Ion piezoelectric self-powered flexible sensor and preparation method and application thereof

Abstract

This invention belongs to the field of sensor material technology and discloses a method for preparing an ion-piezoelectric self-powered flexible sensor. The specific method is as follows: First, quaternized gelatin is prepared; then, a quaternized gelatin / polyacrylic acid dual-network hydrogel is prepared, and an ionic liquid and an aminated cage-like polysilsesquioxane are introduced into it. Finally, the sensor is encapsulated to form a self-powered flexible sensor. This invention also discloses the ion-piezoelectric self-powered flexible sensor prepared according to the above method and its applications, solving the problems of existing ion-piezoelectric hydrogels, which mostly use synthetic polymers as matrix materials and have relatively limited functionality, insufficient biocompatibility, and poor degradation performance.

Description

Technical Field

[0001] This invention belongs to the field of sensor material technology, specifically relating to an ion piezoelectric self-powered flexible sensor, and also to a method for preparing and using the aforementioned flexible sensor. Background Technology

[0002] With the rapid development of artificial intelligence technology, smart devices are placing higher demands on the performance of sensing terminals. As the "eyes" and "nerves" of smart devices, sensing devices are evolving towards high performance, low cost, high portability, and scenario-specific adaptability. Flexible wearable sensors, capable of stable operation under large deformation conditions such as stretching, compression, and bending, and characterized by their lightweight, portability, and good fit, have become an important development direction for next-generation smart sensing terminals.

[0003] Traditional sensing materials such as metals and semiconductors typically suffer from problems such as high rigidity, poor biocompatibility, insufficient interfacial adaptability, and high manufacturing costs, making it difficult to meet the application requirements of wearable devices for long-term, safe, and stable contact with human skin or biological tissues. Hydrogels, a class of three-dimensional polymer network materials composed of natural or synthetic polymers, have advantages such as high water content, tunable mechanical properties, good biocompatibility, and designable ionic conductivity, and have been widely used in sensors, actuators, soft robots, and biomedical devices.

[0004] Compared to traditional elastomers such as rubber and silicone, the three-dimensional network structure and high water content of hydrogels facilitate the uniform dispersion of conductive fillers and the transport of electrolyte ions, thus endowing the material with excellent electrical conductivity. Simultaneously, by controlling the polymer network structure, the elastic modulus of the hydrogel can be matched with that of human skin or biological tissue, reducing discomfort and potential damage caused by interfacial mechanical mismatch. Furthermore, good biocompatibility helps achieve healthy contact between the hydrogel and human skin or biological tissue, reducing the risk of inflammatory reactions. Therefore, hydrogel-based strain and pressure sensors have broad application prospects in fields such as electronic skin, health monitoring, human-computer interaction, and implantable devices.

[0005] Ion-piezoelectric hydrogel sensors can convert mechanical energy into electrical energy through the directional migration of ions and the establishment of concentration gradients under external force. They are self-powered sensors requiring no external power source and possess high tensile strength, good flexibility, and biocompatibility, aligning with the development trend of passive, lightweight, and highly biocompatible flexible sensors, thus attracting widespread attention in recent years. Their basic working principle is as follows: external mechanical stimulation causes deformation of the hydrogel. The difference in migration rates between anions and cations within the hydrogel leads to an asymmetric distribution, resulting in a net charge imbalance and potential difference. This converts the mechanical stimulation into a detectable electrical signal, thereby achieving self-driven pressure or strain detection.

[0006] However, existing ion-piezoelectric hydrogels mostly use synthetic polymers as matrix materials, which still suffer from problems such as relatively limited functionality, insufficient biocompatibility, and poor degradation performance, thus restricting their further application in long-term wearable monitoring, biomedical sensing, and implantable devices. Therefore, it is crucial to develop an ion-piezoelectric hydrogel sensor that combines good flexibility, biocompatibility, self-powered sensing capability, mechanical stability, and ion conductivity. Summary of the Invention

[0007] The first objective of this invention is to provide an ion-piezoelectric self-powered flexible sensor, which solves the problems of existing ion-piezoelectric hydrogels, which are mostly based on synthetic polymers, and have relatively simple functions, insufficient biocompatibility, and poor degradation performance.

[0008] A second objective of this invention is to provide a method for fabricating the flexible sensor described above.

[0009] A third objective of this invention is to provide applications using the aforementioned flexible sensor.

[0010] The first technical solution adopted in this invention is: a method for preparing an ion piezoelectric self-powered flexible sensor. The specific method for preparing the self-powered flexible sensor is as follows: first, quaternized gelatin is prepared, then quaternized gelatin / polyacrylic acid dual-network hydrogel is prepared, and ionic liquid and aminated cage-type polysilsesquioxane are introduced therein, and finally encapsulation is performed to form a self-powered flexible sensor.

[0011] The first technical solution adopted in this invention is further characterized by: The fabrication method of the ion piezoelectric self-powered flexible sensor is specifically carried out according to the following steps: Step 1: Add a certain amount of gelatin to deionized water to swell for a period of time, then stir and dissolve it in a hot water bath. After adjusting the pH, add 2,3-epoxypropyltrimethylammonium chloride to react. Freeze-dry the solution after the reaction to obtain powder. Add a certain amount of organic solvent to extract the powder, and finally dry the powder to obtain quaternized ammonium gelatin. Step 2: Mix the quaternized gelatin prepared in Step 1 with acrylic acid and deionized water, add a certain amount of crosslinking agent and initiator, and stir to dissolve; Step 3: Based on the solution prepared in Step 2, add a certain amount of ionic liquid and disperse it evenly. Add a certain amount of aminated cage-type polysilsesquioxane to it, sonicate it, pour it into a template, and heat-cur it to obtain a hydrogel. Step 4: Finally, the hydrogel is encapsulated with copper tape, copper wires and polyimide to obtain an ion piezoelectric self-powered flexible sensor.

[0012] In step 1, the swelling time is 2-4 h; the water bath temperature is 35-55 ℃; the pH is 10-11; the freeze-drying time is 24-72 h; and the drying temperature is 45-60 ℃.

[0013] In step 1, the mass of gelatin is 2-8 wt.% of deionized water; the concentration of 2,3-epoxypropyltrimethylammonium chloride in deionized water is 3-7 mol / L; and the amount of organic solvent added is 10-20 times the mass of 2,3-epoxypropyltrimethylammonium chloride.

[0014] The organic solvent in step 1 is selected from one or more of acetone, butanone, diethyl ether, toluene, xylene, tetrahydrofuran, ethylene glycol, N,N-dimethylformamide, or N,N-dimethylacetamide.

[0015] In step 2, the mass of acrylic acid is 20-80% of the mass of deionized water, the mass ratio of quaternized gelatin to acrylic acid is 0.25-1.5, the mass of crosslinking agent is 0.1-1% of the total mass, and the mass of initiator is 1-2% of the total mass.

[0016] In step 3, the mass of the ionic liquid is 1% to 10% of the total mass; the mass of the aminated cage-type polysilsesquioxane is 0.5% to 2.5% of the total mass; and the thermosetting temperature is 60-80 ℃. The ionic liquid in step 3 is a hydrophilic imidazole chloride salt selected from one or more of the following: 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium acetate, 1-butylpyridine chloride, and tetrabutylammonium chloride.

[0017] The second technical solution adopted in this invention is: an ion piezoelectric self-powered flexible sensor obtained according to the above preparation method.

[0018] The third technical solution adopted in this invention is: the application of the above-mentioned ion piezoelectric self-powered flexible sensor in self-powering.

[0019] The fourth technical solution adopted in this invention is: the application of the above-mentioned ion piezoelectric self-powered flexible sensor in sensing.

[0020] The beneficial effects of this invention are: (1) The self-powered flexible sensor of the present invention is based on the ion piezoelectric effect, which can generate an ion piezoelectric response through the synergistic effect of mechanical stress-induced asymmetric ion migration dynamics and interface polarization effect. Among them, the dual network formed by quaternized ammonium gelatin and polyacrylic acid provides a stable channel for ion migration, the dissociation of ionic liquid provides sufficient mobile ions, and the aminated cage-like polysilsesquioxane significantly improves the force-to-electric conversion efficiency by optimizing the network structure, amplifying the difference in ion mobility and enhancing interface polarization. The three factors work together to achieve excellent ion piezoelectric performance. Under these conditions, the flexible sensor prepared by composite hydrogel forms a stable hybrid network, and the mechanical properties and piezoelectric output performance are optimal.

[0021] (2) The self-powered flexible sensor prepared by the present invention has good reversibility, fast response capability and cycle stability. It maintains stable output after multiple cycle tests, which meets the long-term application requirements.

[0022] (3) The present invention introduces two types of fillers into the hydrogel matrix, and through the synergistic effect of each component, the mechanical properties, piezoelectric properties and application properties are optimized and balanced. Attached Figure Description

[0023] Figure 1 This is a synthetic route diagram of the quaternized gelatin prepared in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the hydrogel prepared in Example 1 of the present invention; Figure 3 This is a schematic diagram of the stress-strain curves of hydrogels prepared by different proportions of ionic liquid and aminated cage-type polysilsesquioxane according to the present invention. Figure 4 This is a schematic diagram of the output voltage response curves of the self-powered flexible sensors prepared by different proportions of ionic liquid and aminated cage-type polysilsesquioxane according to the present invention. Figure 5 The graph shows the sensing performance of the self-powered flexible sensor prepared in Example 1 of this invention for monitoring the finger bending angle during human motion. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] This invention provides a method for preparing an ion-piezoelectric self-powered flexible sensor, wherein the specific preparation process of quaternized gelatin is as follows: Figure 1 As shown, the fabricated self-powered flexible sensor exhibits excellent performance, specifically as follows: Figure 2-5 As shown; First, quaternized gelatin is prepared, then a quaternized gelatin / polyacrylic acid dual-network hydrogel is prepared, and ionic liquid and aminated cage-type polysilsesquioxane are introduced into it. Finally, it is encapsulated to form a self-powered flexible sensor. The specific preparation steps are as follows: Step 1: Add a certain amount of gelatin to deionized water and let it swell for 2-4 hours. Then, stir and dissolve it in a hot water bath at a temperature of 35-55 ℃. Adjust the pH to 10-11 and add 2,3-epoxypropyltrimethylammonium chloride to react. Freeze-dry the solution after the reaction to obtain powder. Add a certain amount of organic solvent to extract the powder. Finally, dry the powder at 45-60 ℃ to obtain quaternized gelatin. The mass of gelatin is 2-8 wt.% of deionized water; the concentration of 2,3-epoxypropyltrimethylammonium chloride in deionized water is 3-7 mol / L; the amount of organic solvent added is 10-20 times the mass of 2,3-epoxypropyltrimethylammonium chloride. The organic solvent is selected from one or more of acetone, butanone, diethyl ether, toluene, xylene, tetrahydrofuran, ethylene glycol, N,N-dimethylformamide, or N,N-dimethylacetamide; Step 2: Mix the quaternized gelatin prepared in Step 1 with acrylic acid and deionized water, add a certain amount of crosslinking agent and initiator, and stir to dissolve; The mass of acrylic acid is 20-80% of the mass of deionized water, and the mass ratio of quaternized gelatin to acrylic acid is 0.25-1.5; the mass of crosslinking agent is 0.1-1% of the total mass, and the mass of initiator is 1-2% of the total mass. Step 3: Based on the solution prepared in Step 2, add a certain amount of ionic liquid and disperse it evenly. Add a certain amount of aminated cage-type polysilsesquioxane to it, sonicate it, pour it into a template, and heat-cur it to obtain a hydrogel. The ionic liquid accounts for 1% to 10% of the total mass; the aminated cage-type polysilsesquioxane accounts for 0.5% to 2.5% of the total mass; the thermosetting temperature is 60-80 ℃. The ionic liquid in step 3 is a hydrophilic imidazole chloride salt selected from one or more of the following: 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-ethyl-3-methylimidazolium chloride (EMIMCl), 1-propyl-3-methylimidazolium chloride (PMIMCl), 1-hexyl-3-methylimidazolium chloride (HMIMCl), 1-octyl-3-methylimidazolium chloride (OMIMCl), 1-allyl-3-methylimidazolium chloride (AMIMCl), 1-butyl-2,3-dimethylimidazolium chloride (BMMIMCl), 1-butyl-3-methylimidazolium bromide ([BMIM]Br), 1-butyl-3-methylimidazolium acetate ([BMIM]Ac), 1-butylpyridine chloride ([BPy]Cl), and tetrabutylammonium chloride ([TBA]Cl). Step 4: Finally, the hydrogel is encapsulated with copper tape, copper wires and polyimide to obtain an ion piezoelectric self-powered flexible sensor.

[0026] The present invention also discloses an ion piezoelectric self-powered flexible sensor obtained according to the above preparation method.

[0027] The present invention also discloses the application of the above-mentioned ion piezoelectric self-powered flexible sensor in self-powering applications.

[0028] The present invention also discloses the application of the above-mentioned ion piezoelectric self-powered flexible sensor in sensing.

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Example 1 This embodiment provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (9.57 g, 6.38 wt.%) was added to deionized water (150 mL) and swollen (2 h); then it was placed in a hot water bath (50 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 10 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (11.37 g, 5 mol / L) were added to a three-necked flask and stirred in a hot water bath (50 °C) for 5 h. After the reaction was completed, the product was freeze-dried and extracted with acetone (170 mL, 15 times) for 72 h. Finally, it was dried at 45 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 1g of EPTAC-Gel prepared in S1 and mix it with 1g of acrylic acid (AA), and add 3mL of water, 0.25wt.% N,N-methylenebisacrylamide (MBAA) and 1wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0031] (3) Based on the solution prepared in S2, 5% BMIMCl (ionic liquid) and 2% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 60℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained by simple encapsulation with copper tape, copper wires, and polyimide.

[0032] Figure 2 Here are scanning electron microscope images of the ion-piezoelectric hydrogel prepared in Example 1 of this invention; From Figure 2 It can be seen that the prepared ion-piezoelectric hydrogel has a well-organized three-dimensional network structure and contains a large number of uniformly distributed pores. The porous structure in the matrix can serve as a migration channel for charge carriers. This structural feature is beneficial to promoting ion migration during the subsequent ion piezoelectric output process, providing a structural basis for the ion-piezoelectric properties of the hydrogel.

[0033] Figure 5 This is a graph showing the performance of the self-powered flexible sensor prepared in Example 1 of this invention for monitoring the finger bending angle during human motion. Figure 5 It can be seen that the prepared self-powered flexible sensor has excellent sensing performance. When the sensor is attached to the joint of a human finger, as the bending amplitude of the joint increases, the deformation of the hydrogel increases synchronously, and the corresponding output voltage also increases, which provides support for the good sensing performance of the self-powered flexible sensor.

[0034] Example 2 This embodiment provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (3.19 g, 2.13 wt.%) was added to deionized water (150 mL) and swollen (3 h); then it was placed in a hot water bath (35 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 10 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (6.82 g, 3 mol / L) were added to a three-necked flask and stirred in a hot water bath (35 °C) for 5 h. After the reaction was completed, the product was freeze-dried and extracted with butanone (70 mL, 10 times) for 24 h. Finally, it was dried at 50 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 0.15g of EPTAC-Gel prepared in S1 and mix it with 0.6g of acrylic acid (AA), and add 3mL of water, 0.1wt.% N,N-methylenebisacrylamide (MBAA) and 1.5wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0035] (3) Based on the solution prepared in S2, 1% EMIMCl (ionic liquid) and 0.5% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 70℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained through simple encapsulation with copper tape, copper wires, and polyimide.

[0036] Example 3 This embodiment provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (6.4 g, 4.2 wt.%) was added to deionized water (150 mL) and swollen (2 h); then it was placed in a hot water bath (45 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 11 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (13.64 g, 6 mol / L) were added to a three-necked flask and stirred in a hot water bath (45 °C) for 5 h. After the reaction was completed, the product was freeze-dried and extracted with diethyl ether (245 mL, 18 times) for 48 h. Finally, it was dried at 55 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 0.9g of EPTAC-Gel prepared in S1 and mix it with 1.8g of acrylic acid (AA), and add 3mL of water, 0.75wt.% N,N-methylenebisacrylamide (MBAA) and 1.5wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0037] (3) Based on the solution prepared in S2, 2.5% PMIMCl (ionic liquid) and 1.5% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 70℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained through simple encapsulation with copper tape, copper wires, and polyimide.

[0038] Example 4 This embodiment provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (12g, 8wt.%) was added to deionized water (150mL) and swollen (2h); then it was placed in a hot water bath (55℃) and stirred (1h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 11 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (15.92g, 7mol / L) were added to a three-necked flask and stirred in a hot water bath (55℃) for 5h. After the reaction was completed, the product was freeze-dried and extracted with acetone and butanone (320mL, 20 times) for 60h. Finally, it was dried at 60℃ to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 3.6g of EPTAC-Gel prepared in S1 and mix it with 2.4g of acrylic acid (AA), and add 3mL of water, 1wt.% N,N-methylenebisacrylamide (MBAA) and 2wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0039] (3) Based on the solution prepared in S2, 10% HMIMCl (ionic liquid) and 2.5% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in an 80℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained through simple encapsulation with copper tape, copper wires, and polyimide.

[0040] Example 5 This embodiment provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (7.5 g, 5 wt.%) was added to deionized water (150 mL) and swollen (2 h); then it was placed in a hot water bath (40 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 10 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (9.09 g, 4 mol / L) were added to a three-necked flask and stirred in a hot water bath (40 °C) for 5 h. After the reaction was completed, the product was freeze-dried and extracted with acetone and diethyl ether (120 mL, 13 times) for 50 h. Finally, it was dried at 50 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 0.9g of EPTAC-Gel prepared in S1 and mix it with 1.2g of acrylic acid (AA), and add 3mL of water, 0.75wt.% N,N-methylenebisacrylamide (MBAA) and 1.75wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0041] (3) Based on the solution prepared in S2, 7.5% OMIMCl (ionic liquid) and 1% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 70℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained through simple encapsulation with copper tape, copper wires, and polyimide.

[0042] Comparative Example 1 This comparative example provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (9.57 g, 6.38 wt.%) was added to deionized water (150 mL) and swollen (2 h); then it was placed in a hot water bath (50 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 10 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (11.37 g, 5 mol / L) were added to a three-necked flask and stirred in a hot water bath (50 °C) for 5 h. After the reaction was completed, the product was freeze-dried and extracted with acetone (170 mL, 15 times) for 72 h. Finally, it was dried at 45 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 1g of EPTAC-Gel prepared in S1 and mix it with 1g of acrylic acid (AA), and add 3mL of water, 0.25wt.% N,N-methylenebisacrylamide (MBAA) and 1wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0043] (3) Based on the solution prepared in S2, 0% BMIMCl (ionic liquid) and 2% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 60℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained by simple encapsulation with copper tape, copper wires, and polyimide.

[0044] Comparative Example 2 This comparative example provides an ion-piezoelectric hydrogel for a self-powered flexible sensor. The fabrication method of this self-powered flexible sensor includes the following steps: (1) Gelatin (Gel) (9.57 g, 6.38 wt.%) was added to deionized water (150 mL) and swollen (2 h); then it was placed in a hot water bath (50 °C) and stirred (1 h) until the gelatin was completely dissolved to obtain a gelatin solution. The pH of the above gelatin solution was adjusted to 10 with sodium hydroxide solution, and the solution and EPTAC (2,3-epoxypropyltrimethylammonium chloride) (11.37 g) were added to a three-necked flask and stirred in a hot water bath (50 °C) (5 h). After the reaction was completed, the product was freeze-dried and extracted with acetone (170 mL, 15 times) for 72 h. Finally, it was dried at 45 °C to obtain quaternized ammonium gelatin (EPTAC-Gel) powder; (2) Take 1g of EPTAC-Gel prepared in S1 and mix it with 1g of acrylic acid (AA), and add 3mL of water, 0.25wt.% N,N-methylenebisacrylamide (MBAA) and 1wt.% ammonium persulfate (APS), and stir to dissolve evenly.

[0045] (3) Based on the solution prepared in S2, 5% BMIMCl (ionic liquid) and 0% NH2-POSS (aminated cage-type polysilsesquioxane) were introduced, ultrasonically dispersed, poured into a template, and then placed in a 60℃ oven to cure for 2 hours to obtain a hydrogel. Finally, the ion piezoelectric flexible sensor was obtained by simple encapsulation with copper tape, copper wires, and polyimide.

[0046] Figure 3 The stress-strain curves of ion-piezoelectric hydrogels prepared by different proportions of BMIMCl and NH2-POSS in Examples 1 and 1-2 of this invention are shown. Figure 3 It can be seen that the prepared ion-piezoelectric hydrogel has good mechanical properties, and the strength of the hydrogel further increases with the increase of NH2-POSS content, which can provide support for the good mechanical properties of the self-powered flexible sensor.

[0047] Figure 4 The output voltage response curves of the self-powered flexible sensors prepared in Embodiment 1 and Comparative Examples 1-2 of this invention are shown below; Figure 4 It can be seen that the prepared self-powered flexible sensor has good electrical performance, and with the increase of NH2-POSS content, the voltage output of the self-powered flexible sensor further increases, which provides support for the good electrical performance of the self-powered flexible sensor.

[0048] Example 6 The application of the ion piezoelectric self-powered flexible sensor of the present invention in self-powered applications.

[0049] Example 7 The present invention relates to the application of the ion piezoelectric self-powered flexible sensor in sensing, for example, in human motion monitoring.

Claims

1. Process for the preparation of an ion piezoelectric self-powered flexible sensor, characterized in that, The specific preparation method of the self-powered flexible sensor is as follows: First, quaternized gelatin is prepared, then quaternized gelatin / polyacrylic acid dual-network hydrogel is prepared, and ionic liquid and aminated cage-type polysilsesquioxane are introduced therein. Finally, the sensor is encapsulated to form the self-powered flexible sensor.

2. The method of claim 1, wherein the ion piezoelectric self-powered flexible sensor is prepared by the steps of: Prepare according to the following steps: Step 1: Add a certain amount of gelatin to deionized water to swell for a period of time, then stir and dissolve it in a hot water bath. After adjusting the pH, add 2,3-epoxypropyltrimethylammonium chloride to react. Freeze-dry the solution after the reaction to obtain powder. Add a certain amount of organic solvent to extract the powder, and finally dry the powder to obtain quaternized ammonium gelatin. Step 2: Mix the quaternized gelatin prepared in Step 1 with acrylic acid and deionized water, add a certain amount of crosslinking agent and initiator, and stir to dissolve; Step 3: Based on the solution prepared in Step 2, add a certain amount of ionic liquid and disperse it evenly. Add a certain amount of aminated cage-type polysilsesquioxane to it, sonicate it, pour it into a template, and heat-cur it to obtain a hydrogel. Step 4: Finally, the hydrogel is encapsulated with copper tape, copper wires, and polyimide to obtain the ion piezoelectric self-powered flexible sensor.

3. The method of claim 2, wherein the method further comprises: In step 1, the swelling time is 2-4 hours; the water bath temperature is 35-55°C; the pH is 10-11; the freeze-drying time is 24-72 hours; and the drying temperature is 45-60°C.

4. The method for preparing the ion piezoelectric self-powered flexible sensor according to claim 2, characterized in that, In step 1, the mass of gelatin is 2-8 wt.% of deionized water; the concentration of 2,3-epoxypropyltrimethylammonium chloride in deionized water is 3-7 mol / L; and the amount of organic solvent added is 10-20 times the mass of 2,3-epoxypropyltrimethylammonium chloride.

5. The method for preparing the ion piezoelectric self-powered flexible sensor according to claim 2, characterized in that, The organic solvent in step 1 is selected from one or more of acetone, butanone, diethyl ether, toluene, xylene, tetrahydrofuran, ethylene glycol, N,N-dimethylformamide, or N,N-dimethylacetamide.

6. The method for preparing the ion piezoelectric self-powered flexible sensor according to claim 2, characterized in that, In step 2, the mass of acrylic acid is 20-80% of the mass of deionized water, the mass ratio of quaternized gelatin to acrylic acid is 0.25-1.5, the mass of crosslinking agent is 0.1-1% of the total mass, and the mass of initiator is 1-2% of the total mass.

7. The method for preparing the ion piezoelectric self-powered flexible sensor according to claim 2, characterized in that, In step 3, the mass of the ionic liquid is 1% to 10% of the total mass; the mass of the aminated cage-type polysilsesquioxane is 0.5% to 2.5% of the total mass; and the thermosetting temperature is 60-80℃. The ionic liquid in step 3 is a hydrophilic imidazole chloride ionic liquid selected from one or more of the following: 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-allyl-3-methylimidazolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium acetate, 1-butylpyridine chloride, and tetrabutylammonium chloride.

8. The ion piezoelectric self-powered flexible sensor obtained by the preparation method according to any one of claims 1-7.

9. The application of the ion piezoelectric self-powered flexible sensor according to claim 8 in self-powering applications.

10. The application of the ion piezoelectric self-powered flexible sensor according to claim 8 in sensing.

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