Ionically conductive hydrogel and preparation method and application thereof

Abstract

The application discloses an ion conductive hydrogel and a preparation method and application thereof, relates to the technical field of functional hydrogel and sensors, and discloses the ion conductive hydrogel which comprises a gel-forming monomer, a crosslinking agent, an inorganic salt and a photoinitiator; the gel-forming monomer comprises acrylamide and zwitterionic monomer sulfobetaine methacrylate; the crosslinking agent is N, N'-methylene bisacrylamide; the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone; and the solvent is deionized water. Based on the ion conductive hydrogel, an ion conductive hydrogel electrode patch can be prepared; by means of a wearable device, the ion conductive hydrogel electrode patch can be adhered to a human heart part, safe and comfortable heart rate variability data acquisition of the human body can be realized, and then the detection of CAN can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of functional hydrogels and sensors, and in particular to an ion-conductive hydrogel and a preparation method and application thereof. Background Art

[0002] Cardiac autonomic neuropathy (CAN) is one of the most serious and often overlooked complications of diabetic renal function. This dysfunction of the autonomic nervous system, caused by diabetic neuropathy, leads to damaged nerve fibers, reducing the heart's adaptability to the ever-changing internal and external environment. CAN is reported to increase the risk of cardiovascular death by approximately fivefold, and the prevalence of CAN in people with diabetes is as high as 90%. In the presence of CAN, the function of the cardiac autonomic nervous system may be affected, leading to changes in the temporal and frequency domain characteristics of cardiac electrical activity. For example, the balance between the cardiac sympathetic and parasympathetic nerves may be disrupted, resulting in changes in heart rate and decreased heart rate variability. With further research, heart rate variability (HRV) has been shown to be a useful tool for detecting and analyzing CAN.

[0003] Furthermore, clinical ECG signal measurement and heart rate variability analysis often involve connecting lead wires to metal electrodes. This acquisition method suffers from drawbacks such as high metal electrode contact impedance, susceptibility to skin conditions, discomfort, and the tendency to fall off. Ion-conductive hydrogels are increasingly being used in the biomedical field due to their excellent sensing properties and biocompatibility. Therefore, a heart rate variability detection solution based on ion-conductive hydrogels is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide an ion conductive hydrogel and its preparation method and application. The prepared ion conductive hydrogel can continuously and reliably collect human electrocardiogram signals, and perform HRV analysis through wearable devices to realize the detection of CAN.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] An ion-conductive hydrogel includes a gel-forming monomer, a cross-linking agent, an inorganic salt, and a photoinitiator; the gel-forming monomer includes acrylamide (AAm) and sulfobetaine methacrylate (SBMA), the cross-linking agent is N,N'-methylenebisacrylamide (MBAA), the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (IR2959), and the solvent is deionized water.

[0007] Furthermore, the mass ratio of acrylamide, sulfobetaine methacrylate, N,N′-methylenebisacrylamide, inorganic salt, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is 1000-1200:2000-2400:1:50-150:1-10.

[0008] Furthermore, the inorganic salt is at least one of NaCl and KCl.

[0009] Furthermore, the tensile strength of the ion-conductive hydrogel reaches 25-50 kPa, and the tensile deformation is between 1200% and 2100%.

[0010] The present invention also provides a method for preparing the ion-conductive hydrogel, comprising the following steps:

[0011] S1. Dissolve sulfobetaine methacrylate in deionized water and stir thoroughly at room temperature;

[0012] S2. Add acrylamide to the solution obtained in S1 and dissolve it;

[0013] S3. Add N, N'-methylenebisacrylamide to the solution obtained in S2 and stir evenly;

[0014] S4. Add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone to the solution obtained in S3 and dissolve it, and store it in the dark;

[0015] S5. Add a set content of inorganic salt to the solution obtained in S4 and stir to obtain the final hydrogel precursor solution;

[0016] S6. Take an appropriate amount of the hydrogel precursor solution obtained in S5 and inject it into the mold, and form a gel under ultraviolet light to obtain an ion conductive hydrogel.

[0017] Furthermore, the set content refers to that the amount ratio of the inorganic salt to the sulfobetaine methacrylate is 15%, 20%, 25% or 30%.

[0018] Furthermore, the molar ratio of the acrylamide and sulfobetaine methacrylate is 1:1 or 1:2 or 1:10; the mass of the sulfobetaine methacrylate is 5.0283 g; the added concentration of N,N′-methylenebisacrylamide is 0.2 mol% of the sum of the added concentrations of acrylamide and sulfobetaine methacrylate;

[0019] Furthermore, the mass of the sulfobetaine methacrylate is 5.0283 g; the deionized water is 10 ml, the mass of the acrylamide is 2.5588 g, the cross-linking agent is 2.2 mg; the mass of the photoinitiator is 20 mg; the power of the ultraviolet lamp is 20 W, the wavelength is 365 nm, and the irradiation time is 30 min.

[0020] The present invention also provides an application of the ion conductive hydrogel for ionic skin, wearable devices, and resistive sensors.

[0021] Furthermore, the application of ion-conductive hydrogel in wearable devices is as follows: the ion-conductive hydrogel is made into an ion-conductive hydrogel electrode patch, which is adhered to the human heart to obtain the human ECG signal; the wearable device includes an ECG acquisition device and multiple sets of ion-conductive hydrogel electrode patches;

[0022] The ECG acquisition device includes a microcontroller module, an ECG signal acquisition module, a power management module connected to the microcontroller module, and an ECG measurement module;

[0023] The power management module is used to supply power to the microcontroller module, the electrocardiogram measurement module, and the ECG signal acquisition module;

[0024] The microcontroller module is connected to the heart rate variability analysis module and is used to control the opening and closing of the electrocardiogram acquisition device;

[0025] The ECG signal acquisition module is connected to the ion conductive hydrogel electrode patch and is used to receive the ECG signal of the human body transmitted by the ion conductive hydrogel electrode patch;

[0026] The electrocardiogram measurement module is used to perform bandpass filtering processing on the ECG signal, perform data denoising through bandpass filtering, and achieve long-term electrocardiogram measurement through ion-conductive hydrogel electrodes through computational filtering to obtain electrocardiogram data.

[0027] Furthermore, the wearable device also includes a communication module, and the wearable device is communicatively connected to the heart rate variability analysis system through the communication module. The heart rate variability analysis system is used to receive the electrocardiogram data and perform time domain analysis, frequency domain analysis, nonlinear analysis and analysis results display based on the electrocardiogram data.

[0028] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: The heart rate variability detection system and method using ion conductive hydrogel provided by the present invention have the following advantages:

[0029] 1. The use of wearable devices based on ion-conductive hydrogels for heart rate variability analysis can be applied to real-time monitoring of cardiac autonomic nervous system function. It has the characteristics of convenient operation and lightweight device, and can meet the requirements of real-time physiological monitoring. It realizes the detection of CAN and provides a multi-dimensional method for daily monitoring of diabetic patients.

[0030] 2. The conductive ion hydrogel can adhere well to the electrodes of the flexible patch and the human skin, with high signal acquisition accuracy and clarity, simple production process, and reusability.

[0031] 3. The wearable device based on ion-conductive hydrogel proposed in the present invention has low requirements for usage conditions, is easy to operate, has good operating stability, is highly versatile, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 Graph showing the tensile stress-strain properties of the ion-conductive hydrogel in Example 1 of the present invention;

[0034] Figure 2 Graph showing the electrical conductivity of the ion-conductive hydrogel in Example 1 of the present invention;

[0035] Figure 3 Figure 1 shows the adhesion performance of the ion-conductive hydrogel in Example 1 of the present invention, where (a) shows the adhesion between the hydrogel and wood, cardboard, metal, rubber, plastic, and glass, respectively; (b) shows the shear and displacement curves of the hydrogel and glass at different NaCl concentrations; and (c) shows the adhesion strength of the hydrogel at different NaCl concentrations.

[0036] Figure 4 This is a schematic diagram of wearing the wearable device according to Example 3 of the present invention;

[0037] Figure 5 This is the WeChat applet interface diagram in Example 3 of the present invention;

[0038] Figure 6: The time domain and frequency domain analysis results of heart rate variability in the embodiment of the present invention, where (a) represents SDNN, (b) represents SDSD, (c) represents RMSSD, (d) represents PNN50, (e) represents the frequency domain analysis result HF, and (f) represents the frequency domain analysis result LF. Numbers n1-n14 are the results of normal subjects, and pl-p3 are the results of diabetic subjects.

[0039] Figure 7 1 and 2 are the nonlinear analysis results of heart rate variability in an embodiment of the present invention, wherein (a) represents the nonlinear analysis result of heart rate variability of a normal test subject; (b) represents the nonlinear analysis result of heart rate variability of a diabetic patient. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] The purpose of the present invention is to provide an ion conductive hydrogel and its preparation method and application. The prepared ion conductive hydrogel can continuously and reliably collect human electrocardiogram signals, and perform HRV analysis through wearable devices to realize the detection of CAN.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] An embodiment of the present invention provides an ion-conductive hydrogel, comprising a gel-forming monomer, a cross-linking agent, an inorganic salt, and a photoinitiator; the gel-forming monomer includes acrylamide (AAm), a zwitterionic monomer sulfobetaine methacrylate (SBMA), the cross-linking agent is N,N′-methylenebisacrylamide (MBAA), the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (IR2959), and the solvent is deionized water.

[0045] In this embodiment, the mass ratio of acrylamide, sulfobetaine methacrylate, N,N′-methylenebisacrylamide, inorganic salt, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is 1000-1200:2000-2400:1:50-150:1-10.

[0046] In this embodiment, the inorganic salt is at least one of NaCl and KCl.

[0047] The obtained ion conductive hydrogel was tested as follows:

[0048] (1) Mechanical properties test: The tensile test of ion conductive hydrogel was performed to obtain the stress-strain curve. Figure 1 As shown, the tensile deformation of the ion-conductive hydrogel is between 1200% and 2100%, and the tensile strength is about 25-50 kPa. When the molar ratio of NaCl to SBMA is 25%, the tensile deformation of the ion-conductive hydrogel is 2005%.

[0049] (2) Conductivity test: Figure 2 The electrical conductivity of the ion conductive hydrogel is related to the NaCl content. When the ratio of NaCl to SBMA is 25%, the electrical conductivity of the ion conductive hydrogel is 190 mS / m.

[0050] (3) Adhesion ability test: Figure 3 As shown, the ion conductive hydrogel was adhered to the surfaces of different materials, and the adhesion strength was calculated based on the typical curves of force and displacement.

[0051] The ion-conductive hydrogel prepared in this embodiment can firmly adhere the wearable device to the skin and ensure that the electrodes of the ion-conductive hydrogel patch can stably and efficiently collect electrocardiographic signals for HRV analysis. It can also be repeatedly pasted and used for a long time, and the adhesiveness and conductivity can be maintained by replacing the hydrogel electrodes.

[0052] Example 2

[0053] The present embodiment provides a method for preparing the ion conductive hydrogel described in Example 1, comprising the following steps:

[0054] S1. Dissolve 5.0283 g of sulfobetaine methacrylate (SBMA) in 10 ml of deionized water and stir thoroughly at room temperature.

[0055] S2. Add 2.5588 g of another monomer, acrylamide (AAm), to the solution obtained in S1 and dissolve it;

[0056] S3. Add 2.2 mg of the crosslinking agent N, N′-methylenebisacryloyl (MBAA) to the solution obtained in S2 and stir evenly;

[0057] S4. Add 20 mg of photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (IR2959) to the solution obtained in S3 and dissolve it, and store it in the dark;

[0058] S5. Adding different amounts of conductive ion NaCl to the solution obtained in S4, the ratio of NaCl to SBMA was controlled to 0%, 15%, 20%, 25%, and 300%, and stirring to obtain the final hydrogel precursor solution;

[0059] S6. Take an appropriate amount of the solution obtained in S5 and inject it into the mold. Irradiate it under a UV lamp with a power of 20 W and a wavelength of 365 nm for 30 minutes to form a gel.

[0060] In this embodiment, the molar ratios of the inorganic salt to the sulfobetaine methacrylate in the hydrogel precursor solution are 15%, 20%, 25%, and 30%.

[0061] In this embodiment, the molar ratio of acrylamide to sulfobetaine methacrylate is 1:1 or 1:2 or 1:10, preferably 1:2.

[0062] In this embodiment, the added concentration of N,N′-methylenebisacrylamide is 0.2 mol % of the sum of the added concentrations of acrylamide and sulfobetaine methacrylate.

[0063] The ion-conductive hydrogel prepared in this embodiment can firmly adhere the ECG acquisition device to the skin and ensure that the electrodes of the ion-conductive hydrogel patch can stably and efficiently collect ECG signals for HRV analysis. It can also be repeatedly pasted and used for a long time, and the adhesion and conductivity can be maintained by replacing the hydrogel electrodes.

[0064] Example 3

[0065] The embodiments of the present invention provide applications of the ion-conductive hydrogel described in Example 1, which are used in ionic skin, wearable devices, and resistive sensors.

[0066] In this embodiment, the application of ion conductive hydrogel in wearable devices is as follows: the ion conductive hydrogel is made into an ion conductive hydrogel electrode patch, which is adhered to the skin of the fourth intercostal space on the left side of the sternum of the human body (such as Figure 4 ), obtaining human ECG signals. Specifically, the ion-conductive hydrogel electrode patch was adhered to the rear electrode of the electrocardiogram acquisition device, and then the whole was placed at the fourth intercostal space on the left side of the human sternum. The ECG signal of the human body was collected in a sitting position for 5 minutes for heart rate variability analysis;

[0067] The wearable device includes an electrocardiogram acquisition device and multiple groups of ion-conductive hydrogel electrode patches;

[0068] The ECG acquisition device includes a microcontroller module (MCU), an ECG signal acquisition module, a power management module connected to the microcontroller module, and an ECG measurement module;

[0069] The power management module is used to supply power to the microcontroller module, the electrocardiogram measurement module, and the ECG signal acquisition module;

[0070] The microcontroller module is connected to the heart rate variability analysis module and is used to control the opening and closing of the electrocardiogram acquisition device;

[0071] The ECG signal acquisition module is connected to the ion conductive hydrogel electrode patch and is used to receive the ECG signal of the human body transmitted by the ion conductive hydrogel electrode patch;

[0072] The electrocardiogram measurement module is used to perform bandpass filtering processing on the ECG signal, perform data denoising through bandpass filtering, and achieve long-term electrocardiogram measurement through ion-conductive hydrogel electrodes through computational filtering to obtain electrocardiogram data.

[0073] In this embodiment, the wearable device also includes a communication module, and the wearable device is communicated with the heart rate variability analysis system through the communication module. The heart rate variability analysis system is used to receive the electrocardiogram data and perform time domain analysis, frequency domain analysis, nonlinear analysis based on the electrocardiogram data, and display the analysis results.

[0074] In a further embodiment, the communication module is a Bluetooth module; the heart rate variability analysis system is a mobile phone terminal, or a WeChat applet of the mobile phone terminal, such as Figure 5 As shown, the WeChat applet has an ECG data display button and a heart rate variability analysis button. Clicking them starts data analysis and displays the data results in the corresponding area. In this embodiment, the Bluetooth module establishes a connection with the microcontroller via serial communication. As a bridge between the hardware system and the mobile terminal (WeChat applet), it can assist the mobile terminal in controlling the hardware system, processing ECG signals, analyzing and displaying heart rate variability characteristics, and controlling the opening and closing of the wearable device.

[0075] In this embodiment, the power management module uses a 3.7V lithium battery.

[0076] In this embodiment, the power management module further includes a 3.7V input to 3.3V module that converts 3.7V input to 3.3V output through a TPS7A5301RPSR chip.

[0077] In this embodiment, the MCU uses the STM32L432KBU6 chip, which interacts and controls the power management module, ECG measurement module, and Bluetooth module through SPI communication, IIC communication, serial communication, and level output of the chip IO port. The ECG measurement module uses the AD8232ACPZ-R7 chip to build the ECG measurement circuit. The ECG signal acquisition electrodes are connected to the ion-conductive hydrogel via three serial ports, thereby achieving close contact between the electrodes and the skin. The Bluetooth module establishes a connection with the MCU via serial communication. As a bridge between the hardware system and the mobile terminal, it can assist in the WeChat applet on the mobile terminal to control the hardware system, process ECG signals, and analyze and display heart rate variability characteristics.

[0078] In this embodiment, the sizes of the serial ports connecting the ECG signal acquisition electrodes to the electrodes of the ion-conductive hydrogel patch are 10 mm*10 mm, 5 mm*20 mm, and 10 mm*10 mm.

[0079] In this embodiment, the mold used is an acrylic mold.

[0080] In this embodiment, the heart rate variability analysis includes time domain analysis, frequency domain analysis, and nonlinear analysis of the obtained ECG data. In the time domain analysis, four parameters are selected: SDSD (standard deviation between each two adjacent RRs), RMSSD (square root of the mean square of the difference between adjacent RR intervals), SDNN (standard deviation of RR intervals), and PNN50 (indicating the proportion of consecutive RR interval differences exceeding 50 milliseconds). In the frequency domain analysis, two parameters, HF (high frequency power) and LF (low frequency power), are selected. In the nonlinear analysis, a Poincaré Plot is used to display the relationship between consecutive heartbeat intervals in the form of a two-dimensional scatter plot. Furthermore, in this embodiment, the time domain analysis, frequency domain analysis, and nonlinear analysis of the obtained ECG data specifically include:

[0081] (1) Time domain analysis: It is used to reflect the status of the cardiac autonomic nervous system by evaluating the duration of each heart beat. SDNN represents the standard deviation of each adjacent NN interval:

[0082]

[0083] SDSD is mainly affected by the parasympathetic nervous system. By calculating SDSD, we can obtain the standard deviation of heart rate interval differences, thereby evaluating the volatility of heart rate in the short term.

[0084]

[0085] Among them, ΔNN i represents the difference between two consecutive heartbeats, Represents the mean of all heart rate changes between the previous and next two beats;

[0086] RMSSD represents the square root of the mean square of the difference between adjacent RR intervals and is used to measure the role of parasympathetic regulation during continuous changes in heart rate;

[0087]

[0088] Among them, NN i+1 and NN i Represents the interval between two consecutive heartbeats;

[0089] PNN50 indicates the proportion of consecutive NN intervals (intervals between normal heartbeats) with a difference of more than 50 milliseconds. This indicator reflects the rapid changes in heart rate to a certain extent;

[0090] (2) Frequency domain analysis: used to provide a detailed view of the heart rate signal by measuring the strength of different frequency components; the high frequency information HF of the frequency analysis is obtained by performing a fast Fourier transform on the ECG frequency data in the range of 0.15 to 0.04 Hz;

[0091]

[0092] Where PSD(f) represents the power spectral density at frequency f,

[0093] The low-frequency signal is obtained by analyzing the frequency range from 0.04 to 0.15 Hz:

[0094]

[0095] (3) Nonlinear analysis: used to reveal complex patterns and structures in heart rate data, providing a method to explore the complexity and dynamics of heart rate signals, and supplementing traditional time domain and frequency domain analysis methods. Two of the indicators, SD1 and SD2, reflect short-term heart rate variability and long-term heart rate variability, respectively.

[0096]

[0097] Through multiple parameters in time domain, frequency domain, nonlinearity, etc., a more comprehensive analysis of the sympathetic nervous system and parasympathetic nervous system in the cardiac autonomic nervous system is performed to determine the patient's cardiac function status, stress status, health status and activity status of the autonomic nervous system.

[0098] The present invention uses a heart rate variability detection system composed of an ion conductive hydrogel electrode patch and a wearable device to analyze the heart rate variability of healthy subjects and diabetic patients under the same conditions. The results of time domain, frequency domain and nonlinear parameters are as follows Figure 6-7As shown in Figure 2, it can be seen that the ion-conductive hydrogel can be well connected with wearable devices, thereby realizing the extraction of heart rate variability.

[0099] In summary, the present invention provides an ion-conductive hydrogel, its preparation method, and its application. The ion-conductive hydrogel is prepared and a wearable device is constructed using ion-conductive hydrogel electrode patches, enabling wearable heart rate variability measurement. This facilitates the detection of CAN by measuring heart rate variability, providing a multi-dimensional approach for daily monitoring of diabetic patients. The present invention applies this heart rate variability detection system to real-time monitoring of cardiac autonomic nervous system function. It features convenient operation and lightweight device, meeting the requirements of real-time physiological monitoring.

[0100] The remaining technical features of this embodiment can be flexibly selected by those skilled in the art to meet different specific practical needs based on actual circumstances. However, it is obvious to those skilled in the art that these specific details are not required to practice the present invention. In other examples, to avoid obscuring the present invention, well-known components, structures, or parts are not described in detail, and are therefore within the scope of the technical solutions claimed in the claims of the present invention.

[0101] Modifications and variations made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the claims appended hereto. In the foregoing description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessarily required to practice the present invention. In other instances, well-known techniques, such as specific construction details, operating conditions, and other technical requirements, are not described in detail to avoid obscuring the present invention.

[0102] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An ion-conductive hydrogel, characterized in that The invention comprises a gel-forming monomer, a cross-linking agent, an inorganic salt, a photoinitiator and a solvent; the gel-forming monomer comprises acrylamide and sulfobetaine methacrylate, the cross-linking agent is N,N-methylenebisacrylamide, the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, and the solvent is deionized water; the ion-conductive hydrogel has a tensile strength of 25-50 kPa and a tensile deformation between 1200% and 2100%; the mass ratio of acrylamide, sulfobetaine methacrylate, N,N′-methylenebisacrylamide, inorganic salt and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is 1000-1200:2000-2400:1:50-150:1-10.

2. The ion-conductive hydrogel according to claim 1, characterized in that The inorganic salt is at least one of NaCl and KCl.

3. The method for preparing the ion-conductive hydrogel according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Dissolve sulfobetaine methacrylate in deionized water and stir thoroughly at room temperature; S2. Add acrylamide to the solution obtained in S1 and dissolve it; S3. Add N, N'-methylenebisacrylamide to the solution obtained in S2 and stir evenly; S4. Add 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone to the solution obtained in S3 and dissolve it, and store it in the dark; S5. Add a set content of inorganic salt to the solution obtained in S4 and stir to obtain the final hydrogel precursor solution; S6. Take an appropriate amount of the hydrogel precursor solution obtained in S5 and inject it into the mold. Under ultraviolet light, the initiator begins to act to promote gelation, thereby obtaining an ion-conductive hydrogel.

4. The method for preparing the ion conductive hydrogel according to claim 3, wherein: The set content in S5 refers to that the amount ratio of the inorganic salt to the sulfobetaine methacrylate is 15%, 20%, 25% or 30%.

5. The method for preparing the ion conductive hydrogel according to claim 3, wherein: The mass of the sulfobetaine methacrylate is 5.0283 g; the mass of the deionized water is 10 ml, the mass of the acrylamide is 2.5588 g, the mass of the cross-linking agent is 2.2 mg; the mass of the photoinitiator is 20 mg; the power of the ultraviolet lamp is 20 W, the wavelength is 365 nm, and the irradiation time is 30 min.

6. Use of the ion-conductive hydrogel according to any one of claims 1 to 2, characterized in that: Used in ionic skin, wearable devices, and resistive sensors.

7. The use of the ion conductive hydrogel according to claim 6, characterized in that: The application of ion-conductive hydrogel in wearable devices is as follows: the ion-conductive hydrogel is made into an ion-conductive hydrogel electrode patch, which is adhered to the human heart to obtain the human ECG signal; the wearable device includes an ECG acquisition device and multiple sets of ion-conductive hydrogel electrode patches; The ECG acquisition device includes a microcontroller module, an ECG signal acquisition module, a power management module connected to the microcontroller module, and an ECG measurement module; The power management module is used to supply power to the microcontroller module, the electrocardiogram measurement module, and the ECG signal acquisition module; The microcontroller module is connected to the heart rate variability analysis system and is used to control the opening and closing of the electrocardiogram acquisition device; The ECG signal acquisition module is connected to the ion conductive hydrogel electrode patch and is used to receive the ECG signal of the human body transmitted by the ion conductive hydrogel electrode patch; The electrocardiogram measurement module is used to perform bandpass filtering processing on the ECG signal, perform data denoising through bandpass filtering, and achieve long-term electrocardiogram measurement through ion-conductive hydrogel electrodes through computational filtering to obtain electrocardiogram data.

8. The use of the ion conductive hydrogel according to claim 7, characterized in that: The wearable device also includes a communication module, and the wearable device is connected to the heart rate variability analysis system through the communication module. The heart rate variability analysis system is used to receive the electrocardiogram data and perform time domain analysis, frequency domain analysis, nonlinear analysis and analysis result display based on the electrocardiogram data.

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