Ultra-stretchable high-sensitivity fatigue-resistant conductive hydrogel and preparation method and application thereof

Abstract

The application discloses a kind of super-drawing high-sensitivity anti-fatigue conductive hydrogel and its preparation method and application, belong to the technical field of hydrogel.The preparation method includes the following steps: (1) MXene material, metal organic framework material, oxidized sodium alginate, hydrophilic monomer and metal ion salt are dispersed in water to obtain precursor solution;(2) add persulfate solution to the precursor solution, after mixing evenly, reaction is carried out, and is prepared.The preparation method of the application is simple and fast, low in cost, can realize large-scale production, by excellent structure design and the introduction of functional materials, give double-network conductive hydrogel various excellent performance, including super tensile property, strong adhesion, fatigue resistance and high conductivity.After further assembly, not only can be used for monitoring human movement, but also can be assembled into conductive patch, real-time monitoring includes electrocardio and myoelectricity in physiological signal, and show more excellent effect than commercial gel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogel preparation, and particularly relates to a super-stretching high-sensitivity anti-fatigue conductive hydrogel, a preparation method and application thereof. BACKGROUND

[0002] In recent years, flexible wearable electronic devices have attracted extensive attention of researchers due to their ability to continuously monitor and record physiological signals of human body, avoiding traditional and tedious long-term health monitoring which requires large-scale instruments. These wearable devices provide key data for some diseases that need long-term monitoring for diagnosis, and further provide convenience for the realization of personalized medicine. More and more researches focus on the development of wearable electronic devices based on flexible substrates, such as strain sensors, electronic skin and soft robots, which can simulate the perception of human skin by converting external stimuli into electrical signals, or directly transduce various weak electrical signals in human body, ultimately realizing real-time monitoring of physiological signals of human body. The core of flexible wearable devices lies in the selection of conductive fillers and matrix materials and the design of their structure. Various flexible substrates combined with conductive fillers, such as conductive polymers, carbon nanotubes, graphene, etc., are developed and introduced into the design and preparation of flexible wearable devices. However, due to the poor compatibility of conductive materials with some flexible substrates and the poor skin-fitting property, such wearable devices have problems of low sensitivity, poor wearing experience and incomplete monitoring signals. Therefore, it is necessary to select appropriate flexible substrates and conductive materials to prepare high-performance wearable electronic devices.

[0003] Hydrogels have become an ideal material for constructing flexible wearable electronic devices due to their unique three-dimensional (3D) network structure, good flexibility, stretchability and biocompatibility. In recent years, significant progress has been made in the preparation of conductive hydrogels, but their mechanical properties, low conductivity and anti-fatigue properties cannot meet the long-term monitoring requirements, and many other unfavorable characteristics seriously hinder their application in constructing high-performance flexible electronic devices. In addition, traditional conductive hydrogels are difficult to simultaneously realize high-sensitivity and low-noise monitoring of full-scale human activities and tiny electrical physiological signals, which also limits their application in the fields of human health monitoring and intelligent medical diagnosis.

[0004] The introduction of various functional materials and network structures in hydrogels provides a potential solution to existing problems in hydrogel design, but these methods usually require complex procedures and long manufacturing times, and often rely on external energy input (such as light, heat or ultrasound). These not only put higher requirements on the relevant equipment and facilities, but also increase the cost and safety problems in the production process. In addition, complex manufacturing processes and long time periods also limit the large-scale production of these multifunctional hydrogels. Therefore, how to simplify the preparation process, reduce energy dependence and production cost has become an important issue in the research of multifunctional hydrogels. One of the current frontiers in the field of conductive hydrogels is to simplify the preparation steps and reduce the dependence on external energy as much as possible while endowing hydrogel materials with excellent mechanical properties, sensing properties and multifunctionalities through rational structural design and the introduction of functional materials. This helps to overcome the application limitations of conductive hydrogels in flexible wearable devices and promotes their application in a wider range of scenarios. SUMMARY

[0005] To solve the above technical problems, the purpose of the present application is to provide a super-stretching high-sensitivity fatigue-resistant conductive hydrogel and its preparation method and application, in order to solve the problem that the existing conductive hydrogel is difficult to maintain the mechanical properties and sensing properties of the hydrogel while simplifying the preparation steps and shortening the gelation time, and the multifunctionality of the conductive hydrogel.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] A preparation method of a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0008] (1) dispersing MXene material, metal framework material, oxidized sodium alginate, hydrophilic monomer and metal ion salt in water to obtain a precursor solution;

[0009] (2) adding a persulfate solution to the precursor solution, mixing uniformly, and then reacting to obtain.

[0010] The present application provides a preparation method of a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, which has the advantages of simple preparation method, fast gelation rate, and the conductive hydrogel has the characteristics of super-stretching, high sensitivity and fatigue resistance, and can be applied to assemble wearable human physiological signal monitoring sensors.

[0011] Further, in step (1), the MXene material is two-dimensional Ti2C3T xMXene nanosheets, 0.1%-0.5% of the total mass of the precursor solution; the metal organic framework material is Fe-MIL-88NH2, 0.002%-0.008% of the total mass of the precursor solution.

[0012] Preferably, the MXene material in step (1) is two-dimensional Ti2C3T x MXene nanosheets, 0.25% of the total mass of the precursor solution; the metal organic framework material is Fe-MIL-88NH2, 0.004% of the total mass of the precursor solution.

[0013] The beneficial effects of the above further technical solutions are: the present application introduces a new two-dimensional MXene material, which has excellent electrical conductivity and rich surface functional groups (-OH, -O, -F, etc.), as a high-performance conductive filler, it can also catalyze the rapid decomposition of persulfate at room temperature with Fe-MIL-88NH2 with peroxidase activity, to generate free radicals. Finally, with the oxidation of sodium alginate and Ca 2+ The two-network structure is formed, and a conductive hydrogel with super-stretching, high sensitivity and fatigue resistance is obtained.

[0014] Further, the hydrophilic monomer is acrylic acid, 10%-30% of the total mass of the precursor solution.

[0015] Preferably, the hydrophilic monomer is acrylic acid, 21% of the total mass of the precursor solution.

[0016] Further, in step (1), the mass ratio of the hydrophilic monomer to the oxidized sodium alginate is 10:1-100:1; the mass ratio of the hydrophilic monomer to the metal ion salt is 2:1-10:1, and the metal ion salt includes at least one of calcium chloride, iron chloride and zirconium chloride.

[0017] Preferably, in step (1), the mass ratio of the hydrophilic monomer to the oxidized sodium alginate is 30:1; the mass ratio of the hydrophilic monomer to the metal ion salt is 5:1, and the metal ion salt is calcium chloride.

[0018] The beneficial effects of the above further technical solutions are: the present application prepares a double-network conductive hydrogel structure by combining a hydrophilic monomer, a functional filler and oxidized sodium alginate, the first network structure of the double-network hydrogel structure is composed of oxidized sodium alginate and metal ions, and the second network structure is composed of a hydrophilic monomer polymer and MXene, Fe-MIL-88NH2 and metal ions. The double-network structure and the rich bonding effects including multiple hydrogen bonds, ionic bonds and coordination bonds in the hydrogel endow the conductive hydrogel with excellent mechanical properties, self-adhesion and conductivity.

[0019] Further, the concentration of the persulfate solution in step (2) is 100-200 mg / mL, the volume ratio of the persulfate solution to the precursor solution is 1:5-1:20, and the persulfate is sodium persulfate.

[0020] Preferably, the concentration of the persulfate solution in step (2) is 120 mg / mL, the volume ratio of the persulfate solution to the precursor solution is 1:10, and the persulfate is sodium persulfate.

[0021] The beneficial effects of the above further technical solutions are that the persulfate is used as an initiator to react with MXene, and a large number of free radicals are generated by using the excellent catalytic property of Fe-MIL-88NH2, so that the hydrophilic monomer is rapidly polymerized to form the main structure of the hydrogel, and the MXene and Fe-MIL-88NH2 have various surface functional groups (-OH, -O and -NH2, etc.), which can replace the traditional crosslinking agent to form a crosslinked network with the polymer chain segment, and then combined with OSA and Ca 2+ The double-network high-toughness hydrogel: polyacrylic acid / MXene / oxidized sodium alginate / Fe-MIL-88NH2 (PAA / MXene / OSA / Fe-MIL-88NH2, abbreviated as PM x OF y wherein x and y are the mass percentages of MXene and Fe-MIL-88NH2 to the mass of the acrylic acid monomer in the precursor solution, respectively.

[0022] Further, the reaction temperature in step (2) is 20-30 DEG C, and the reaction time is 10-900 s.

[0023] The beneficial effects of the above further technical solutions are that the hydrogel can be quickly prepared at room temperature, the preparation method is simple and fast, the cost is low, and large-scale production can be realized.

[0024] An ultra-stretching high-sensitivity anti-fatigue conductive hydrogel is prepared by the above preparation method.

[0025] The above ultra-stretching high-sensitivity anti-fatigue conductive hydrogel is applied to the preparation of a sensor.

[0026] A sensor comprises the above ultra-stretching high-sensitivity anti-fatigue conductive hydrogel.

[0027] The beneficial effects of the present application are that the sensor prepared by using the hydrogel obtained by the present application has excellent sensing performance, and the experimental results show that the hydrogel sensor has high sensitivity and good cycle stability.

[0028] The above sensor is applied to the monitoring of human joint activities and electrophysiological signals.

[0029] The sensor prepared by taking the hydrogel obtained in the application as a raw element can well monitor the strain signal generated when the human body moves, has good reliability for monitoring human movement, and the assembled electrocardio test equipment and electromyography test system can well display electrocardio signals and electromyography signals, compared with commercial gel electrodes, has clearer signals, lower signal-to-noise ratio, and has the ability of real-time monitoring of human electrophysiological signals.

[0030] The application has the following beneficial effects:

[0031] (1) The application combines the reduction property of MXene itself and the peroxide enzyme characteristics of Fe-MIL-88NH2 to construct an efficient catalytic system to catalyze the decomposition of persulfate to generate free radicals, and form a hydrogel within tens of seconds without external energy input. At the same time, MXene also acts as a conductive filler and crosslinking agent in the hydrogel system and participates in the gelation process. Without the need to introduce traditional hydrogel crosslinking agents and external energy sources, a high-performance conductive hydrogel is prepared within tens of seconds, and the preparation method is simple and fast, the cost is low, and large-scale production can be realized.

[0032] (2) The application gives the double-network conductive hydrogel various excellent properties, including super-stretching performance, strong adhesion, fatigue resistance and high conductivity, through excellent structural design and the introduction of functional materials. After further assembly, it can not only be used for monitoring human movement, but also can be assembled into a conductive patch to monitor electrophysiological signals including electrocardio and electromyography in real time, and shows better signals than commercial gels.

[0033] (3) The application can effectively control various properties of the conductive hydrogel, including stretchability, adhesion, conductivity and stability, by controlling the amount of Fe-MIL-88NH2 added in the precursor solution, thereby having the potential to realize personalized customization of flexible wearable devices based on conductive hydrogels. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a schematic diagram and optical photo of the gelation reaction of the PMOF hydrogel in test example 1 and a scanning electron microscope graph of the hydrogel, wherein a is a schematic diagram of the gelation of the hydrogel, b is an optical photo of the gelation process of the hydrogel, and c is a scanning electron microscope photo of different hydrogel samples;

[0035] Figure 2Figures for testing the influence of different proportions of Fe-MIL-88NH2 or MXene on the mechanical properties of PMOF hydrogel in Example 2 and the macroscopic mechanical properties of Example 1, wherein a is the influence of different proportions of Fe-MIL-88NH2 on the tensile properties of PMOF, b is the Young's modulus and breaking stress of the hydrogel obtained from the tensile stress-strain diagram in the a figure, c is the influence of different proportions of Fe-MIL-88NH2 on the compression properties of PMOF, d is the compression modulus and maximum bearing stress of the hydrogel obtained from the compression stress-strain diagram in the c figure, e is the influence of different proportions of MXene on the tensile properties of PMOF, f is the Young's modulus and breaking stress of the hydrogel obtained from the tensile stress-strain diagram in the e figure, and g is the mechanical properties in the macroscopic state, including tensile, kink, knot, expansion, high toughness (bearing 500 g) and compression recovery;

[0036] Figure 3 Figures for testing the adhesion of PMOF hydrogel in Example 3, wherein a is an optical photograph of the adhesion of PMOF hydrogel to various surfaces in the macroscopic state, b is the adhesion strength of PMOF hydrogel to different substrates, and c is a schematic diagram of the adhesion principle of PMOF hydrogel;

[0037] Figure 4 Figures for testing the conductivity of PMOF hydrogel in Example 4 and the sensing performance of the sensor assembled from PMOF, wherein a is the conductivity of the hydrogel with different MXene contents, b is the conductivity of the hydrogel with different Fe-MIL-88NH2 contents, c is the response time of the hydrogel connection and disconnection, d is a diagram of the sensing sensitivity of the sensor assembled from PMOF, e and f are respectively a diagram of the strain frequency response characteristics and a diagram of the strain size response characteristics of the PMOF hydrogel-based sensor, and g is the fatigue resistance of the sensor assembled from PMOF in 1500 cycles of stretching, and the small graphs in the g figure are magnified graphs of the local resistance change rate before and after 400 s, 800 s and 1200 s;

[0038] Figure 5 Figures for testing the relative resistance change of PMOF hydrogel for real-time monitoring of human joint activity in Example 5, wherein a is a schematic diagram of the monitoring process, b is a diagram of the relative resistance change signal generated by finger movement, c is a diagram of the relative resistance change signal generated by wrist movement, d is a diagram of the relative resistance change signal generated by elbow movement, e is a diagram of the relative resistance change generated by facial smiling, and f is a diagram of the resistance signal change when saying "MXene" is monitored in the throat;

[0039] Figure 6Signal diagrams of the electrophysiological signal sensor assembled with the PMOF hydrogel electrode in Experimental Example 6 for monitoring human electrophysiological signals, wherein a is an electrocardiogram signal diagram recorded by the PMOF electrode and a commercial electrode, b is a muscle electrical signal diagram of the biceps brachii muscle recorded by the PMOF electrode and a commercial electrode, c is a muscle electrical signal diagram of the brachioradialis muscle recorded by the PMOF electrode under different forces, and d is a muscle electrical signal diagram of the brachioradialis muscle recorded by the PMOF electrode under different gestures. DETAILED DESCRIPTION

[0040] The principles and features of the present application are described below in conjunction with the accompanying drawings, which are only used to explain the present application and are not intended to limit the scope of the present application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is specified, it is a conventional product that can be purchased on the market.

[0041] Example 1:

[0042] A preparation method of a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0043] (1) Synthesis of two-dimensional Ti2C3T MXene nanosheets x Synthesis of MXene nanosheets

[0044] Ti2C3T MXene nanosheets were synthesized by specific etching of Ti2AlC3 MAX phase using the minimum layer strength peeling method (MILD) x MXene, the process is as follows: 1 g of LiF is dispersed in 20 mL of concentrated hydrochloric acid solution (9 mol / L), and the reaction is carried out at 35°C for 24 h, and then the Al atomic layer of the Ti2AlC3 MAX material is specifically etched by the generated HF, and then Ti2C3T is obtained after further ultrasonic and centrifugal treatment x MXene solution, and finally freeze-dried to obtain sheet-shaped Ti2C3T with metallic luster x MXene, and stored at 4°C after sealing for standby use.

[0045] (2) Synthesis of metal-organic framework material (MOFs) Fe-MIL-88NH2 with octahedral structure

[0046] Fe-MIL-88NH2 was synthesized by solvothermal method. The specific process is as follows: 0.2507 g of NH2-BDC (1.3838 mmol) and 0.3743 g of FeCl3·6H2O (1.3838 mmol) are dissolved in 30 mL of DMF, and after stirring, the reaction is carried out at 120°C for 12 h, and then washed and dried at 40°C under vacuum to obtain the product, which is stored in a sealed container in the dark for standby use.

[0047] (3) Synthesis of oxidized sodium alginate

[0048] Oxidized sodium alginate with specific oxidation degree was obtained by sodium periodate oxidation. The detailed process was as follows: 1 g of sodium alginate was dissolved in deionized water to form a 1 wt.% sodium alginate solution, 1.08 g of NaIO4 was added and stirred in the dark for 4 h. Then 1.5 mL of ethylene glycol was added to quench the reaction, and then the solution was collected and dialyzed in deionized water for three days (maximum molecular weight cut-off 3500). The dialyzed solution was collected and freeze-dried to obtain a sponge-like oxidized sodium alginate.

[0049] (4) 3 g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, and the above percentage contents were all the mass percentage of the added substances in acrylic acid. After vortex, stirring and ultrasonic, they were uniformly dispersed in 4 mL of deionized water; and 5 mL of 6.0 mg / mL Ti2C3T x MXene dispersion liquid was mixed, stirred and ultrasonically uniformly to obtain a hydrogel precursor solution.

[0050] (5) 1 mL of 120 mg / mL sodium persulfate solution was added to the hydrogel precursor solution obtained in step (4), and after rapid mixing and uniformity, it was poured into a mold, and after waiting for several tens of seconds, a super-stretching, high-sensitivity and fatigue-resistant conductive hydrogel PM1OF 0.015 .

[0051] Example 2:

[0052] A preparation method of a super-stretching, high-sensitivity and fatigue-resistant conductive hydrogel, comprising the following steps:

[0053] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0054] The same as example 1.

[0055] (2) Synthesis of metal-organic framework (MOFs) Fe-MIL-88NH2 with octahedral structure

[0056] The same as example 1.

[0057] (3) Synthesis of oxidized sodium alginate

[0058] The same as example 1.

[0059] (4) 3 g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.010% of Fe-MIL-88NH2 were weighed respectively, and the above percentage contents were all the mass percentage of the added substances in acrylic acid. After vortex, stirring and ultrasonic, they were uniformly dispersed in 4 mL of deionized water; and 5 mL of 6.0 mg / mL Ti2C3Tx MXene dispersion liquid is mixed, stirred and ultrasonically treated to be uniform, to obtain a hydrogel precursor solution.

[0060] (5) 1 mL of 120 mg / mL sodium persulfate solution is added to the hydrogel precursor solution obtained in step (4), and after rapid mixing and uniformity, the mixture is poured into a mold, and after waiting for tens of seconds, a conductive hydrogel PM1OF is prepared. 0.01 .

[0061] Example 3:

[0062] A method for preparing a super-stretching, high-sensitivity and fatigue-resistant conductive hydrogel includes the following steps:

[0063] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0064] The same as example 1.

[0065] (2) Synthesis of metal-organic framework material (MOFs) Fe-MIL-88NH2 with octahedral structure

[0066] The same as example 1.

[0067] (3) Synthesis of oxidized sodium alginate

[0068] The same as example 1.

[0069] (4) 3 g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.0200% of Fe-MIL-88NH2 are weighed, respectively, and the above percentage content is the mass percentage of the added substance in acrylic acid, which is uniformly dispersed in 4 mL of deionized water after vortex, stirring and ultrasonic treatment; 5 mL of 6.0 mg / mL Ti2C3T x MXene dispersion liquid is mixed, stirred and ultrasonically treated to be uniform, to obtain a hydrogel precursor solution.

[0070] (5) 1 mL of 120 mg / mL sodium persulfate solution is added to the hydrogel precursor solution obtained in step (4), and after rapid mixing and uniformity, the mixture is poured into a mold, and after waiting for tens of seconds, a conductive hydrogel PM1OF is prepared. 0.02 .

[0071] Example 4:

[0072] A method for preparing a super-stretching, high-sensitivity and fatigue-resistant conductive hydrogel includes the following steps:

[0073] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0074] The same as example 1.

[0075] (2) Synthesis of metal-organic framework (MOFs) Fe-MIL-88NH2 with octahedral structure

[0076] The same as Example 1.

[0077] (3) Synthesis of oxidized sodium alginate

[0078] The same as Example 1.

[0079] (4) 3g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.030% of Fe-MIL-88NH2 were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water after vortex, stirring and ultrasonic treatment; mixed with 5mL of 6.0mg / mL Ti2C3T x MXene dispersion solution, stirred and uniformly ultrasonicated to obtain a hydrogel precursor solution.

[0080] (5) 1mL of 120mg / mL sodium persulfate solution was added to the hydrogel precursor solution obtained in step (4), quickly mixed uniformly and then poured into a mold, and a conductive hydrogel PM1OF 0.03 was prepared after waiting for several tens of seconds.

[0081] Example 5:

[0082] A preparation method of a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0083] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0084] The same as Example 1.

[0085] (2) Synthesis of metal-organic framework (MOFs) Fe-MIL-88NH2 with octahedral structure

[0086] The same as Example 1.

[0087] (3) Synthesis of oxidized sodium alginate

[0088] The same as Example 1.

[0089] (4) 3g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water after vortex, stirring and ultrasonic treatment; mixed with 5mL of 3.0mg / mL Ti2C3T x MXene dispersion solution, stirred and uniformly ultrasonicated to obtain a hydrogel precursor solution.

[0090] (5) To the hydrogel precursor solution obtained in step (4), 1 mL of 120 mg / mL sodium persulfate solution was added, and after rapid mixing, it was poured into a mold. After waiting for tens of seconds, the gel was prepared into a conductive hydrogel PM 0.5 OF 0.015 .

[0091] Example 6:

[0092] A method for preparing a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0093] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0094] The same as example 1.

[0095] (2) Synthesis of metal-organic framework material (MOFs) Fe-MIL-88NH2 with octahedral structure

[0096] The same as example 1.

[0097] (3) Synthesis of oxidized sodium alginate

[0098] The same as example 1.

[0099] (4) 3g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, and the above percentage content was the mass percentage of the added substance in acrylic acid. After vortex, stirring and ultrasonic, they were uniformly dispersed in 4 mL of deionized water; and 5 mL of 9.0 mg / mL Ti2C3T x MXene dispersion liquid was mixed, stirred and ultrasonically dispersed to obtain a hydrogel precursor solution.

[0100] (5) To the hydrogel precursor solution obtained in step (4), 1 mL of 120 mg / mL sodium persulfate solution was added, and after rapid mixing, it was poured into a mold. After waiting for tens of seconds, the gel was prepared into a conductive hydrogel PM 1.5 OF 0.015 .

[0101] Example 7:

[0102] A method for preparing a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0103] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0104] The same as example 1.

[0105] (2) Synthesis of metal-organic framework (MOFs) Fe-MIL-88NH2 with octahedral structure

[0106] The same as Example 1.

[0107] (3) Synthesis of oxidized sodium alginate

[0108] The same as Example 1.

[0109] (4) 3g of acrylic acid, 3.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water by vortex, stirring and ultrasonic treatment; mixed with 5mL of 12.0mg / mL Ti2C3T x MXene dispersion solution, stirred and uniformly ultrasonicated to obtain a hydrogel precursor solution.

[0110] (5) 1mL of 120mg / mL sodium persulfate solution was added to the hydrogel precursor solution obtained in step (4), and after rapid mixing and uniformity, it was poured into a mold, and after waiting for several tens of seconds, a conductive hydrogel PM2OF 0.015 was prepared.

[0111] Comparative Example 1:

[0112] A preparation method of a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0113] (1) Synthesis of two-dimensional Ti2C3T x MXene nanosheet

[0114] The same as Example 1.

[0115] (2) Synthesis of oxidized sodium alginate

[0116] The same as Example 1.

[0117] (3) 3g of acrylic acid, 3.0% of oxidized sodium alginate and 20% of calcium chloride were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water by vortex, stirring and ultrasonic treatment; mixed with 5mL of 6.0mg / mL Ti2C3T x MXene dispersion solution, stirred and uniformly ultrasonicated to obtain a hydrogel precursor solution.

[0118] (4) 1mL of 120mg / mL sodium persulfate solution was added to the hydrogel precursor solution obtained in step (3), and after rapid mixing and uniformity, it was poured into a mold, and after waiting for several minutes, a conductive hydrogel PM1OF 0.00 , abbreviated as PMO hydrogel.

[0119] Comparative Example 2:

[0120] A preparation method of the super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0121] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0122] The same as Example 1.

[0123] (2) Synthesis of oxidized sodium alginate

[0124] The same as Example 1.

[0125] (3) 3g of acrylic acid, 1.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water after vortex, stirring and ultrasonic treatment; and 5mL of 6.0mg / mL Ti2C3T x MXene dispersion liquid was mixed, stirred and ultrasonically treated uniformly to obtain a hydrogel precursor solution.

[0126] (4) 1mL of 120mg / mL sodium persulfate solution was added to the hydrogel precursor solution obtained in step (3), and after rapid mixing and uniformity, it was poured into a mold, and after waiting for several tens of seconds, a conductive hydrogel was prepared.

[0127] Comparative Example 3:

[0128] A preparation method of the super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0129] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0130] The same as Example 1.

[0131] (2) Synthesis of oxidized sodium alginate

[0132] The same as Example 1.

[0133] (3) 3g of acrylic acid, 5.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, the above percentage contents were all mass percentages of the added substances in acrylic acid, and were uniformly dispersed in 4mL of deionized water after vortex, stirring and ultrasonic treatment; and 5mL of 6.0mg / mL Ti2C3T x MXene dispersion liquid was mixed, stirred and ultrasonically treated uniformly to obtain a hydrogel precursor solution.

[0134] (4) To the hydrogel precursor solution obtained in step (3), 1 mL of 120 mg / mL sodium persulfate solution was added, and after rapid mixing, it was poured into the mold, and after waiting for tens of seconds, the gel was prepared into a conductive hydrogel.

[0135] Comparative Example 4:

[0136] A method for preparing a super-stretching high-sensitivity fatigue-resistant conductive hydrogel, comprising the following steps:

[0137] (1) Two-dimensional Ti2C3T x Synthesis of MXene nanosheets

[0138] The same as Example 1.

[0139] (2) Synthesis of oxidized sodium alginate

[0140] The same as Example 1.

[0141] (3) 3 g of acrylic acid, 7.0% of oxidized sodium alginate, 20% of calcium chloride and 0.015% of Fe-MIL-88NH2 were weighed respectively, and the above percentage content was the mass percentage of the added substance in acrylic acid. After vortex, stirring and ultrasonic, they were uniformly dispersed in 4 mL of deionized water; and 5 mL of 6.0 mg / mL Ti2C3T x MXene dispersion liquid was mixed, stirred and ultrasonically dispersed to obtain a hydrogel precursor solution.

[0142] (4) To the hydrogel precursor solution obtained in step (3), 1 mL of 120 mg / mL sodium persulfate solution was added, and after rapid mixing, it was poured into the mold, and after waiting for tens of seconds, the gel was prepared into a conductive hydrogel.

[0143] Test Example 1: Hydrogel gelation process and surface morphology

[0144] The gelation process of PMOF hydrogel was drawn, and the optical photo of the gelation process was taken. The scanning electron microscope (SEM) was used to characterize the influence of different Fe-MIL-88NH2 addition amounts (Examples 1-4 and Comparative Example 1) on the micro-morphology of PM1O y F hydrogel.

[0145] The experimental results are shown in Figure 1 .

[0146] As shown in Figure 1 Fig. a and Fig. b, the PMOF hydrogel can form a complete hydrogel structure at room temperature in about 50 s. As shown in Figure 1As shown in Figure c, the hydrogel prepared in Comparative Example 1 without Fe-MIL-88NH2 exhibits a dense structure. With increasing amounts of Fe-MIL-88NH2, the internal structure of the PMOF hydrogel gradually changes from dense to more loose, with an increase in the number and size of pores. This is because the initial amount of Fe-MIL-88NH2 is relatively small, resulting in a slow precursor gelation process and more complete cross-linking. Simultaneously, the highly efficient catalytic system of MXene / Fe-MIL-88NH2 triggers the rapid decomposition of persulfate and the generation of oxygen, further promoting the formation of pores within the PMOF hydrogel.

[0147] Test Example 2: Mechanical Properties

[0148] The effects of different amounts of Fe-MIL-88NH2 (Examples 1-4 and Comparative Example 1) and different amounts of MXene (Examples 1 and Examples 8-10) on the mechanical properties of PMOF hydrogels, including tensile and compressive properties, were characterized using a universal testing machine. The changes in Young's modulus and fracture stress were calculated. Macroscopic mechanical properties of the PMOF hydrogels were photographed.

[0149] Experimental results are as follows Figure 2 As shown.

[0150] like Figure 2 As shown in Figure a, the mechanical properties of the hydrogel changed significantly as the structure evolved from the dense, non-porous structure of Comparative Example 1 to the porous structures of Examples 1-4. The increase in the number and size of pores provided energy dissipation structures within the hydrogel, further improving tensile strength and elongation at break. However, as the structure became increasingly porous, the mechanical properties decreased, with fracture stress and strain showing a trend of first increasing and then decreasing. Fracture strain and stress decreased from PM1OF... 0.00 The 1215% and 76kPa increase to PM1OF 0.015 The hydrogel exhibited a fracture strain of 2200% and a stress of 110 kPa, which subsequently decreased to PM1OF. 0.03 The overall mechanical properties initially increased and then decreased, reaching 1455% and 63.5 kPa. Simultaneously, the addition of Fe-MIL-88NH2 also altered the compressibility of the PMOF hydrogel, such as... Figure 2 As shown in Figure b, under a fixed compressive strain of 65%, the maximum stress of PMOF hydrogels with different Fe-MIL-88NH2 contents gradually decreases, from 155 kPa for PMO hydrogels to PM1OF. 0.03 The hydrogel's strength of 13 kPa indicates that the PMOF hydrogel gradually softens with increasing Fe-MIL-88NH2 content. Further investigation was conducted into the effect of MXene content on the mechanical properties of the PMOF hydrogel, such as... Figure 2As shown in e and f, with the increase of MXene content, the Young's modulus of the PMOF hydrogel gradually increases from 5.46 kPa to 12.22 kPa with the increase of crosslinking degree, while the fracture stress shows an increasing trend followed by a decreasing trend. This is also related to the degree of crosslinking within the hydrogel. The degree of crosslinking is directly proportional to the MXene content, while excessive crosslinking will reduce the toughness of the hydrogel, leading to premature fracture. Based on the obtained mechanical property data, PM1OF was selected. 0.015 Further macroscopic mechanical studies, such as Figure 2 As shown in the middle g figure, the results indicate that PM1OF 0.015 It possesses excellent mechanical properties, can maintain its shape under various external forces, can lift a 500g weight without breaking, and can recover its original shape after being compressed by 500g, exhibiting high tensile strength, high toughness and excellent recovery performance.

[0151] Experimental Example 3: Self-adhesion

[0152] The adhesion properties of PMOF hydrogel were tested by sandwiching it between various materials and applying tensile force. Specifically, the hydrogel and the test object were cut into rectangles with a length, width, and thickness of 30 mm, 20 mm, and 3 mm, respectively. After applying a fixing force to make the material sandwich the PMOF hydrogel, the objects were mounted on a universal testing machine, and tensile force was applied to both sides. The adhesion force was recorded, and the adhesion strength was obtained by combining the contact area between the material and the substrate. The self-adhesion force of the samples prepared in Examples 1-4 and Comparative Example 1 was tested.

[0153] Experimental results are as follows Figure 3 As shown.

[0154] like Figure 3 As shown in Figure a, the PMOF hydrogel exhibits strong adhesion to various surfaces, such as polypropylene, glass, polytetrafluoroethylene, metal, paper, and wood chips, demonstrating multi-surface adhesion. The adhesion strength is sufficient to lift a 200g weight. Despite its high viscosity, it leaves no residue after removal from the skin, indicating high practicality. With increasing Fe-MIL-88NH2 content, the number and size of pores in the hydrogel structure increase, further increasing the contact area between the hydrogel and the substrate surface, thus increasing the adhesion strength of the PMOF hydrogel. Figure 3Fig. 2b, PMO hydrogel showed certain adhesion to different substrates, but the adhesion strength was low and easy to separate. With the increase of Fe-MIL-88NH2content in the hydrogel, PMOF hydrogel showed enhanced adhesion, and the adhesion increased with the increase of the amount of Fe-MIL-88NH2. The maximum adhesion strength of PMOF hydrogel to wood, paperboard, metal and pigskin was 18.24 kPa, 24.24 kPa, 8.4 kPa and 9.6 kPa respectively, indicating that PMOF hydrogel had good adhesion and potential adhesion strength adjustability. For example, Figure 3 Fig. 2c, a schematic diagram of the adhesion principle of PMOF hydrogel was drawn. The various functional groups inside the hydrogel could interact with the specific groups on the surface of the substrate, producing various bonding effects such as hydrogen bonds, coordination bonds, etc., giving the material excellent adhesion. With the increase of the amount of Fe-MIL-88NH2, the increase of the pore structure on the surface of the hydrogel improved the contact area between the hydrogel and the substrate, resulting in the increase of the free carboxyl, aldehyde and hydroxyl groups participating in the adhesion interaction, and further leading to the increase of the adhesion strength.

[0155] Test Example 4: Electrochemical performance and sensing performance

[0156] The conductivity of PMOF hydrogel was tested by using a digital bridge (LCR), and a strain sensor was assembled to test the corresponding resistance change under the application of tension. The sensitivity was calculated by the resistance change rate (AR / R0) of the sensor during stretching and the strain change ε, where R and R0 represent the real-time resistance and the initial resistance, respectively, and the linearity was obtained by linear fitting; the cycle stability was tested by recording the relative resistance change rate of the strain sensor under 60% strain after 1500 continuous cycles, and the cycle and resistance change rate waveform diagram was obtained. The hydrogels prepared in Examples 1-4 and Examples 8-10 were characterized.

[0157] The experimental results are shown in Figure 4 As the amount of MXene and Fe-MIL-88NH2increased, the conductivity of the hydrogel increased, as shown in Figure 4 Fig. 2a, as the amount of MXene increased, the conductivity of the hydrogel increased from 3.24 S / m of PM 0.5 OF 0.015 to 3.79 S / m of PM2OF 0.015 , and as the amount of Fe-MIL-88NH2increased, the conductivity of the hydrogel increased from 2.8 S / m of PMO to 3.92 S / m of PM1OF 0.03 , proving that PMOF hydrogel had excellent conductivity, and the electrical self-healing of PMOF hydrogel was tested by using an electrochemical workstation (Gamry Reference 600) when the hydrogel was disconnected and connected, andFigure 4 c, the PMOF hydrogel in the circuit cut off after re-contacting only 40 ms can resume access, to prove the excellent electrical self-healing of the hydrogel. The present application is further verified by experiment, the PM1OF 0.015 The sensitivity of the flexible strain sensor (defined as the percentage of the ratio of the relative change rate of resistance to strain) can remain good linearity in the large strain range of 0-1000%, as shown in Figure 4 The middle d graph, the three linear regions 0%-300%, 300%-700% and 700%-1000% sensitivity are 3.03, 6.53 and 9.51 respectively. Further verify the strain frequency response and strain size response of PMOF hydrogel, as shown in Figure 4 e and f, the results show that PMOF hydrogel can make specific and repeatable response to different frequency of strain and different size of strain, which proves that the hydrogel has the performance of identifying various strains, and can be further assembled into wearable sensors to identify the strain signals generated by various behaviors of human body such as joint activities, expressions and sound making. At the same time, the sensor has good stability, as shown in Figure 4 The middle g graph, after 1500 times of 60% strain range of stretching cycle, the output signal remains stable. It shows that PM1OF 0.015 The hydrogel sensor has high sensitivity and good cycle stability, and can be well used for long-term detection of various behaviors of human body.

[0158] Test example 5: application of hydrogel in strain sensor

[0159] The hydrogel PM1OF prepared in example 1 0.015 Assembled into a strain sensor with LCR instrument, and attached to the target area of the body, including fingers, wrists and elbows, the relative resistance change rate of the strain sensor during joint movement was recorded, and the relative resistance change was further calculated.

[0160] The experimental results are shown in Figure 5 .

[0161] PM1OF 0.015 First as a strain sensor for human motion detection, the measurement schematic diagram is shown in Figure 5 The middle a graph, the resistance signal caused by the periodic bending and recovery movement of joints such as fingers, wrists and elbows was monitored, and significant repeatable signal was obtained, and the signals obtained by different movement amplitudes were different, for example, the relative resistance change rate caused by the bending of fingers was about 60%, and the relative resistance change caused by the bending of elbow was about 175%, as shown in Figure 5As shown in Figures b-d, the results demonstrate that the hydrogel prepared in this invention possesses the ability to record and identify different joint movements in human motion monitoring, and exhibits good reliability. Furthermore, this strain sensor can also be used to monitor minute strain signals such as facial expressions and sounds, including changes in resistance caused by smiling or saying the word "MXene." Figure 5 EF diagram.

[0162] Experimental Example 6: Application of Hydrogels in Electrocardiogram Testing Systems

[0163] The hydrogel PM1OF prepared using the examples 0.015 When combined with an ECG testing chip (BMD101, Wuxi Borunyin), it forms an ECG testing device. The signal is transmitted to a computer (PC) via a Bluetooth adapter to display the subject's real-time heart rate. Simultaneously, when combined with a dual-channel electromyography (EMG) testing device (Wuxi Borunyin), it forms a human EMG testing system to test the electrical signals generated by the muscles in the human body.

[0164] Experimental results are as follows Figure 6 As shown.

[0165] The results show that the hydrogel PM1OF prepared in this invention... 0.015 The ECG signals measured by the electrodes are comparable to those of commercial gel electrodes (Hangzhou Xunda Radio Equipment Co., Ltd.), and the signals are clearer, with the P, Q, R, S, and T peaks clearly visible (e.g., Figure 6 (As shown in Figure a). The assembled electromyography (EMG) testing system can display the EMG signals of the test volunteers in real time, such as... Figure 6 Image b in the middle, and PM1OF 0.015 The signal obtained in the test has a lower signal-to-noise ratio (PM1OF) compared to commercial gel electrodes. 0.015 Gel: 11.40 dB, commercial gel: 5.18 dB). Meanwhile, as... Figure 6 Figures c-d show that this electromyography (EMG) testing device can record and differentiate EMG signals generated by different force outputs and hand gestures. This demonstrates that PMOF conductive hydrogel has the ability to assemble wearable devices for real-time monitoring of human electrophysiological signals.

[0166] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a super- stretchable, high- sensitivity, fatigue- resistant, electrically conductive hydrogel, characterized by, The method comprises the following steps: (1) dispersing MXene material, metal organic framework material, oxidized sodium alginate, hydrophilic monomer and metal ion salt in water to obtain a precursor solution; (2) adding a persulfate solution to the precursor solution, mixing uniformly, and then reacting to obtain a product; The MXene material in the step (1) is two-dimensional Ti2C3T x MXene nanosheets, 0.1%-0.4% of the total mass of the precursor solution; metal organic framework material is Fe-MIL-88NH2, 0.0025%-0.0075% of the total mass of the precursor solution; In step (1), the hydrophilic monomer is acrylic acid, and the mass of the hydrophilic monomer is 20%-30% of the total mass of the precursor solution.

2. The process for the preparation of ultra-stretched, highly sensitive, fatigue resistant, electrically conductive hydrogel according to claim 1, characterized in that, In step (1), the mass ratio of the hydrophilic monomer to the oxidized sodium alginate is 15:1-100:1, and the mass ratio of the hydrophilic monomer to the metal ion salt is 4:1-10:1, wherein the metal ion salt includes at least one of calcium chloride, iron chloride and zirconium chloride.

3. The process for the preparation of ultra-stretched, highly sensitive, fatigue resistant, electrically conductive hydrogel according to claim 1, characterized in that, In step (2), the concentration of the persulfate solution is 100-200 mg / mL, the volume ratio of the persulfate solution to the precursor solution is 1:5-1:20, and the persulfate is sodium persulfate.

4. The process for the preparation of ultra-stretched, highly sensitive, fatigue resistant, electrically conductive hydrogel according to claim 1, characterized in that, In step (2), the reaction temperature is 20-30 ℃, and the reaction time is 10-900 s.

5. A super- stretchable, high-sensitivity, fatigue-resistant, electrically conductive hydrogel, characterized in that, The product is prepared by the method of any one of claims 1-4.

6. Use of the ultra-stretchable, high-sensitivity and fatigue-resistant conductive hydrogel of claim 5 in the preparation of a sensor.

7. A sensor, characterized by The sensor comprises the ultra-stretchable, high-sensitivity and fatigue-resistant conductive hydrogel of claim 6.

8. Use of the sensor of claim 7 in the identification and monitoring of human joint activities, facial micro-expressions, sounds and electrophysiological signals for non-disease diagnosis purposes.

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