A hydrogel material, a method for preparing the same, and a sensor

Abstract

The application discloses a hydrogel material and a preparation method and a sensor thereof.For the hydrogel material, 2-8 parts of polyacrylamide and 2-8 parts of polyethylene oxide are included in terms of weight parts.The application provides a hydrogel material which can be continuously manufactured, is easy to store for a long time, has fast adhesion, long-term stability, biocompatibility and convenient use, and can be used in a sensor for underwater health monitoring, so that the monitoring and evaluation of the state of an underwater organism can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogel materials, and particularly relates to a hydrogel material, a preparation method thereof and a sensor. BACKGROUND

[0002] Hydrogel is a kind of material formed by chemical or physical cross-linking of natural or synthetic polymers, which has good biocompatibility, softness and biomimetic structure. These characteristics make it widely used in various fields such as surgical medicine and sports.

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

[0004] In sports, whether it is competitive sports that challenge human limits or mass sports that strengthen the body and shape the body, they need to be carried out under scientific monitoring and guidance. With the rapid development of flexible sensing technology, people's demand for sports sensors has evolved from accurate data collection to lightweight, ultra-thin, flexible, small, and other characteristics that can be worn comfortably for a long time, do not affect sports, are convenient to take off and put on, and are suitable for any scene. However, wet environment, especially water sports such as swimming and diving, pose great challenges to flexible electronic products attached to the skin, which are prone to fall off the skin and have poor signal stability.

[0005] Currently, multi-physiological sensing technology and wet adhesion have made some research progress. In terms of multi-physiological sensing technology, most of them are land-based collection technology, and there are still challenges in multi-physiological signal collection in underwater environment, miniaturization and flexibility of sensors. Although significant progress has been made in the field of wet adhesion, there are still limitations in fast adhesion response, continuous preparation, stable wet adhesion, especially in high-salt environments and biocompatibility. SUMMARY

[0006] The technical problem solved by the present application is to provide a hydrogel material, a preparation method thereof and a sensor, which solves the problems of easy falling off between underwater sensor and skin, poor adhesion, long adhesion time, decreased adhesion performance in complex wet environment, complex preparation process, low biocompatibility in long-term health monitoring, and allergic reaction after removal.

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

[0008] The application also provides a preparation method of the hydrogel material, which is used for preparing the hydrogel material, and comprises the following steps: 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; performing drying treatment on the pre-hydrogel to obtain a xerogel film; and performing swelling and curing on the xerogel film to obtain the hydrogel material.

[0009] The application also provides a sensor, which comprises a multi-physiological signal sensing body, a coating layer and the hydrogel material.

[0010] The application has the beneficial effects that the application discloses a hydrogel material, a preparation method thereof and a sensor, for the hydrogel material, by weight, 2-8 parts of polyacrylamide and 2-8 parts of polyethylene oxide are included. The application provides a hydrogel material which can be continuously manufactured, is easy to store for a long time, has fast adhesion, long-term stability, biocompatibility and convenient use, and thus can be used in a sensor for underwater health monitoring, so as to realize monitoring and evaluation of the state of an underwater organism. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a flow chart in an embodiment of the preparation method of the hydrogel material of the application;

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

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

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

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

[0016] Figure 6 is an infrared spectrum diagram of the xerogel film with different mass ratios of PAM and PEO in an embodiment of the hydrogel material of the application;

[0017] Figure 7is a fluorescence microstructure image of the hydrogel material with grafting and without grafting NHS in an embodiment of the hydrogel material of the present application;

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

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

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

[0021] Figure 11 is a graph of the standard 180° peeling test and lap shear experiment of PAMP-5:5 with different swelling times in an embodiment of the hydrogel material of the present application, and the relationship between the swelling characteristics and adhesion of PAMP-5:5 obtained;

[0022] Figure 12 is a graph of the swelling time required for the hydrogel material with different PEO molecular weights and the hydrogel material with different PAM to PEO mass ratios to reach a water content of more than 91% in an embodiment of the hydrogel material of the present application;

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

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

[0025] Figure 15 is an adhesion principle schematic diagram of the process of the hydrogel material adhering to the skin in an embodiment of the hydrogel material of the present application;

[0026] Figure 16 is an experimental graph of the 180° peeling experiment of the hydrogel material with different PEO molecular weights and the hydrogel material with different PAM to PEO mass ratios after swelling respectively in an embodiment of the hydrogel material of the present application;

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

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

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

[0030] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

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

[0032] The present application will be described in detail below in conjunction with specific embodiments.

[0033] In the present application, a hydrogel material is provided, which includes 2-8 parts by weight of polyacrylamide (PAM) and 2-8 parts by weight of polyethylene oxide (PEO).

[0034] Further, 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 the 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 cohesive force and interfacial adhesion of the hydrogel material through entanglement effect, and the two work together to form a three-dimensional network structure of double-continuous phase separation; the entanglement effect of flexible high molecular weight PEO molecules enhances the ductility and adhesion of the hydrogel material, preventing the hydrogel material from being torn by external force.

[0036] Further, the hydrogel material further includes a crosslinking agent for chemically crosslinking the polyacrylamide and the polyethylene oxide.

[0037] Further, the crosslinking agent uses Ca 2+Ca 2+ The conductive-structure dual-function modification can be realized, and the mixed and uniform PAM molecules and PEO molecules form a sacrificial toughening network through the post-crosslinking of Ca 2+ The post-crosslinking of Ca

[0038] Further, the surface of the hydrogel material is grafted with N-hydroxysuccinimide ester (NHS), so that the underwater adhesion of the hydrogel material is enhanced.

[0039] Based on the same inventive concept, the present application also provides a preparation method of the hydrogel material, for preparing the above hydrogel material, which comprises the following steps: Figure 1

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

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

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

[0043] S4: swelling and curing the dry gel film to obtain the hydrogel material.

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

[0045] The raw materials include polyacrylamide (PAM), polyethylene oxide (PEO), polyethylene terephthalate (PET), N-hydroxysuccinimide ester (NHS), dimethyl sulfoxide (DMSO), anhydrous calcium chloride, N-acryloyl succinimide, 6-amino fluorescein, anhydrous ethanol and deionized water, etc. The preparation instruments include an electronic balance, an ultraviolet lamp, an oven, an electronic universal testing machine, a defoaming stirrer, an infrared spectrometer, a fluorescence microscope, a freeze dryer, a micrometer, an ion sputtering instrument and a high-resolution scanning electron microscope, etc.

[0046] In combination with the above description, the present application also provides a hydrogel material prepared by the above method. Figure 2 ​For steps S1-S3, a certain amount of PAM and PEO were mixed uniformly to obtain a pre-hydrogel solution 7. Then, on a printing table, a 2-mm-thick pre-hydrogel solution 7 was coated on a hydrophobic-coating-treated roll-shaped PET substrate 8 (made of polyethylene terephthalate) using a blade to obtain a pre-hydrogel. Subsequently, the pre-hydrogel was naturally dried at 60°C to form a continuous dry gel film 9.

[0047] Further, in step S4, to introduce the NHS ester network, the dry gel film was cut into a desired size, swelled in water for 15 seconds to reach a water content of 90% to obtain a swollen hydrogel; then, the swollen hydrogel was immersed in a solution of 2 mg / mL NHS ester in anhydrous DMSO, and then cured under 365-nm ultraviolet light for 30 seconds to complete the polymerization reaction to obtain 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 dry gel film is a polyacrylamide / polyethylene oxide (PAMP) dry gel, and the PAMP dry gel forms a three-dimensional porous network with a bicontinuous phase separation through polymer entanglement, which optimizes the water transport channel. This unique structure significantly improves the swelling rate and achieves instant adhesion through rapid hydration kinetics. When the dry gel film contacts the moist tissue of a living body, it will rapidly swell within 10 seconds and transform into a PAMP hydrogel. When the water content reaches 90%, the adhesion reaches a maximum value within 15 seconds, and an adhesion key is formed between the skin through various molecular interactions, thereby establishing stable adhesion.

[0049] Further, 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. Then, the prepared hydrogel materials with different PAM to PEO mass ratios were characterized and performance tested.

[0050] Among them, to study the micro-morphology of the hydrogel material, scanning electron microscopy was used to characterize the micro-morphology structure of the dry gel film, the hydrogel material (corresponding to PAMP-10:0, PAMP-6:4, PAMP-5:5, PAMP-4:6, and PAMP-0:10, respectively), and the peeling interface between the hydrogel material and the substrate with different PAM to PEO mass ratios (10:0, 6:4, 5:5, 4:6, and 0:10). The results show that different mass ratios significantly affect the phase separation behavior and network continuity of the hydrogel material.

[0051] As Figure 3As shown, the morphology of dry gel films with different PAM to 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 10μm).

[0052] In a pure component system, such as Figure 3 As shown in (a), the surface of the dry gel film corresponding to PAMP-10:0 (pure PAM) exhibits a dense, non-porous structure with locally visible slight cracks, 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) exhibits a loose layered structure with discrete pore size distribution and obvious pore wall collapse, indicating that the lack of a supporting phase leads to a loose network and pore wall collapse.

[0053] In non-uniform composite systems, such as Figure 3 As shown in (b), the dry gel film corresponding to PAMP-6:4 (PAM-dominant) initially exhibits 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), no obvious phase separation occurred in the dry gel film corresponding to PAMP-4:6 (PEO-dominant), which may be due to the non-uniform distribution of the two phases in the non-uniform system.

[0054] For equal-proportion composite systems, such as Figure 3 As shown in (c), the dry gel film corresponding to PAMP-5:5 exhibits a bicontinuous interpenetrating network structure with uniform pore size. This confirms that when the mass ratio of PAM to 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 the interpenetrating network.

[0055] like Figure 4 As shown, the morphology of cryopreserved hydrogel materials with different PAM to 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 100μm).

[0056] In a pure component system, such as Figure 4 As shown in (a), the surface of PAMP-10:0 (pure PAM) is dense, with locally visible irregular cracks and sharp edges. This may be due to the lack of a toughening phase in the single PAM network, making it difficult for moisture to swell uniformly. Figure 4As shown in (e) of FIG. 1, the surface of PAMP-0:10 (pure PEO) showed a loose lamellar structure with a non-uniform super-large pore size (300 pm), which might be due to the lack of support phase in the single PEO network, resulting in a loose network skeleton.

[0057] In the non-equimolar composite system, such as Figure 4 As shown in (b) of FIG. 1, PAMP-6:4 (PAM-based) showed a porous structure, but the pore size was not uniform, and the continuity was poor, and there was a non-porous area on the surface. This might be due to uneven two-phase separation, resulting in uneven water diffusion during swelling, leading to uneven pore size. As shown in (c) of FIG. 1, PAMP-5:5 showed a uniform bicontinuous phase separation interpenetrating network structure with uniform pore size (50±5 pm), which might be due to the coordination of PAM molecular skeleton and PEO flexible chain segment through hydrogen bonding with Ca Figure 4 As shown in (d) of FIG. 1, PAMP-4:6 (PEO-based) showed a non-uniform large-pore mesh structure (100 pm) with uneven surface and crystallization, which might be due to the fact that the two phases did not separate significantly, and the toughening phase was too much to cause the destruction of the molecular network skeleton during the swelling of the xerogel film.

[0058] For the equimolar composite system, such as Figure 4 As shown in (c) of FIG. 1, PAMP-5:5 showed a uniform bicontinuous phase separation interpenetrating network structure with uniform pore size (50±5 pm), which might be due to the coordination of PAM molecular skeleton and PEO flexible chain segment through hydrogen bonding with Ca 2+ coordination to form a stable topological structure. Therefore, among the freeze-preserved hydrogel materials, the group with PAM and PEO mass ratio of 5:5 also showed a more uniform and continuous porous mesh structure. Therefore, from the perspective of microstructure, the hydrogel material PAMP-5:5 showed the best structural characteristics when the mass ratio of PAM to PEO was 5:5.

[0059] As shown in (c) of FIG. 1, PAMP-5:5 showed a uniform bicontinuous phase separation interpenetrating network structure with uniform pore size (50±5 pm), which might be due to the coordination of PAM molecular skeleton and PEO flexible chain segment through hydrogen bonding with Ca Figure 5 As shown in (a) of FIG. 2, the microstructure of PAMP-5:5 is shown, and the microstructure of the adhesion of the substrate to the filament is shown. Among them, Figure 5 (a) of FIG. 2 is the microstructure of PAMP-5:5, and the scale is 200 pm. Figure 5 (b) of FIG. 2 is a microstructure diagram of the adhesion of PAMP-5:5 to the substrate to the filament, and the scale is 100 pm. Figure 5(c) is a micrograph of the hydrogel fiber generated by the phenomenon of fiber drawing in the process of adhesion to the substrate, the scale is 200 pm. It can be seen from the analysis of the microstructure diagram that the PAMP-5:5 after cryopreservation presents a uniform three-dimensional porous network structure with a bicontinuous phase separation, and the average pore size is 80 ± 20 pm; when the PAMP-5:5 is peeled off from the substrate, the interface region presents a dense fibrous adhesion fiber structure, indicating that a strong interaction is formed between the PAMP-5:5 and the substrate. This is because the PAM molecules provide skeletal support as the supporting phase, and the PEO molecules form a continuous hydrophilic channel through the entanglement effect and hydrogen bonding, promoting the rapid conduction of water molecules or ions, forming hydrogen bonds, and realizing rapid adhesion.

[0060] Secondly, in order to verify the functional groups in the hydrogel, it is determined that the desired hydrogel material is synthesized, and the Fourier transform infrared spectroscopy (FTIR) detection is performed on the dry gel film of different PAM and PEO mass ratios prepared to determine the specific functional groups. Among them, in a dry environment, the attenuated total reflection accessory is placed in the light path of the infrared spectrometer, the air background is scanned, and then the surface of the hydrogel material sample is tightly attached to the crystal face of the ATR accessory, and the infrared spectrum of the sample is collected.

[0061] As shown in Figure 6 , the infrared spectrum diagrams 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 wide peak near 3391 cm -1 is the O-H stretching vibration in the hydrogel material, the enhanced absorption band near 3384 cm -1 is the stretching vibration peak of N-H in the hydrogel material, the absorption band near 2879 cm -1 is the C-H molecular skeleton of the hydrogel material, the peaks at 1649 cm -1 and 1600 cm -1 correspond to the stretching vibration of the carbonyl C=O in the amide group and the bending vibration of N-H, respectively. 1460 cm -1 is the C-H molecular skeleton in the hydrogel material, 1331 cm -1 is the C-N stretching vibration peak in the amide bond, 1280 cm -1 , 1240 cm -1 , 1100 cm -1 , 957 cm -1 nearby is the C-O stretching vibration peak of the ether group (-O-) in the hydrogel material, 842 cm -1 is the long-chain C-C skeleton, and 478 cm -1The lattice vibration of inorganic substance was observed, thus proving that the desired hydrogel material was successfully prepared.

[0062] Further, in order to prove that the N-hydroxysuccinimide ester bond was successfully grafted on the surface of the hydrogel material, it is necessary to observe the grafted and non-grafted NHS hydrogel materials by fluorescence microscopy. Among them, in order to verify the existence of NHS ester bond on the surface of the hydrogel material, the hydrogel materials containing and not containing NHS ester bond are immersed in 6-amino fluorescein solution for 2h in the dark, and after three times of ultrasonic cleaning (10min / time), the fluorescence signal distribution at the interface is observed by fluorescence microscope.

[0063] As shown in Figure 7 , the fluorescence microstructure of the grafted and non-grafted NHS hydrogel materials is shown, and the scale is 100μm. It is known from the analysis of fluorescence microscopy results that the hydrogel material with NHS ester bond is dyed green, and the hydrogel material without NHS ester bond is black, thus proving the successful grafting of NHS ester bond.

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

[0065] Specifically, under constant temperature (25±0.5℃) conditions, the hydrogel samples (15mm×5mm) are respectively immersed in water and 3.6%wt NaCl2 solution for swelling. The change of three-dimensional size is measured by micrometer, and the swelling rate of the length / width / thickness direction of the hydrogel material is calculated according to the first swelling formula, which is:

[0066] ;

[0067] Among them, and are the sizes before and after swelling, respectively, and x, y and z represent the length, width and thickness directions of the hydrogel material, respectively.

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

[0069] ;

[0070] Among them, and are the mass of dry PAMP and swollen PAMP, respectively.

[0071] Further, the water content is determined by weighing method, and calculated according to the water content formula, which is:

[0072] ;

[0073] wherein, and are the mass of dry PAMP and swollen PAMP, respectively.

[0074] As shown in FIG. 1, a schematic diagram of anisotropic swelling of PAMP-5:5 is shown. Wherein, 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. Figure 8 As shown in FIG. 2, a graph of the relationship between the swelling time and the swelling rate of PAMP-5:5 is shown.

[0075] (a) of FIG. 3 shows the relationship between the swelling time and the swelling rate of PAMP-5:5 in the length L, width W, and thickness T directions, Figure 9 (b) of FIG. 3 shows the relationship between the swelling time and the swelling rate of PAMP-5:5 as a whole, and the test frequency is 3 times. According to the structural analysis of anisotropic swelling, when PAMP-5:5 is completely swollen, the change in the thickness direction is significant, and the swelling rate can reach 3200%, while the changes in the length and width directions are almost negligible, and PAMP-5:5 reaches an equilibrium state when the swelling time reaches 1800s. This property makes PAMP-5:5 swell only in the thickness direction, which can be well adapted to flexible patch adhesion materials. Figure 9 Figure 9 As shown in FIG. 4, a graph of the relationship between the swelling time and the swelling rate and water content of PAMP-5:5 is shown. In combination with (b) of FIG. 3, As shown in FIG. 4, a graph of the relationship between the swelling time and the swelling rate and water content of PAMP-5:5 is shown. In combination with (b) of FIG. 3,

[0076] As shown in FIG. 4, a graph of the relationship between the swelling time and the swelling rate and water content of PAMP-5:5 is shown. In combination with (b) of FIG. 3, Figure 10 As shown in FIG. 4, a graph of the relationship between the swelling time and the swelling rate and water content of PAMP-5:5 is shown. In combination with (b) of FIG. 3, Figure 9 As shown in FIG. 4, a graph of the relationship between the swelling time and the swelling rate and water content of PAMP-5:5 is shown. In combination with (b) of FIG. 3,

[0077] Further, in order to further explore the relationship between the swelling properties and adhesion of PAMP-5:5, the standard 180° peeling test and lap shear test were performed on PAMP-5:5 with different swelling times. Among them, PAMP-5:5 with the same size was prepared, and after the substrate and PAMP-5:5 were completely adhered, they were pre-pressed for 30 s under the same pressure (1 kPa) to make them fully adhere, and then tested using an electronic universal testing machine according to the standard lap shear test, and the test speed was kept constant (100 mm / min). The interfacial toughness was calculated by dividing the peak force in the 180° peeling test by the width of the tissue sample, and the shear strength was calculated by dividing the peak force by the adhered area, which met the corresponding ASTM standard.

[0078] As shown in FIG. 1, Figure 11 , Figure 11 (a) in FIG. 1 is a schematic diagram of the 180° peeling test experiment, Figure 11 (c) in FIG. 1 is a schematic diagram of the lap shear test, Figure 11 (b) in FIG. 1 shows a graph of the relationship between swelling time and interfacial toughness and shear strength, and the substrate uses silica gel. From the analysis, it can be seen that as the soaking time gradually increases, the adhesion of PAMP-5:5 gradually increases, and when the soaking time is 15 s, the adhesion of PAMP-5:5 reaches a maximum value, the interfacial toughness is 210 J / m 2 , and the shear strength is 53 kPa, and the water content at this time is 91%; when the soaking time of PAMP-5:5 reaches 60 s, the adhesion is still very strong, the interfacial toughness of PAMP-5:5 and the substrate reaches 190 J / m 2 , and the shear strength is more than 50 kPa, and the water content at this time is 93%. However, when the soaking time of PAMP-5:5 reaches 1800 s, the adhesion decreases, the interfacial toughness of PAMP-5:5 and the substrate is 108 J / m 2 , and the shear strength is more than 29 kPa, and the water content at this time is more than 96%, and the interfacial toughness and shear strength at this time are still higher than half of the peak interfacial toughness and shear strength, which fully proves the wet-state adhesion of PAMP-5:5. The interfacial toughness and shear strength when the water content is about 91% completely meet the adhesion requirements of flexible bioelectronic devices, so generally PAMP-5:5 can be used after swelling for 15 s, and because PAMP-5:5 is closely adhered to the skin and electronic devices during use, it is difficult to re-absorb water during underwater movement, so the water content of PAMP-5:5 during movement will be relatively stable at the initial amount.

[0079] Therefore, the adhesion of PAMP-5:5 initially increases and then slightly decreases with increasing water content. This is mainly because in the initial swelling stage, water molecules rapidly penetrate the PAMP hydrogel network, enhancing the physical cross-linking (hydrogen bonding, electrostatic interaction) of the bimolecular network and potentially promoting the diffusion of functional groups (such as carboxyl and amino groups) to the substrate surface, thus strengthening the hydrogen and covalent bonds between PAMP-5:5 and the surface substrate. However, when the water content is too high (96%), the large number of water molecules in the three-dimensional network may increase the distance between polymers, reducing the intermolecular interaction force and making it difficult for PAMP-5:5 to resist peel stress, resulting in a decrease in adhesion.

[0080] Furthermore, to investigate the effects of different PEO molecular weights and different PAM to 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 to 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, with a PEO molecular weight of 8000kDa in all cases) were tested three times each, measuring the time required for the water content to be greater than 91%.

[0081] like Figure 12 As shown in (a), the swelling time required for hydrogel materials with different PEO molecular weights to reach a water content exceeding 91% is displayed. It can be seen that as the molecular weight of PEO gradually increases, the swelling rate increases, and the time required to reach a water content of 91% decreases. For a PEO molecular weight of 100 kDa, it takes 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 greater degrees of freedom, enabling it to absorb water and expand more quickly, thus increasing the rate at which water molecules enter the hydrogel material during the swelling process. Furthermore, the interactions between high molecular weight PEO molecules may be strengthened, such as hydrogen bonds and van der Waals forces, which facilitate the penetration of water molecules into the hydrogel material, further accelerating the swelling rate. Moreover, the hydrogel material formed by high molecular weight PEO has a higher degree of polymerization due to entanglement, resulting in a more complex internal structure and more pores to accommodate water. Therefore, high molecular weight PEO leads to a faster swelling rate in hydrogel materials.

[0082] like Figure 12As shown in (b), the swelling time required for hydrogel materials with different PAM to PEO mass ratios to reach a water content exceeding 91% is displayed. It can be seen that in pure component systems (pure PAM or pure PEO), the time required to reach a water content of 91% is relatively long, greater than 300 s. In non-uniform molecular systems, i.e., when the PAM to PEO mass ratio is 6:4 and 4:6, the required time is relatively short, around 20 s. In uniform molecular systems, i.e., when the PAM to PEO mass ratio in the hydrogel material is 5:5, the time required for PAMP-5:5 to reach a water content exceeding 91% is the shortest, around 15 s. This is because in a single PAM molecular system, the high density of PAM molecules hinders the diffusion of water molecules. In a single PEO hydrogel system, the high molecular weight PEO chains undergo strong molecular entanglement, making it difficult for water molecules to penetrate quickly, thus reducing the swelling rate. In non-uniform molecular systems, the PAM framework provides structural support, while PEO introduces larger intermolecular gaps, 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 oxygen groups (-O-) of PEO can form hydrogen bonds, which helps improve the hydration of the hydrogel, allowing water molecules to enter the hydrogel structure more rapidly. Therefore, in uniform molecular systems, PAMP-5:5 exhibits the optimal molecular structure, with its uniform bicontinuous phase-separated network channels enabling water molecules to enter the hydrogel structure more quickly, resulting in the fastest swelling rate.

[0083] Furthermore, in order to investigate the morphological characteristics of hydrogels with different PAM to PEO mass ratios after swelling in water and salt water (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 salt water to a water content of 91%.

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

[0085] This is likely because the pure component system cannot form a biphase separated network structure. Therefore, during swelling, water molecules diffuse in any direction, resulting in isotropic swelling characteristics. The high density of PAM molecules makes the swollen hydrogel feel harder, while the softness of PEO molecules makes it softer. In non-uniform molecular systems, when the PAM:PEO molecular ratio is 6:4, the molecular structure initially exhibits a biphase separated continuous network structure. Water molecules penetrate along the network structure, thus exhibiting anisotropic swelling characteristics. However, when the PAM:PEO molecular ratio is 4:6, because the two phases are not clearly separated and there is more toughening phase, water molecules are more likely to disrupt the molecular network framework when penetrating the hydrogel in any direction, resulting in blurred hydrogel boundaries. In uniform molecular systems, the hydrogel exhibits an excellent molecular structure, with water molecules penetrating along the network structure, exhibiting anisotropic swelling characteristics. This swelling phenomenon further verifies the structural characteristics of hydrogel materials with different PAM:PEO mass ratios.

[0086] Furthermore, to investigate the tensile mechanical characteristics of hydrogel materials with different PAM and PEO mass ratios, hydrogel materials with PAM to PEO (molecular weight of 8000 kDa) mass ratios of 10:0, 6:4, 5:5, 4:6, and 0:10 were used for tensile property testing in 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 testing speed was kept constant (1 mm / s). The Young's modulus of the hydrogel material could then be calculated from the slope of the stress-strain curve.

[0087] like Figure 14 The figure shows the stress-strain curves of hydrogel materials with different PAM to PEO mass ratios (10:0, 6:4, 5:5, 4:6, and 0:10). It can be seen that as the PEO molecular concentration increases, the elongation at break of the corresponding hydrogel material first increases and then decreases, while the tensile strength gradually decreases. In the pure component system, the elongation at break of pure PAM hydrogel is only 120%, and the maximum tensile strength reaches 83 kPa; while the elongation at break of pure PEO hydrogel reaches 390%, and the minimum tensile strength is only 10 kPa. In the non-uniform molecular system, when the PAM to PEO mass ratio is 6:4, the elongation at break is 550%, and the tensile strength is 58 kPa; when the PAM to PEO mass ratio is 4:6, the elongation at break is 650%, and the tensile strength is 38 kPa. In the uniform molecular system, the maximum elongation at break is 700%, and the tensile strength is 50 kPa.

[0088] This can be due to the relatively large strength of pure PAM hydrogel and low toughness, resulting in the lowest elongation at break and the highest tensile strength; but the toughness of pure PEO hydrogel is larger and the strength is lower, resulting in the lowest tensile strength, but without the support of PAM as the molecular skeleton, it is easier to break during stretching, so the elongation at break is lower than that of the non-proportional molecular system. In the non-proportional molecular system, PAM acts as a molecular skeleton, fixing the whole hydrogel through crosslinking points, providing the basic structure and mechanical support of the gel system, forming a stable three-dimensional network, and PEO molecular chain is long and flexible, which can cause chain segment slip under stress, and distribute in the network to enhance the flexibility and toughness of the system. The dynamic slip of PEO molecules and the limiting effect of PAM skeleton cooperate and synergize to enhance 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 and 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 and 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, PAMP-5:5 shows the best molecular structure, and under the synergistic effect of PAM and PEO, the elongation at break of PAMP-5:5 reaches the maximum value.

[0089] As shown in Figure 14 , the stress-strain curve of PAMP-5:5 is shown, and according to the curve analysis, the Young's modulus of PAMP-5:5 is 60 kPa, and the Young's modulus of the skin is several to several hundred kilopascals, so the Young's modulus of PAMP-5:5 meets the demand of skin-like softness. Among them, during the PAMP-5:5 stretching experiment, the length of PAMP-5:5 before stretching is 1 cm, and the length of PAMP-5:5 after stretching (before breaking) reaches 9 cm.

[0090] As shown in Figure 15The adhesion principle of the process of the hydrogel material adhering to the skin is shown. Specifically, the process of the substrate of the electronic device adhering to the hydrogel material, the hydrogel material forming rapid physical cross-linking with the wet skin, and the hydrogel material forming stable covalent cross-linking with the skin is shown. Among them, the hydrogel material first forms stable adhesion with the substrate through van der Waals force, hydrogen bond, and covalent bond. Subsequently, the PAMP hydrogel contacts the skin surface to form rapid physical cross-linking (van der Waals force, hydrogen bond), and the hydrogen bond is mainly derived from the polar functional groups on the PEO molecular chain, such as the hydroxyl group (-OH) and the amide group (-CONH2) on the PAM chain, to form hydrogen bonds with the functional groups on the skin surface, such as the hydroxyl group (-OH), the amino group (-NH2), or the carboxyl group (-COOH). Then, the ester group (C4H5NO3) of the grafted NHS on the surface of the hydrogel molecule, which contains a five-membered ring structure (succinimidyl ring) and an ester group (-COO-), forms a covalent bond with the amine group (-NH2) on the skin surface. After the reaction, the five-membered ring naturally falls off and naturally decomposes into a non-toxic product, which is harmless to the human body and the environment. The PAMP hydrogel can achieve stable adhesion with the skin within 10s. Therefore, by using the PAMP hydrogel as an intermediate adhesion layer, the flexible bioelectronic device can achieve strong wet adhesion with the skin, thereby increasing the application scenarios and range of the bioelectronic device.

[0091] Among them, the PAM molecules provide structural stability and mechanical strength to the hydrogel as a supporting phase, and the flexible high molecular weight PEO molecules enhance the cohesive force and interfacial adhesion of the gel network through entanglement effect, and the two work together to form a network structure with double continuous phase separation; the high molecular weight entanglement points can act as pinning points to enhance the toughness of the hydrogel, preventing the hydrogel material from being torn by external force; in addition, the grafted NHS on the surface can form a covalent bond with the amine group (-NH2) on the skin surface to enhance the adhesion of the hydrogel.

[0092] Further, in order to explore the influence of different PEO molecular weights and different PAM and PEO mass ratios on the adhesion performance of the hydrogel material, standard 180° peeling experiments and lap shear experiments were performed. Among them, five groups of PAMP hydrogels with PEO molecular weights of 100kDa, 500kDa, 1000kDa, 5000kDa, and 8000kDa were used, and five groups of hydrogel materials with PAM and PEO mass ratios of 10:0, 6:4, 5:5, 4:6, and 0:10 were used. The experimental conditions of all samples were the same, and silica gel was used as the substrate, with a size of 2cm*0.5cm. Each dry gel film sample was cut into a rectangle with a size of 1.5cm*0.5cm. After the dry gel film sample was swelled to a water content of 91%, the adhesion experiment was performed. After the silica gel and the hydrogel material were well attached, they were pre-pressed for 30s under the same pressure (1kPa) to ensure sufficient adhesion. In order to avoid the influence of long-term storage on the adhesion force, the hydrogel material and the silica gel were immediately subjected to the experiment after being well attached.

[0093] As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. Figure 16 As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. Figure 16 FIG. 1 1 (a) shows the 180° peeling experiment of the 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 FIG. 1 1 (b) shows the 180° peeling experiment of the hydrogel materials with PAM to PEO mass ratios of 10:0, 6:4, 5:5, 4:6 and 0:10 respectively after swelling in water and saline.

[0094] As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. Figure 17 As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times.

[0095] As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. Figure 17 As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. 2 As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times. 2 As shown in FIG. 1 1 (a), the 180° peeling experiment of the hydrogel materials with different PEO molecular weights and the 180° peeling experiment of the hydrogel materials with different PAM to PEO mass ratios were carried out respectively after swelling in water. The substrate used was silica gel, and each group of experiments was tested three times.

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

[0097] Further, in order to explore the adhesion of PAMP-5:5 on different substrates, the durability of PAMP-5:5, and the influence of the storage time of PAMP-5:5 on its adhesion, 180° peeling and lap shear experiments of PAMP-5:5 adhesion with different substrates (including silica gel, PET, paper, pigskin, fabric and rubber), post-freezing storage of PAMP hydrogel swelling for different days, and repeated use of PAMP-5:5 were carried out.

[0098] As shown in Figure 18 , the relationship between the substrate material, storage time and use frequency of PAMP-5:5 and the interfacial toughness and shear strength of PAMP-5:5 is shown.

[0099] As shown in Figure 18 (a), when PAMP-5:5 is adhered to paper and fabric, its adhesion is obviously stronger, the interfacial toughness of PAMP-5:5 adhered to paper reaches 400 J / m2 , the shear strength reached 190 kPa; PAMP-5:5: the interfacial toughness of adhesion to fabric reached 420 J / m 2 , the shear strength reached 235 kPa. This may be due to the fact that the surface roughness of both paper and fabric is large, which increases the contact area during adhesion; in addition, the paper and fabric surfaces have abundant cellulose and lignin, which can provide a large number of hydrophilic groups, such as hydroxyl, carboxyl, ester, ether, etc., which can interact with the amine, hydroxyl, ether, etc. functional groups on the surface of the hydrogel through hydrogen bonds, thereby enhancing the adhesion performance. The interfacial toughness and shear strength of PAMP-5:5 adhesion to rubber, pigskin, and silica gel and PET treated with silica gel (silica gel surface treatment agent J-750 was coated and naturally air-dried) are similar, and the interfacial toughness is greater than 200 J / m 2 , the shear strength is greater than 50 kPa.

[0100] As shown in (b) and (c) of Figure 18 , the relationship between the interfacial toughness and shear strength of PAMP-5:5 and PAMP-5:5 under different storage times and different use frequencies is shown. It can be seen that the PAMP-5:5 after swelling and freezing has little effect on its adhesion performance after 14 days of storage, and the interfacial toughness is still greater than 180 J / m 2 , the shear strength is greater than 49 kPa; repeated use has little effect on its adhesion, and the interfacial toughness is greater than 220 J / m 2 , the shear strength is greater than 49 kPa. This fully proves that PAMP-5:5 can be used repeatedly on different substrate surfaces, and the effect of long-term storage on its adhesion can be ignored.

[0101] Further, in order to explore the effect of different PAM to PEO mass ratios on the conductivity of the hydrogel material, five groups of hydrogel materials with PAM to PEO mass ratios of 10:0, 6:4, 5:5, 4:6 and 0:10 (the molecular weight of PEO is 8000 kDa) were tested for conductivity by the probe method. Among them, the resistance of the hydrogel material was first measured by the probe, and then the ionic conductivity of the hydrogel material was calculated. The calculation formula of the ionic conductivity σ of the hydrogel material is:

[0102] ;

[0103] Wherein, L is the electrode spacing, unit: cm; A is the effective conductive area of the hydrogel material, unit: cm 2 ; R is the resistance of the hydrogel material, unit: Ω.

[0104] As shown in Figure 19The figure shows the ion conductivity of the hydrogel material with different PAM / PEO mass ratios. It can be seen that the higher the PEO molecular content, the higher the ion conductivity of the hydrogel material. When the mass ratio of PAM to PEO is 0:10, the ion conductivity of PAMP-0:10 is the highest, reaching 6.5×10 -2 S / m; when the mass ratio of PAM to PEO is 4:6, the ion conductivity of PAMP-4:6 is 4×10 -2 S / m; when the mass ratio of PAM to PEO is 5:5, the ion conductivity of PAMP-5:5 is 3×10 -2 S / m, meeting the conductivity required by flexible bioelectronics; when the mass ratio of PAM to PEO is 6:4, the ion conductivity of PAMP-6:4 is 1×10 -2 S / m; when the mass ratio of PAM to PEO is 10:0, the ion conductivity of PAMP-10:0 is 0.5×10 -2 S / m. This is because the ether oxygen (-O-) of the PEO molecule forms a dynamic coordination bond with Ca 2+ , facilitating the migration of Ca 2+ , and in addition, the loose network structure of the PEO molecule reduces the ion diffusion resistance. However, with the increase of the content of PAM molecules, the dense network of PAM molecules hinders the migration of Ca 2+ , resulting in a decrease in the ion conductivity of the hydrogel material.

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

[0106] Based on the same inventive concept, the 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 packaged in the coating layer; the hydrogel material is attached to the surface of the coating layer, and is used to adhere to a living body, so that the multi-physiological signal sensing body collects multi-physiological signals of the living body.

[0107] In summary, based on the molecular synergistic mechanism, the application innovatively constructs a polyacrylamide / polyethylene oxide (PAMP) double-continuous phase separation three-dimensional porous network crosslinking system with a high molecular weight (8000 kDa), realizes conductive-structure dual functional modification by introducing Ca 2+ crosslinking agent, and successfully develops a PAMP hydrogel material with biomimetic wet adhesion by combining with the surface N-hydroxysuccinimide ester (NHS) grafting technology. The hydrogel material exhibits excellent wet adhesion performance (interfacial toughness > 230 J / m 2) Beyond the adhesion strength of biological soft tissue, skin-like mechanical properties (Young's modulus 60kPa), fast response capability (10s within the adhesion), optimized conductive performance (conductivity up to × 10 -2 S / m) to meet the needs of biological electric signal acquisition, the synergistic mechanism of polymer entanglement and ionic crosslinking effectively solves the technical problem of easy falling off of underwater electronic devices.

[0108] It can be seen that the application discloses a hydrogel material, a preparation method thereof and a sensor, for the hydrogel material, by weight, 2-8 parts of polyacrylamide and 2-8 parts of polyethylene oxide are included. The application provides a hydrogel material which can be continuously manufactured, is easy to store for a long time, has fast adhesion, long-term stability, biocompatibility and is convenient to use, and the hydrogel material can be used in a sensor for underwater health monitoring, so that the monitoring and evaluation of the state of an underwater organism can be realized, and the hydrogel material can also be used for adhesion in a surgical operation.

[0109] The above is only an embodiment of the application, and does not limit the patent scope of the application, and any equivalent structural transformation using the content of the specification and the drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A hydrogel material, characterized in that, 2-8 parts of polyacrylamide and 2-8 parts of polyethylene oxide by weight; The hydrogel material further comprises a crosslinking agent, the crosslinking agent employing Ca 2+ ; The surface of the hydrogel material is grafted with N-hydroxysuccinimide ester; The molecular weight of the polyethylene oxide is 8000 kDa.

2. The hydrogel material of claim 1, wherein, The mass ratio of the polyacrylamide and the polyethylene oxide is 1:

1.

3. A method of preparing a hydrogel material, characterized by, A method for preparing the hydrogel material as claimed in any one of claims 1-2, the method comprising 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; Subjecting the pre-hydrogel to a drying treatment to obtain a dry gel film; Swelling and curing the dry gel film, swelling the dry gel film to obtain a swollen hydrogel; After immersing the swollen hydrogel in a solution containing N-hydroxysuccinimide ester, using ultraviolet light for curing to obtain the hydrogel material; The method further comprises: disposing a crosslinking agent on the substrate, wherein the crosslinking agent is in the form of Ca 2+ .

4. A sensor characterized by, A multi-physiological signal sensing body, a coating layer and the hydrogel material as claimed in any one of claims 1-2; The multi-physiological signal sensing body is encapsulated in the coating layer; The hydrogel material is attached to the surface of the coating layer for attaching to a living body, so that the multi-physiological signal sensing body collects multi-physiological signals of the living body.

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