Hydrogel material, preparation method thereof and sensor

Abstract

The invention discloses a hydrogel material, a preparation method thereof and a sensor, and the hydrogel material comprises the following components in parts by weight: 2-8 parts of polyacrylamide and 2-8 parts of polyethylene oxide. The hydrogel material provided by the invention can be continuously manufactured, is easy to store for a long time, and has the advantages of rapid adhesion, long-term stability, biocompatibility and convenience in use, so that the hydrogel material can be used in a sensor for underwater health monitoring, and the state of an underwater organism is monitored and evaluated.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogel materials, and in particular to a hydrogel material, a preparation method thereof, and a sensor. Background Art

[0002] Hydrogels are a class of materials formed by chemically or physically cross-linking natural or synthetic polymers. They possess excellent biocompatibility, flexibility, and biomimetic structures. These properties have led to their widespread application in various fields, including surgery, medicine, and sports.

[0003] In the field of medical surgery, suturing can easily cause secondary damage to fragile tissues. Hydrogel materials can achieve tissue adhesion through chemical cross-linking or physical adsorption, combining both bonding strength and biocompatibility.

[0004] In sports, whether it's competitive sports that challenge human limits or mass sports that strengthen the body, lose weight, and shape the body, they all need to be conducted under scientific monitoring and guidance. With the rapid development of flexible sensing technology, people's demand for motion sensors has evolved from accurate data collection to features such as lightness, ultra-thinness, flexibility, and compactness, and the ability to be worn comfortably for long periods of time without affecting exercise, easy to put on and take off, and suitable for any scenario. However, wet environments, especially sports in water such as swimming and diving, pose great challenges to flexible electronic products attached to the skin. They are easy to detach from the skin and have poor signal stability.

[0005] While research on multi-physiological sensing technologies and wet adhesion has yielded some promising results, the majority of these technologies focus on terrestrial acquisition. While challenges remain in acquiring multi-dimensional physiological signals in underwater environments, miniaturization, lightweighting, and flexibility of sensors, significant progress has been made in the field of wet adhesion. However, limitations remain in rapid adhesion response, continuous fabrication, stable wet adhesion, particularly in high-salt environments, and biocompatibility. Summary of the Invention

[0006] The main technical problem solved by this application is to provide a hydrogel material and its preparation method and sensor, so as to solve the problems of easy detachment between underwater sensors and skin, weak adhesion, long adhesion time, decreased adhesion performance in complex humid environments, complex preparation process, low biocompatibility in long-term health monitoring, and allergic reactions after removal.

[0007] In order to solve the above technical problems, a technical solution adopted in the present application is to provide a hydrogel material, which comprises 2 to 8 parts of polyacrylamide and 2 to 8 parts of polyethylene oxide by weight.

[0008] The present application also provides a method for preparing a hydrogel material, which is used to prepare the above-mentioned hydrogel material. The method comprises the steps of: mixing the polyacrylamide and the polyethylene oxide to obtain a pre-hydrogel solution; coating the pre-hydrogel solution on a substrate to obtain a pre-hydrogel; drying the pre-hydrogel to obtain a dry gel film; and swelling and curing the dry gel film to obtain the hydrogel material.

[0009] The present application also provides a sensor, comprising a multi-physiological signal sensing body, a coating layer and the above-mentioned hydrogel material; the multi-physiological signal sensing body is encapsulated in the coating layer; the hydrogel material is adhered to the surface of the coating layer and is used to be attached to a biological body, so that the multi-physiological signal sensing body collects the multi-physiological signals of the biological body.

[0010] The beneficial effects of this application are as follows: This application discloses a hydrogel material, a preparation method thereof, and a sensor. The hydrogel material comprises, by weight, 2 to 8 parts of polyacrylamide and 2 to 8 parts of polyethylene oxide. This application provides a hydrogel material that can be continuously manufactured, easily stored for a long time, exhibits rapid adhesion, long-term stability, is biocompatible, and is easy to use. This hydrogel material can then be used in sensors for underwater health monitoring, enabling monitoring and assessment of the status of underwater organisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a flow chart of an embodiment of a method for preparing a hydrogel material of the present application;

[0012] Figure 2 This is a flow chart for preparing a xerogel film in an embodiment of a method for preparing a hydrogel material of the present application;

[0013] Figure 3 This is a microstructure diagram of a dry gel film with different PAM and PEO mass ratios in an embodiment of a hydrogel material of the present application;

[0014] Figure 4 This is a microstructure diagram of a hydrogel material stored frozen at different PAM and PEO mass ratios in an embodiment of the present application;

[0015] Figure 5 This is a microstructure diagram of PAMP-5:5 in an embodiment of a hydrogel material of the present application, and a microstructure diagram of the adhesion and drawing of the hydrogel material to the substrate;

[0016] Figure 6 This is an infrared spectrum of different PAM and PEO mass ratios in an embodiment of a hydrogel material of the present application;

[0017] Figure 7This is a fluorescence microscopic structure diagram of a hydrogel material with and without NHS grafted in one embodiment of the hydrogel material of the present application;

[0018] Figure 8 This is a schematic diagram of the swelling behavior of PAMP-5:5 in one embodiment of a hydrogel material of the present application;

[0019] Figure 9 This is a relationship diagram between the swelling time and swelling rate of PAMP-5:5 in an embodiment of a hydrogel material of the present application;

[0020] Figure 10 This is a graph showing the relationship between the swelling time and water content of PAMP-5:5 in one embodiment of a hydrogel material of the present application;

[0021] Figure 11 Figures 1 and 2 show a standard 180° peel test and lap shear test of PAMP-5:5 with different swelling times in an embodiment of a hydrogel material of the present application, as well as a relationship between the swelling characteristics and adhesion of the obtained PAMP-5:5.

[0022] Figure 12 This is a graph showing the swelling time required for hydrogel materials with different PEO molecular weights and hydrogel materials with different PAM to PEO mass ratios to swell to a water content exceeding 91% in one embodiment of a hydrogel material of the present application;

[0023] Figure 13 This is a diagram showing the swelling results of hydrogel materials with different PAM to PEO mass ratios in water and saline in an embodiment of a hydrogel material of the present application;

[0024] Figure 14 This is a stress-strain curve diagram of a hydrogel material with different PAM to PEO mass ratios in an embodiment of the present application;

[0025] Figure 15 This is a schematic diagram of the adhesion principle of a hydrogel material for adhering electronic devices to the skin in one embodiment of the present application;

[0026] Figure 16 This is an experimental diagram of a 180° peeling test after swelling of hydrogel materials with different PEO molecular weights and hydrogel materials with different PAM to PEO mass ratios in one embodiment of a hydrogel material of the present application;

[0027] Figure 17 This is a graph showing the relationship between the interface toughness and shear strength of hydrogel materials with different PEO molecular weights and hydrogel materials with different PAM to PEO mass ratios in one embodiment of a hydrogel material of the present application;

[0028] Figure 18This is a graph showing the relationship between the substrate material to which PAMP-5:5 adheres, storage time, and usage frequency and the interfacial toughness and shear strength of PAMP-5:5 in an embodiment of a hydrogel material of the present application;

[0029] Figure 19 This is a graph of the ionic conductivity of a hydrogel material with different PAM to PEO mass ratios in an embodiment of the present application. DETAILED DESCRIPTION

[0030] To facilitate understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. The accompanying drawings provide preferred embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0031] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0032] The present invention is described in detail below with reference to specific embodiments.

[0033] The present invention provides a hydrogel material, which comprises 2 to 8 parts by weight of polyacrylamide (PAM) and 2 to 8 parts by weight of polyethylene oxide (PEO).

[0034] Furthermore, the mass ratio of polyacrylamide to polyethylene oxide is preferably 1:1, and the molecular weight of polyethylene oxide is preferably 8000 kDa.

[0035] In this hydrogel material, PAM molecules act as a supporting phase to provide structural stability and mechanical strength to the hydrogel material, and PEO molecules act as a toughening phase to enhance the cohesion and interfacial adhesion of the hydrogel material through the entanglement effect. The two work synergistically to form a three-dimensional network structure with bicontinuous phase separation; the entanglement effect of the flexible high-molecular-weight PEO molecules enhances the ductility and adhesion of the hydrogel material, preventing the hydrogel material from being torn by external forces.

[0036] Furthermore, the hydrogel material also includes a cross-linking agent for chemically cross-linking polyacrylamide and polyethylene oxide.

[0037] Furthermore, the crosslinking agent is Ca 2+, Ca 2+ Conductive and structural dual functional modification can be achieved, and the uniformly mixed PAM molecules and PEO molecules are 2+ The post-crosslinking forms a sacrificial toughening network, thereby achieving high fracture toughness of the hydrogel material.

[0038] Furthermore, N-hydroxysuccinimide ester (NHS) is grafted on the surface of the hydrogel material, which enhances the underwater adhesion of the hydrogel material.

[0039] Based on the same inventive concept, Figure 1 As shown, the present invention also provides a method for preparing a hydrogel material, which is used to prepare the above-mentioned hydrogel material, and the method comprises the following steps:

[0040] Step S1: Mix polyacrylamide and polyethylene oxide to obtain a pre-hydrogel solution.

[0041] Step S2: coating the pre-hydrogel solution on a substrate to obtain a pre-hydrogel.

[0042] Step S3: drying the pre-hydrogel to obtain a dry gel film.

[0043] Step S4: Swelling and solidifying the dry gel film to obtain a hydrogel material.

[0044] It should be noted that, before step S1, raw materials and preparation instruments for preparing the hydrogel material need to be prepared.

[0045] Raw materials include polyacrylamide (PAM), polyethylene oxide (PEO), polyethylene terephthalate (PET), N-hydroxysuccinimide ester (NHS), dimethyl sulfoxide (DMSO), anhydrous calcium chloride, N-acryloylsuccinimide, 6-aminofluorescein, anhydrous ethanol, and deionized water. Preparation instruments include an electronic balance, UV lamp, oven, electronic universal testing machine, degassing mixer, infrared spectrometer, fluorescence microscope, freeze dryer, micrometer, ion sputtering instrument, and high-resolution scanning electron microscope.

[0046] Combine Figure 2For steps S1-S3, appropriate amounts of PAM and PEO were first mixed to obtain a pre-hydrogel solution 7. Then, on a printing station, a blade was used to apply a 2 mm thick layer of pre-hydrogel solution 7 onto a roll of hydrophobically coated PET substrate 8 (made of polyethylene terephthalate) to obtain a pre-hydrogel. The pre-hydrogel was then naturally dried at 60°C to form a continuous xerogel film 9.

[0047] Furthermore, in step S4, to introduce the NHS ester network, the xerogel film was cut into the desired size and swollen in water for 15 seconds to reach a water content of 90%, yielding a swollen hydrogel. The swollen hydrogel was then immersed in an anhydrous DMSO solution containing 2 mg / mL NHS ester and subsequently cured by irradiation with 365 nm UV light for 30 seconds to complete the polymerization reaction and yield a hydrogel material. Finally, the prepared hydrogel material was stored at -20°C using a freeze dryer until further use.

[0048] It should be noted that the main component of the xerogel film is polyacrylamide / polyethylene oxide (PAMP) xerogel. PAMP xerogel forms a three-dimensional porous network with bicontinuous phase separation through polymer entanglement, optimizing water transport channels. This unique structure significantly increases the swelling rate and achieves instant adhesion through rapid hydration dynamics. When the xerogel film comes into contact with moist tissue of an organism, it rapidly expands within 10 seconds and transforms into a PAMP hydrogel. When the water content reaches 90%, the adhesion reaches its maximum within 15 seconds, forming an adhesive bond with the skin through multiple molecular interactions, thereby establishing stable adhesion.

[0049] Furthermore, to obtain the optimal PAM to PEO mass ratio and the optimal PEO molecular weight, hydrogel materials with different PAM to PEO mass ratios and different PEO molecular weights were prepared using the above preparation method. The prepared hydrogel materials with various PAM to PEO mass ratios were then characterized and their performance tested.

[0050] To investigate the micromorphology of the hydrogels, scanning electron microscopy was used to characterize the microstructure of xerogel films, hydrogels (corresponding to PAMP-10:0, PAMP-6:4, PAMP-5:5, PAMP-4:6, and PAMP-0:10), and the interface between the hydrogels and substrates at different PAM to PEO mass ratios (10:0, 6:4, 5:5, 4:6, and 0:10, respectively). The results showed that different mass ratios significantly affected the phase separation behavior and network continuity of the hydrogels.

[0051] like Figure 3As shown, the morphology of the xerogel films with different PAM and PEO mass ratios (10:0, 6:4, 5:5, 4:6 and 0:10) was characterized by scanning electron microscopy ( Figure 3 (a)-(e), scale bar is 10 μm).

[0052] In pure component systems, such as Figure 3 As shown in (a), the surface of the dry gel film corresponding to PAMP-10:0 (pure PAM) presents a dense non-porous structure, with slight cracks visible locally, indicating that the single PAM network is prone to brittle fracture due to the lack of a toughening phase. Figure 3 As shown in (e), the surface of the dry gel film corresponding to PAMP-0:10 (pure PEO) presents a loose layered structure, discrete pore size distribution, and obvious pore wall collapse, indicating that the network is loose and the pore wall collapses due to the lack of a supporting phase.

[0053] In non-equal proportion composite systems, such as Figure 3 As shown in (b), the dry gel film corresponding to PAMP-6:4 (mainly PAM) initially presents a two-phase separation structure, but the size difference between the PEO continuous phase (dark area) and the PAM dispersed phase (bright area) is significant. Figure 3 As shown in (d), the dry gel film corresponding to PAMP-4:6 (mainly PEO) did not undergo obvious phase separation, which may be due to the uneven distribution of the two phases in the non-equal proportion system.

[0054] For a composite system of equal proportions, such as Figure 3 As shown in (c), the dry gel film corresponding to PAMP-5:5 presents a bicontinuous interpenetrating network structure with consistent pore size, which confirms that when the mass ratio of PAM and PEO is 5:5, the dry gel film corresponding to PAMP-5:5 forms a uniform bicontinuous network through phase separation, verifying the key role of component symmetry in the construction of interpenetrating networks.

[0055] like Figure 4 As shown, the morphology of cryopreserved hydrogel materials with different PAM and PEO mass ratios (10:0, 6:4, 5:5, 4:6 and 0:10) was characterized by scanning electron microscopy ( Figure 4 (a)-(e), scale bar is 100 μm).

[0056] In pure component systems, such as Figure 4 As shown in (a), the surface of PAMP-10:0 (pure PAM) is dense, with irregular cracks and sharp edges visible locally. This may be because the single PAM network lacks a toughening phase, making it difficult for water to swell evenly. Figure 4As shown in (e), the surface of PAMP-0:10 (pure PEO) presents a loose layered structure with uneven ultra-large pores (300 μm), which may be due to the lack of a supporting phase in the single PEO network, resulting in a loose network skeleton.

[0057] In non-equal proportion composite systems, such as Figure 4 As shown in (b), PAMP-6:4 (mainly PAM) presents a porous structure, but the pore sizes vary, the continuity is poor, and there are non-porous areas on the surface. This may be due to the uneven separation of the two phases, which leads to uneven diffusion of water during swelling and causes different pore sizes. Figure 4 As shown in (d), PAMP-4:6 (mainly PEO) presents an uneven network structure with larger pore size (100μm), and the surface is uneven, showing crystallization. This may be due to the lack of obvious separation of the two phases and the excessive toughening phase, which causes the molecular network skeleton to be destroyed when the dry gel film swells.

[0058] For a composite system of equal proportions, such as Figure 4 As shown in (c), PAMP-5:5 presents a uniform bicontinuous phase separation interpenetrating network structure with uniform pore size (50±5μm), which may be due to the PAM molecular skeleton and PEO flexible chain segments through hydrogen bonds with Ca 2+ The coordination synergy forms a stable topological structure. Consequently, the hydrogel material stored frozen with a PAM to PEO mass ratio of 5:5 exhibits a more uniform and continuous porous network structure. Therefore, from a microstructural perspective, the hydrogel material PAMP-5:5 exhibits the best structural characteristics when the PAM to PEO mass ratio is 5:5.

[0059] like Figure 5 As shown, the microstructure of PAMP-5:5 with a mass ratio of PAM to PEO of 5:5 is shown, and the microstructure of the wire drawing after adhering to the substrate is shown. Figure 5 (a) shows the microstructure of PAMP-5:5, with a scale bar of 200 μm. Figure 5 (b) is a schematic diagram of the microstructure of the adhesion wire between PAMP-5:5 and the substrate, with a scale of 100 μm. Figure 5(c) is a microscopic diagram of the hydrogel fibers produced by the stringing phenomenon during the adhesion of PAMP-5:5 to the substrate. The scale is 200 μm. Analysis of the microstructure reveals that cryopreserved PAMP-5:5 exhibits a uniform, three-dimensional, porous network structure with bicontinuous phase separation, with an average pore size of 80 ± 20 μm. When PAMP-5:5 is peeled from the substrate, the interfacial region exhibits a dense, stringy, fibrous adhesion structure, indicating a strong interaction between PAMP-5:5 and the substrate. This is due to the PAM molecules, as the supporting phase, providing skeletal support, while the PEO molecules, as the toughening phase, form continuous hydrophilic channels through entanglement and hydrogen bonding, promoting the rapid conduction of water molecules or ions, forming hydrogen bonds, and achieving rapid adhesion.

[0060] Secondly, to verify the functional groups in the hydrogel and confirm the synthesis of the desired hydrogel material, Fourier Transform Infrared Spectroscopy (FTIR) was performed on xerogel films prepared with different PAM to PEO mass ratios to identify their specific functional groups. In a dry environment, an attenuated total reflectance accessory was placed in the optical path of the infrared spectrometer to scan the air background. The hydrogel sample surface was then placed close to the crystal surface of the ATR accessory to collect the sample's infrared spectrum.

[0061] like Figure 6 As shown in the figure, the infrared spectra of different PAM and PEO mass ratios (10:0, 6:4, 5:5, 4:6 and 0:10) are shown. Through infrared spectrum analysis, it can be seen that the infrared spectrum at 3391cm -1 The broad peak near 3384 cm is the OH stretching vibration in the hydrogel material. -1 The enhanced absorption band nearby is the stretching vibration peak of NH in the hydrogel material, located at 2879 cm -1 The nearby absorption band is the CH molecular skeleton of the hydrogel material, located at 1649 cm -1 and 1600cm -1 The peaks at 1460 cm-1 correspond to the carbonyl C=O stretching vibration and NH bending vibration in the amide group. -1 It is the CH molecular skeleton in the hydrogel material, 1331cm -1 It is the CN stretching vibration peak in the amide bond, 1280cm -1 , 1240cm -1 , 1100cm -1 , 957cm -1 The nearby peak is the CO stretching vibration peak of the ether group (-O-) in the hydrogel material, 842 cm -1 It is a long chain CC skeleton, 478cm -1It is the lattice vibration of inorganic matter, which confirms the successful preparation of the required hydrogel material.

[0062] Furthermore, to verify the successful grafting of N-hydroxysuccinimide ester bonds onto the hydrogel surface, fluorescence microscopy was used to observe both the grafted and non-grafted NHS hydrogels. To verify the presence of NHS ester bonds on the hydrogel surface, the hydrogels containing and not grafted NHS ester bonds were immersed in a 6-aminofluorescein solution in the dark for 2 hours. After three ultrasonic cleanings (10 minutes each), the interfacial fluorescence signal distribution was observed using a fluorescence microscope.

[0063] like Figure 7 Figure 2 shows the fluorescence microstructure of hydrogel materials with and without NHS grafting, with a scale of 100 μm. Fluorescence microscopy results show that the hydrogel material with NHS ester bonds is stained green, while the hydrogel material without NHS ester bonds is black, thus confirming the successful grafting of NHS ester bonds.

[0064] Furthermore, in order to explore the swelling properties of hydrogel materials, a group of PAMP-5:5 with the best molecular structure was subjected to experiments on immersion time, swelling rate and water content.

[0065] Specifically, at a constant temperature (25 ± 0.5°C), hydrogel samples (15 mm × 5 mm) were immersed in water and a 3.6% wt NaCl₂ solution, respectively, to allow them to swell. A micrometer was used to measure the changes in the three dimensions, and the swelling ratios in the length, width, and thickness directions of the hydrogel were calculated using the first swelling formula:

[0066] ;

[0067] in, and are the dimensions before and after swelling, and x, y, and z represent the length, width, and thickness of the hydrogel material, respectively.

[0068] Secondly, the swelling rate of the hydrogel material as a whole is calculated according to the second swelling formula, which is:

[0069] ;

[0070] in, and are the masses of dry PAMP and swollen PAMP, respectively.

[0071] Furthermore, the moisture content is measured by weighing method and calculated according to the moisture content formula, which is:

[0072] ;

[0073] in, and are the masses of dry PAMP and swollen PAMP, respectively.

[0074] like Figure 8 Schematic diagram showing the anisotropic swelling of PAMP-5:5 during swelling, where L0 represents the initial length, L represents the length after swelling, W0 represents the initial width, W represents the width after swelling, T0 represents the initial thickness, and T represents the thickness after swelling.

[0075] like Figure 9 As shown, a graph showing the relationship between the swelling time and the swelling ratio of PAMP-5:5 is shown. Figure 9 (a) shows the relationship between swelling time and swelling ratio of PAMP-5:5 in length L, width W and thickness T directions. Figure 9 (b) shows the relationship between swelling time and the overall swelling ratio of PAMP-5:5, measured three times. Structural analysis of anisotropic swelling reveals that when PAMP-5:5 is fully swollen, the swelling ratio changes significantly in the thickness direction, reaching 3200%, while changes in the length and width directions are almost negligible. Equilibrium is reached after 1800 seconds of swelling. This characteristic allows PAMP-5:5 to swell only in the thickness direction, making it well-suited for use as a flexible patch adhesive material.

[0076] like Figure 10 As shown, the relationship between the swelling time, swelling ratio and water content of PAMP-5:5 is shown. Figure 9 As shown in (b), the swelling rate and water content of PAMP-5:5 gradually increase with immersion time. At 1800 seconds, the swelling equilibrium is reached, with a swelling rate exceeding 2800% and a water content exceeding 96%. After 5 seconds of swelling, the swelling rate of PAMP-5:5 reaches nearly 700% and a water content exceeding 85%. After 15 seconds of swelling, the swelling rate reaches 1000% and the water content reaches 91%, fully demonstrating the ability of PAMP-5:5 to exceed water content and rapidly swell.

[0077] To further investigate the relationship between the swelling properties and adhesion of PAMP-5:5, standard 180° peel tests and lap shear tests were performed on PAMP-5:5 with different swelling times. PAMP-5:5 sheets of identical dimensions were prepared. After complete adhesion between the substrate and the PAMP-5:5, they were pre-pressed for 30 seconds at the same pressure (1 kPa) to ensure full adhesion. The lap shear test was then performed using an electronic universal testing machine at a constant speed (100 mm / min) according to the standard lap shear test. Interfacial toughness was calculated by dividing the peak force in the 180° peel test by the width of the tissue sample, and shear strength was calculated by dividing the peak force by the adhesion area, in accordance with the corresponding ASTM standards.

[0078] like Figure 11 As shown, Figure 11 (a) is a schematic diagram of the 180° peel test experiment. Figure 11 (c) is a schematic diagram of the lap shear experiment. Figure 11 (b) shows the relationship between swelling time, interfacial toughness, and shear strength. The substrate is silicone. From this analysis, it can be seen that as the immersion time gradually increases, the adhesion of PAMP-5:5 gradually increases. When the immersion time is 15 seconds, the adhesion of PAMP-5:5 reaches its maximum value, and the interfacial toughness is 210 J / m 2 , the shear strength is 53kPa, and the water content at this time is 91%; when the immersion time of PAMP-5:5 reaches 60s, the adhesion is still very strong, and the interface toughness of PAMP-5:5 and the substrate reaches 190J / m 2 The shear strength exceeded 50 kPa, and the water content was 93%. However, when the immersion time of PAMP-5:5 reached 1800 s, the adhesion decreased, and the interface toughness between PAMP-5:5 and the substrate was 108 J / m 2 The shear strength exceeds 29 kPa, and the water content at this time exceeds 96%. The interfacial toughness and shear strength at this time are still higher than half of the peak interfacial toughness and shear strength, which fully demonstrates the wet adhesion of PAMP-5:5. The interfacial toughness and shear strength at a water content of around 91% fully meet the adhesion requirements of flexible bioelectronic devices. Therefore, under normal circumstances, PAMP-5:5 can be used after swelling for 15 seconds. Moreover, during use, since PAMP-5:5 adheres tightly to the skin and electronic devices, it is difficult to be immersed in water during underwater exercise. Therefore, the water content of PAMP-5:5 during exercise will remain relatively stable at the initial amount.

[0079] Therefore, the adhesion of PAMP-5:5 shows a trend of first increasing and then slightly weakening with the increase of water content. This is mainly because in the early stage of swelling, water molecules quickly penetrate into the PAMP hydrogel network, enhancing the physical cross-linking (hydrogen bonds, electrostatic effects) of the bimolecular network, and may promote the diffusion of functional groups (such as carboxyl groups and amino groups) to the substrate surface, thereby enhancing the hydrogen bonds and covalent bonds between PAMP-5:5 and the surface substrate; when the water content is too high (96%), the large number of water molecules in the three-dimensional network may cause the distance between polymers to increase, reduce the intermolecular interaction force, make it difficult for PAMP-5:5 to resist peeling stress, and the adhesion force decreases accordingly.

[0080] Furthermore, in order to explore the effects of different PEO molecular weights and different PAM and PEO mass ratios on the swelling properties of PAMP hydrogels, five groups of hydrogel materials with PEO molecular weights of 100kDa, 500kDa, 1000kDa, 5000kDa and 8000kDa and five groups of hydrogel materials with PAM and PEO mass ratios of 10:0, 6:4, 5:5, 4:6 and 0:10 (corresponding to PAMP-10:0, PAMP-6:4, PAMP-5:5, PAMP-4:6 and PAMP-0:10, respectively, and the molecular weight of PEO was 8000kDa) were tested three times to test the time required for the water content to be greater than 91%.

[0081] like Figure 12 Figure (a) shows the swelling time required for hydrogels with different PEO molecular weights to reach a water content exceeding 91%. As can be seen, as the PEO molecular weight increases, the swelling rate accelerates, and the time required to reach 91% water content decreases. For a PEO molecular weight of 100 kDa, the swelling time is 500 s, while for a PEO molecular weight of 8000 kDa, it only takes 15 s. This is because high-molecular-weight PEO has longer molecular chains and more degrees of freedom, allowing it to absorb water and expand more quickly, accelerating the rate at which water molecules enter the hydrogel during the swelling process. Furthermore, high-molecular-weight PEO may strengthen intermolecular interactions, such as hydrogen bonding and van der Waals forces. These interactions facilitate water penetration into the hydrogel, further accelerating the swelling rate. Furthermore, the entanglement of high-molecular-weight PEO hydrogels results in a higher degree of polymerization, making the internal structure of the hydrogel more complex and providing more pores to accommodate water. Therefore, high-molecular-weight PEO results in a faster swelling rate for hydrogels.

[0082] like Figure 12Figure (b) shows the swelling time required for hydrogel materials with different PAM to PEO mass ratios to reach a water content exceeding 91%. It can be seen that in pure component systems (pure PAM or pure PEO), the time required to reach 91% water content is relatively long, exceeding 300 seconds. In non-isometric molecular systems, namely, those with PAM to PEO mass ratios of 6:4 and 4:6, the required time is relatively low, both around 20 seconds. In isometric molecular systems, namely, when the PAM to PEO mass ratio in the hydrogel is 5:5, PAMP-5:5 takes the least time to reach a water content exceeding 91%, at around 15 seconds. This is because in a system with only PAM molecules, the high density of the PAM molecules hinders the diffusion of water molecules. In a hydrogel system with only PEO molecules, the high molecular weight PEO chains form strong molecular entanglements, making it difficult for water molecules to quickly penetrate, thereby reducing the swelling rate. In the non-isometric molecular system, the PAM backbone provides structural support, while PEO introduces larger intermolecular spaces, allowing water to diffuse more quickly within the network and creating a synergistic water absorption effect. Furthermore, the polar amide groups (-CONH2) of PAM and the ether groups (-O-) of PEO can form hydrogen bonds, which help improve the hydration of the hydrogel and allow water molecules to enter the hydrogel structure more quickly. Therefore, in the isometric molecular system, PAMP-5:5 exhibits the optimal molecular structure, namely, a uniform bicontinuous phase separation network channel that allows water molecules to enter the hydrogel structure more quickly, resulting in the fastest swelling rate.

[0083] Furthermore, in order to explore the morphological characteristics of hydrogels with different PAM to PEO mass ratios after swelling in water and saline (3.6% sodium chloride solution), five groups of hydrogel materials with PAM to PEO mass ratios of 10:0, 6:4, 5:5, 4:6 and 0:10 were swollen in water and saline to a water content of 91%.

[0084] like Figure 13 Figure 2 shows the swelling results of hydrogel materials with different PAM to PEO mass ratios in water and saline. Post-swelling structural analysis reveals that for all hydrogel materials, the swelling results in water and saline are comparable, with negligible differences. For the pure component systems, both pure PAM and pure PEO hydrogels exhibit distinct isotropic swelling characteristics. The pure PAM hydrogel feels noticeably harder after swelling, while the pure PEO hydrogel feels softer after swelling. In the non-isometric molecular system, when the PAM to PEO mass ratio is 6:4, PAMP-6:4 exhibits relatively pronounced anisotropic swelling. When the PAM to PEO mass ratio is 4:6, PAMP-4:6 exhibits isotropic swelling with blurred boundaries. In the isometric molecular system, PAMP-5:5 exhibits even more pronounced anisotropic swelling with clear boundaries.

[0085] This is likely because the pure components cannot form a biphasic network structure. Therefore, during swelling, water molecules diffuse in all directions, resulting in isotropic swelling. The high density of the PAM molecules makes the swollen hydrogel feel firmer, while the softness of the PEO molecules makes the swollen hydrogel feel softer. In a non-isometric system, when the PAM:PEO ratio is 6:4, the molecular structure initially exhibits a bicontinuous phase-separated network structure, with water molecules infiltrating along the network structure, resulting in anisotropic swelling. In contrast, when the PAM:PEO ratio is 4:6, due to the lack of clear biphasic separation and the predominance of the toughening phase, water molecules infiltrating the hydrogel in all directions more easily disrupt the molecular network, resulting in a blurred hydrogel boundary. In the isometric system, the hydrogel exhibits a superior molecular structure, with water molecules infiltrating along the network structure, exhibiting anisotropic swelling. This swelling phenomenon further confirms the structural characteristics of hydrogel materials with varying PAM:PEO mass ratios.

[0086] Furthermore, in order to explore the tensile mechanical characteristics of hydrogel materials with different mass ratios of PAM and PEO, hydrogel materials with mass ratios of PAM to PEO (molecular weight 8000 kDa) of 10:0, 6:4, 5:5, 4:6 and 0:10 were used to carry out tensile performance tests on an electronic universal testing machine. Test samples with a width of 5 mm and a length of 2 m (effective length of 15 mm) were prepared, and the test speed was kept constant (1 mm / s). The Young's modulus of the hydrogel material can then be calculated from the slope of the stress-strain curve.

[0087] like Figure 14 Figure 2 shows stress-strain curves for hydrogels with different PAM to PEO mass ratios (10:0, 6:4, 5:5, 4:6, and 0:10). As can be seen, with increasing PEO concentration, the elongation at break of the corresponding hydrogels first increases and then decreases, while the tensile strength gradually decreases. In the pure component system, the elongation at break of the pure PAM hydrogel is only 120%, with a maximum tensile strength of 83 kPa; whereas, the elongation at break of the pure PEO hydrogel reaches 390%, with a minimum tensile strength of only 10 kPa. In the non-isometric system, the elongation at break of 550% and a tensile strength of 58 kPa are achieved at a PAM to PEO mass ratio of 6:4; the elongation at break of 650% and a tensile strength of 38 kPa are achieved at a PAM to PEO mass ratio of 4:6. In the isometric system, the elongation at break reaches a maximum of 700%, with a tensile strength of 50 kPa.

[0088] This may be due to the relatively high strength and low toughness of pure PAM hydrogels, resulting in the lowest elongation at break and the highest tensile strength. However, pure PEO hydrogels have greater toughness and lower strength, resulting in the lowest tensile strength. However, without the support of PAM as a molecular backbone, they are more likely to break when stretched, resulting in a lower elongation at break than the non-isometric molecular system. In this non-isometric molecular system, PAM acts as the molecular backbone, anchoring the hydrogel as a whole through crosslinks, providing the basic structure and mechanical support for the gel system and forming a stable three-dimensional network. The long and flexible PEO molecular chains allow for segmental slip under stress, and their distribution within the network enhances the system's flexibility and toughness. The dynamic slip of the PEO molecules, in synergistic interaction with the restraining effect of the PAM backbone, enhances the ductility and adhesion of the hydrogel system. Among them, when the mass ratio of PAM to PEO is 6:4, the tensile strength of PAMP-5:5 is relatively high, while the elongation at break is relatively low, due to the higher content of PAM molecules as the molecular skeleton; when the mass ratio of PAM to PEO is 4:6, the tensile strength of PAMP-4:6 is relatively low, while the elongation at break is relatively high, due to the higher content of PEO molecules as the toughening phase; in the equal-proportion molecular system, since PAMP-5:5 presents the best molecular structure, the elongation at break of PAMP-5:5 reaches the maximum value under the synergistic effect of PAM and PEO.

[0089] like Figure 14 Figure 2 shows the stress-strain curve of PAMP-5:5. Analysis of the curve reveals that the Young's modulus of PAMP-5:5 is 60 kPa, while the Young's modulus of skin ranges from tens to hundreds of kPa. Therefore, the Young's modulus of PAMP-5:5 meets the requirement for skin-like softness. In a tensile test of PAMP-5:5, the length of the material before stretching was 1 cm, but after stretching (before breaking), it reached 9 cm.

[0090] like Figure 15Figure 2 shows a schematic diagram illustrating the adhesion mechanism of a hydrogel material used to adhere an electronic device to skin. Specifically, the diagram illustrates the process of adhesion between the electronic device substrate and the hydrogel material, rapid physical crosslinking between the hydrogel material and moist skin, and stable covalent crosslinking between the hydrogel material and the skin. The hydrogel material first forms stable adhesion to the substrate through van der Waals forces, hydrogen bonds, and covalent bonds. The PAMP hydrogel then comes into contact with the skin surface, forming rapid physical crosslinks (Derwaard forces and hydrogen bonds). These hydrogen bonds primarily originate from polar functional groups such as the hydroxyl (-OH) groups on the PEO molecular chains and the amide (-CONH2) groups on the PAM chains, which form hydrogen bonds with other functional groups on the skin surface, such as hydroxyl (-OH), amino (-NH2), or carboxyl (-COOH) groups. Subsequently, the ester groups of NHS (C4H5NO3, containing a five-membered ring structure (succinimide ring) and an ester group (-COO-)) grafted onto the hydrogel molecules form covalent bonds with amine (-NH2) groups on the skin surface. After the reaction, the five-membered rings naturally fall off and decompose into non-toxic products that are harmless to the human body and the environment. The PAMP hydrogel can achieve stable adhesion to the skin within 10 seconds. Therefore, using the PAMP hydrogel as an intermediate adhesion layer allows for strong wet adhesion between flexible bioelectronic devices and skin, expanding their application scenarios and scope.

[0091] Among them, PAM molecules serve as the supporting phase to provide structural stability and mechanical strength to the hydrogel, and the flexible high molecular weight PEO molecules serve as the toughening phase to enhance the cohesion and interfacial adhesion of the gel network through the entanglement effect. The two work synergistically to form a network structure with bicontinuous phase separation; the high molecular weight entanglement points can serve as pinning points to enhance the toughness of the hydrogel and prevent the hydrogel material from being torn by external forces; in addition, the surface-grafted NHS can form covalent bonds with the amino groups (-NH2) on the skin surface to enhance the adhesion of the hydrogel.

[0092] To further explore the effects of different PEO molecular weights and PAM / PEO mass ratios on the adhesion properties of the hydrogels, standard 180° peel and lap shear tests were conducted. Five PAMP hydrogels with PEO molecular weights of 100 kDa, 500 kDa, 1000 kDa, 5000 kDa, and 8000 kDa, and five hydrogels with PAM / PEO mass ratios of 10:0, 6:4, 5:5, 4:6, and 0:10, were used. All samples were subjected to identical experimental conditions: a 2 cm x 0.5 cm silica gel substrate. Each xerogel film sample was cut into a 1.5 cm x 0.5 cm rectangle. Adhesion tests were performed after the xerogel film samples were swollen to a water content of 91%. After the silica gel and hydrogel were bonded, they were pre-pressed at the same pressure (1 kPa) for 30 seconds to ensure full adhesion. To minimize the effects of long-term storage on adhesion, the experiments were performed immediately after bonding the hydrogel and silica gel.

[0093] like Figure 16 As shown, the experimental diagrams of 180° peeling experiments after swelling of hydrogel materials with different PEO molecular weights and hydrogel materials with different PAM to PEO mass ratios are shown. The substrate is silica gel, and each group of experiments is tested three times. Figure 16 (a) shows the experimental images of the 180° peeling test of hydrogel materials with PEO molecular weights of 100 kDa, 500 kDa, 1000 kDa, 5000 kDa, and 8000 kDa (corresponding to PEO-10w, PEO-50w, PEO-100w, PEO-500w, and PEO-800w, respectively) after swelling in water; Figure 16 (b) shows the experimental images of 180° peeling experiments of hydrogel materials with PAM to PEO mass ratios of 10:0, 6:4, 5:5, 4:6 and 0:10 after swelling in water and saline, respectively.

[0094] like Figure 17 As shown, the relationship between the interface toughness and shear strength of hydrogel materials with different PEO molecular weights and hydrogel materials with different PAM to PEO mass ratios is shown.

[0095] in, Figure 17 (a) shows the relationship between the interfacial toughness and shear strength of hydrogel materials with different PEO molecular weights. It can be seen that the interfacial toughness and shear strength of the hydrogel material gradually increase with the increase of PEO molecular weight. When the PEO molecular weight is 100kDa, the adhesion of the hydrogel material is the smallest, and the interfacial toughness at this time is 20J / m 2 , the shear strength is 8kPa; when the molecular weight of PEO is 8000kDa, the adhesion of the hydrogel material reaches its maximum value, and the interface toughness at this time is 220J / m 2 , and the shear strength is 53kPa. This is because high-molecular-weight PEO has longer molecular chains, making it easier for physical entanglement to occur between chain segments. These entangled structures form stronger intermolecular forces between the hydrogel and the substrate interface, improving adhesion. In addition, the larger the molecular weight of PEO, the stronger the hydrogen bond effect, and the more sites on the PEO chain that can form hydrogen bonds, thereby enhancing adhesion. Furthermore, high-molecular-weight PEO has higher molecular flexibility, which increases the contact area and makes it easier to spread on the solid surface. This large-area contact can improve the physical adsorption and adhesion properties of PEO on the substrate.

[0096] Figure 17(b) shows the relationship between the interfacial toughness and shear strength of hydrogel materials with different PAM to PEO mass ratios swollen in saline to a water content of 91%. It can be seen that the adhesion performance of the hydrogel material increases with the increase of PEO content, but when the mass ratio of PAM to PEO is 4:6, the adhesion performance of the hydrogel decreases, and the interfacial toughness at this time is 180 J / m 2 , the shear strength is about 48kPa; when the mass ratio of PAM to PEO is 5:5 and 0:10, the adhesion of the corresponding hydrogel material is the largest, and the interface toughness is about 220J / m 2 , the shear strength is about 53kPa; when the mass ratio of PAM to PEO is 6:4, the adhesion of the corresponding hydrogel material is relatively low, and the interface toughness at this time is 130J / m 2 , the shear strength is 41kPa; when the mass ratio of PAM to PEO is 10:0, the adhesion of the corresponding hydrogel material is the lowest, and the interface toughness at this time is 70J / m 2 , the shear strength is 18kPa. The adhesion properties of hydrogel materials with different PAM to PEO mass ratios are the same in saline and water, which fully proves that hydrogel materials can be used in water and under sweating conditions. Among them, the significant difference in the adhesion properties of hydrogel materials with different PAM to PEO mass ratios may be because the physical entanglement effect of PEO's high molecular weight is the decisive factor in the adhesion properties of hydrogels. Therefore, as the PEO content gradually increases, the adhesion of the hydrogel material increases. However, when the mass ratio of PAM to PEO is 5:5, its excellent bicontinuous phase separation network structure makes the internal structure of the molecule more stable, enhances the intermolecular interaction, and has a stronger van der Waals force when it contacts the substrate surface, which can produce more hydrogen bonds, so the adhesion performance is stronger.

[0097] Furthermore, in order to explore the adhesion properties of PAMP-5:5 on different substrates, the durability of PAMP-5:5, and the effect of storage time of PAMP-5:5 on its adhesion, we conducted adhesion experiments on PAMP-5:5 to different substrates (including silicone, PET, paper, pigskin, fabric, and rubber), frozen storage after swelling of PAMP hydrogel for different days, and 180° peeling and lap shear experiments on repeated use of PAMP-5:5.

[0098] like Figure 18 As shown, the relationships between the substrate material, storage time, and usage frequency of PAMP-5:5 adhesion and the interfacial toughness and shear strength of PAMP-5:5 are shown, respectively.

[0099] like Figure 18 As shown in (a), when PAMP-5:5 adheres to paper and fabric, its adhesion is significantly stronger, and the interfacial toughness of PAMP-5:5 and paper reaches 400 J / m2 The shear strength reaches 190kPa; the interface toughness of PAMP-5:5 and fabric adhesion reaches 420J / m 2 , the shear strength reaches 235kPa. This may be due to the large surface roughness of paper and fabric, which increases the contact area during adhesion; in addition, the surface of paper and fabric is rich in cellulose and lignin, which can provide a large number of hydrophilic groups, such as hydroxyl, carboxyl, ester, ether, etc., which can interact with the amino, hydroxyl, ether and other functional groups on the surface of the hydrogel to form hydrogen bonds, thereby enhancing its adhesion performance. The interfacial toughness and shear strength of PAMP-5:5 adhesion to rubber, pigskin, and silicone and PET treated with silicone surface treatment agent J-750 (naturally dried after coating) are similar, and the interfacial toughness is greater than 200J / m 2 , shear strength is greater than 50kPa.

[0100] like Figure 18 (b) and (c) show the relationship between the interfacial toughness and shear strength of PAMP-5:5 and PAMP-5:5 with different storage time and different usage frequency. It can be seen that the adhesion performance of PAMP-5:5 after swelling and freezing is not significantly affected by storage for 14 days, and the interfacial toughness is still greater than 180 J / m 2 , the shear strength is greater than 49kPa; repeated use has little effect on its adhesion, and its interface toughness is greater than 220J / m after the 9th repeated use. 2 The shear strength was greater than 49 kPa. This fully proves that PAMP-5:5 can be reused multiple times on different substrate surfaces, and the effect of long-term storage on its adhesion is negligible.

[0101] Furthermore, to explore the effect of different PAM to PEO mass ratios on the conductivity of hydrogel materials, five groups of hydrogel materials (each with a PAM to PEO molecular weight of 8000 kDa) with PAM to PEO mass ratios of 10:0, 6:4, 5:5, 4:6, and 0:10 were tested for conductivity using a probe method. The probe first measures the resistance of the hydrogel material, and then calculates the ionic conductivity of the hydrogel material. The formula for calculating the ionic conductivity σ of the hydrogel material is:

[0102] ;

[0103] Where L is the electrode distance, in cm; A is the effective conductive area of ​​the hydrogel material, in cm 2 ; R is the resistance of the hydrogel material, in Ω.

[0104] like Figure 19As shown in the figure, the ionic conductivity of hydrogel materials with different PAM to PEO mass ratios is shown. It can be seen that the higher the PEO molecular ratio, the higher the ionic conductivity of the hydrogel material. When the mass ratio of PAM to PEO is 0:10, the ionic conductivity of the corresponding PAMP-0:10 is the highest, which is 6.5×10 -2 S / m; when the mass ratio of PAM to PEO is 4:6, the ionic conductivity of PAMP-4:6 is 4×10 -2 S / m; when the mass ratio of PAM to PEO is 5:5, the corresponding ionic conductivity of PAMP-5:5 is 3×10 -2 S / m, which meets the conductivity required by flexible bioelectronics. When the mass ratio of PAM to PEO is 6:4, the corresponding ionic conductivity of PAMP-6:4 is 1×10 -2 S / m; when the mass ratio of PAM to PEO is 10:0, the ionic conductivity of PAMP-10:0 is 0.5×10 -2 S / m. This is because the ether oxygen (-O-) of the PEO molecule 2+ Formation of dynamic coordination bonds promotes Ca 2+ In addition, the loose network structure of PEO molecules reduces the ion diffusion resistance. However, as the content of PAM molecules increases, the dense network of PAM molecules hinders the migration of Ca 2+ The migration of ions leads to a decrease in the ionic conductivity of the hydrogel material.

[0105] In summary, the optimal PAM to PEO mass ratio is 5:5, and the optimal PEO molecular weight is 8000 kDa.

[0106] Based on the same inventive concept, the present application also provides a sensor, including a multi-physiological signal sensing body, a coating layer and the above-mentioned hydrogel material; the multi-physiological signal sensing body is encapsulated in the coating layer; the hydrogel material is adhered to the surface of the coating layer and is used to be attached to a biological body, so that the multi-physiological signal sensing body can collect multiple physiological signals of the biological body.

[0107] In summary, this application innovatively constructs a three-dimensional porous network cross-linked system of polyacrylamide / high molecular weight (8000kDa) polyethylene oxide (PAMP) bicontinuous phase separation based on the molecular synergistic mechanism. 2+ The crosslinker achieves conductive and structural dual-functional modification, and combined with surface N-hydroxysuccinimide ester (NHS) grafting technology, a PAMP hydrogel material with biomimetic wet adhesion properties has been successfully developed. The hydrogel material exhibits excellent wet adhesion properties (interface toughness > 230J / m 2) surpasses the adhesion strength of biological soft tissue, has skin-like mechanical properties (Young's modulus 60kPa), fast response capability (adhesion completed within 10s), optimized conductive properties (conductivity up to ×10 -2 The synergistic mechanism of polymer entanglement and ionic cross-linking effectively solves the technical problem of easy detachment of underwater electronic devices.

[0108] Thus, the present invention discloses a hydrogel material, a preparation method thereof, and a sensor. The hydrogel material comprises, by weight, 2 to 8 parts of polyacrylamide and 2 to 8 parts of polyethylene oxide. This application provides a hydrogel material that can be continuously manufactured, easily stored for long periods of time, exhibits rapid adhesion, long-term stability, is biocompatible, and is easy to use. This hydrogel material can be used in sensors for underwater health monitoring, enabling monitoring and assessment of the status of underwater organisms. It can also be used for bonding during surgical procedures.

[0109] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural transformations made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A hydrogel material, characterized in that: Calculated by weight, it comprises 2 to 8 parts of polyacrylamide and 2 to 8 parts of polyethylene oxide.

2. The hydrogel material according to claim 1, characterized in that The mass ratio of the polyacrylamide to the polyethylene oxide is 1:

1.

3. The hydrogel material according to claim 1, characterized in that The hydrogel material further includes a cross-linking agent for chemically cross-linking the polyacrylamide and the polyethylene oxide.

4. The hydrogel material according to claim 2, characterized in that The cross-linking agent is Ca 2+ .

5. The hydrogel material according to claim 1, characterized in that N-hydroxysuccinimide ester is grafted on the surface of the hydrogel material.

6. The hydrogel material according to claim 1, characterized in that The molecular weight of the polyethylene oxide is 8000 kDa.

7. A method for preparing a hydrogel material, characterized in that: For preparing the hydrogel material according to any one of claims 1 to 6, the method comprises the steps of: mixing the polyacrylamide and the polyethylene oxide to obtain a pre-hydrogel solution; coating the pre-hydrogel solution on a substrate to obtain a pre-hydrogel; Drying the pre-hydrogel to obtain a dry gel film; The dry gel film is swollen and solidified to obtain the hydrogel material.

8. The preparation method according to claim 7, characterized in that The method further comprises: arranging a cross-linking agent on the substrate for chemically cross-linking the polyacrylamide and the polyethylene oxide to obtain the pre-hydrogel.

9. The preparation method according to claim 7, characterized in that The step of swelling and solidifying the dry gel film to obtain the hydrogel material comprises: Swelling the xerogel film to obtain a swollen hydrogel; The swollen hydrogel is immersed in a solution containing N-hydroxysuccinimide ester and then cured using ultraviolet light to obtain the hydrogel material.

10. A sensor, characterized in that: It comprises a multi-physiological signal sensing body, a coating layer and a hydrogel material according to any one of claims 1 to 6; The multi-physiological signal sensor body is encapsulated in the coating layer; The hydrogel material is attached to the surface of the coating layer and is used to be attached to a biological body, so that the multi-physiological signal sensing body collects the multi-physiological signals of the biological body.

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