A conductive hydrogel, a preparation method thereof, an electrode assembly and a patch electrode, and application thereof, and a photothermal stimulation-electrical signal acquisition system and method

Abstract

The application provides a conductive hydrogel and a preparation method, an electrode assembly, a patch electrode and application, a photothermal stimulation-electrical signal acquisition system and method thereof, and relates to the technical field of bioelectric signal acquisition.The conductive hydrogel provided by the application is characterized in that the three phases of the polymer triphasic interpenetrating network are polyacrylamide, a natural hydrophilic polymer and polyaniline, the polyacrylamide and the natural hydrophilic polymer are crosslinked by a crosslinking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network, and the composite MXene-polyaniline is dispersed and anchored in the polyacrylamide-natural hydrophilic polymer interpenetrating network by bonding with the polyacrylamide.When the conductive hydrogel is applied to photothermal stimulation-electrical signal acquisition, the photothermal stimulation does not inject external stimulation current to the recording electrode, the electrical stimulation artifact can be significantly reduced, the photothermal stimulation and the electrical signal acquisition can occur at the same time without mutual interference, and the synchronization of the photothermal stimulation and the electrical signal acquisition is realized.

Description

Technical Field

[0001] This invention relates to the field of bioelectric signal acquisition technology, specifically to a conductive hydrogel and its preparation method, electrode assembly and patch electrode and their applications, and a photothermal stimulation-electric signal acquisition system and method. Background Technology

[0002] Bioelectric signal acquisition technology has become a core tool in the management of cardiovascular and neurological diseases. High-quality electrocardiogram (ECG) and electroencephalogram (EEG) recordings are crucial for disease early warning (such as arrhythmia monitoring), clinical diagnosis (such as epilepsy localization), and long-term rehabilitation assessment (such as sleep disorder analysis). With the increasing demand for bioelectric signal acquisition, traditional single-signal recording can no longer meet clinical needs. Constructing a closed-loop bioelectronic system with "acquisition-feedback-regulation" capabilities, and intervening in neural activity by regulating the balance of sympathetic and parasympathetic nerves, has become an important direction for development.

[0003] Currently, the most widely used bioelectrode is the Ag / AgCl electrode. However, existing Ag / AgCl electrode technology has significant physical and chemical limitations: on the one hand, there is a severe mechanical mismatch between its rigid electrode interface and soft human skin tissue, and it relies on liquid electrolytes for conductivity. During long-term wear, this rigid contact is susceptible to signal drift due to movement, and the evaporation or permeation of the liquid electrolyte often triggers skin irritation and inflammatory reactions, making it difficult to meet the needs of dynamic, long-term health monitoring.

[0004] To address the aforementioned interface compatibility issues, flexible conductive hydrogels, due to their unique soft and wet properties and similarity to biological tissues, have become an ideal material to replace traditional rigid electrodes. Although existing conductive hydrogels (such as systems based on alginate, gelatin, or polydopamine composites) have made some progress in improving interfacial adhesion and biocompatibility, most focus on optimizing a single function, either solely for signal acquisition or solely for electrical stimulation therapy (such as wound healing or nerve repair). This is because electrical stimulation and electrophysiological signal acquisition are difficult to reconcile within the same channel. Traditional electrical stimulation methods generate significant electrical artifacts during modulation, which can overwhelm weak physiological signals, making it impossible to acquire signals simultaneously with stimulation. This mutual exclusion between "acquisition" and "stimulation" severely limits the application of wearable devices in closed-loop neuromodulation. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a conductive hydrogel and its preparation method, an electrode assembly and patch electrode and their applications, and a photothermal stimulation-electrical signal acquisition system and method. The conductive hydrogel provided by this invention can simultaneously achieve photothermal stimulation and electrical signal acquisition.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a conductive hydrogel comprising a polymer triple interpenetrating network, and water and ionizable inorganic salts dispersed in the pores of the polymer triple interpenetrating network. The polymers forming the polymer tri-interpenetrating network include polyacrylamide, natural hydrophilic polymers, and polyaniline; The polyaniline is coated on the MXene surface to form a composite MXene-polyaniline; The polyacrylamide and the natural hydrophilic polymer are cross-linked by a cross-linking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network. The composite MXene-polyaniline is dispersed in the polyacrylamide-natural hydrophilic polymer interpenetrating network, and the composite MXene-polyaniline is bonded to the polyacrylamide.

[0007] Preferably, the ionizable inorganic salt includes one or more of sodium chloride, potassium chloride, and calcium chloride; The crosslinking agent includes N,N'-methylenebisacrylamide; The natural hydrophilic polymer includes one or more of chitosan, sodium alginate, gelatin, carboxymethyl cellulose, and bacterial cellulose; The mass ratio of the polyacrylamide to the natural hydrophilic polymer is 20~35:1; The mass ratio of the polyacrylamide to the ionizable inorganic salt is 15~35:10; The mass ratio of polyacrylamide to polyaniline is 1:0.03~0.04; The mass ratio of polyaniline to MXene is 1:0.03~0.2.

[0008] This invention provides a method for preparing the conductive hydrogel described above, comprising the following steps: Aniline, MXene, acid and water were mixed, subjected to interfacial induced polymerization and then resuspended to obtain an MXene-polyaniline composite dispersion; Acrylamide, natural hydrophilic polymer, ionizable inorganic salt, protic acid and water are thermally mixed to obtain a mixed solution; The mixed solution, MXene-polyaniline composite dispersion, crosslinking agent and initiator are mixed and crosslinked and cured to obtain a conductive hydrogel.

[0009] Preferably, the interface-induced polymerization temperature is ≤10℃ and the time is ≥12h; The concentration of composite MXene-polyaniline in the MXene-polyaniline composite dispersion is 5~20 mg / mL; The protic acid includes one or more of HCl, acetic acid, phytic acid, and citric acid; The initiator includes ammonium persulfate and / or potassium persulfate; The mass ratio of acrylamide to initiator is 1:0.025~0.05; The cross-linking and curing temperature is 50~60℃.

[0010] This invention provides an electrode assembly, comprising an electrical signal lead-out layer and an electrode core stacked sequentially; The electrode core is made of the conductive hydrogel described in the above technical solution or the conductive hydrogel prepared by the preparation method described in the above technical solution.

[0011] This invention provides a patch electrode, comprising an adhesive tape and the electrode assembly described in the above technical solution; The tape has a backing layer and an adhesive layer; the adhesive layer has a central opening, and the electrode assembly is disposed within the central opening of the adhesive layer; The electrode core of the electrode assembly is disposed on the side of the electrical signal lead-out layer away from the backing layer, and the side of the electrode core away from the backing layer is flush with or higher than the adhesive layer.

[0012] The present invention provides the application of the electrode assembly or patch electrode described in the above technical solution in photothermal stimulation and / or electrical signal acquisition for purposes other than disease diagnosis and treatment.

[0013] This invention provides a photothermal stimulation-electric signal acquisition system, including patch electrodes, a light source, and a signal processing component; The patch electrode is communicatively connected to the signal processing component; The patch electrode is the patch electrode described in the above technical solution.

[0014] Preferably, the light source includes a near-infrared light source; The photothermal stimulation-electric signal acquisition system also includes a temperature monitoring component; The signal processing component includes a signal conditioning component, a signal analysis component, and a signal transmission component connected in sequence.

[0015] This invention provides a method for acquiring photothermal stimulation-electrical signals using the photothermal stimulation-electrical signal acquisition system described above, comprising the following steps: Photothermal stimulation: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode is in contact with the skin, and a light source is used to irradiate the skin with the patch electrode attached to perform photothermal stimulation. Electrical signal acquisition: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode contacts the skin to obtain an electrical signal; the electrical signal is acquired using a signal processing unit.

[0016] This invention provides a conductive hydrogel comprising a polymeric triple interpenetrating network (TIPN), and water and ionizable inorganic salts dispersed in the pores of the TIPN. The polymers forming the TIPN include polyacrylamide, a natural hydrophilic polymer, and polyaniline. The polyaniline is coated on the surface of MXene to form a composite MXene-polyaniline. The polyacrylamide and the natural hydrophilic polymer are crosslinked by a crosslinking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network. The composite MXene-polyaniline is dispersed in the polyacrylamide-natural hydrophilic polymer interpenetrating network, and the composite MXene-polyaniline is bonded to the polyacrylamide. In the conductive hydrogel provided by this invention, the three phases in the polymer triple interpenetrating network are polyacrylamide, natural hydrophilic polymer, and polyaniline. Polyacrylamide and natural hydrophilic polymer are cross-linked by a cross-linking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network. Polyacrylamide and natural hydrophilic polymer form a rigid network, while polyacrylamide is cross-linked by a cross-linking agent to form a flexible network. The two networks interpenetrate to form a double network structure. Composite MXene-polyaniline is dispersed and anchored in the polyacrylamide-natural hydrophilic polymer interpenetrating network by bonding with polyacrylamide, forming a polymer triple interpenetrating network. Composite MXene-polyaniline is uniformly dispersed in the polymer triple interpenetrating network.When the conductive hydrogel provided by this invention is applied to patch electrodes for photothermal stimulation-electric signal acquisition, near-infrared light is irradiated by a near-infrared light source. After passing through the conductive hydrogel, the near-infrared light is absorbed by the MXene nanosheets and converted into heat energy through non-radiative relaxation. The heat is then uniformly transferred to the dermis of the skin via a composite MXene-polyaniline, activating the temperature-sensitive ion channels TRPV3 and TRPV4 expressed in the keratinocytes. This activates ATP release and sends signals to adjacent nerve endings, completing the photothermal stimulation. The free cations formed by the ionization of ionizable inorganic salts in the conductive hydrogel and the naturally occurring sweat electrolytes on the surface of the stratum corneum form a double-layer capacitance effect at the gel-skin interface. The double-layer capacitance reaches the microfarad level in the 0.05~100Hz frequency band, effectively reducing the interfacial coupling impedance and enhancing the conductivity of the hydrogel. The hydrogel exhibits a real impedance Rp below 100 Ω in the key bioelectric signal frequency band. The composite MXene-polyaniline provides an electronic conduction pathway, while ionizable inorganic salts in the pores of the triple interpenetrating network migrate within the polymer chain interstices, providing an ionic conduction pathway. These two components work synergistically to maintain stable low impedance characteristics in the 0.1–1000 Hz range, with a thermal noise voltage spectral density of 1.01–1.23 nV / √Hz. This allows for the capture of microvolt-level electrical signals with extremely low thermal noise, enabling effective electrical signal acquisition. Photothermal stimulation does not inject external stimulation current into the recording electrodes, significantly reducing electrical stimulation artifacts. Under the test conditions, the patch electrodes maintain continuous electrical signal acquisition during photothermal stimulation without observing significant saturation, baseline drift, or acquisition interruption, achieving synchronous photothermal stimulation and electrical signal acquisition. The conductive hydrogel provided by this invention possesses excellent electrochemical properties, biomimetic mechanical properties, and a broad-spectrum photothermal response capability, showing promising application prospects in closed-loop neural modulation.

[0017] The preparation method provided by this invention involves mixing aniline, MXene, acid, and water, performing interfacial-induced polymerization, and then resuspending the mixture to obtain an MXene-polyaniline composite dispersion. During the polymerization process, MXene acts as a polymerization-inducing template or nucleation support. Aniline monomers are adsorbed onto the surface and interlayer of MXene under acidic conditions, and interfacial-induced polymerization occurs under the combined action of MXene surface functional groups, interfacial charge transfer, and oxidizing species in the system. This "growth-like" bonding method creates a tight core-shell interface between polyaniline and MXene, forming a microscopic composite aggregate. This eliminates the interfacial gaps and contact resistance between the filler and polymer in traditional physical mixing methods, allowing for seamless electron transfer between polyaniline and MXene. Furthermore, this invention introduces composite MXene-polyaniline during the acrylamide polymerization process, which anchors and disperses the composite MXene-polyaniline in the polyacrylamide-natural hydrophilic polymer interpenetrating network. The large specific surface area and sheet-like morphology of MXene enable it to overlap in the polymer matrix to form a long-range continuous conductive network. Electrons can be efficiently transported through the MXene-polyaniline-MXene transition path, which significantly shortens the electron transport path length and reduces impedance. Attached Figure Description

[0018] Figure 1 Electrochemical impedance spectroscopy for commercial gel electrodes, PAM gels, and conductive hydrogels prepared in Example 1; Figure 2 XPS full spectrum of conductive hydrogel; Figure 3 Na, a conductive hydrogel 1 s, O 1 s, Ti 2 p and C 1 High-resolution XPS spectra of s and peak separation fitting results; Figure 4 A comparison of the thermal noise performance of PAM gel and the conductive hydrogel prepared in Example 1. Figure 5 The image shows the SEM characterization of the conductive hydrogel prepared in Example 1. Figure 6 This is an exploded view of the patch electrode structure; Figure 7 This is a schematic diagram of the electrical signal acquisition process for the patch electrode; Figure 8 A schematic diagram of the photothermal stimulation process for patch electrodes; Figure 9 A comparison of the physiological signal acquisition performance of a commercial Ag / AgCl gel electrode and a patch electrode prepared in Example 2; Figure 10 The UV-Vis-NIR absorption spectra of the lyophilized gel samples are shown. Figure 11 These are the results of wavelength-independent temperature rise tests. Detailed Implementation

[0019] The present invention provides a conductive hydrogel comprising a polymer triple interpenetrating network, and water and ionizable inorganic salts dispersed in the pores of the polymer triple interpenetrating network. The polymers forming the polymer tri-interpenetrating network include polyacrylamide (PAM), natural hydrophilic polymers, and polyaniline (PANI). The polyaniline is coated on the MXene surface to form a composite MXene-polyaniline; The polyacrylamide and the natural hydrophilic polymer are cross-linked by a cross-linking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network. The composite MXene-polyaniline is dispersed in the polyacrylamide-natural hydrophilic polymer interpenetrating network, and the composite MXene-polyaniline is bonded to the polyacrylamide.

[0020] In this invention, the molecular weight of the polyacrylamide can be 50,000 to 2,000,000 Da, specifically 100,000 Da, 500,000 Da, 1,000,000 Da, or 1,500,000 Da; the natural hydrophilic polymer can include one or more of chitosan (CS), sodium alginate, gelatin, carboxymethyl cellulose, and bacterial cellulose; the molecular weight of the natural hydrophilic polymer can be 50,000 to 500,000 Da, specifically 200,000 Da, 350,000 Da, or 150,000 Da; the mass ratio of the polyacrylamide to the natural hydrophilic polymer can be 20 to 35:1, specifically 25:1, 28:1, 30:1, or 32:1. In one embodiment of this invention, chitosan contains abundant amino and hydroxyl groups, which can form hydrogen bonds and physical entanglements with polyacrylamide to construct a dual network (DN) structure, while simultaneously endowing the conductive hydrogel with biocompatibility and antibacterial properties. Chitosan forms a dense hydrogen bond network with PAM chains through its abundant amino and hydroxyl groups, constituting the first network (rigid skeleton). This network interpenetrates with the second network (flexible skeleton) formed by PAM crosslinked by a crosslinking agent, forming a dual-network structure. When subjected to stress, the first network, acting as a "sacrificial network," breaks and dissipates energy, while the second network maintains elastic recovery.

[0021] In this invention, the ionizable inorganic salt may include one or more of sodium chloride, potassium chloride, and calcium chloride; the mass ratio of the polyacrylamide to the ionizable inorganic salt may be 15-35:10, specifically 20:10, 25:10, 28:10, or 30:10. In one embodiment of this invention, sodium chloride can promote polymer chain aggregation and entanglement through the Hofmeister effect (salting-out effect), enhancing the mechanical strength of the conductive hydrogel; simultaneously, it can ionize to generate sodium ions, providing an ion conductivity pathway. After ionization, NaCl mainly exists as free Na+. + and Cl - The form (free sodium ions account for 82.95% of all sodium ions) is distributed in the gaps of the polymer network, providing ion migration channels and complementing the electronic conduction pathway of PANI-MXene.

[0022] In this invention, the crosslinking agent may include N,N'-methylenebisacrylamide (MBAA); the mass ratio of the polyacrylamide to the crosslinking agent may be 1:0.002~0.01, specifically 1:0.004, 1:0.006 or 1:0.008.

[0023] In this invention, the molecular weight of the polyaniline can be 10,000~100,000 Da, specifically 20,000 Da, 50,000 Da, or 80,000 Da; the mass ratio of the polyacrylamide to the polyaniline can be 1:0.03~0.04, specifically 1:0.032, 1:0.034, 1:0.036, or 1:0.038; the MXene can include Ti3C2Tx (titanium carbide MXene); the mass ratio of the polyaniline to the MXene can be 1:0.03~0.2, specifically 1:0.05, 1:0.1, or 1:0.15.

[0024] This invention provides a method for preparing the conductive hydrogel described above, comprising the following steps: Aniline, MXene, acid and water were mixed, subjected to interfacial induced polymerization and then resuspended to obtain an MXene-polyaniline composite dispersion; Acrylamide, natural hydrophilic polymer, ionizable inorganic salt, protic acid and water are thermally mixed to obtain a mixed solution; The mixed solution, MXene-polyaniline composite dispersion, crosslinking agent and initiator are mixed and crosslinked and cured to obtain a conductive hydrogel.

[0025] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0026] This invention involves mixing aniline, MXene, acid, and water, performing interfacial-induced polymerization, and then resuspending the mixture to obtain an MXene-polyaniline composite dispersion.

[0027] In this invention, the acid may include one or more of HCl, sulfuric acid, and acetic acid; the acid and water may be used in the form of an aqueous solution of the acid; the concentration of the aqueous solution of the acid may be 0.5~2 mol / L, specifically 1 mol / L or 1.5 mol / L; the pH value of the acid may be ≤1, specifically 0.1, 0.5, or 0.8. In this invention, the volume ratio of the aniline to the aqueous solution of the acid may be 0.05~0.2:1, specifically 0.1:1 or 0.15:1.

[0028] In this invention, MXene is used in the form of an MXene dispersion; the concentration of the MXene dispersion can be 5~20 mg / mL, specifically 10 mg / mL or 15 mg / mL; the volume ratio of aniline to MXene dispersion can be 0.05~0.2:1, specifically 0.1:1 or 0.15:1.

[0029] In this invention, the mixing may include oscillatory mixing; the rotation speed of the oscillatory mixing may be 200~300 rpm. This invention ensures complete dispersion of MXene through oscillatory mixing.

[0030] In this invention, the temperature of the interface-induced polymerization can be ≤10℃, specifically 4℃, 6℃ or 8℃; the time of the interface-induced polymerization can be ≥12h, specifically 14h, 16h or 18h.

[0031] After completing the interface-induced polymerization, the present invention may further include solid-liquid separation of the polymer solution obtained from the interface-induced polymerization, washing the resulting solid to obtain a wet precipitate. The present invention does not have specific limitations on the method of solid-liquid separation and the number of washing cycles; conventional solid-liquid separation methods and washing cycles in the art can be used.

[0032] In this invention, the resuspension may include the following steps: dispersing the wet precipitate in water to obtain an MXene-polyaniline composite dispersion. In this invention, the concentration of the composite MXene-polyaniline in the MXene-polyaniline composite dispersion can be 105~120 mg / mL, specifically 110 mg / mL or 115 mg / mL. Aniline is a strong free radical polymerization inhibitor; its chain transfer constant Cz for acrylamide is approximately 44, and even a trace amount can terminate the acrylamide chain growth, leading to the conductive hydrogel not curing or a significant decrease in mechanical properties. Furthermore, the water content of the wet precipitate is uncertain, making it impossible to accurately measure the actual amount added, resulting in significant batch-to-batch variations. Therefore, this invention removes residual aniline monomers by resuspending the wet precipitate, simultaneously increasing the concentration of the composite MXene-polyaniline and converting it into an accurately measurable MXene-polyaniline composite dispersion.

[0033] This invention utilizes the adsorption of aniline monomers onto the surface and interlayer of MXene under acidic conditions. Interfacial-induced polymerization occurs under the combined effects of MXene surface functional groups, interfacial charge transfer, and oxidizing species in the system, forming a core-shell structure of "MXene core-PANI shell." PANI chains, using the MXene surface and interlayer as growth templates, unfold two-dimensionally along the nanosheet surface, forming a tight coating layer. The characteristics of this connection method are: gapless interface: PANI and MXene are in atomically close contact, eliminating interfacial resistance in physical mixing methods; synergistic conductivity: the π-conjugated chains of PANI and the metallic d-electron bands of MXene form a synergistic electron transport pathway; structural stability: the PANI shell protects MXene from oxidative degradation, improving the stability of the conductive hydrogel.

[0034] This invention involves thermally mixing acrylamide, a natural hydrophilic polymer, an ionizable inorganic salt, a protic acid, and water to obtain a mixed solution.

[0035] In this invention, the protonic acid may include one or more of HCl, acetic acid, phytic acid, and citric acid; the protonic acid may be used in the form of a protonic acid solution; the concentration of the protonic acid solution may be 0.5~2 mol / L, specifically 1 mol / L or 1.5 mol / L; the volume percentage of the protonic acid solution in the mixed solution may be 0.5~2%, specifically 1% or 1.5%. This invention dissolves chitosan through protonic acid and protonates the amino groups of chitosan (-NH2→-NH3). + This causes it to ionize and dissolve in water.

[0036] In this invention, the concentration of acrylamide in the mixed solution can be 25-30% (w / v), specifically 27% (w / v) or 29% (w / v); the concentration of the natural hydrophilic polymer in the mixed solution can be 0.5-2% (w / v), specifically 1% (w / v) or 1.5% (w / v); the concentration of the ionizable inorganic salt in the mixed solution can be 5-15% (w / v), specifically 8% (w / v), 10% (w / v), or 12% (w / v). In this invention, the temperature for thermal mixing can be 50-60°C, specifically 52°C, 55°C, or 58°C.

[0037] After obtaining the mixed solution and the MXene-polyaniline composite dispersion, the present invention mixes the mixed solution, the MXene-polyaniline composite dispersion, the crosslinking agent and the initiator, and performs crosslinking and curing to obtain a conductive hydrogel.

[0038] In this invention, the initiator may include ammonium persulfate (APS) and / or potassium persulfate; the mass ratio of acrylamide to initiator may be 1:0.025~0.05, specifically 1:0.03 or 1:0.04; the volume ratio of the mixed solution to the MXene-polyaniline composite dispersion may be 1:5~15, specifically 1:8, 1:10 or 1:12.

[0039] In this invention, the crosslinking and curing temperature can be 50~60℃, specifically 52℃, 55℃, or 58℃. This invention does not have a specific limitation on the crosslinking and curing time, as long as the crosslinked and cured product is completely gelled. In this invention, during the crosslinking and curing process, when the viscosity of the reaction solution is 100~500 mPa·s (i.e., when the reaction solution changes from a fluid state to a high-viscosity state that can be drawn into threads), this invention may further include shaking or stirring the crosslinked and cured reaction solution. This invention prevents MXene agglomeration by supplementing the viscosity increase stage in the early stage of polymerization with shaking or stirring.

[0040] In this invention, the cross-linking and curing process may further include: allowing the obtained gelled product to stand and dehydrate to obtain the conductive hydrogel. In this invention, the temperature for standing and dehydrating can be room temperature; the time for standing and dehydrating can be 12-36 hours, specifically 18 hours, 24 hours, or 30 hours. This invention achieves microstructural restructuring of the conductive hydrogel and improves its mechanical strength by allowing the cross-linked and cured gelled product to stand and dehydrate at room temperature.

[0041] This invention involves uniformly dispersing composite MXene-polyaniline in a mixed solution, which is then "captured" and anchored within a chemically cross-linked PAM three-dimensional network during acrylamide polymerization. Specific connection methods include: physical anchoring: after the formation of the PAM chemical cross-linked network, the composite MXene-polyaniline is fixed within the polymer backbone; hydrogen bonding: oxygen-containing functional groups (-O, -OH) on the MXene surface form hydrogen bonds with the amide groups (-CONH2) of the PAM chain; and amino (-NH-) / imino (=NH) groups of PANI. - The MXene-polyaniline complex forms hydrogen bonds with the amide groups of the PAM chain, while the composite MXene-polyaniline is anchored in the PAM network through physical entanglement and interfacial interactions.

[0042] This invention provides an electrode assembly, comprising an electrical signal lead-out layer and an electrode core stacked sequentially; The electrode core is made of the conductive hydrogel described in the above technical solution or the conductive hydrogel prepared by the preparation method described in the above technical solution.

[0043] In this invention, the electrode core can be disc-shaped; the diameter of the electrode core can be 20mm; and the thickness of the electrode core can be 0.5~3mm, specifically 1mm or 2mm.

[0044] In this invention, the electrical signal extraction layer comprises conductive carbon cloth and conductive leads; the conductive carbon cloth is at least partially in contact with the electrode core; the conductive leads may include copper foil leads. This invention, by providing an electrical signal extraction layer, allows the electrical signal captured by the electrode core to be extracted through the electrical signal extraction layer.

[0045] This invention provides a patch electrode, comprising an adhesive tape and the electrode assembly described in the above technical solution; The tape has a backing layer and an adhesive layer; the adhesive layer has a central opening, and the electrode assembly is disposed within the central opening of the adhesive layer; The electrode core of the electrode assembly is disposed on the side of the electrical signal lead-out layer away from the backing layer, and the side of the electrode core away from the backing layer is flush with the adhesive layer.

[0046] In this invention, the tape can be a pressure-sensitive tape. This invention uses a central opening in the adhesive layer of the tape to expose the working surface of the electrode core and allow it to directly contact the skin, while the outer edge of the tape can adhere to the skin.

[0047] The present invention provides the application of the electrode assembly or patch electrode described in the above technical solution in photothermal stimulation and / or electrical signal acquisition for purposes other than disease diagnosis and treatment.

[0048] The patch electrode provided by this invention can be specifically applied in the following three fields: (1) Sports training and human-computer interaction signal acquisition: This invention attaches the patch electrode to the intact skin area of ​​the chest wall, forearm, upper arm, lower limb or target skeletal muscle surface, and with the help of portable signal acquisition equipment and data analysis software, it collects electrocardiogram signals, electromyogram signals or skin conductance response signals during exercise, and analyzes heart rate changes, muscle activation sequence, muscle force intensity or movement pattern. It can be used for sports intensity recording, movement recognition, human-computer interaction control, sports science research or wearable device performance verification in sports training.

[0049] (2) Photothermal material response and temperature control performance test: This invention covers the patch electrode on the surface of an intact skin area, an ex vivo skin model or a phantom model, and directs the light source toward the gel-covered area. The surface or interface temperature of the gel is monitored in real time by a contact temperature sensor, and the output power or irradiation time of the light source is adjusted by an external driving circuit and a feedback control algorithm. It can be used for photothermal material response performance evaluation, temperature control algorithm verification, wearable photothermal module performance testing, surface temperature management research or thermal comfort assessment in non-medical scenarios.

[0050] (3) Engineering verification of synchronous operation of acquisition and photothermal parameter regulation: The present invention uses the patch electrode and the near-infrared light source separately. While the patch electrode acquires physiological electrical signals, the photothermal parameters are regulated by aligning the spatial optical path with the gel-covered area. The signal quality, signal-to-noise ratio, baseline stability and interface temperature changes during the baseline period, illumination period and recovery period are recorded. This can be used to verify the feasibility of the system to acquire physiological electrical signals synchronously during photothermal action, evaluate the electrical interference of photothermal regulation on the acquisition channel, and verify the collaborative working performance of the patch electrode, circuit module, light source and feedback control module. It can be used for engineering performance evaluation, equipment debugging and scientific research testing.

[0051] This invention provides a photothermal stimulation-electric signal acquisition system, including patch electrodes, a light source, and a signal processing component; The patch electrode is communicatively connected to the signal processing component; The patch electrode is the patch electrode described in the above technical solution.

[0052] The photothermal stimulation-electric signal acquisition system provided by this invention includes patch electrodes. In this invention, the number of patch electrodes can be 2 to 5, specifically 3 or 4. This invention uses multiple patch electrodes, each attached to a designated area of ​​the human skin, to acquire multi-channel bioelectrical signals.

[0053] The photothermal stimulation-electric signal acquisition system provided by this invention includes a light source. In this invention, the light source may include a near-infrared light source; the near-infrared light source may include a near-infrared light generating device and a driving circuit. In this invention, the near-infrared light generating device may be an infrared laser and / or an LED module; the wavelength of the near-infrared light generating device may be 850 nm; the divergence angle of the near-infrared light generating device may be 5~30°, specifically 6°, 10°, or 20°. In this invention, the distance between the near-infrared light generating device and the skin surface may be 1~10 cm, specifically 3 cm, 5 cm, or 8 cm. This invention generates near-infrared light through the near-infrared light generating device and aligns it with the patch electrode on the skin's coverage area via a spatial optical path.

[0054] In this invention, the optical power of the near-infrared light source can be 50~100mW, specifically 60mW, 70mW or 80mW; the optical power of the near-infrared light source can be adjusted by the driving circuit.

[0055] The photothermal stimulation-electric signal acquisition system provided by the present invention may also include a temperature monitoring component.

[0056] In this invention, the temperature monitoring component can be a contact temperature sensor. By attaching the temperature monitoring component to the edge of the patch electrode or next to the near-infrared light spot irradiation area, the invention monitors the gel surface temperature in real time, controlling the interface temperature within the range of 37~42℃. This temperature range activates the temperature-sensitive ion channels TRPV3 and TRPV4 expressed in skin keratinocytes, which send signals to adjacent nerve endings through ATP release.

[0057] The photothermal stimulation-electric signal acquisition system provided by the present invention includes a signal processing component.

[0058] In this invention, the signal processing component may include a signal conditioning component, a signal analysis component, and a signal transmission component connected in sequence.

[0059] In this invention, the signal conditioning component may include a signal amplifier, a filter, and an analog-to-digital converter (ADC). The amplification factor of the signal amplifier can be 1000 to 10000 times, specifically 2000 times, 5000 times, or 8000 times. The filter can be a bandpass filter. The electrical signal filtering frequency of the bandpass filter can be 0.05 to 100 Hz, specifically 0.1 Hz, 1 Hz, 10 Hz, or 50 Hz. The ADC can be a 24-bit ADC. In this invention, the electrical signal lead-out layer of each patch electrode is communicatively connected to one signal conditioning component. This invention connects the electrical signal lead-out layer of the patch electrode to the signal conditioning component, amplifies the captured electrical signal through a signal amplifier, filters it through a bandpass filter, and finally performs analog-to-digital conversion through an ADC to output a digital signal. This invention does not limit the signal conditioning method; conventional signal conditioning methods in the art can be used.

[0060] In this invention, the signal analysis component can be a microcontroller or an embedded processor. This invention uses the signal analysis component to perform signal processing and feedback control algorithms on the digital signal input from the signal conditioning component. This invention does not explicitly limit the signal processing and feedback control algorithms; conventional algorithms in the art can be used.

[0061] In this invention, the signal transmission component may include a Bluetooth Low Energy (BLE) or Wi-Fi module. This invention transmits the analysis data from the signal analysis component to a terminal, such as a mobile phone, tablet computer, or workstation, via the signal transmission component.

[0062] This invention provides a method for acquiring photothermal stimulation-electrical signals using the photothermal stimulation-electrical signal acquisition system described above, comprising the following steps: Photothermal stimulation: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode is in contact with the skin, and the skin with the patch electrode attached is irradiated with a near-infrared light source to perform photothermal stimulation. Electrical signal acquisition: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode contacts the skin to obtain an electrical signal; the electrical signal is acquired using a signal processing unit.

[0063] In this invention, the near-infrared light source irradiation time during the photothermal stimulation process is ≥5 min, specifically 5.5 min, 6 min, or 6.5 min. In this invention, when the electrical signal is an electrocardiogram (ECG) signal, the patch electrode is applied to the right arm (RA), left arm (LA), left leg (LL), or chest wall at positions V2 and V4; when the electrical signal is an electroencephalogram (EEG) signal, the patch electrode is applied to the forehead at positions Fp1, Fp2, Fp2, or mastoid process A2.

[0064] To further illustrate the present invention, the solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0065] In all embodiments and test examples of this invention, aniline (ANI, 99%), hydrochloric acid solution (HCl, 1 mol / L), acrylamide (AAm, 99%), chitosan (degree of deacetylation ≥ 95%), sodium chloride (NaCl, analytical grade), ammonium persulfate (APS, 99.99%), and N,N′-methylenebisacrylamide (MBAA, 99%) were purchased from Maclean Biotechnology Co., Ltd. (China); deionized water with a resistivity of 18.2 MΩ·cm was used in both embodiments and test examples; unless otherwise stated, all reagents were used directly without further purification; MXene was a Ti3C2Tx dispersion with a concentration of 10 mg / mL; the commercially available gel electrode was "Shenxin Disposable ECG Electrode", an Ag / AgCl gel electrode.

[0066] Example 1 0.1 mL of aniline and 1 mL of 1 mol / L hydrochloric acid were mixed, and then 1 mL of 10 mg / mL MXene dispersion was added. The mixture was shaken at 200–300 rpm to ensure complete dispersion of MXene. The mixture was incubated at 4 °C for 14 h (polymerization reaction) to allow aniline to adsorb onto the surface and interlayer of the MXene sheets, resulting in interfacial induced polymerization. After the interfacial induced polymerization was completed, the resulting polymer solution was centrifuged. The obtained solid was washed with water to remove unreacted substances, resulting in a wet precipitate. The wet precipitate was resuspended and dispersed in 1 mL of deionized water to obtain an MXene-polyaniline composite dispersion with a total concentration of approximately 110 mg / mL.

[0067] Acrylamide, chitosan, sodium chloride, hydrochloric acid, and water were mixed and dissolved by stirring at 55°C to obtain a mixed solution. The concentration of hydrochloric acid was 1 mol / L; the volume percentage of hydrochloric acid in the mixed solution was 1%, the concentration of acrylamide was 28.2% (w / v), the concentration of chitosan was 1% (w / v), and the concentration of sodium chloride was 10% (w / v).

[0068] 1 mL of the obtained MXene-polyaniline composite dispersion and 10 mL of the obtained mixed solution were mixed, and 0.1 g of ammonium persulfate and 0.01 g of MBAA were added. The mixture was heated to 55 °C in a mold for crosslinking and curing. During the initial stage of viscosity increase in the crosslinking and curing process, oscillation or rapid stirring was used to prevent MXene agglomeration. Heating was continued until complete gelation to obtain a gelled product. The obtained gelled product was allowed to stand at room temperature for 24 h to dehydrate, resulting in a conductive hydrogel, denoted as PAM-PANI-MXene, abbreviated as PPMX.

[0069] Test Example 1 The properties of the conductive hydrogel prepared in Example 1 were tested, and the specific test methods and results are as follows: 1. Impedance The complex impedance of conductive hydrogels was measured using electrochemical impedance spectroscopy (EIS) in the frequency range of 0.1 to 1000 Hz, and the real part resistance Rp was extracted.

[0070] Figure 1 Electrochemical impedance spectroscopy (EIS) spectra of a commercial gel electrode, PAM gel, and the conductive hydrogel prepared in Example 1. Figure 1 It can be seen that the conductive hydrogel prepared in Example 1 has a gel resistance of only 40.9Ω, which is about 86.5% lower than that of commercial gel electrodes (303.4Ω).

[0071] The impedance reduction is caused by the interfacial induced polymerization of PANI on the MXene surface and the subsequent formation of a dense interpenetrating network structure. The specific mechanism is as follows: (1) Interface-induced polymerization reduces interfacial resistance: Under acidic conditions, aniline monomers adsorb onto the surface and interlayer of MXene, and undergo interface-induced polymerization under the combined effects of MXene surface functional groups, interfacial charge transfer, and oxidizing species in the system. This process allows PANI chains to grow directly on the MXene surface, rather than freely polymerizing in solution and then mixing. This "growth-type" bonding method forms a tight core-shell interface between PANI and MXene, eliminating the interfacial gaps and contact resistance between the filler and polymer in traditional physical mixing methods. Electrons can be seamlessly transferred between the conductive PANI chains and the conductive MXene backbone.

[0072] (2) Interpenetrating network constructs a three-dimensional continuous conductive pathway: PANI-coated MXene nanosheets (composite MXene-polyaniline) are uniformly dispersed in PAM precursor solution (mixed solution) and anchored in the chemically cross-linked PAM three-dimensional network during acrylamide polymerization. The large specific surface area and sheet-like morphology of MXene nanosheets enable them to overlap in the polymer matrix to form a long-range continuous conductive network. Electrons can be efficiently transported through the MXene-PANI-MXene transition path, significantly shortening the electron transport path length.

[0073] (3) Synergistic drag reduction through dual conductivity mechanisms: The conductive hydrogel contains both electronic conductivity pathways (PANI-MXene network) and ionic conductivity pathways (free Na+). + The conductive hydrogel was characterized using X-ray photoelectron spectroscopy (XPS) to assess its migration. Figure 2 This is the XPS full spectrum of the conductive hydrogel. Figure 3 Na, a conductive hydrogel 1 s, O 1 s, Ti 2 p and C 1 High-resolution XPS spectra and peak separation fitting results of s. Figure 2 and Figure 3 It can be seen that XPS Na 1 Na in the s spectrum + The relatively high proportion of the relevant peak area indicates that Na mainly exists in the ionic state. These mobile ions migrate in the gaps between polymer networks, providing additional ionic conductivity in the low-frequency region (0.05~100Hz), and working in conjunction with the electronic pathway to reduce the overall impedance.

[0074] (4) The double layer effect reduces interfacial coupling impedance: When the conductive hydrogel comes into contact with the skin, the free ions in the gel and the electrolytes in the sweat on the skin surface form a double layer (EDL) capacitance effect at the interface. This effect generates microfarads (10) in the low-frequency region. -6 F) Capacitors effectively reduce the coupling impedance at the electrode-skin interface.

[0075] 2. Thermal noise The thermal noise voltage spectral density is calculated using the Johnson-Nyquist theoretical formula: Vn=√(4kTRΔf), where k is the Boltzmann constant, T is the absolute temperature, R is the measured resistance value, and Δf is the measurement bandwidth.

[0076] Plot the thermal noise performance diagram with Δf as the x-axis and Vn as the y-axis. Figure 4 A comparison of the thermal noise performance of PAM gel and the conductive hydrogel prepared in Example 1. Figure 4It is evident that the theoretical thermal noise voltage spectral density of the conductive hydrogel prepared in Example 1 is as low as 1.01~1.23 nV / √Hz, significantly lower than that of the PAM gel (1.52~1.56 nV / √Hz). This low thermal noise directly stems from the gel's low resistance. According to the Johnson-Nyquist equation, thermal noise is proportional to the square root of the resistance. The gel resistance (40.9 Ω) of the conductive hydrogel prepared in Example 1 is much lower than that of the PAM gel, thus reducing thermal noise by approximately 2.7 times. This low-noise characteristic enables the conductive hydrogel provided by this invention to resolve weak bioelectrical signals at the microvolt level (such as electroencephalogram signals, only 10~20 μV), providing a physical basis for high-precision physiological signal acquisition.

[0077] 3. Bionic mechanical properties Tensile property testing was conducted according to the national standard GB / T 1040.3-2006, "Determination of Tensile Properties of Plastics". The gel was cut into dumbbell-shaped or rectangular standard strips, clamped in a universal testing machine (such as AI-3000-U type), and subjected to uniaxial tensile testing at a tensile rate of 1~10 mm / min. The stress-strain curves were recorded. Young's modulus was calculated based on the slope of the linear segment within the 20~30% strain range of the stress-strain curve; the fracture energy was obtained by the area integral under the stress-strain curve.

[0078] Tests showed that the conductive hydrogel prepared in Example 1 had a Young's modulus of 0.375 MPa (after dehydration), which highly matched the elastic modulus range of human skin (0.1~0.5 MPa); a fracture energy of 50.12 N·mm (after dehydration), which was about 76% higher than that of the initial state (the fracture energy of the gelled product before static dehydration was 28.52 N·mm); and a fracture elongation of about 250%, which can adapt to dynamic deformations such as joint bending.

[0079] The biomimetic mechanical properties of conductive hydrogels are achieved through the following material structural features and synergistic effects: (1) Double Network Structure: Chitosan acts as the first network (rigid backbone), forming dense hydrogen bonds with PAM chains through abundant amino and hydroxyl groups; PAM acts as the second network (flexible backbone), forming a three-dimensional chemical network through MABA chemical cross-linking. In the double network structure, the rigid first network preferentially breaks under stress to dissipate energy as "sacrificial bonds", while the flexible second network maintains the integrity of the overall structure and provides elastic recovery capability.

[0080] (2) Morphology of microsprings: Figure 5 This is a SEM image of the conductive hydrogel prepared in Example 1. Figure 5It is known that the polymer matrix in conductive hydrogels forms oriented, wrinkled fiber bundles with a curved micro-spring structure. This structure stores elastic potential energy in a coiled conformation when unstretched, and gradually unfolds and orients under external force, providing structural flexibility and enabling the conductive hydrogel to conform to the microscopic morphology of the skin surface.

[0081] (3) Energy dissipation mechanism: During the stretching process, the coiled molecular chains unfold and orient along the stress direction, and effectively dissipate the fracture energy through chain slip and the debonding-rebonding process of the interface between the composite MXene-polyaniline and the PAM matrix, thus preventing brittle fracture caused by stress concentration.

[0082] (4) Static dehydration and toughening: After the cross-linked and cured gel product is statically dehydrated at room temperature for 24 hours, the polymer network of the conductive hydrogel undergoes structural relaxation and equilibrium, and the hydrogen bonds are rearranged to form a better cross-linking distribution. At the same time, moderate dehydration increases the network density, resulting in Young's modulus increasing from 0.298 MPa (before dehydration) to 0.375 MPa, and fracture energy increasing from 28.52 N·mm (before dehydration) to 50.12 N·mm.

[0083] Example 2 Figure 6 This is an exploded view of the structure of the patch electrode. The conductive hydrogel obtained in Example 1 was used to prepare an electrode core with a diameter of 20 mm and a thickness of 2 mm. A hole was made in the center of the adhesive layer of the pressure-sensitive tape (which has a backing layer and an adhesive layer). Conductive carbon cloth was embedded in the hole as an electrical signal lead-out layer. The conductive carbon cloth led out the electrical signal through copper foil leads. The electrode core was stacked on the side of the electrical signal lead-out layer away from the backing of the pressure-sensitive tape. The hole made the surface of the electrode core flush with the adhesive layer, so that the electrode core could directly contact the skin and the edge of the pressure-sensitive tape could adhere to the skin.

[0084] Figure 7 This is a schematic diagram of the electrical signal acquisition process for a surface-mount electrode. The electrode signal generated by the surface-mount electrode is converted into a digital signal by a signal conditioning component (instrumentation amplifier, with a gain of 5000 times, a 0.05~100Hz bandpass filter, and a 24-bit analog-to-digital converter), and then transmitted to a mobile terminal or workstation for analysis and processing via a signal transmission component.

[0085] During testing, patch electrodes were applied to the subject's chest wall or standard ECG lead locations (without applying conductive gel or using skin pretreatment solution), while a commercially available Ag / AgCl gel electrode was used as a control electrode. ECG signals from both electrodes were acquired while the subject was at rest. After acquisition, the raw signals underwent baseline correction and filtering, and typical ECG cycles were extracted. The time-domain waveform characteristics of the signals acquired by the two electrodes were compared, including P wave, QRS complex, and T wave morphology, amplitude stability, and baseline drift. Simultaneously, frequency domain analysis was performed on the acquired signals, comparing the spectral peak positions and energy distribution within the 0–5 Hz main ECG energy frequency band.

[0086] Figure 9 A comparison of the physiological signal acquisition performance of a commercial Ag / AgCl gel electrode and the patch electrode prepared in Example 2. Figure 9 It can be seen that the ECG signal acquired by the patch electrode prepared in Example 2 has a stable baseline and can clearly distinguish typical ECG features such as P waves, QRS complexes, and T waves. Its waveform morphology and amplitude characteristics are basically consistent with those of the commercial Ag / AgCl gel electrode. Frequency domain analysis results show that within the main ECG energy frequency band of 0-5Hz, the spectral peak positions and energy distributions of the signals acquired by the two electrodes are highly consistent, indicating that the patch electrode provided by this invention can achieve low-frequency bioelectrical signal acquisition performance comparable to that of the commercial Ag / AgCl electrode. At the same time, when compared with the commercial Ag / AgCl electrode under resting conditions, the time domain waveform of the patch electrode has a stable baseline and a clear P-QRS-T morphology, and the spectral peak positions and energy distributions of the main ECG energy frequency band of 0-5Hz in the frequency domain overlap.

[0087] Example 3 An integrated photothermal stimulation-electrical signal acquisition system was constructed. The photothermal stimulation utilizes… Figure 8 The schematic diagram of the photothermal stimulation process of the patch electrode is shown. The patch electrode and the near-infrared light source are used in a separate structure. The near-infrared light source is a near-infrared LED module with a wavelength of 850nm and a divergence angle of 15°, placed independently of the patch electrode at a distance of 5cm from the skin surface, and aligned with the gel coverage area through a spatial light path. The light power of the near-infrared light source is adjusted by an external driving circuit, with an adjustment range of 50~100mW. During irradiation, a contact temperature sensor is used to monitor the gel surface temperature in real time. The gel surface temperature rise is approximately 2~8℃. The interface temperature is controlled within the range of 37~42℃ through a PID feedback algorithm. This temperature range activates the temperature-sensitive ion channels TRPV3 and TRPV4 expressed in the keratinocytes of the skin, which send signals to adjacent nerve endings through ATP release.

[0088] The patch electrodes are applied to designated areas of the human skin (limb leads RA / LA / LL or forehead Fp1 / FpZ / Fp2), and simultaneously connected to ECG / EEG signal acquisition equipment and a near-infrared light source. Figure 7 and Figure 8 ).

[0089] Perform photothermal stimulation and electrical signal acquisition according to the following workflow: Baseline acquisition: Apply the patch electrodes to the designated skin area and continuously acquire baseline bioelectrical signals for at least 5 minutes. If acquiring electrocardiogram signals, apply the patch electrodes to the right arm, left arm, left leg, or chest wall at positions V2 and V4.

[0090] Photothermal stimulation: A near-infrared light source is activated, and the skin area where the patch electrode is applied is continuously irradiated with a power of 50-100mW for at least 5 minutes. During this period, the patch electrode synchronously and continuously collects bioelectrical signals and records changes in physiological indicators during stimulation. Temperature-time curves are recorded in situ using a contact temperature sensor.

[0091] Recovery period data acquisition: After turning off the near-infrared light source, continue to acquire recovery signals for no less than 5 minutes and record the recovery trajectory of physiological indicators after stimulation.

[0092] State assessment and feedback adjustment: Heart rate variability (HRV) indicators, including the standard deviation of the long axis (SD2) of the Poincaré diagram and the low-frequency / high-frequency power ratio (LF / HF), are extracted from the acquired ECG signals. Alpha band differential entropy (DE) and power spectral density (PSD) are extracted from the EEG signals. Furthermore, the EEG differential entropy features are fused with the ECG heart rate variability features and input into a support vector machine (SVM) model for three-stage state classification. Based on the classification results, the power and irradiation duration of the near-infrared light source are automatically adjusted for the next round of stimulation parameter optimization.

[0093] The performance testing methods and results of the photothermal stimulation-electrical signal acquisition system are as follows: 1. Signal quality and signal-to-noise ratio Comparing the signal quality and signal-to-noise ratio during photothermal stimulation and baseline acquisition, the ECG signal signal-to-noise ratio was approximately 30 dB, comparable to commercial Ag / AgCl electrodes; the EEG signal signal-to-noise ratio was 12–16 dB, indicating that the system provided in Example 3 can resolve weak signals of 10–20 μV; signal acquisition during photothermal stimulation was uninterrupted, without saturation or baseline drift, indicating stable signal quality. The specific mechanism for achieving high signal quality and signal-to-noise ratio is explained below: (1) Photothermal stimulation instead of electrical stimulation: Traditional closed-loop systems use electrical pulse stimulation, and the high voltage (several volts) generated by the stimulation pulse directly saturates the front-end amplifier, causing the acquisition channel to completely fail during stimulation (i.e., the "stimulation artifact" problem). This invention uses near-infrared photothermal stimulation. Near-infrared light acts independently on the skin through a spatial optical path without passing through the electrode-amplifier circuit. Therefore, there is no electrical connection between it and the signal acquisition channel, which fundamentally eliminates electrical crosstalk.

[0094] (2) Verification of the feasibility of synchronous operation: During irradiation with 850nm near-infrared light, the gel electrode can still continuously acquire ECG and EEG signals, and the signal-to-noise ratio remains consistent with the baseline period. This is because the physical mechanism of photothermal stimulation (photon absorption → lattice vibration → heat conduction) is relatively independent of the electrochemical mechanism of electrical signal acquisition (ion migration + charge transfer), which can significantly reduce electrical stimulation artifacts. The two can occur simultaneously in the same physical space without interfering with each other.

[0095] (3) Physiological regulatory effects Photothermal stimulation increased SD2 from 46.4 ms to 70.9 ms and decreased the LF / HF ratio from 2.99 to 1.62, indicating that the system of this invention can detect changes in heart rate variability-related parameters before and after photothermal stimulation. Regarding central nervous system-related indicators, the EEG differential entropy in the alpha band (8–13 Hz) significantly increased, and the power spectral density increased synchronously, indicating that the system of this invention can acquire and distinguish changes in EEG frequency band characteristics before and after photothermal stimulation. In terms of state classification, the multimodal SVM three-class classification model constructed based on EEG differential entropy and ECG heart rate variability characteristics can distinguish between the baseline period, the photothermal stimulation period, and the recovery period, with a classification accuracy of 98.75%. These results demonstrate that the patch electrode can be used for engineering verification of simultaneous physiological electrical signal acquisition, photothermal parameter regulation, and physiological state changes.

[0096] 2. Photothermal response capability The conductive hydrogel of Example 1 was prepared into a lyophilized gel sample. The transmission / reflection of the lyophilized gel sample in the wavelength range of 200~1400nm was measured using a Shimadzu 3600 Plus UV-Vis-NIR spectrophotometer, and the absorption rate was calculated.

[0097] Multiple wavelengths (such as 680nm, 780nm, 850nm, and 980nm) were selected within the range of 680~980nm, and the power was kept constant. The heating curves and equilibrium temperatures at each wavelength were compared.

[0098] Figure 10 The UV-Vis-NIR absorption spectrum of the lyophilized gel sample is obtained from... Figure 10It can be seen that the conductive hydrogel prepared in Example 1 has a light absorption rate of >90% in the range of 200~1400nm and an average absorption rate of >97% in the 780nm near-infrared region.

[0099] Figure 11 The results are from wavelength-independent temperature rise tests. Figure 11 It is known that the photothermal response of the patch electrode is wavelength-independent, exhibiting stability in the 680–980 nm wavelength range. The temperature rise curves at different near-infrared wavelengths (680–980 nm) almost overlap, with equilibrium temperature differences less than 1 °C, facilitating the use of different light sources. The mechanism behind these effects is analyzed as follows: (1) High photon trapping ability of MXene: MXene (Ti3C2Tx) has a metal-like electronic structure and a high extinction coefficient over a wide spectral range. Its two-dimensional sheet-like morphology provides a large light scattering cross section. Incident light is reflected and scattered multiple times between the nanosheets, forming a "light trap" effect, which significantly improves the light absorption efficiency.

[0100] (2) Complementary absorption of PANI: As a conductive polymer, PANI has additional light absorption contribution in the visible-near infrared region. After PANI is compounded with MXene, their absorption spectra are complementary and superimposed, further broadening the effective absorption band.

[0101] (3) Wavelength-independent thermal response: MXene has a continuous band structure, and its light absorption does not depend on electronic transitions at a specific wavelength. Instead, it achieves broadband absorption through intraband transitions and surface plasmon resonances. This characteristic simplifies the selection of light sources and improves the system's light source adaptability and operational flexibility.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A conductive hydrogel, characterized in that, It includes a polymer triple interpenetrating network, and water and ionizable inorganic salts dispersed in the pores of the polymer triple interpenetrating network; The polymers forming the polymer tri-interpenetrating network include polyacrylamide, natural hydrophilic polymers, and polyaniline; The polyaniline is coated on the MXene surface to form a composite MXene-polyaniline; The polyacrylamide and the natural hydrophilic polymer are cross-linked by a cross-linking agent to form a polyacrylamide-natural hydrophilic polymer interpenetrating network. The composite MXene-polyaniline is dispersed in the polyacrylamide-natural hydrophilic polymer interpenetrating network, and the composite MXene-polyaniline is bonded to the polyacrylamide.

2. The conductive hydrogel according to claim 1, characterized in that, The ionizable inorganic salts include one or more of sodium chloride, potassium chloride, and calcium chloride; The crosslinking agent includes N,N'-methylenebisacrylamide; The natural hydrophilic polymer includes one or more of chitosan, sodium alginate, gelatin, carboxymethyl cellulose, and bacterial cellulose; The mass ratio of the polyacrylamide to the natural hydrophilic polymer is 20~35:1; The mass ratio of the polyacrylamide to the ionizable inorganic salt is 15~35:10; The mass ratio of polyacrylamide to polyaniline is 1:0.03~0.04; The mass ratio of polyaniline to MXene is 1:0.03~0.

2.

3. The method for preparing the conductive hydrogel according to claim 1 or 2, characterized in that, Includes the following steps: Aniline, MXene, acid and water were mixed, subjected to interfacial induced polymerization and then resuspended to obtain an MXene-polyaniline composite dispersion; Acrylamide, natural hydrophilic polymer, ionizable inorganic salt, protic acid and water are thermally mixed to obtain a mixed solution; The mixed solution, MXene-polyaniline composite dispersion, crosslinking agent and initiator are mixed and crosslinked and cured to obtain a conductive hydrogel.

4. The preparation method according to claim 3, characterized in that, The interface-induced polymerization temperature is ≤10℃ and the time is ≥12h; The concentration of composite MXene-polyaniline in the MXene-polyaniline composite dispersion is 5~20 mg / mL; The protic acid includes one or more of HCl, acetic acid, phytic acid, and citric acid; The initiator includes ammonium persulfate and / or potassium persulfate; The mass ratio of acrylamide to initiator is 1:0.025~0.05; The cross-linking and curing temperature is 50~60℃.

5. An electrode assembly, characterized in that, It includes an electrical signal lead-out layer and an electrode core stacked in sequence; The electrode core is made of the conductive hydrogel as described in any one of claims 1 to 2 or the conductive hydrogel prepared by the preparation method described in any one of claims 3 to 4.

6. A patch electrode, characterized in that, Includes the tape and the electrode assembly as described in claim 5; The tape has a backing layer and an adhesive layer; the adhesive layer has a central opening, and the electrode assembly is disposed within the central opening of the adhesive layer; The electrode core of the electrode assembly is disposed on the side of the electrical signal lead-out layer away from the backing layer, and the side of the electrode core away from the backing layer is flush with or higher than the adhesive layer.

7. The application of the electrode assembly of claim 5 or the patch electrode of claim 6 in photothermal stimulation and / or electrical signal acquisition for purposes other than disease diagnosis and treatment.

8. A photothermal stimulation-electrical signal acquisition system, characterized in that, Includes patch electrodes, light source, and signal processing components; The patch electrode is communicatively connected to the signal processing component; The patch electrode is the patch electrode as described in claim 6.

9. The photothermal stimulation-electrical signal acquisition system according to claim 8, characterized in that, The light source includes a near-infrared light source; The photothermal stimulation-electric signal acquisition system also includes a temperature monitoring component; The signal processing component includes a signal conditioning component, a signal analysis component, and a signal transmission component connected in sequence.

10. A method for acquiring photothermal stimulation-electrical signals using the photothermal stimulation-electrical signal acquisition system as described in claim 8 or 9, characterized in that, Includes the following steps: Photothermal stimulation: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode is in contact with the skin, and a light source is used to irradiate the skin with the patch electrode attached to perform photothermal stimulation. Electrical signal acquisition: The patch electrode is attached to the skin so that one side of the electrode core in the patch electrode contacts the skin to obtain an electrical signal; the electrical signal is acquired using a signal processing unit.

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