Polyvinyl alcohol fabric hydrogel and its preparation method and application

Abstract

The application discloses a polyvinyl alcohol fabric hydrogel and a preparation method and application thereof, the polyvinyl alcohol fabric contains sodium chloride, glycerol and water, the fabric is coated by the polyvinyl alcohol hydrogel, the vinylon fabric is soaked in a sulfuric acid aqueous solution, the vinylon is reduced to polyvinyl alcohol, the polyvinyl alcohol fabric is obtained by washing with deionized water, the polyvinyl alcohol, glycerol, sodium chloride and deionized water are mixed, the impregnation solution is obtained by stirring, the polyvinyl alcohol fabric is added into the impregnation solution, and soaking is carried out until the polyvinyl alcohol fabric is fully swollen; the swollen polyvinyl alcohol fabric is placed between two layers of polypropylene films, the impregnation solution is squeezed out, the polyvinyl alcohol fabric hydrogel is obtained by subjecting the polyvinyl alcohol fabric to at least three freeze-thaw cycles, and the polyvinyl alcohol fabric hydrogel is applied as a strain sensor and a touch screen, and the touch screen is used for a computer for piano playing; the polyvinyl alcohol fabric hydrogel has the comprehensive performance of anti-freezing and moisturizing, anti-swelling, good mechanical properties, good strain sensing performance and touch screen function.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new materials, and particularly relates to a hydrogel, especially a polyvinyl alcohol fabric hydrogel, and a preparation method and application of the polyvinyl alcohol fabric hydrogel. BACKGROUND

[0002] Hydrogels have a high water content similar to human tissues and have excellent flexibility and biocompatibility. According to the difference in mechanical properties, hydrogels can be divided into anisotropic hydrogels and isotropic hydrogels. Hydrogels are widely used in the fields of artificial intelligent skin, biomedicine and bionic flexible drivers. Compared with various animal and fabric tissues, the common hydrogels have poor mechanical properties, for example, the tensile strength of unmodified polyvinyl alcohol (PVA) hydrogel is only 401 kPa, which greatly limits the promotion of hydrogels. At present, the main methods for toughening hydrogels are as follows:

[0003] 1. Adding nanomaterials such as carbon nanotubes, graphene oxide and magnetic iron oxide into the hydrogel. This method has the problem of being difficult to reasonably control the amount of addition, because the toughening effect of adding a small amount of nanomaterials is not obvious, and adding a large amount of nanomaterials will reduce the transparency, flexibility and biocompatibility of the hydrogel.

[0004] 2. Developing double-network hydrogels. The double-network hydrogel usually contains a hard and brittle cross-linked network and a soft and tough cross-linked network. The mechanical properties of the hydrogel prepared by this method are still unable to compare with the anisotropic biological tissues such as ligaments and tendons.

[0005] 3. Preparing unidirectional toughened hydrogels through special processes such as directional freezing and dry stretching. Although the hydrogels prepared by these processes have very good tensile properties in a certain direction, the hydrogels will inevitably be subjected to loads from all directions in various application scenarios, which requires the hydrogels to have good mechanical properties in different directions. In addition, the preparation conditions of these special processes are usually harsh and difficult to accurately control.

[0006] 4. Compounding materials with a woven structure with hydrogels. Although the hydrogels prepared by this method have good tensile strength in all directions, the breaking elongation of common materials with a woven structure, such as glass fiber fabric and cotton fiber fabric, is too low, which greatly limits the application of hydrogels.

[0007] In addition, typical hydrogels also have the problems of easy swelling, poor freeze resistance and poor dry resistance. SUMMARY

[0008] The polyvinyl alcohol fabric hydrogel has the advantages that: 1. excellent mechanical properties, good tensile strength and certain breaking elongation in different directions, and good tear resistance; 2. good anti-swelling performance, water retention performance, low-temperature resistance and transparency; 3. good conductivity and strain sensing performance, the conductivity can reach 0.102 S / m, the sensitivity of resistance change caused by strain is high in the strain range of 0-100%, can reach 1.41, and the linearity of resistance change with strain change is 0.999, and the polyvinyl alcohol fabric hydrogel can be used as a strain sensor to detect human motion deformation in real time.

[0009] In order to solve the above technical problems, the polyvinyl alcohol fabric hydrogel provided by the application adopts the technical scheme that: the polyvinyl alcohol fabric contains sodium chloride, glycerol and water, and the fabric is covered by the polyvinyl alcohol hydrogel.

[0010] The preparation method of the polyvinyl alcohol fabric hydrogel provided by the application adopts the technical scheme that includes the following steps:

[0011] Step (1): the vinylon fabric is soaked in a sulfuric acid aqueous solution, so that the vinylon is reduced to polyvinyl alcohol, and then the polyvinyl alcohol fabric is obtained by washing with deionized water;

[0012] Step (2): the polyvinyl alcohol, glycerol, sodium chloride and deionized water are mixed to obtain a uniform impregnation solution by stirring;

[0013] Step (3): the polyvinyl alcohol fabric is added to the impregnation solution, and is soaked until the polyvinyl alcohol fabric is fully swollen, then the swollen polyvinyl alcohol fabric is placed between two layers of polypropylene film, the impregnation solution in the polyvinyl alcohol fabric is squeezed out, and then the polyvinyl alcohol fabric is subjected to at least three freeze-thaw cycles to obtain the polyvinyl alcohol fabric hydrogel.

[0014] The application of the polyvinyl alcohol fabric hydrogel provided by the application is that: the polyvinyl alcohol fabric hydrogel is used as a strain sensor and a touch screen, and further, the touch screen is used for a computer for piano playing.

[0015] The polyvinyl alcohol fabric hydrogel provided by the application has the advantages that:

[0016] 1. excellent mechanical properties, good tensile strength and certain breaking elongation in different directions, and good tear resistance;

[0017] 2. good anti-swelling performance, water retention performance, low-temperature resistance and transparency;

[0018] 3. good conductivity and strain sensing performance, the conductivity can reach 0.102 S / m, the sensitivity of resistance change caused by strain is high in the strain range of 0-100%, can reach 1.41, and the linearity of resistance change with strain change is 0.999, and the polyvinyl alcohol fabric hydrogel can be used as a strain sensor to detect human motion deformation in real time.

[0019] 4. Good touch screen application function, capable of accurately detecting the position of the touch point. Integrating the hydrogel touch screen into a computer system can realize piano playing. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0021] Figure 1 The infrared spectra of PVFM, PVA hydrogel and PVA fabric hydrogel;

[0022] Figure 2 The structure of PVA fabric hydrogel under scanning electron microscope;

[0023] Figure 3 The tensile property curve of PVA hydrogel and PVA fabric hydrogel along the 0° direction;

[0024] Figure 4 The tensile property of PVA fabric hydrogel along the 0°, 45° and 90° directions;

[0025] Figure 5 The tear strength-displacement curve (width of 20mm) of PVA hydrogel and PVA fabric hydrogel;

[0026] Figure 6 The effective tear energy curve of PVA hydrogel and PVA fabric hydrogel under different widths;

[0027] Figure 7 The swelling rate curve of PVA hydrogel and PVA fabric hydrogel in deionized water;

[0028] Figure 8 The mass change rate graph of PVA fabric hydrogel in a constant temperature and humidity environment for 12 days;

[0029] Figure 9 The transparency diagram of PVFM fabric, PVA fabric and PVA fabric hydrogel;

[0030] Figure 10 The impedance spectrum curve of PVA fabric hydrogel;

[0031] Figure 11 The relative resistance change rate curve of PVA fabric hydrogel stretching;

[0032] Figure 12 The resistance change rate curve of the bending motion for monitoring the bending of human fingers;

[0033] Figure 13 The resistance change rate curve of the bending motion for monitoring the bending of human wrists;

[0034] Figure 14 Resistance rate of change graph for monitoring flexion movement of elbow flexion of human body;

[0035] Figure 15 Resistance rate of change graph for monitoring flexion movement of knee flexion of human body;

[0036] Figure 16 Test schematic diagram for one-dimensional ionic touch screen;

[0037] Figure 17 Test circuit diagram for one-dimensional ionic touch screen;

[0038] Figure 18 A1 current graph for different contact points (α = 0.25, 0.5 and 0.75);

[0039] Figure 19 Contact position and current relationship graph;

[0040] Figure 20 Structure diagram of two-dimensional ionic touch screen;

[0041] Figure 21 Test circuit diagram of two-dimensional ionic touch screen;

[0042] Figure 22 Physical schematic diagram of two-dimensional touch screen;

[0043] Figure 23 Corresponding current graph when clicking points A, B, C and D, while four ammeters are used for measurement. DETAILED DESCRIPTION

[0044] First, prepare the polyvinyl alcohol (PVA) fabric: soak the polyvinylformal (PVFM) fabric in an aqueous sulfuric acid solution to reduce it to PVA, then rinse it with a large amount of deionized water to obtain the PVA fabric.

[0045] Before putting the PVFM fabric into the aqueous sulfuric acid solution, it is first soaked in ethanol and ultrasonically treated for at least 30 minutes to remove surface impurities of the PVFM fabric. The concentration of the aqueous sulfuric acid solution is 50-60%, and the PVFM fabric is soaked in the 50-60% aqueous sulfuric acid solution for at least 30 minutes to allow it to react sufficiently.

[0046] Next, prepare the impregnation solution: mix polyvinyl alcohol, glycerol, sodium chloride and deionized water thoroughly to obtain a uniform solution by stirring.

[0047] Wherein, polyvinyl alcohol is 5-10 wt%, glycerol is 10-45 wt%, sodium chloride is 0.1-0.6 wt%, and deionized water is 45-80 wt% by weight (wt). Polyvinyl alcohol is added to a mixed solution composed of glycerol, sodium chloride and deionized water, and stirred at 85-95℃ for 1-2 hours to obtain a uniform solution.

[0048] Finally, the PVA fabric hydrogel is prepared: the PVA fabric is added to the immersion solution, and soaked at 50-60℃ for at least 12 hours to make the PVA fabric fully swollen, then the PVA fabric is placed between two layers of polypropylene film, and the excess immersion solution is squeezed out, and then subjected to at least 3 freeze-thaw cycles to obtain the PVA fabric hydrogel.

[0049] The polyvinyl alcohol fabric hydrogel prepared by the above method contains sodium chloride, glycerol and water in the polyvinyl alcohol fabric, and the polyvinyl alcohol fabric is coated with polyvinyl alcohol hydrogel.

[0050] The polyvinyl alcohol fabric hydrogel prepared by the above method has good conductivity and strain sensing performance, and therefore can be used as a strain sensor, which can detect the deformation of the human body in real time. The prepared polyvinyl alcohol fabric hydrogel can also be used as a touch screen to make a hydrogel touch screen, which can accurately detect the position of the touch point. And when the hydrogel touch screen is integrated into a computer system, it can realize piano playing and become a computer for piano playing.

[0051] The following provides three embodiments of the preparation method of the polyvinyl alcohol fabric hydrogel of the present application:

[0052] Example 1

[0053] The polyvinyl alcohol fabric hydrogel is prepared by the following steps:

[0054] Step 1, preparation of PVA fabric structure:

[0055] The vinylon (PVFM) fabric is soaked in ethanol and ultrasonically treated for 40 minutes to remove surface impurities. The vinylon PVFM fabric is immersed in a 55% aqueous sulfuric acid solution for 40 minutes to reduce it to PVA, and then washed with a large amount of deionized water to obtain the PVA fabric.

[0056] According to the principle of polyvinyl formal reaction, polyvinyl formal undergoes reversible reaction with polyvinyl alcohol and formaldehyde under acidic conditions. That is, the acetal is subjected to forward reaction by absorbing water with concentrated sulfuric acid, and dilute sulfuric acid promotes the hydrolysis of acetal into the original aldehyde and alcohol:

[0057]

[0058] Step 2, preparation of immersion solution:

[0059] Glycerol 10 g, sodium chloride 0.1 g and deionized water 60 g were mixed, and then stirred with a planetary mixer for 1 minute to obtain a uniform mixed solution; 5 g of PVA (1799, 98-99%, produced by Shanghai Maikelin Biotechnology Co., Ltd.) was added to the mixed solution, and the preparation of the impregnation solution was completed by stirring at 85°C for 1 hour.

[0060] Step 3, preparation of PVA fabric hydrogel:

[0061] The PVA fabric was soaked in the impregnation solution and stood for 13 hours at 50°C for sufficient swelling; then the swollen PVA fabric was placed between two layers of polypropylene film, and the excess solution was squeezed out; finally, it was frozen at -20°C for 12 hours, then transferred to room temperature for 2 hours to melt, and repeated 4 times to complete the freeze-thaw cycle, obtaining the PVA fabric hydrogel.

[0062] Example 2

[0063] The vinylon (PVFM) fabric was soaked in ethanol and ultrasonically treated for 35 minutes to remove surface impurities. The vinylon PVFM fabric was soaked in a 60% sulfuric acid aqueous solution for 35 minutes to reduce it to PVA, and then washed with a large amount of deionized water to obtain a PVA fabric.

[0064] Glycerol 30 g, sodium chloride 0.6 g and deionized water 80 g were mixed, and then stirred with a planetary mixer for 1 minute to obtain a uniform mixed solution; 8 g of PVA (1799, 98-99%, produced by Shanghai Maikelin Biotechnology Co., Ltd.) was added to the mixed solution, and the impregnation solution was prepared by stirring at 95°C for 2 hours.

[0065] The PVA fabric was soaked in the impregnation solution and stood for 13 hours at 60°C for sufficient swelling; then the swollen PVA fabric was placed between two layers of polypropylene film, and the excess solution was squeezed out; finally, it was frozen at -20°C for 12 hours, then transferred to room temperature for 2 hours to melt, and repeated 3 times to complete the freeze-thaw cycle, obtaining the PVA fabric hydrogel.

[0066] Example 3

[0067] The polyvinyl alcohol fabric hydrogel was prepared as follows:

[0068] Step 1, preparation of PVA fabric structure:

[0069] The vinylon (PVFM) fabric was soaked in ethanol and ultrasonically treated for 30 minutes to remove surface impurities. The vinylon PVFM fabric was soaked in a 50% sulfuric acid aqueous solution for 30 minutes to reduce it to PVA, and then washed with a large amount of deionized water to obtain a PVA fabric.

[0070] Step 2, preparation of impregnation solution:

[0071] Glycerol 45 g, sodium chloride 0.5 g and deionized water 45 g were mixed, and then stirred with a planetary mixer for 1 min to obtain a uniform mixed solution; 10 g of PVA (1799, 98-99%, produced by Shanghai Maikelin Biochemical Technology Co., Ltd.) was added to the mixed solution, and the preparation of the impregnation solution was completed by stirring at 90 °C for 2 h.

[0072] Step 3, preparation of PVA fabric hydrogel:

[0073] The PVA fabric was soaked in the impregnation solution and allowed to swell at 55 °C for 12 h; then the swelled PVA fabric was placed between two layers of polypropylene film to squeeze out the excess solution; finally, it was frozen at -20 °C for 12 h, and then transferred to room temperature for 2 h to melt, and the freeze-thaw cycle was repeated for 3 times to obtain the PVA fabric hydrogel.

[0074] The following provides a comparative example for Example 3:

[0075] Preparation of polyvinyl alcohol hydrogel, according to the following steps:

[0076] Step 1, preparation of impregnation solution:

[0077] Glycerol 45 g, sodium chloride 0.5 g and deionized water 45 g were mixed, and then stirred with a planetary mixer for 1 min to obtain a uniform mixed solution; 10 g of PVA was added to the mixed solution, and the preparation of the impregnation solution was completed by stirring at 90 °C for 2 h.

[0078] Step 2, preparation of PVA hydrogel:

[0079] The impregnation solution was dropped on a smooth glass plate, and the PVA hydrogel was obtained after 3 freeze-thaw cycles.

[0080] Characterization of PVA fabric hydrogel:

[0081] The molecular structures of vinylon (PVFM) fabric, PVA fabric and PVA fabric hydrogel were tested by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and the results are shown in Figure 1 The characteristic peaks of -OH, -CH2, C-C and C-O appeared at different positions in the three materials, and the C-O-C stretching vibration peak of the vinylon fabric disappeared in the molecular structures of the PVA fabric and the PVA fabric hydrogel, indicating that the acetal was hydrolyzed and the vinylon fabric was reduced. The microstructure of the PVA fabric hydrogel was observed by scanning electron microscopy (SEM), as shown in Figure 2 The woven structure can be clearly observed from Figure 2 ​

[0082] Performance testing of PVA fabric hydrogel:

[0083] 1. Mechanical property testing

[0084] The mechanical properties of the hydrogel were tested at room temperature using a universal electronic testing machine (EZ-L, Shimadzu, Japan). The thickness of a single specimen was measured using vernier calipers, with a testing speed of 30 mm / min and a testing length of 8 mm.

[0085] Tensile tests were conducted on PVA hydrogel and PVA fabric hydrogel, and the test results are as follows: Figure 3 As shown, the tensile strength, elongation at break, modulus, and toughness of the PVA fabric hydrogel are 18.5±0.6 MPa, 72.4±2.9%, 28.2±2.8 MPa, and 10.6±1.4 MJ / m, respectively. 3 Compared with PVA hydrogels prepared by directly cyclically freezing and thawing the impregnation solution, although its elongation at break is reduced, its tensile strength, modulus and toughness are greatly improved.

[0086] Tensile tests were performed on PVA fabric samples along different directions using the same test method. The test results are as follows: Figure 4 As shown, the tensile strength of PVA fabric hydrogel in the 0° direction is better than that in the 90° direction, but its modulus in the 0° direction is lower than that in the 90° direction. PVA fabric hydrogel exhibits high elongation at break (205±22.2%) and good toughness (14.7±2.9 MJ / m) in the 45° direction. 3 However, its strength (14.4±1.1MPa) and modulus (2.7±0.5MPa) are relatively low.

[0087] The tear resistance of the hydrogel was tested using a trouser tear test, such as... Figure 5 As shown, the tear strength of PVA fabric hydrogel can reach up to 35 N / mm, which is much greater than the tear strength of PVA hydrogel prepared by cyclic freeze-thaw treatment of its impregnating solution (<0.4 N / mm). This indicates that introducing a braided structure into the hydrogel can greatly improve its tear resistance.

[0088] The effective tear energy (G) was calculated using the following formula, and the results are shown in [link to formula]. Figure 6 As shown:

[0089]

[0090] Each hydrogel was measured 5 times, and its mean and standard deviation were calculated.

[0091] G is the effective tearing energy, where the sample length L = 20 mm, the sample width W = 10, 20, 40 mm, the PVA hydrogel sample thickness t = 1 mm, the PVA fabric hydrogel sample thickness t = 0.3 mm, Δ is the tearing opening length, and F is the tearing load. The tearing energy of the PVA fabric hydrogel can be as high as 53312 ± 7190 J / m 2 , which is much higher than that of the PVA hydrogel. The energy dissipation mode of the fabric hydrogel includes fiber breakage, pull-out and internal fabric organization disintegration. When the width of the fabric hydrogel increases, the difficulty of fiber pull-out also increases. Therefore, the tearing energy of the fabric hydrogel increases with the increase of the width.

[0092] 2. Physical property test

[0093] The PVA hydrogel and the PVA fabric hydrogel were immersed in deionized water, and the weight was measured at intervals. The ratio of the increased weight to the original weight was considered as the swelling rate. As shown in Figure 7 , the swelling rate of the PVA fabric hydrogel was always lower than 8%, which was due to the fabric structure contained therein, compared with the swelling rate (75.7%) of the PVA hydrogel without fabric structure. After 72 hours of immersion, the volume of the PVA hydrogel without fabric structure increased significantly, while the volume of the PVA fabric hydrogel remained almost unchanged. Therefore, the presence of the fabric structure in the PVA hydrogel helps to improve its good anti-swelling performance, making it very suitable for stable operation under wet conditions.

[0094] The PVA fabric hydrogel was placed in a constant temperature (25°C) and constant humidity (50%) environment for 12 days. The ratio of the weight loss to the initial weight was considered as the dehydration rate. As shown in Figure 8 , the dehydration rate of the PVA fabric hydrogel was not more than 6%, and the hydrogel still maintained good flexibility, indicating that it was endowed with excellent water retention ability by the fabric structure.

[0095] The PVA fabric hydrogel could still be bent and knotted after being placed at -20°C for 24 hours, and could lift a weight of 5 kg, which indicated that the hydrogel maintained good flexibility and load-bearing capacity at low temperature.

[0096] As shown in Figure 9 , the three materials of PVFM fabric, PVA hydrogel and PVA fabric hydrogel were placed on a color disc, and the PVA fabric hydrogel showed more clearly, that is, the PVA fabric hydrogel had high transparency.

[0097] The above properties indicate that the PVA fabric hydrogel has good environmental stability, which helps it to effectively function under various conditions.

[0098] 3. Electrical property and strain sensing property test

[0099] At room temperature, the conductivity of the hydrogel was tested using an impedance analyzer (TH2839, Tonghui Electronics Co., Ltd.). The formula for calculating conductivity (σ) is: σ = L / (R × S), where L is the distance between adjacent electrodes, and R and S are the resistance and cross-sectional area of ​​the hydrogel, respectively. Using a digital multimeter (VICTOR 86E, Derektech, USA) and a universal electronic testing machine (EZ-L, Shimadzu, Japan), the change in hydrogel resistance after strain was recorded. The formula for calculating the relative resistance change rate is: ΔR / R0 = (R - R0) / R0 × 100%, where R0 and R are the resistances of the hydrogel before and after stretching, respectively. The sensitivity factor GF = (ΔR / R0) / ε is used to evaluate the sensitivity to strain-induced resistance changes, where ε is the applied strain.

[0100] The high-frequency band of the electrochemical impedance spectroscopy (EIS) of the fabric hydrogel was obtained using an electrochemical workstation, such as... Figure 10 As shown, the intercepts of the PVA fabric hydrogel in the EIS high-frequency band before and after the addition of NaCl were 19.5 and 129, respectively. Using the formula σ=L / (R×S), the conductivity of the fabric hydrogel containing NaCl was calculated to be 0.102 S / m, which is 5.8 times higher than that of the fabric hydrogel without NaCl (0.015 S / m).

[0101] like Figure 11 As shown, the PVA fabric hydrogel exhibits good sensitivity within a strain range of 0-100%, with a strain-induced resistance change sensitivity (GF) of 1.41 and a linearity (R0) between the two. 2 The value is 0.999.

[0102] like Figure 12 , 13 As shown in Figures 14 and 15, PVA fabric hydrogel is used as a strain sensor to monitor real-time signals of human movement. When fingers, wrists, elbows, and knees bend at different angles, the PVA fabric hydrogel sensor deforms, resulting in corresponding changes in resistance. This hydrogel sensor can instantly convert motion deformation into corresponding electrical signals, and these signals are stable, clear, and repeatable.

[0103] 4. Touch performance test

[0104] PVA fabric hydrogel is flexible, transparent, and conductive, making it suitable as an ion-based touch panel. It provides a simple and intuitive interface for interacting with display devices. In various types of touch systems, PVA fabric hydrogel employs a surface capacitance system, which is simple in structure but limited to single-point touch. In a surface capacitance touch system, the same voltage is applied to all corners of the panel, creating a uniform electrostatic field. When a conductor (such as a human finger) touches the panel, the contact point is grounded, creating a potential difference between the electrode and the contact point. This potential difference causes current to flow from the electrode through the finger. The magnitude of the current is determined by the distance between the contact point and the electrode; as the distance decreases, a larger current is induced.

[0105] The structure of a one-dimensional (1D) ion touch band is as follows Figure 16 As shown, a PVA fabric hydrogel is used as an ion conductor, with both ends connected to copper (Cu) electrodes. An AC voltage (F = 20 kHz, V) is applied to both ends through ammeters A1 and A2. PP =1V). When a finger touches the touch strip, a closed loop is formed because the finger is grounded. Current flows from both ends of the touch strip to the contact point and is detected by the ammeters on both sides. See the circuit diagram of the ion touch strip (see...). Figure 17 In this circuit, the contact point divides the touch strip into two resistive segments. Each resistor is connected in series with a double-layer capacitor and an ammeter, and then in parallel. This parallel circuit is then connected in series with a capacitor formed by the fingers. The double-layer capacitor is large and operates at a high frequency, so its capacitive effect is negligible.

[0106] The position of the touch point is represented by a normalized distance α, with the left and right ends of the touch strip corresponding to α = 0 and α = 1, respectively. The current flowing through the two resistors can be expressed by the following formula:

[0107]

[0108]

[0109] Where I1 and I2 are the contact currents measured by ammeters A1 and A2, respectively, I t =I1+I2.

[0110] like Figure 18 As shown, the ammeter can detect a baseline current in the microampere range. When touched by a finger, ammeter A1 detects a stable current change. The closer the touch point is to the electrode connected to ammeter A1, the greater the detected current.

[0111] like Figure 19As shown, the current was measured by the ammeter A1 and A2 when the left electrode and the right electrode were touched every 0.8 cm. The distance between the contact points and the current showed a near-linear relationship. As the contact point moved to the right, the sum of I1 and I2 remained constant, I1 decreased linearly, and I2 increased linearly.

[0112] As shown in Figure 20 The structure of a two-dimensional (2D) ionic touch panel. After connecting the four corners of the PVA fabric hydrogel with Cu electrodes, AC was applied to the four corners by ammeters A1, A2, A3, and A4. When a finger touches the panel, it can be divided into four resistance sections by the touch point. As shown in Figure 21 In the circuit, the four resistance sections are connected in parallel and then in series with the capacitor formed by the finger.

[0113] As shown in Figure 22 The PVA fabric hydrogel is a rectangular transparent film. When used as a two-dimensional ionic touch panel, it can clearly display the positions of the four test points A, B, C, and D.

[0114] As shown in Figure 23 By clicking on the positions of the four test points in turn, the changes in current were tested by the four ammeters installed in the corners. When touching point A, the ammeter A1 closest to point A showed the maximum current, and the ammeter A4 farthest from point A showed the minimum current. Similar to the case of the touch strip, the contact current measured by the four ammeters was proportional to the distance from the electrode to the contact point.

[0115] In addition, the PVA fabric hydrogel was used as a one-dimensional ionic touch strip and integrated into a computer system through a data acquisition device (mic-1810), which could be used to control the keys of an electronic piano. When the finger pressed different positions, the corresponding piano keys would be pressed, and beautiful music could be played. This application could be extended to other electronic musical instruments or games.

Claims

1. A method for preparing a polyvinyl alcohol fabric hydrogel, characterized in that: Includes the following steps: Step (1): Soak the vinylon fabric in a sulfuric acid aqueous solution to reduce the vinylon to polyvinyl alcohol, rinse with deionized water to obtain polyvinyl alcohol fabric; the concentration of the sulfuric acid aqueous solution is 50-60 wt%, and the vinylon fabric is soaked in the sulfuric acid aqueous solution for at least 30 minutes. Step (2): Mix polyvinyl alcohol, glycerin, sodium chloride, and deionized water, and stir to obtain a uniform impregnation solution; the polyvinyl alcohol is 5-10 wt%, glycerin is 10-45 wt%, sodium chloride is 0.1-0.6 wt%, and deionized water is 45-80 wt%. Step (3): Add the polyvinyl alcohol fabric to the impregnation solution and let it stand and soak until the polyvinyl alcohol fabric is fully swollen. Then place the swollen polyvinyl alcohol fabric between two layers of polypropylene film, squeeze out the impregnation solution from the polyvinyl alcohol fabric, and then subject the polyvinyl alcohol fabric to at least three freeze-thaw cycles to obtain polyvinyl alcohol fabric hydrogel. The impregnation soaking is carried out at 50-60°C for at least 12 hours.

2. The preparation method according to claim 1, characterized in that: in In step (2), polyvinyl alcohol is added to a mixed solution of glycerol, sodium chloride and deionized water, and stirred at 85-95°C for 1-2 hours.

3. The preparation method according to claim 1, characterized in that: in In step (1), the polyvinyl alcohol fabric is soaked in ethanol and ultrasonically treated for at least 30 minutes before being placed in the sulfuric acid aqueous solution to remove surface impurities.

4. A polyvinyl alcohol fabric hydrogel obtained by the preparation method as described in claim 1, characterized in that: in In the polyvinyl alcohol fabric hydrogel, the polyvinyl alcohol fabric contains sodium chloride, glycerin and water, and the fabric is coated with polyvinyl alcohol hydrogel.

5. An application of the polyvinyl alcohol fabric hydrogel as described in claim 4, characterized in that: It is used as a strain sensor.

6. An application of the polyvinyl alcohol fabric hydrogel as described in claim 4, characterized in that: It is used as a touchscreen application.

7. The application of the polyvinyl alcohol fabric hydrogel according to claim 6, characterized in that: A touchscreen made from the aforementioned polyvinyl alcohol fabric hydrogel is used in a computer for piano playing.

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