A dual-signal sensing gel skin, its preparation method and application

Abstract

This invention provides a dual-signal sensing gel skin, its preparation method, and its application, relating to the field of flexible sensing technology. The preparation method of the dual-signal sensing gel skin involves dispersing superparamagnetic iron oxide colloidal nanoparticles in a hydrogel precursor solution to obtain a gel solution, which is then solidified under a magnetic field to obtain the gel skin. Water and glycerol are mixed uniformly, and anhydrous lithium chloride powder is added repeatedly under ultrasonic conditions to obtain a displacement solution. The gel skin is then completely immersed in the displacement solution to obtain the dual-signal sensing gel skin. Superparamagnetic iron oxide colloidal nanoparticles are used as a photonic crystal color-changing material to achieve optical sensing. A glycerol / water binary solvent is used as an environmentally resistant solvent, improving the low-temperature tolerance of the gel skin. Anhydrous lithium chloride is used as a highly conductive unit and a self-regenerating material; the synergistic effect of anhydrous lithium chloride and glycerol in lowering the freezing point results in almost no ice crystal formation within a temperature range of 20°C to -40°C.

Description

Technical Field

[0001] This invention relates to the field of flexible sensing technology, and more specifically, to a dual-signal sensing gel skin, its preparation method, and its application. Background Technology

[0002] Inspired by chromatic organisms in nature, researchers have conducted in-depth studies on the sensor integration of color-changing materials to achieve optical synergy similar to the skin of chromatic organisms. These materials include cholesteric liquid crystals, color-changing dyes, photonic crystals, and quantum dots. In recent years, these sensor devices integrating color-changing materials have shown great potential and are expected to be widely used in fields such as human-computer interaction, wearable flexible devices, and motion monitoring in the future. To date, photonic crystal color-changing materials (PC) with periodic micro / nano structures have received widespread attention in the field of flexible sensing due to their vibrant structural colors and mechanically responsive color-changing capabilities.

[0003] Hydrogels, due to their excellent mechanical properties and rich water networks, stand out among many flexible materials and are widely recognized as one of the most promising materials for fabricating flexible sensing gel skin and wearable devices. However, due to differences in geographical environment, water-based hydrogels with high water content often struggle to adapt to extreme climate changes in different regions. Some extreme climates can damage the stability of the gel, severely affecting the sensing capabilities of the gel skin. For example, in low-temperature and cold environments, the water in the gel network freezes, causing the gel to crack and leading to sensor failure; in high-temperature and dry environments, the large-scale evaporation of water from the hydrogel causes the gel skin to dry out, interfering with the sensing signal. Summary of the Invention

[0004] The problem addressed by this invention is how to solve the problem that existing gel skins have difficulty maintaining their sensing capabilities in low-temperature cold environments and high-temperature dry environments.

[0005] To address the above problems, this invention provides a dual-signal sensing gel skin, its preparation method, and its application.

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

[0007] S1: Superparamagnetic iron oxide colloidal nanoparticles are dispersed in a hydrogel precursor solution. Ammonium persulfate solution and tetramethylethylenediamine are added dropwise to the hydrogel precursor solution. After mixing evenly, a gel solution is obtained. The solution is poured into a mold and cured under a magnetic field to obtain gel skin.

[0008] S2: Mix water and glycerol in a volume ratio of 1:1 until homogeneous to obtain a mixed solution. Add anhydrous lithium chloride powder to the mixed solution multiple times under ultrasonic conditions until no precipitate is found, and then stop adding to obtain a displacement solution.

[0009] S3: Immerse the gel skin obtained in step S1 completely in the replacement solution obtained in step S2, and remove it after more than 2 hours to obtain dual-signal sensing gel skin.

[0010] Optionally, step S1 further includes: preparing superparamagnetic iron oxide colloidal nanoparticles using a hydrothermal method, dissolving ferrocene in acetone solution, sonicating for more than 5 minutes, stirring until homogeneous, adding hydrogen peroxide solution dropwise, stirring for 20-30 minutes, heating at or above 210°C for more than 48 hours, and drying under magnetic field conditions to obtain superparamagnetic iron 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 drying step under magnetic field conditions specifically includes: ultrasonic cleaning with acetone and anhydrous ethanol in sequence, followed by drying under magnetic field conditions at 35-45°C.

[0013] Optionally, step S1 further includes: dissolving gelatin, acrylamide and N,N-methylenebisacrylamide in water under water bath heating at 80°C or above, and stirring magnetically 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 cured for more than 5 hours under a magnetic field of 240-260 mt at a low temperature below 0°C to obtain gel skin.

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

[0017] Secondly, the present invention provides a dual-signal sensing gel skin, which is prepared by the method for preparing dual-signal sensing gel skin as described in any of the preceding claims.

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

[0019] The beneficial effects of the dual-signal sensing gel skin, its preparation method, and its application of the present invention are as follows: Superparamagnetic iron oxide colloidal nanoparticles are used as photonic crystal color-changing materials. After the superparamagnetic iron oxide colloidal nanoparticles self-assemble under magnetic field conditions and are solidified in the gel skin by hydrogel precursor solution, they produce brilliant structural colors. As the gel body undergoes mechanical strain, the band gap of the photonic crystal color-changing material will change accordingly. According to the Bragg diffraction formula, the reflected wavelength is proportional to the band gap size, thereby realizing the structural color response strain-coordinated color change of the gel skin and thus achieving optical sensing.

[0020] Using a glycerol / water binary solvent as an environmentally resistant solvent, glycerol has a low freezing point and forms a large number of hydrogen bonds with water molecules, which disrupts the formation and arrangement of ice crystals under low temperature conditions, greatly reducing the freezing point of the gel skin and improving the low temperature environment tolerance of the gel skin. 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.

[0021] Using anhydrous lithium chloride as a highly conductive unit and a self-regenerating material, and using anhydrous lithium chloride as an electrolyte, free Li can be generated in aqueous solution. + and Cl - This endows the gel skin with electrical sensing capabilities, giving it a sensitive electrical sensing ability with a specification factor (GF) of up to 3.311. This allows the gel skin to perform synergistic dual-signal sensing through optical color changes and electrical resistance signal changes. Furthermore, anhydrous lithium chloride has high hygroscopicity, and it can absorb a large amount of moisture from the air in its powder state. When introduced into the gel skin, the gel skin will be in a low vapor pressure state when it is dehydrated, and it can spontaneously capture water molecules from the surrounding high vapor pressure environment to achieve self-regeneration.

[0022] Furthermore, anhydrous lithium chloride generates free Li in aqueous solution. + and Cl - It can combine with multiple water molecules, disrupting the hydrogen bond interactions between water molecules under low temperature conditions, thus disrupting the formation and arrangement of ice crystals under low temperature conditions. In turn, it has a synergistic effect with glycerol in lowering the freezing point, and can achieve almost no ice crystal formation within a temperature range of 20℃ to -40℃. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation method of dual-signal sensing gel skin according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure color of the superparamagnetic iron oxide colloidal nanoparticle solution under a magnetic field in Example 1 of the present invention;

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

[0026] Figure 4 This is a DSC experimental result curve of the dual-signal sensing gel skin for antifreeze treatment according to Example 1 of the present invention;

[0027] Figure 5 A schematic diagram showing the comparison of water loss over 15 days between hydrogel, organic gel and the dual-signal sensing gel skin of Example 1 of the present invention.

[0028] Figure 6 A comparative curve of the self-regeneration capacity of hydrogel, organic gel and dual-signal sensing gel skin of Example 1 of the present invention;

[0029] Figure 7 This is a schematic diagram of the reflectance spectrum of the dual-signal sensing gel skin under different strains in Embodiment 1 of the present invention;

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

[0031] Figure 9 This is a comparison diagram of the swelling phenomenon of dual-signal sensing gel skin obtained under the conditions of whether the replacement solution contains LiCl, according to an embodiment of the present invention.

[0032] Figure 10 This is an electrical sensing diagram of the skin-attached part of the dual-signal sensing gel in Embodiment 1 of the present invention at the finger area;

[0033] Figure 11 This is an electrical sensing diagram of the dual-signal sensing gel skin in contact with the ankle area of ​​the human body according to Embodiment 1 of the present invention.

[0034] Figure 12 This is an electrical sensing diagram of the dual-signal sensing gel skin attached to the knee area of ​​the human body according to Embodiment 1 of the present invention. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only 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 this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0037] The term "comprising" and its variations as used herein are open-ended inclusion, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below.

[0038] To address the problems existing in the aforementioned related technologies, this embodiment provides a dual-signal sensing gel skin, its preparation method, and its application.

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

[0040] S1: Superparamagnetic iron oxide colloidal nanoparticles are dispersed in a hydrogel precursor solution. Ammonium persulfate solution and tetramethylethylenediamine are added dropwise to the hydrogel precursor solution. After mixing evenly, a gel solution is obtained. The solution is poured into a mold and cured under a magnetic field to obtain gel skin.

[0041] S2: Mix water and glycerol in a volume ratio of 1:1 until homogeneous to obtain a mixed solution. Add anhydrous lithium chloride powder to the mixed solution multiple times under ultrasonic conditions until no precipitate is found, and then stop adding to obtain a displacement solution.

[0042] S3: Immerse the gel skin obtained in step S1 completely in the replacement solution obtained in step S2, and remove it after more than 2 hours to obtain dual-signal sensing gel skin.

[0043] In this embodiment, superparamagnetic iron oxide colloidal nanoparticles are used as photonic crystal color-changing materials. After the superparamagnetic iron oxide colloidal nanoparticles self-assemble under magnetic field conditions and are solidified in the gel skin by the hydrogel precursor solution, the band gap of the photonic crystal color-changing material will change after the gel body undergoes mechanical strain. According to the Bragg diffraction formula, the reflected wavelength is proportional to the band gap size, so as to realize the structural color response strain-coordinated color change of the gel skin, thereby realizing optical sensing.

[0044] Using a glycerol / water binary solvent as an environmentally resistant solvent, glycerol has a low freezing point and forms a large number of hydrogen bonds with water molecules, which disrupts the formation and arrangement of ice crystals under low temperature conditions, greatly reducing the freezing point of the gel skin and improving its low-temperature environmental tolerance. 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 a self-regenerating material, and using anhydrous lithium chloride as an electrolyte, free Li can be generated in aqueous solution. + and Cl - This endows the gel skin with electrical sensing capabilities, giving it a sensitive electrical sensing ability with a specification factor of up to 3.311. This allows the gel skin to perform synergistic dual-signal sensing through optical color changes and electrical resistance signal changes. Furthermore, anhydrous lithium chloride has high hygroscopicity, and it can absorb a large amount of moisture from the air even in powder form. When introduced into the gel skin, the gel skin will be in a low vapor pressure state when dehydrated, and can spontaneously capture water molecules from the surrounding high vapor pressure environment to achieve self-regeneration.

[0046] Furthermore, anhydrous lithium chloride generates free Li in aqueous solution. + and Cl - It can combine with multiple water molecules, disrupting the hydrogen bond interactions between water molecules under low temperature conditions, thus disrupting the formation and arrangement of ice crystals under low temperature conditions. In turn, it has a synergistic effect with glycerol in lowering the freezing point, and can achieve almost no ice crystal formation within a temperature range of 20℃ to -40℃.

[0047] Optionally, step S1 further includes: preparing superparamagnetic iron oxide colloidal nanoparticles using a hydrothermal method, dissolving ferrocene in acetone solution, sonicating for more than 5 minutes, stirring until homogeneous, adding hydrogen peroxide solution dropwise, stirring for 20-30 minutes, heating at or above 210°C for more than 48 hours, and drying under magnetic field conditions to obtain superparamagnetic iron oxide colloidal nanoparticles.

[0048] In this optional embodiment, after adding hydrogen peroxide solution and stirring evenly, the solution is placed in a hydrothermal reactor. The hydrothermal reactor is placed in a forced-air drying oven and heated at or 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 drying step under magnetic field conditions specifically includes: ultrasonic cleaning with acetone and anhydrous ethanol in sequence, followed by 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, and after being ultrasonically cleaned several times with acetone and anhydrous ethanol, it is dried under a magnetic field at 40°C to obtain superparamagnetic iron oxide colloidal nanoparticles.

[0052] Optionally, step S1 further includes: dissolving gelatin, acrylamide and N,N-methylenebisacrylamide in water under water bath heating at 80°C or above, and stirring magnetically to obtain a hydrogel precursor solution.

[0053] In this optional embodiment, the gel skin can form a dual-network structure through the physical cross-linking of gelatin and the chemical cross-linking of acrylamide, with N,N'-methylenebisacrylamide as the cross-linking agent, to obtain a hydrogel precursor solution, and 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 cured for more than 5 hours under a magnetic field of 240-260 mt at a low temperature below 0°C to obtain gel skin.

[0056] In this optional embodiment, superparamagnetic iron oxide colloidal nanoparticles can self-assemble into a photonic crystal nanoarray under the action of a magnetic field. After the gel skin is cured, it is fixed inside the gel skin, producing a brilliant structural color.

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

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

[0059] The present invention provides a dual-signal sensing gel skin, which is prepared by the dual-signal sensing gel skin preparation method described in any of the preceding embodiments.

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

[0061] This invention provides an application of the dual-signal sensing gel skin described above in the field of flexible sensing devices.

[0062] The present invention will be further described below with reference to specific embodiments.

[0063] Example 1: Preparation of dual-signal sensing gel skin.

[0064] Superparamagnetic iron oxide colloidal nanoparticles were synthesized via a hydrothermal method. 0.54 g of ferrocene was dissolved in 54 ml of acetone solution and sonicated for 5 minutes. The mixture was then stirred uniformly using a magnetic stirrer. Subsequently, 2 ml of 30% hydrogen peroxide solution was added dropwise using a syringe, and magnetic stirring continued for 30 minutes, resulting in an orange solution. The orange solution was poured into a 100 ml hydrothermal reactor and heated at 210°C for 48 hours in a forced-air drying oven before cooling to room temperature. The solution from the hydrothermal reactor was then poured into a beaker and ultrasonically cleaned several times with acetone and anhydrous ethanol, followed by drying under a magnetic field at 40°C to obtain superparamagnetic iron oxide colloidal nanoparticles. Figure 2 As shown, a structural color photograph of the superparamagnetic iron oxide colloidal nanoparticle solution under a magnetic field can be observed. Furthermore, SEM images were obtained by scanning the surface of the iron oxide colloidal nanoparticle solution point-by-point with a focused electron beam, as shown below. Figure 3 As shown.

[0065] To prepare the hydrogel precursor solution, 0.5 g gelatin, 2 g acrylamide and 0.008 g N,N-methylenebisacrylamide were dissolved in water under a water bath at 80 °C, and the mixture was magnetically stirred until homogeneous. The water bath heating time was 15 min to obtain the hydrogel precursor solution.

[0066] In situ polymerization was used. 0.3g of superparamagnetic iron oxide colloidal nanoparticles were dispersed in a hydrogel precursor solution at 80℃. After the gel precursor solution cooled to room temperature, 0.1ml of ammonium persulfate solution as initiator and 10uL of tetramethylethylenediamine as accelerator were added dropwise to the hydrogel precursor solution. After mixing evenly, a gel solution was obtained. The gel solution was quickly poured into a mold and solidified under a 250mt magnetic field at low temperature (0℃) to obtain a gel skin. The thickness of the gel skin can be controlled as needed by adjusting the mold height, with the optimal thickness being 0.5-1mm.

[0067] To prepare the displacement solution, water and glycerol were mixed evenly at a volume ratio of 1:1 to obtain a mixed solution. Anhydrous lithium chloride powder was added to the mixed solution multiple times under ultrasonic conditions (after the addition was completed, LiCl accounted for 30% of the total mass fraction of the mixed solution) until no white precipitate was found, and then the addition was stopped to obtain the displacement solution.

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

[0069] Comparative Example 1: Preparation of hydrogel and organic gel skin.

[0070] Superparamagnetic iron oxide colloidal nanoparticles were synthesized via a hydrothermal method. 0.54 g of ferrocene was dissolved in 54 ml of acetone solution and sonicated for 5 minutes. The mixture was then stirred uniformly using a magnetic stirrer. Subsequently, 2 ml of 30% hydrogen peroxide solution was added dropwise using a syringe, and magnetic stirring continued for 30 minutes, resulting in an orange solution. The orange solution was poured into a 100 ml hydrothermal reactor and heated at 210°C for 48 hours in a forced-air drying oven before cooling to room temperature. The solution from the hydrothermal reactor was then poured into a beaker and ultrasonically cleaned several times with acetone and anhydrous ethanol, followed by drying under a magnetic field at 40°C to obtain superparamagnetic iron oxide colloidal nanoparticles. Figure 2 As shown, a structural color photograph of the superparamagnetic iron oxide colloidal nanoparticle solution under a magnetic field can be observed. Furthermore, SEM images were obtained by scanning the surface of the iron oxide colloidal nanoparticle solution point-by-point with a focused electron beam, as shown below. Figure 3 As shown.

[0071] To prepare the hydrogel precursor solution, 0.5 g gelatin, 2 g acrylamide and 0.008 g N,N-methylenebisacrylamide were dissolved in water under a water bath at 80 °C, and the mixture was magnetically stirred until homogeneous. The water bath heating time was 15 min to obtain the hydrogel precursor solution.

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

[0073] To prepare the displacement solution, water and glycerol were mixed evenly at a volume ratio of 1:1.

[0074] Organic gel skin is prepared by solvent displacement method. The hydrogel skin is completely immersed in the displacement solution and removed after 2 hours to obtain organic gel skin. The residual liquid on the surface of the organic gel skin is then cleaned with filter paper.

[0075] Effect Example

[0076] The dual-signal sensing gel skin prepared in Example 1 was subjected to a freeze-thaw DSC experiment. The testing method used differential scanning calorimetry to measure the freezing point of the dual-signal sensing gel skin under low-temperature conditions, thereby verifying its stable operation under low-temperature conditions. Figure 4 As shown, the freezing point of the dual-signal sensing gel on the skin is approximately -46.4℃.

[0077] The water loss resistance of the dual-signal sensing gel skin prepared in Example 1 was tested. The test method involved setting up a humidity and temperature measuring instrument and an electronic balance platform to test the water loss of different gel skins. Figure 5 As shown, three types of skin were tested: the dual-signal sensing gel skin (i.e., gel skin) of Example 1, the hydrogel and the organic gel of Comparative Example 1. In the 15-day experiment under room temperature conditions (25℃-50%RH), the dual-signal sensing gel skin showed a very strong resistance to water loss.

[0078] The self-regeneration capacity of the dual-signal sensing gel skin prepared in Example 1 was tested. The test method involved setting up a forced-air drying oven and an electronic balance platform to assess the self-regeneration capacity of different gel skins. Figure 6 As shown, the mass changes of three types of skin—the dual-signal sensing gel skin (i.e., gel skin) of Example 1, the hydrogel skin of Comparative Example 1, and the organic gel skin—were tested after heating at 60°C for 40 hours. During the 40-hour experiment, the dual-signal sensing gel skin exhibited a very strong self-regeneration ability. Specifically, after heating at 60°C for 12 hours, the total mass of the dual-signal sensing gel skin decreased to approximately 80% of its initial mass, and then gradually captured moisture from the air after 28 hours, restoring its original mass.

[0079] Optical signal detection was performed on the dual-signal sensing gel skin prepared in Example 1. The detection method involved testing the changes in the reflectance peaks of the gel skin using a self-built Y-shaped optical fiber and spectrometer platform. Figure 7 As shown, the reflection peak shifts from red to blue as strain increases, demonstrating that gel skin can be applied to the optical sensing capabilities of human motion monitoring.

[0080] The dual-signal sensing gel skin prepared in Example 1 was subjected to electrical signal detection. The detection method involved testing the resistance signal changes of the gel skin using a self-built electrochemical workstation, a rotary motor, and a slider platform. Figure 8 As shown, the resistance signal increases continuously with increasing strain, proving that gel skin can be applied to the electrical sensing capabilities of human motion monitoring.

[0081] The motion sensing capability of the dual-signal sensing gel skin prepared in Example 1 was verified. The effect of the dual-signal sensing gel skin in solvents containing and without LiCl was also verified. A set of replacement solutions without LiCl was prepared, and sensing gel skin was fabricated accordingly. Figure 9As shown, almost no swelling occurs in the dual-signal sensing gel skin obtained by displacement with LiCl-containing replacement solution. This is due to the salting-out effect. The high concentration of salt reduces the amount of "free water" in the solvent, which inhibits the swelling effect of the gel. Therefore, the internal photonic crystal structure color is not affected. However, the sensing gel skin obtained by displacement with a simple water-glycerol binary solvent will cause the gel to swell over a large area, resulting in instability of the structure color.

[0082] The motion sensing capability of the dual-signal sensing gel skin prepared in Example 1 was verified. The verification method involved testing the motion sensing capability of the gel skin using PI tape, conductive copper foil tape, and an electrochemical platform. Changes in the resistance signal of the gel skin under movement at different locations (finger, ankle, knee) were detected. Figure 10 As shown, the resistance signal of the gel skin changes during finger movement; as... Figure 11 As shown, the resistance signal changes of the gel skin during ankle movement; Figure 12 As shown, the resistance signal of the gel skin changes during movement at the knee. It is evident that the dual-signal sensing gel skin of Example 1 exhibits good motion sensing capabilities at different locations.

[0083] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing dual-signal sensing gel skin, characterized in that, Includes the following steps: S1: Superparamagnetic iron oxide colloidal nanoparticles are dispersed in a hydrogel precursor solution. Ammonium persulfate solution and tetramethylethylenediamine are added dropwise to the hydrogel precursor solution and mixed evenly to obtain a gel solution. The gel solution is poured into a mold and cured under a magnetic field to obtain a gel skin. In this process, gelatin, acrylamide, and N,N-methylenebisacrylamide are dissolved in water under a water bath heating temperature above 80°C and magnetically stirred evenly to obtain the hydrogel precursor solution. S2: Mix water and glycerol in a volume ratio of 1:1 until homogeneous to obtain a mixed solution. Add anhydrous lithium chloride powder to the mixed solution multiple times under ultrasonic conditions until no precipitate is found, and then stop adding to obtain a displacement solution. S3: Immerse the gel skin obtained in step S1 completely in the replacement solution obtained in step S2, and remove it after more than 2 hours to obtain dual-signal sensing gel skin.

2. The method for preparing dual-signal sensing gel skin according to claim 1, characterized in that, Step S1 further includes: preparing the superparamagnetic iron oxide colloidal nanoparticles using a hydrothermal method, dissolving ferrocene in acetone solution, sonicating for more than 5 minutes, stirring until homogeneous, adding hydrogen peroxide solution dropwise, stirring for 20-30 minutes, heating at or above 210°C for more than 48 hours, and drying under magnetic field conditions to obtain the superparamagnetic iron oxide colloidal nanoparticles.

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

5. The method for preparing dual-signal sensing gel skin according to claim 1, characterized in that, The mass ratio of gelatin, acrylamide, and N,N-methylenebisacrylamide was 0.5:2:0.

008.

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

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

8. A dual-signal sensing gel skin, characterized in that, It is prepared using the method for preparing dual-signal sensing gel skin as described in any one of claims 1-7.

9. The application of the dual-signal sensing gel skin as described in claim 8 in the field of flexible sensing devices.

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