfort and irritation. Figure 21 This is a biocompatibility test image of the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 21 In the diagram, a represents the cotton fabric substrate, b represents LM, c represents Example 4, and d represents the commercial gel electrode.

[0084] Figure 22 The air permeability of the liquid metal-fabric electrode prepared in Example 4 of this invention is discussed. Figure 22 In the diagram, a represents the water weight retention rate, and b represents the water vapor transmission rate. For example... Figure 22 As shown, the water vapor transmission rate (WVTR) of the LMPC electrode is close to that of the original cotton textile (measured at approximately 1324 g·m). -2 ·day -1 This is significantly superior to commercial gel electrodes (approximately 322 g·m⁻¹). -2 ·day -1 Cytotoxicity assays (HUVEC cells, 24h) and skin compatibility tests showed that the material had no significant toxic or irritating effects on cells and skin, supporting the feasibility of long-term skin contact wear.

[0085] Figure 23 The images show the ECG signal and signal-to-noise ratio under different extreme treatments of the liquid metal-fabric electrode prepared in Example 4 of this invention. Figure 23 In the diagram, a shows the ECG signal and corresponding signal-to-noise ratio after 7 wear-to-desorption cycles; b shows the ECG signal and corresponding signal-to-noise ratio after 7 days of air exposure; and c shows the ECG signal and corresponding signal-to-noise ratio after dust adhesion. Figure 23 As shown, comparing the skin electrode interface impedance of LMPC with that of commercial gel electrodes in the frequency domain, LMPC exhibits significantly lower impedance values ​​across the entire test frequency range. This directly translates to higher SNR and higher fidelity ECG / EMG waveforms.

[0086] Figure 24 This is a comparison of the SNR of the liquid metal-fabric electrode prepared in Example 4 of the present invention under different treatments. Figure 24As shown, after multiple comprehensive tests simulating application and removal, dust contamination, and sweat exposure, the SNR of LMPC was the lowest at 22.82 dB after complex environmental treatment, while that of commercial gel electrodes was only 12.70 dB, indicating that LMPC maintains better electrical performance in complex real-world usage environments.

[0087] LMPC electrodes were used for ECG and EMG recording in endurance training (such as continuous indoor cycling) and strength training (such as dumbbell curls, bench presses, and leg presses). Figure 25 This is an ECG electrophysiological signal image collected by the liquid metal-fabric electrode prepared in Example 4 of the present invention. Figure 25 In the diagram, a represents the overall electrophysiological signal, while b and c represent electrophysiological signal at different stages. Figure 26 This is an EMG electrophysiological signal image collected by the LM-fabric electrode prepared in Example 4 of this invention. Figure 26 In the diagram, a represents the overall electrophysiological signal map, while b, c, and d represent electrophysiological signal maps at different stages. Figure 25 As shown, during prolonged sweating and high-intensity exercise, LMPC can continuously suppress exercise artifacts and stably record changes in heart rate and electromyography. Figure 26 As shown, during strength training, LMPC captures typical electromyographic changes during muscle contraction and relaxation cycles, and can detect features such as spectrum shift to lower frequencies and SNR decrease as fatigue accumulates. These indicators can serve as a quantitative assessment basis for immediate training load and muscle fatigue.

[0088] Example 5 A method for preparing a breathable and interfacially durable liquid metal-fabric electrode includes the following steps: S1. Add 1g of Glu solution to 1g of LM (EGaIn, Ga and In mass ratio of 3:1). The Glu solution is prepared with a Glu to deionized water mass ratio of 1:1. Under ice bath conditions, use a 3mm diameter ultrasonic probe to sonicate at 600W power for 1min (ultrasonic power density approximately 8500W / cm³). 2 Then, let it stand for 4 hours to allow the LM particles to settle, discard the supernatant, and obtain the surface-modified LM slurry.

[0089] S2. Apply the LM slurry evenly to the PA / PU composite fabric substrate using a template, and let it dry completely at room temperature for 12 hours to obtain the liquid metal-fabric electrode precursor. Apply an external load to the coated area until the coated area changes from gray-black to a bright silver state with metallic luster to obtain the liquid metal-fabric electrode, named GLME.

[0090] The liquid metal-fabric electrode prepared in Example 5 was subjected to structural and performance tests. The structure is as follows: Figure 27 The XPS spectrum of the liquid metal-fabric electrode prepared in Example 5 of this invention is shown below. Figure 27 As shown, the successful modification of LM is reflected in the overall shift of the binding energy of the system in the C1s fitting spectrum, that is, from 284.6 eV to 284.8 eV.

[0091] Figure 28 Digital photographs of the surface adhesion of the LM (Liquid Metal-Fabric Electrode) before and after tape peeling off, for the liquid metal-fabric electrode prepared in Example 5 of this invention. Figure 28 As shown, after peeling, the LM remains uniformly spread on the textile surface, thanks to the introduced interfacial interactions that overcome the peeling force of the tape, demonstrating the effectiveness of this interfacial enhancement strategy in improving electrode durability.

[0092] Figure 29 This is an ECG signal data graph of the liquid metal-fabric electrode prepared in Example 5 of the present invention. Figure 29 As shown, compared to commercial gel electrodes, this electrode exhibits a larger amplitude ECG signal, thanks to the superior electrical properties provided by LM.

[0093] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for preparing a breathable and interfacially durable liquid metal-fabric electrode, characterized in that, Includes the following steps: An interface modifier was added to liquid metal, and the liquid metal was dispersed into micro / nano particles by ultrasound and its surface was coordinated to obtain a modified liquid metal slurry. The modified liquid metal slurry is coated onto the fabric substrate and dried at room temperature until cured, so that the interface modifier and the fabric substrate can interact at the interface, anchoring the liquid metal on the fabric substrate to obtain the electrode precursor. An external force is applied to the electrode precursor to rupture the oxide film on the surface of the liquid metal particles, causing the liquid metal particles to form a continuous conductive network structure between the fibers, thus obtaining a liquid metal-fabric electrode.

2. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 1, characterized in that, The interface modifier is (3-mercaptopropyl)triethoxysilane, phytic acid, or glucose.

3. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 2, characterized in that, When the interface modifier is (3-mercaptopropyl)triethoxysilane, the mass ratio of liquid metal to (3-mercaptopropyl)triethoxysilane is 1:0.05 to 0.2; when the interface modifier is phytic acid, the mass ratio of liquid metal to phytic acid is 1:0.5 to 2.5; and when the interface modifier is glucose, the mass ratio of liquid metal to glucose is 1:1 to 5.

4. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 1, characterized in that, The liquid metal is a gallium-indium alloy with a mass ratio of gallium to indium of 3:

1.

5. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 1, characterized in that, The ultrasound was performed under ice bath conditions, with a power of 400W to 800W and a duration of 30s to 90s. After ultrasound, the cells were allowed to settle for 4h to 8h.

6. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 1, characterized in that, The fabric base is polyester fiber / fabric, polyamide fiber / fabric, polyurethane fiber / fabric, or cotton fiber / fabric.

7. The method for preparing the breathable and interface-durable liquid metal-fabric electrode according to claim 1, characterized in that, When an external force is applied to break the oxide film on the surface of liquid metal particles, the color of the coated area changes.

8. A breathable and interfacially durable liquid metal-fabric electrode, characterized in that, It is prepared using the preparation method according to any one of claims 1 to 7.

Images