A multifunctional conductive eutectic gel based on N-isopropylacrylamide and its preparation method and application

Abstract

This invention belongs to the field of intelligent soft materials and discloses a multifunctional conductive eutectic gel based on N-isopropylacrylamide, its preparation method, and applications. The multifunctional conductive eutectic gel comprises a eutectic solvent, a polymer monomer, PDA@Ag, a crosslinker, an initiator, and water. Strain sensing tests have demonstrated that the gel exhibits excellent strain sensing performance, making it suitable for monitoring movement of different parts of the human body and personal health. Furthermore, the gel exhibits a liquid crystal transition (LCST), enabling transparency switching at temperatures above and below the LCST, broadening its application in anti-counterfeiting applications.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent soft materials, and in particular relates to a multifunctional conductive eutectic gel based on N-isopropylacrylamide, and a preparation method and application thereof. Background Art

[0002] Hydrogels are porous materials with high water content and three-dimensional networks. They are formed by physical or chemical crosslinking of hydrophilic natural or synthetic polymers. The flexibility and tunable elastic modulus of hydrogels reduce mechanical mismatch with biological tissues, making them promising materials for the preparation of sensors. Conductive hydrogels have attracted widespread attention in the field of flexible electronics due to their excellent biocompatibility, suitable Young's modulus and outstanding conductivity. However, the inherent water-rich nature and insufficient interfacial adhesion of hydrogels hinder the stability and reliability of hydrogel-based devices in complex environments. Therefore, solving the problems of hydrogels' easy water loss and insufficient interfacial adhesion will help promote the application of conductive hydrogels in flexible sensor devices. Summary of the Invention

[0003] In order to overcome the shortcomings and deficiencies in the above-mentioned prior art, the primary purpose of the present invention is to provide a method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide; this method constructs a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel through reasonable molecular design, wherein the polymer monomers (AA and SBMA) can improve the adhesion performance, PDA@Ag can improve the photothermal conversion efficiency, photothermal conversion capacity and adhesion performance of the gel system, and the deep eutectic solvent can improve the antifreeze and water retention properties and sensing performance of the hydrogel; the polymer monomer NIPAM also gives the gel LCST, which can achieve the switching of the gel between transparency and opacity, so that the hydrogel can not only monitor human movement through strain sensing, but also has the anti-counterfeiting ability of transparency switching.

[0004] Another object of the present invention is to provide a multifunctional conductive eutectic gel based on N-isopropylacrylamide prepared by the above preparation method.

[0005] Another object of the present invention is to provide an application of the multifunctional conductive eutectic gel based on N-isopropylacrylamide.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide comprises the following steps:

[0008] (1) dopamine hydrochloride, ammonium persulfate, anhydrous ethanol and pure water are prepared into a dopamine hydrochloride ethanol / water mixed solution by a solution oxidation method, the pH value of the dopamine hydrochloride ethanol / water mixed solution is adjusted with an alkali solution, and the mixture is stirred to react, and the dopamine hydrochloride is oxidized and self-polymerized to form polydopamine nanoparticles, which are centrifugally washed with a detergent and freeze-dried to obtain polydopamine freeze-dried powder; the polydopamine freeze-dried powder is then prepared into a polydopamine dispersion; silver nitrate, pure water, ammonia water and the above polydopamine dispersion are then mixed, stirred to react, and PDA@Ag nanoparticles are formed, which are centrifugally washed with a detergent and freeze-dried to obtain PDA@Ag freeze-dried powder;

[0009] (2) According to the molar ratio of ethylene glycol (EG) to the conductive agent being 4:1, the conductive agent was added to ethylene glycol (EG), and the mixture was stirred in a hot water bath until dissolved to prepare a eutectic solvent;

[0010] (3) Using a one-pot mixing method, the PDA@Ag freeze-dried powder obtained in step (1), polymer monomer, cross-linking agent, initiator and pure water are added to the eutectic solvent obtained in step (2), and the mixture is evenly mixed to obtain a prepolymer solution; the prepolymer solution is filled into a mold, and ultraviolet light is irradiated to induce polymerization to obtain a multifunctional conductive eutectic gel based on N-isopropylacrylamide.

[0011] The pH value of step (1) is adjusted to 9-12; the temperature of the stirring reaction is 20-40°C, the reaction time is 12-36h, and the stirring speed is 300-800rpm.

[0012] The molar ratio of dopamine hydrochloride to ammonium persulfate in step (1) is 2:1; the volume ratio of anhydrous ethanol to pure water is 2:7; and the total amount of dopamine hydrochloride and ammonium persulfate is 0.85 wt % of the dopamine hydrochloride ethanol / water mixed solution.

[0013] The alkali solution in step (1) is ammonia water, sodium hydroxide solution, potassium hydroxide solution or sodium bicarbonate solution; and the detergent is pure water and anhydrous ethanol.

[0014] The temperature of the hot water bath in step (2) is 70-75°C.

[0015] The polymer monomers in step (3) are N-isopropylacrylamide (NIPAM), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (SBMA) and acrylic acid (AA); the conductive agent is one of lithium chloride, zinc chloride, magnesium chloride, ferric chloride and aluminum chloride; the cross-linking agent is N,N'-methylenebisacrylamide, bisacrylamide, polyethylene glycol diacrylate or polyethylene glycol dimethacrylate; and the initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0016] In step (3), the amount of PDA@Ag used is 0.075-0.102wt% of the multifunctional conductive eutectic gel; the amount of the polymer monomer used is 29-39wt% of the multifunctional conductive eutectic gel; the amount of the deep eutectic solvent used is 16.95-37.99% of the multifunctional conductive eutectic gel; the amount of the crosslinker used is 0.192-0.258wt% of the multifunctional conductive eutectic gel; the amount of the initiator used is 1.2-1.6wt% of the multifunctional conductive eutectic gel; and the ultraviolet light induced polymerization is irradiated under a 36W ultraviolet light source for 30 minutes.

[0017] The mold in step (3) is a sandwich structure constructed of glass sheets; the thickness of the multifunctional conductive eutectic gel obtained by filling the prepolymer into the mold is controlled by controlling the distance between the upper and lower glass sheets of the sandwich structure.

[0018] A multifunctional conductive eutectic gel based on N-isopropylacrylamide prepared by the above-mentioned preparation method is characterized in that: the multifunctional conductive eutectic gel monitors human body movement through changes in electrical signal peak value and peak shape, and realizes on-demand switching between transparency and opacity through reversible switching of near-infrared.

[0019] The above-mentioned multifunctional conductive eutectic gel based on N-isopropylacrylamide is used in sensors and anti-counterfeiting layers.

[0020] The above-mentioned multifunctional conductive eutectic gel based on N-isopropylacrylamide can be used in flexible wearable devices, human-computer interaction or medical health monitoring by monitoring human movement.

[0021] The present invention has the following advantages and beneficial effects compared to the prior art:

[0022] (1) The multifunctional conductive eutectic gel based on N-isopropylacrylamide of the present invention not only has excellent photothermal conversion ability and excellent strain sensing performance, but also has significant transparency switching ability, so it can be used not only in the field of flexible sensor devices, but also in the field of anti-counterfeiting.

[0023] (2) The multifunctional conductive eutectic gel based on N-isopropylacrylamide prepared by the present invention is used in the fields of anti-counterfeiting and sensing, and has the functions of transparency switching and human motion detection; its excellent strain sensing performance can be used to monitor human motion and personal health; in addition, its excellent photothermal performance and transparency switching ability in response to temperature make it useful in the field of anti-counterfeiting, greatly broadening its scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1The infrared spectra of polymer monomers NIPAM, SBMA, AA, and PSBMA / PNIPAM / PAA / PDA@Ag conductive gel;

[0025] Figure 2 The tensile strength at break curves of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gels with different eutectic solvent contents;

[0026] Figure 3 The adhesion strength of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel on different substrates;

[0027] Figure 4 Strain sensing sensitivity curve of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel;

[0028] Figure 5 Cyclic test of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel under different tensile strains and different tensile frequencies;

[0029] Figure 6 This is the photothermal heating curve of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel;

[0030] Figure 7 Pictures of the phase transition of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel at different temperatures. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to specific examples, but these examples should not be construed as limiting the present invention.

[0032] The preparation process of the multifunctional conductive eutectic gel based on N-isopropylacrylamide in the following examples follows the following steps:

[0033] (1) dopamine hydrochloride, ammonium persulfate, anhydrous ethanol and pure water are prepared into a dopamine hydrochloride ethanol-water mixed solution by a solution oxidation method, the pH of the dopamine hydrochloride ethanol / water mixed solution is adjusted to 9-12 with an alkali solution, stirred at a stirring speed of 300-800 rpm at 20-40°C for 12-36 hours, washed by centrifugation with pure water and anhydrous ethanol, and freeze-dried to obtain polydopamine freeze-dried powder; the polydopamine freeze-dried powder is then prepared into a polydopamine (PDA) dispersion; silver nitrate, pure water, ammonia water and the above polydopamine dispersion are then mixed, stirred for reaction, stirred at a stirring speed of 300-800 rpm at 20-40°C for 12-36 hours to form PDA@Ag nanoparticles, washed by centrifugation with a detergent, and freeze-dried to obtain PDA@Ag freeze-dried powder;

[0034] (2) According to the molar ratio of ethylene glycol (EG) to conductive agent (ZnCl2) of 4:1, the conductive agent (ZnCl2) was added to ethylene glycol (EG), and the mixture was stirred in a hot water bath until dissolved to prepare a eutectic solvent;

[0035] (3) Using a one-pot mixing method, the PDA@Ag freeze-dried powder obtained in step (1), polymer monomer, cross-linking agent, initiator and pure water are added to the eutectic solvent obtained in step (2), and the mixture is evenly mixed to obtain a prepolymer solution; the prepolymer solution is filled into a mold, and ultraviolet light is irradiated to induce polymerization to obtain a multifunctional conductive eutectic gel based on N-isopropylacrylamide.

[0036] Example 1

[0037] This embodiment provides a method for preparing a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, comprising the following steps:

[0038] (1) Dopamine hydrochloride (225 mg), ammonium persulfate (139.5 mg), anhydrous ethanol (10 mL) and pure water (35 mL) were mixed uniformly, and the pH was adjusted to 9-12 by adding ammonia water. The mixture was stirred at a stirring speed of 500 rpm at 20-40 ° C for 24 h. After centrifugal washing with pure water and anhydrous ethanol and freeze-dried, polydopamine freeze-dried powder was obtained; AgNO3 (606.3 mg) and pure water (140 mL) were vigorously stirred for 0.5 h, and ammonia water (1 mL) was added dropwise until the solution changed from brown to transparent to obtain an AgNO3 mixed solution; the polydopamine freeze-dried powder prepared above (147 mg) was dispersed in 10 mL of pure water and slowly added to the above AgNO3 mixed solution. The mixture was stirred at a stirring speed of 500 rpm at 20-40 ° C in the dark for 0.5 h. After centrifugal washing with pure water and anhydrous ethanol and freeze-dried, PDA@Ag freeze-dried powder was obtained;

[0039] (2) Add zinc chloride (1.06 g) to ethylene glycol (1.94 g), place in a hot water bath at 70-75°C and stir until dissolved to prepare a eutectic solvent with a molar ratio of EG to ZnCl2 of 4:1;

[0040] (3) The PDA@Ag freeze-dried powder (6 mg) obtained in step (1), N-isopropylacrylamide (1.44 g), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide (0.388 g) and acrylic acid (0.5 mL), N,N'-methylenebisacrylamide (0.0076 g), and 2-hydroxy-2-methyl-1-phenyl-1-propanone (90 μL) were added to the eutectic solvent obtained in step (2), and mixed evenly to obtain a PSBMA / PNIPAM / PAA / PDA@Ag prepolymer solution; the PSBMA / PNIPAM / PAA / PDA@Ag prepolymer solution was filled into the interlayer of the "sandwich" structure mold, and the thickness of the final gel was controlled by controlling the distance between the upper and lower glass sheets of the interlayer. After irradiation with a 36W ultraviolet lamp for 30 minutes, a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel was obtained. By only changing the amount of the eutectic solvent prepared in step (2) to 1 g, 2 g and 3 g, and keeping the other steps and raw material amounts unchanged, PSBMA / PNIPAM / PAA / PDA@Ag-1, PSBMA / PNIPAM / PAA / PDA@Ag-2 and PSBMA / PNIPAM / PAA / PDA@Ag-3 conductive eutectic gels can be prepared respectively.

[0041] Experimental results: FTIR spectra of monomer and conductive eutectic gel are as follows: Figure 1 In the spectrum of SBMA, the peak appears at 1723 cm -1 The peak value is at 1184 cm-1, which is attributed to the stretching vibration of C=O on the ester carbonyl group. -1 and 1041cm -1 It is attributed to the vibration of the sulfonic acid group. In the spectrum of NIPAM, the peak appears at 3302 cm -1 and 1550cm -1 The peak value is at 1662 cm, which is attributed to the stretching vibration and bending vibration of NH on the amide group. -1 It is attributed to the stretching vibration of C=O on the amide group, with a peak at 2970 cm -1 It is attributed to the stretching vibration of CH on the isopropyl group. In the spectrum of AA, the peak is at 3517cm -1 and 3064cm -1 It is attributed to the stretching vibration of -OH and -CH. The peak appears at 1623cm -1 and 1706cm -1 The peaks are attributed to C=C and C=O vibrations, respectively. In the PSBMA / PNIPAM / PAA / PDA@Ag eutectic gel, the C=O on the NIPAM amide group forms hydrogen bonds with other monomers, and the peaks are from 1662 cm -1 Redshift to 1635 cm -1The gel has the characteristic groups of three monomers at the same time, proving that SBMA, NIPAM and AA have been successfully copolymerized.

[0042] Example 2

[0043] This embodiment provides a method for evaluating the tensile strength at break of a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, which is performed by the following steps:

[0044] A universal testing machine was used to test the tensile properties at break of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel obtained in Example 1. The conductive eutectic gel was clamped neatly at both ends on the tensile testing machine at a tensile speed of 50 mm / min. The stress-strain curve was recorded in real time until the conductive eutectic gel broke.

[0045] Experimental results: Figure 2 As shown, the prepared PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, PSBMA / PNIPAM / PAA / PDA@Ag-1 has a tensile strength of 0.278 MPa and an elongation at break of 372.28%; PSBMA / PNIPAM / PAA / PDA@Ag-2 has a tensile strength of 0.213 MPa and an elongation at break of 342.25%; PSBMA / PNIPAM / PAA / PDA@Ag-3 has a tensile strength of 0.128 MPa and an elongation at break of 266.38%.

[0046] Example 3

[0047] This embodiment provides a method for evaluating the adhesion performance of PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel to different materials, including the following steps:

[0048] Step A: Prepare PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel. The steps are exactly the same as in Example 1, and a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel with a length (25 mm) * width (25 mm) * thickness (1 mm) is prepared.

[0049] Step B: Select three different adhesive substrates: glass, wood, and plastic. Cut each into 70mm (length) x 30mm (width) dimensions. Lay the conductive gel prepared in Step A flatly on one of the cut substrates, edge to edge, length to width to width. Then, use the same substrate to cover the other side of the eutectic gel, starting from the other wide edge. Avoid air bubbles between the bonded surfaces. Clamp the extended ends of the bonded substrates in a tensile testing machine at a tensile speed of 100mm / min. Record the mechanical properties in real time until the two substrates are completely separated. Test each substrate three times in parallel.

[0050] Experimental results: Figure 3 As shown, the adhesion strengths of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel to three substrates, glass, wood, and plastic, reached 65.67, 37.73, and 30.52 kPa, respectively. The prepared hydrogel can adhere to various substrates, such as plastic, glass, and wood, at room temperature and withstand a certain weight without peeling. This is because the abundant carboxyl, amino, and hydroxyl groups on the hydrogel surface can interact with the materials through hydrogen bonding, ion-dipole interactions, dipole-dipole interactions, and metal complexation. These excellent adhesion properties ensure stability during the assembly and testing of flexible strain sensors, meeting the requirements for accurate and stable signal acquisition in flexible strain sensors.

[0051] Example 4

[0052] This embodiment provides a method for evaluating the strain sensing of a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, which includes the following steps:

[0053] A universal testing machine and a multimeter were used to test the strain sensing performance of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel obtained in Example 1. A 5mm-wide strip of conductive copper tape was neatly applied to each end of the conductive eutectic gel. The gel, along with the wrapped conductive copper tape, was then clamped to a tensile testing machine while the tape was extended. The conductive copper tape was then used to connect the conductive eutectic gel to a multimeter. The tensile testing machine then stretched and released the conductive eutectic gel at varying strains, and the sensor's resistance change signal was recorded in real time.

[0054] Experimental results: Figure 4As shown in the figure, when the conductive eutectic gel was stretched / released with different strains using a universal testing machine, the sensing sensitivity (GF) of the conductive eutectic gel reached 1.40 (0-50%), 1.81 (50-150%) and 2.75 (150-250%), respectively, confirming the high sensitivity and wide sensing range of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, which can be used to monitor the changes in electrical signals of various human movements.

[0055] Example 5

[0056] This embodiment provides a method for evaluating the strain sensing of a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel under different tensile strains and different tensile frequencies, including the following steps:

[0057] A universal testing machine and a multimeter were used to test the strain sensing performance of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel sensor obtained in Example 1. A 5mm-wide strip of conductive copper tape was neatly attached to each end of the conductive eutectic gel. The gel, along with the wrapped conductive copper tape, was then clamped on a tensile testing machine. The tape was then extended, and the conductive eutectic gel was connected to a multimeter via the tape. The tensile testing machine then subjected the gel to cyclic stretching / releasing at various strains and frequencies, while the resistance change signal of the conductive eutectic gel was recorded in real time.

[0058] Experimental results: Figure 5 As shown in Figures A and B, when the conductive eutectic gel is subjected to cyclic stretching / releasing at different strains and frequencies using a universal testing machine, the peak values ​​and peak shapes of the electrical signals generated under the same strain and frequency conditions are similar, confirming that the sensing performance of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel has excellent stability, which is a very important performance for flexible sensor devices.

[0059] Example 6

[0060] This embodiment provides a method for evaluating the photothermal performance of a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel, including the following steps:

[0061] Step A: Prepare PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel. The steps are exactly the same as in Example 1, and a PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel with a length (25 mm) * width (25 mm) * thickness (1 mm) is prepared.

[0062] Step B: Use 808nm near-infrared laser to irradiate the conductive eutectic gel sample, and use infrared imager to record the temperature change of the conductive eutectic gel sample during the infrared light irradiation process. The power density of the near-infrared light is 2.0W / cm 2 .

[0063] Experimental results: Figure 6 As shown in Figure 3, as the illumination time increases (0-5min), the temperature of the conductive eutectic gel rises from 35°C to 79°C. Therefore, by adjusting the time of infrared illumination, the photothermal heating of the PSBMA / PNIPAM / PAA / PDA@Ag conductive eutectic gel can be easily controlled to the desired temperature, as shown in Figure 3. Figure 7 As shown, by controlling the temperature of the gel, the gel can be switched between a transparent state at 25°C and a completely opaque state at 35°C, thereby realizing application in the field of anti-counterfeiting.

[0064] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide, characterized in that The following steps are included: (1) dopamine hydrochloride, ammonium persulfate, anhydrous ethanol and pure water are prepared into a dopamine hydrochloride ethanol / water mixed solution by a solution oxidation method, the pH value of the dopamine hydrochloride ethanol / water mixed solution is adjusted with an alkali solution, and the mixture is stirred to react, and the dopamine hydrochloride is oxidized and self-polymerized to form polydopamine nanoparticles, which are centrifugally washed with a detergent and freeze-dried to obtain polydopamine freeze-dried powder; the polydopamine freeze-dried powder is then prepared into a polydopamine dispersion; silver nitrate, pure water, ammonia water and the above polydopamine dispersion are then mixed, stirred to react, and PDA@Ag nanoparticles are formed, which are centrifugally washed with a detergent and freeze-dried to obtain PDA@Ag freeze-dried powder; (2) According to the molar ratio of ethylene glycol to conductive agent being 4:1, the conductive agent is added to ethylene glycol, and the mixture is stirred in a hot water bath until dissolved to prepare a eutectic solvent; (3) Using a one-pot mixing method, the PDA@Ag freeze-dried powder obtained in step (1), polymer monomer, cross-linking agent, initiator and pure water are added to the eutectic solvent obtained in step (2), and the mixture is uniformly mixed to obtain a prepolymer solution; the prepolymer solution is filled into a mold, and ultraviolet light is irradiated to induce polymerization to obtain a multifunctional conductive eutectic gel based on N-isopropylacrylamide; The polymer monomers are N-isopropylacrylamide, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide and acrylic acid; the conductive agent is one of lithium chloride, zinc chloride, magnesium chloride, ferric chloride and aluminum chloride; the cross-linking agent is bisacrylamide, polyethylene glycol diacrylate or polyethylene glycol dimethacrylate; The amount of PDA@Ag used is 0.075-0.102 wt% of the multifunctional conductive eutectic gel; the amount of the polymer monomer used is 29-39 wt% of the multifunctional conductive eutectic gel; and the amount of the eutectic solvent used is 16.95-37.99 wt% of the multifunctional conductive eutectic gel.

2. The method for preparing the multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The pH value of step (1) is adjusted to 9-12; the temperature of the stirring reaction is 20-40°C, the reaction time is 12-36 h, and the stirring speed is 300-800 rpm.

3. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The molar ratio of dopamine hydrochloride to ammonium persulfate in step (1) is 2:1; the volume ratio of anhydrous ethanol to pure water is 2:7; and the total amount of dopamine hydrochloride and ammonium persulfate is 0.85 wt% of the dopamine hydrochloride ethanol / water mixed solution.

4. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The alkali solution in step (1) is ammonia water, sodium hydroxide solution, potassium hydroxide solution or sodium bicarbonate solution; and the detergent is pure water and anhydrous ethanol.

5. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The temperature of the hot water bath in step (2) is 70-75°C.

6. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The initiator in step (3) is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

7. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: In step (3), the amount of the crosslinker used is 0.192-0.258 wt% of the multifunctional conductive eutectic gel; the amount of the initiator used is 1.2-1.6 wt% of the multifunctional conductive eutectic gel; and the ultraviolet light-induced polymerization is performed under a 36W ultraviolet light source for 30 minutes.

8. The method for preparing a multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 1, characterized in that: The mold in step (3) is a sandwich structure constructed of glass sheets; the thickness of the multifunctional conductive eutectic gel obtained by filling the prepolymer into the mold is controlled by controlling the distance between the upper and lower glass sheets of the sandwich structure.

9. A multifunctional conductive eutectic gel based on N-isopropylacrylamide prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The multifunctional conductive eutectic gel monitors human body movements through changes in electrical signal peak value and peak shape, and realizes on-demand switching between transparency and opacity through reversible switching of near-infrared.

10. Use of the multifunctional conductive eutectic gel based on N-isopropylacrylamide according to claim 9 in sensors and anti-counterfeiting layers.

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