Double-signal sensing gel skin as well as preparation method and application thereof

Abstract

The invention provides double-signal sensing gel skin as well as a preparation method and application thereof, and relates to the technical field of flexible sensing. The preparation method of the double-signal sensing gel skin comprises the following steps: dispersing superparamagnetic ferroferric oxide colloidal nanoparticles in a hydrogel precursor solution to obtain a gel solution, and curing the gel solution in a magnetic field to obtain the gel skin, uniformly mixing water and glycerol, and adding anhydrous lithium chloride powder for multiple times under an ultrasonic condition to obtain a displacement liquid; completely immersing the gel skin into the replacement liquid to obtain the double-signal sensing gel skin. Superparamagnetic ferroferric oxide colloidal nanoparticles are used as a photonic crystal color-changing material to realize optical sensing, a glycerol / water binary solvent is used as an environment-resistant solvent to improve the low-temperature environment tolerance of gel skin, and anhydrous lithium chloride is used as a high-conductivity unit and a self-regeneration material to realize self-regeneration of the gel skin. Anhydrous lithium chloride and glycerol generate a synergistic effect of reducing the freezing point, and almost no ice crystal is formed within the temperature change of 20-40 DEG C.

Description

Technical Field

[0001] The present invention relates to the field of flexible sensing technology, in particular to a dual-signal sensing gel skin and a preparation method and application thereof. Background Art

[0002] Inspired by the color-changing organisms in nature, researchers have conducted in-depth research on the sensor integration of color-changing materials to achieve optical synergy functions similar to the skin of color-changing organisms, including: cholesteric liquid crystals, color-changing dyes, photonic crystals, quantum dots, etc. In recent years, these sensor devices integrating color-changing materials have shown great potential and are expected to be widely used in human-computer interaction, wearable flexible devices, and motion monitoring in the future. So far, due to its bright structural color and mechanical response color-changing ability, photonic crystal color-changing materials (PC) with periodic micro-nano structures have received widespread attention in the field of flexible sensing.

[0003] Hydrogels stand out among many flexible materials due to their good mechanical properties and rich water networks, and are recognized as one of the most promising materials for preparing flexible sensing gel skin and wearable devices. However, due to the differences in the geographical environment, water-based hydrogels with high water content are often difficult to adapt to extreme climate changes in different regions. Some extreme climates will destroy the main stability of the gel and seriously affect the sensing ability of the gel skin. For example: in a low-temperature cold environment, the water in the gel network will freeze, causing the gel body to crack, and then the sensing ability will fail; in a high-temperature dry environment, due to the large amount of evaporation of the hydrogel water, the gel skin will lose water and dry, and then the sensing signal will be interfered with. Summary of the invention

[0004] The problem solved by the present invention is how to solve the problem that the existing gel skin is difficult to maintain sensing ability in a low-temperature cold environment and a high-temperature dry environment.

[0005] In order to solve the above problems, the present invention provides a dual-signal sensing gel skin and a preparation method and application thereof.

[0006] In a first aspect, the present invention provides a method for preparing a dual-signal sensing gel skin, comprising the following steps:

[0007] S1: Dispersing superparamagnetic ferroferric oxide colloidal nanoparticles in a hydrogel precursor solution, dropping ammonium persulfate solution and tetramethylethylenediamine into the hydrogel precursor solution, mixing evenly to obtain a gel solution, pouring the solution into a mold and curing it under a magnetic field to obtain a gel skin;

[0008] S2: mixing water and glycerol in a volume ratio of 1:1 to obtain a mixed solution, adding anhydrous lithium chloride powder to the mixed solution multiple times under ultrasonic conditions, and stopping the addition when no precipitation occurs to obtain a replacement solution;

[0009] S3: The gel skin obtained in step S1 is completely immersed in the replacement fluid obtained in step S2, and taken out after more than 2 hours to obtain a dual-signal sensing gel skin.

[0010] Optionally, step S1 further comprises: preparing superparamagnetic ferroferric oxide colloidal nanoparticles by a hydrothermal method, dissolving ferrocene in an acetone solution, ultrasonicating for more than 5 minutes, stirring evenly, adding hydrogen peroxide solution dropwise thereto, stirring for 20-30 minutes, heating at above 210° C. for more than 48 hours, and drying under magnetic field conditions to obtain superparamagnetic ferroferric oxide colloidal nanoparticles.

[0011] Optionally, the concentration of ferrocene dissolved in the acetone solution is 0.01 g / ml, the mass fraction of hydrogen peroxide in the added hydrogen peroxide solution is 25-35%, and the volume of the added hydrogen peroxide solution accounts for 3.8-4% of the volume of the acetone solution.

[0012] Optionally, the step of drying under magnetic field conditions specifically includes: ultrasonic cleaning using acetone and anhydrous ethanol in sequence, and drying under magnetic field conditions at 35-45°C.

[0013] Optionally, step S1 further comprises: dissolving gelatin, acrylamide and N,N-methylenebisacrylamide in water under heating in a water bath at a temperature above 80° C., and uniformly stirring with magnetic force to obtain a hydrogel precursor solution.

[0014] Optionally, the mass ratio of gelatin, acrylamide and N,N-methylenebisacrylamide is 0.5:2:0.008.

[0015] Optionally, in step S1, the gel solution is poured into a mold, and is cured under a magnetic field of 240-260 mt for more than 5 hours at a low temperature below 0°C to obtain a gel skin.

[0016] Optionally, the particle size of superparamagnetic carbon-coated ferroferric oxide is 130-250 nm, the concentration of ammonium sulfate solution is 0.16 g / ml, and the added amount is 5-6% of the mass of superparamagnetic ferroferric oxide colloidal nanoparticles; the added amount of tetramethylethylenediamine is 2-3% of the mass of superparamagnetic ferroferric oxide colloidal nanoparticles.

[0017] In a second aspect, the present invention provides a dual-signal sensing gel skin, which is prepared by the preparation method of the dual-signal sensing gel skin as described in any one of the above items.

[0018] In a third aspect, the present invention provides an application of the dual-signal sensing gel skin as described above in the field of flexible sensing devices.

[0019] The dual-signal sensing gel skin and the preparation method and application thereof of the present invention have the following beneficial effects: superparamagnetic ferroferric oxide colloidal nanoparticles are used as photonic crystal color-changing materials, the superparamagnetic ferroferric oxide colloidal nanoparticles are self-assembled under magnetic field conditions and are solidified by a hydrogel precursor solution and fixed in the gel skin, thereby producing gorgeous structural colors; after the gel body produces mechanical strain, the band gap of the photonic crystal color-changing material changes accordingly; according to the Bragg diffraction formula, it can be known that the reflection wavelength is proportional to the band gap, thereby achieving coordinated color change of the gel skin structural color in response to strain, thereby achieving optical sensing;

[0020] Glycerin / water binary solvent is used as environmentally resistant solvent. Glycerin has a low freezing point and forms a large number of hydrogen bonds with water molecules, which destroys the formation and arrangement of ice crystals under low temperature conditions, greatly reduces the freezing point of the gel skin, and improves the gel skin's tolerance to low temperature environments. At the same time, the introduction of organic solvent glycerin also prevents the structural color of the gel skin from being damaged in high temperature environments.

[0021] Anhydrous lithium chloride is used as a highly conductive unit and self-regenerative material. Anhydrous lithium chloride is used as an electrolyte to generate free Li in aqueous solution. + and Cl - , giving the gel skin electrical sensing ability, making the gel skin have sensitive electrical sensing ability, and the specification factor (GF) can reach 3.311, so that the gel skin can perform coordinated dual signal sensing through optical color changes and electrical resistance signal changes; and anhydrous lithium chloride has high hygroscopicity, it can absorb a large amount of moisture in the air in the powder state. When it is introduced into the gel skin, the gel skin will be in a low vapor pressure state when it is dehydrated, and can spontaneously capture water molecules from the surrounding high vapor pressure environment to achieve self-regeneration;

[0022] Moreover, anhydrous lithium chloride generates free Li in aqueous solution. + and Cl - It can combine with multiple water molecules, destroy the hydrogen bond interaction between water molecules under low temperature conditions, destroy the formation and arrangement of ice crystals under low temperature conditions, and then synergize with glycerol to lower the freezing point, so that almost no ice crystals are formed within the temperature range of 20℃ to -40℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of a method for preparing a dual-signal sensing gel skin according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structural color of the superparamagnetic ferroferric oxide colloidal nanoparticle solution under a magnetic field according to Example 1 of the present invention;

[0025] Figure 3This is a SEM image of superparamagnetic ferroferric oxide colloidal nanoparticles of Example 1 of the present invention;

[0026] Figure 4 This is a curve diagram of the antifreeze DSC experimental results of the dual-signal sensing gel skin of Example 1 of the present invention;

[0027] Figure 5 It is a schematic diagram comparing the water loss of the hydrogel, the organogel and the dual-signal sensing gel skin of Example 1 of the present invention over 15 days;

[0028] Figure 6 It is a comparison curve of the self-regeneration ability of the hydrogel, the organogel and the dual-signal sensing gel skin of Example 1 of the present invention;

[0029] Figure 7 Schematic diagram of the reflectance spectrum of the dual-signal sensing gel skin under different strains according to Example 1 of the present invention;

[0030] Figure 8 This is a schematic diagram of the electrical signal changes of the dual-signal sensing gel skin under different strains according to Example 1 of the present invention;

[0031] Fig. 9 This is a comparison diagram of the swelling phenomenon of the dual-signal sensing gel skin obtained under the condition that the replacement fluid contains LiCl or not according to an embodiment of the present invention;

[0032] Fig.10 This is an electrical sensing diagram of the dual-signal sensing gel skin in Example 1 of the present invention being attached to a human finger;

[0033] Fig.11 This is an electrical sensing diagram of the dual-signal sensing gel skin of Example 1 of the present invention fitted to the ankle of a human body;

[0034] Fig.12 This is an electrical sensing diagram of the dual-signal sensing gel skin in Example 1 of the present invention being attached to the human knee. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention;

[0037] The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to"; the term "based on" means "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description.

[0038] In view of the problems existing in the above-mentioned related technologies, this embodiment provides a dual-signal sensing gel skin and a preparation method and application thereof.

[0039] like Figure 1 As shown, a method for preparing a dual-signal sensing gel skin provided by an embodiment of the present invention comprises the following steps:

[0040] S1: Dispersing superparamagnetic ferroferric oxide colloidal nanoparticles in a hydrogel precursor solution, dropping ammonium persulfate solution and tetramethylethylenediamine into the hydrogel precursor solution, mixing evenly to obtain a gel solution, pouring the solution into a mold and curing it under a magnetic field to obtain a gel skin;

[0041] S2: mixing water and glycerol in a volume ratio of 1:1 to obtain a mixed solution, adding anhydrous lithium chloride powder to the mixed solution multiple times under ultrasonic conditions, and stopping the addition when no precipitation occurs to obtain a replacement solution;

[0042] S3: The gel skin obtained in step S1 is completely immersed in the replacement fluid obtained in step S2, and taken out after more than 2 hours to obtain a dual-signal sensing gel skin.

[0043] In this embodiment, superparamagnetic ferroferric oxide colloidal nanoparticles are used as photonic crystal color-changing materials. The superparamagnetic ferroferric oxide colloidal nanoparticles are self-assembled under magnetic field conditions and are solidified by a hydrogel precursor solution and fixed in the gel skin. As the gel body produces mechanical strain, the band gap of the photonic crystal color-changing material will change accordingly. According to the Bragg diffraction formula, the reflection wavelength is proportional to the band gap, thereby achieving coordinated color change of the gel skin structural color in response to strain, thereby achieving optical sensing.

[0044] Glycerol / water binary solvent is used as the environmentally resistant solvent. Glycerol has a low freezing point and forms a large number of hydrogen bonds with water molecules, which destroys the formation and arrangement of ice crystals under low temperature conditions, greatly reduces the freezing point of the gel skin, and improves the gel skin's tolerance to low temperature environments. At the same time, the introduction of the organic solvent glycerol also prevents the structural color of the gel skin from being damaged in high temperature environments.

[0045] Using anhydrous lithium chloride as a highly conductive unit and self-regenerating material, anhydrous lithium chloride as an electrolyte can generate free Li in aqueous solution + and Cl - , giving the gel skin electrical sensing capabilities, making the gel skin have sensitive electrical sensing capabilities, and the specification factor can reach 3.311, enabling the gel skin to perform coordinated dual-signal sensing through optical color changes and electrical resistance signal changes; and anhydrous lithium chloride has high hygroscopicity, it can absorb a large amount of moisture in the air in a powder state. When it is introduced into the gel skin, the gel skin will be in a low vapor pressure state when it is dehydrated, and can spontaneously capture water molecules from the surrounding high vapor pressure environment to achieve self-regeneration.

[0046] Moreover, anhydrous lithium chloride generates free Li in aqueous solution. + and Cl - It can combine with multiple water molecules, destroy the hydrogen bond interaction between water molecules under low temperature conditions, destroy the formation and arrangement of ice crystals under low temperature conditions, and then synergize with glycerol to lower the freezing point, so that almost no ice crystals are formed within the temperature range of 20℃ to -40℃.

[0047] Optionally, step S1 further comprises: preparing superparamagnetic ferroferric oxide colloidal nanoparticles by a hydrothermal method, dissolving ferrocene in an acetone solution, ultrasonicating for more than 5 minutes, stirring evenly, adding hydrogen peroxide solution dropwise thereto, stirring for 20-30 minutes, heating at above 210° C. for more than 48 hours, and drying under magnetic field conditions to obtain superparamagnetic ferroferric oxide colloidal nanoparticles.

[0048] In this optional embodiment, after adding hydrogen peroxide solution and stirring evenly, the solution is placed in a hydrothermal reactor, and the hydrothermal reactor is placed in a forced air drying oven and heated at above 210° C. for more than 48 hours. After the reaction is completed, the hydrothermal reactor is taken out after cooling to room temperature.

[0049] Optionally, the concentration of ferrocene dissolved in the acetone solution is 0.01 g / ml, the mass fraction of hydrogen peroxide in the added hydrogen peroxide solution is 25-35%, and the volume of the added hydrogen peroxide solution accounts for 3.8-4% of the volume of the acetone solution.

[0050] Optionally, the step of drying under magnetic field conditions specifically includes: ultrasonic cleaning using acetone and anhydrous ethanol in sequence, and drying under magnetic field conditions at 35-45°C.

[0051] In this optional embodiment, after the hydrothermal reactor is cooled to room temperature, the solution in the hydrothermal reactor is poured into a beaker, ultrasonically cleaned several times with acetone and anhydrous ethanol in sequence, and then dried under a 40°C magnetic field to obtain superparamagnetic ferroferric oxide colloidal nanoparticles.

[0052] Optionally, step S1 further comprises: dissolving gelatin, acrylamide and N,N-methylenebisacrylamide in water under heating in a water bath at a temperature above 80° C., and uniformly stirring with magnetic force to obtain a hydrogel precursor solution.

[0053] In this optional embodiment, the gel skin can form a double network structure through physical crosslinking of gelatin and chemical crosslinking of acrylamide, and N,N'methylenebisacrylamide is used as a crosslinking agent to obtain a hydrogel precursor solution. The prepared gel skin can have a bright structural color.

[0054] Optionally, the mass ratio of gelatin, acrylamide and N,N-methylenebisacrylamide is 0.5:2:0.008.

[0055] Optionally, in step S1, the gel solution is poured into a mold, and is cured under a magnetic field of 240-260 mt for more than 5 hours at a low temperature below 0°C to obtain a gel skin.

[0056] In this optional embodiment, superparamagnetic ferroferric oxide colloidal nanoparticles can self-assemble into photonic crystal nanoarrays under the action of a magnetic field, and are fixed inside the gel skin after the gel skin solidifies, producing brilliant structural colors.

[0057] Optionally, the particle size of the superparamagnetic ferroferric oxide colloidal nanoparticles is 130-250 nm, the concentration of the ammonium sulfate solution is 0.16 g / ml, and the added amount is 5-6% of the mass of the superparamagnetic ferroferric oxide colloidal nanoparticles; the added amount of tetramethylethylenediamine is 2-3% of the mass of the superparamagnetic ferroferric oxide colloidal nanoparticles.

[0058] Specifically, the superparamagnetic ferroferric oxide colloidal nanoparticles are carbon-coated ferroferric oxide.

[0059] A dual-signal sensing gel skin provided by an embodiment of the present invention is prepared by using the preparation method of the dual-signal sensing gel skin as described in any one of the above items.

[0060] In this embodiment, the thickness of the dual-signal sensing gel skin can be controlled by the mold height, and the optimal thickness is 0.5-1 mm.

[0061] An embodiment of the present invention provides an application of the dual-signal sensing gel skin as described above in the field of flexible sensing equipment.

[0062] The present invention is further described below in conjunction with specific embodiments.

[0063] Example 1, preparation of dual signal sensing gel skin.

[0064] The hydrothermal method is used to synthesize superparamagnetic ferrocene colloidal nanoparticles. 0.54 g of ferrocene is dissolved in 54 ml of acetone solution. After ultrasonication for 5 minutes, a magnetic bar is placed in the solution and stirred evenly on a magnetic stirrer. Subsequently, 2 ml of hydrogen peroxide solution (30% concentration) is drawn with a syringe and added dropwise thereto. The magnetic stirring is continued for 30 minutes. At this time, the solution is orange. The orange solution is poured into a 100 ml hydrothermal reactor, heated at 210° C. in a forced air drying oven for 48 hours, and then cooled to room temperature. The solution in the hydrothermal reactor is poured into a beaker, ultrasonically cleaned several times with acetone and anhydrous ethanol in turn, and then dried under a 40° C. magnetic field condition to obtain superparamagnetic ferrocene colloidal nanoparticles. Figure 2 As shown, the structural color photograph of the superparamagnetic ferroferric oxide colloidal nanoparticle solution under a magnetic field can be seen, and the SEM image is obtained by scanning the surface of the ferroferric oxide colloidal nanoparticle solution point by point by focusing the electron beam, as shown in FIG. Figure 3 shown.

[0065] The hydrogel precursor solution was prepared by dissolving 0.5 g gelatin, 2 g acrylamide and 0.008 g N,N-methylenebisacrylamide in water under heating at 80° C., stirring evenly with magnetic force, and heating in the water bath for 15 min to obtain a hydrogel precursor solution.

[0066] By using the in-situ polymerization method, 0.3g of superparamagnetic ferroferric oxide colloidal nanoparticles were dispersed in a hydrogel precursor solution at 80°C. After the gel precursor solution was cooled to room temperature, 0.1ml of an initiator ammonium persulfate solution and 10uL of an accelerator tetramethylethylenediamine were dropped into the hydrogel precursor solution. After mixing evenly, a gel solution was obtained. The gel solution was quickly poured into a mold and cured under a 250mt magnetic field at low temperature (0°C) to obtain a gel skin. The thickness of the gel skin can be controlled by the mold height as needed, and the optimal thickness is 0.5-1mm.

[0067] The replacement solution was prepared by mixing water and glycerol in a volume ratio of 1:1 to obtain a mixed solution, and anhydrous lithium chloride powder was added to the mixed solution multiple times under ultrasonic conditions (after the addition was completed, LiCl accounted for 30% by mass of the total mixed solution content), and the addition was stopped when no white precipitate was left to obtain a replacement solution.

[0068] The dual-signal sensing gel skin was prepared by the solvent replacement method. The gel skin was completely immersed in the replacement solution and taken out after 2 hours to obtain the dual-signal sensing gel skin. The residual liquid on the surface of the dual-signal sensing gel skin was cleaned with filter paper.

[0069] Comparative Example 1, preparation of hydrogel and organogel skin.

[0070] The hydrothermal method is used to synthesize superparamagnetic ferrocene colloidal nanoparticles. 0.54 g of ferrocene is dissolved in 54 ml of acetone solution. After ultrasonication for 5 minutes, a magnetic bar is placed in the solution and stirred evenly on a magnetic stirrer. Subsequently, 2 ml of hydrogen peroxide solution (30% concentration) is drawn with a syringe and added dropwise thereto. The magnetic stirring is continued for 30 minutes. At this time, the solution is orange. The orange solution is poured into a 100 ml hydrothermal reactor, heated at 210° C. in a forced air drying oven for 48 hours, and then cooled to room temperature. The solution in the hydrothermal reactor is poured into a beaker, ultrasonically cleaned several times with acetone and anhydrous ethanol in turn, and then dried under a 40° C. magnetic field condition to obtain superparamagnetic ferrocene colloidal nanoparticles. Figure 2 As shown, the structural color photograph of the superparamagnetic ferroferric oxide colloidal nanoparticle solution under a magnetic field can be seen, and the SEM image is obtained by scanning the surface of the ferroferric oxide colloidal nanoparticle solution point by point by focusing the electron beam, as shown in FIG. Figure 3 shown.

[0071] The hydrogel precursor solution was prepared by dissolving 0.5 g gelatin, 2 g acrylamide and 0.008 g N,N-methylenebisacrylamide in water under heating at 80° C., stirring evenly with magnetic force, and heating in the water bath for 15 min to obtain a hydrogel precursor solution.

[0072] Using the in-situ polymerization method, 0.3 g of superparamagnetic ferroferric oxide colloidal nanoparticles were dispersed in a hydrogel precursor solution at 80°C. After the gel precursor solution was cooled to room temperature, 0.1 ml of an initiator ammonium persulfate solution and 10 uL of an accelerator tetramethylethylenediamine were dropped into the hydrogel precursor solution. After mixing evenly, a gel solution was obtained. The gel solution was quickly poured into a mold and cured under a 250 mt magnetic field at low temperature (0°C) to obtain hydrogel skin.

[0073] For the preparation of the replacement solution, water and glycerol were mixed evenly in a volume ratio of 1:1 to obtain the replacement solution.

[0074] The organogel skin was prepared by the solvent replacement method. The hydrogel skin was completely immersed in the replacement solution and taken out after 2 hours to obtain the organogel skin. The residual liquid on the surface of the organogel skin was cleaned with filter paper.

[0075] Effect Example

[0076] The dual-signal sensing gel skin prepared in Example 1 was subjected to an antifreeze DSC experiment. The test method used a differential scanning calorimeter to test the freezing point of the dual-signal sensing gel skin in a low-temperature environment to verify the stable working ability of the dual-signal sensing gel skin in a low-temperature environment. Figure 4 As shown, the freezing point of the dual-signal sensing gel skin is approximately -46.4°C.

[0077] The dual-signal sensing gel skin prepared in Example 1 was tested for its water loss resistance. The test method was to build a humidity and temperature measuring instrument and an electronic balance platform to test the water loss of different gel skins. Figure 5 As shown, the dual-signal sensing gel skin (i.e., gel skin) of Example 1, the hydrogel of Comparative Example 1, and the organic gel of three skins were tested. In the experiment of 15 days at room temperature (25°C-50% RH), the dual-signal sensing gel skin had a very strong ability to resist water loss.

[0078] The self-regeneration ability of the dual-signal sensing gel skin prepared in Example 1 was tested. The test method was to build a blast drying oven and an electronic balance platform to test the self-regeneration ability of different gel skins. Figure 6 As shown, the mass changes of the dual-signal sensing gel skin (i.e., gel skin) of Example 1, the hydrogel and the organic gel of Comparative Example 1 were tested during heating at 60°C for 40 hours. In the 40-hour experiment, the dual-signal sensing gel skin had a very strong self-regeneration ability. Among them, the total mass of the dual-signal sensing gel skin became about 80% of the initial mass during heating at 60°C for 12 hours, and then gradually captured moisture in the air after 28 hours to restore its own mass.

[0079] The dual-signal sensing gel skin prepared in Example 1 was subjected to optical signal detection. The detection method tested the reflection peak change of the gel skin by independently building a Y-type optical fiber and a spectrometer platform, such as Figure 7 As shown, the reflection peak shifts from red to blue as the strain increases, demonstrating the optical sensing capability of the gel skin for human motion monitoring.

[0080] The dual-signal sensing gel skin prepared in Example 1 was subjected to electrical signal detection. The detection method was to build an electrochemical workstation, a rotating motor and a slider platform to test the resistance signal change of the gel skin. Figure 8 As shown, the resistance signal increases continuously with the increase of strain, which proves the electrical sensing ability of the gel skin for human motion monitoring.

[0081] The motion sensing capability of the dual-signal sensing gel skin prepared in Example 1 was verified to verify the effect of the dual-signal sensing gel skin in solvents containing or not containing LiCl, and a group of replacement fluids without LiCl were prepared to prepare the sensing gel skin, such as Fig. 9As shown in the figure, there is almost no swelling in the dual-signal sensing gel skin obtained by replacement with a replacement fluid containing LiCl. This is due to the salting-out effect. The high concentration of salt reduces the amount of "free water" in the solvent, restraining the swelling effect of the gel, so the photonic crystal structural color inside it will not be affected. However, the sensing gel skin obtained by replacement with a simple water-glycerol binary solvent replacement fluid will cause large-scale swelling of the gel, resulting in instability of the structural color.

[0082] The motion sensing capability of the dual-signal sensing gel skin prepared in Example 1 was verified by using PI tape, conductive copper foil tape and electrochemical platform to test the motion sensing capability of the gel skin, and detecting the resistance signal changes of the gel skin under motion of different parts (fingers, ankles, knees), such as Fig.10 As shown in Figure 1, the resistance signal of the gel skin changes when the finger moves. Fig.11 As shown in Figure 1, the resistance signal changes of the gel skin under the movement of the ankle; Fig.12 As shown, the resistance signal changes of the gel skin under the movement of the knee. It can be seen that the dual-signal sensing gel skin of this embodiment 1 has good motion sensing capabilities at different parts.

[0083] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a dual-signal sensing gel skin, characterized in that: The following steps are involved: S1: dispersing superparamagnetic ferroferric oxide colloidal nanoparticles in a hydrogel precursor solution, dropping an ammonium persulfate solution and tetramethylethylenediamine into the hydrogel precursor solution, mixing them evenly to obtain a gel solution, pouring the solution into a mold and curing it under a magnetic field to obtain a gel skin; S2: mixing water and glycerol in a volume ratio of 1:1 to obtain a mixed solution, adding anhydrous lithium chloride powder to the mixed solution for multiple times under ultrasonic conditions, and stopping the addition when no precipitation occurs to obtain a replacement solution; S3: The gel skin obtained in step S1 is completely immersed in the replacement fluid obtained in step S2, and taken out after more than 2 hours to obtain a dual-signal sensing gel skin.

2. The method for preparing the dual-signal sensing gel skin according to claim 1, characterized in that: The step S1 further comprises: preparing the superparamagnetic ferroferric oxide colloidal nanoparticles by a hydrothermal method, dissolving ferrocene in an acetone solution, ultrasonicating for more than 5 minutes, stirring evenly, adding hydrogen peroxide solution dropwise therein, stirring for 20-30 minutes, heating at 210° C. or above for more than 48 hours, and drying under a magnetic field condition to obtain the superparamagnetic ferroferric oxide colloidal nanoparticles.

3. The method for preparing the dual-signal sensing gel skin according to claim 2, characterized in that: The concentration of ferrocene dissolved in the acetone solution is 0.01 g / ml, the mass fraction of hydrogen peroxide in the added hydrogen peroxide solution is 25-35%, and the volume of the added hydrogen peroxide solution accounts for 3.8-4% of the volume of the acetone solution.

4. The method for preparing the dual-signal sensing gel skin according to claim 2, characterized in that: The step of drying under magnetic field conditions specifically includes: ultrasonic cleaning with acetone and anhydrous ethanol in sequence, and drying under magnetic field conditions at 35-45°C.

5. The method for preparing the dual-signal sensing gel skin according to claim 1, characterized in that: The step S1 further comprises: dissolving gelatin, acrylamide and N,N-methylenebisacrylamide in water under heating in a water bath above 80° C., and uniformly stirring with magnetic force to obtain a hydrogel precursor solution.

6. The method for preparing the dual-signal sensing gel skin according to claim 5, characterized in that: The mass ratio of gelatin, acrylamide and N,N-methylenebisacrylamide is 0.5:2:0.

008.

7. The method for preparing the dual-signal sensing gel skin according to claim 1, characterized in that: In the step S1, the gel solution is poured into a mold, and is cured under a magnetic field of 240-260 mt at a low temperature below 0° C. for more than 5 hours to obtain the gel skin.

8. The method for preparing the dual-signal sensing gel skin according to claim 1, characterized in that: The particle size of the superparamagnetic carbon-coated ferroferric oxide is 130-250nm, the concentration of the ammonium sulfate solution is 0.16g / ml, and the added amount is 5-6% of the mass of the superparamagnetic ferroferric oxide colloidal nanoparticles; the added amount of the tetramethylethylenediamine is 2-3% of the mass of the superparamagnetic ferroferric oxide colloidal nanoparticles.

9. A dual-signal sensing gel skin, characterized in that: The dual-signal sensing gel skin is prepared by the preparation method of any one of claims 1 to 8.

10. Application of the dual-signal sensing gel skin as claimed in claim 9 in the field of flexible sensing devices.

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