A pressure-temperature integrated hydrogel array sensor and a preparation method thereof

Abstract

The application relates to the technical field of flexible sensing, in particular to a pressure-temperature integrated hydrogel array sensor and a preparation method thereof. The hydrogel array sensor comprises a plurality of sensing array units arranged in an array; each sensing array unit comprises interdigital electrodes and a hydrogel layer covering the surfaces of the interdigital electrodes; the hydrogel layer is fixed on the interdigital electrodes by a light curing method, and the hydrogel layer is tightly combined with the surfaces of the interdigital electrodes; the interdigital electrodes are two coplanar nested interdigital electrodes prepared by using a flexible circuit board; the hydrogel layer is a hydrogel layer with different crosslinking densities and different heights; and the hydrogel layer comprises a high-crosslinking-density hydrogel area and a low-crosslinking-density hydrogel area. The application designs a flexible sensing structure based on light-cured hydrogel, and through array electrode design and array module acquisition system, pressure signal and temperature signal changes can be monitored simultaneously.

Description

Technical Field

[0001] The present application relates to the field of flexible sensing technology, and in particular to a pressure-temperature integrated hydrogel array sensor and a preparation method thereof. Background Art

[0002] The receptors in the human skin system are composed of ionic conductors, and their signal transduction mechanism is based on ion dynamics. Numerous thermoreceptors and mechanoreceptors are distributed throughout the dermis, enabling precise perception of the spatial distribution of strain and temperature across the skin. Tactile sensing simulates the human skin's functions of temperature, humidity, pressure, and vibration, enabling responses to external stimuli. With the rapid development of the Internet of Things in recent years, flexible tactile sensing has become crucial for the development of numerous cutting-edge technologies, including wearable devices, brain-computer interfaces, and smart healthcare.

[0003] Sensing structures with integrated pressure and temperature sensing enable collaborative sensing between electronic devices, skin, and tissue, crucial for multi-parameter monitoring in complex scenarios. For example, in wound healing, hydrogel dressings with mechanical, temperature, and chemical sensing can enable comprehensive wound monitoring, including sensing stress changes and understanding parameters such as wound surface temperature and reactive oxygen species. Sensing structures that achieve integrated multi-parameter sensing through structural design are a future trend.

[0004] Utilizing ionic pathways to achieve sensing functions can mimic the information processing methods of biological systems and achieve biomimetic sensing functions that are more similar to living organisms. In recent years, ionotropic sensing mechanisms rely on the double-layer structure of the ionic-electron interface, which has high sensitivity. The sensing function of the device can be optimized through the design of ionic materials. Hydrogel materials belong to a class of ionic materials, and their ionic functions can be adjusted through structural design. At the same time, they have the soft characteristics of large deformation and can be applied to sensing structures to achieve highly sensitive feedback to external stimuli. In addition, a variety of biopolymers, natural polymers, and synthetic polymers can be used as components of hydrogels, giving them good biological functionality and thus achieving diverse sensing functions.

[0005] Existing zwitterion-based ionic skin sensor systems utilize temperature-responsive N-isopropylacrylamide and glucose-responsive methacrylamide phenylboronic acid to create a sandwich hydrogel sensor. This overall sensor utilizes capacitive sensing, with the top, middle, and bottom layers each exhibiting distinct response characteristics, enabling monitoring of wound temperature, strain, and interstitial fluid glucose concentration. However, it should be noted that temperature fluctuations in the asymmetric N-isopropylacrylamide hydrogel can cause overall buckling and deformation, potentially interfering with the overall capacitive sensing signal. Summary of the Invention

[0006] The embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor and a preparation method thereof. Based on the ionization sensing and diffusion layer effect of the double-layer theory, a flexible sensing structure based on photocurable hydrogel is designed. Through the array electrode design and the array module acquisition system, the pressure signal and temperature signal changes can be monitored simultaneously.

[0007] To solve the above technical problems, in the first aspect, an embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor, comprising: a plurality of sensor array units arranged in an array; each sensor array unit comprises an interdigitated electrode and a hydrogel layer covering the surface of the interdigitated electrode; the hydrogel layer is fixed on the interdigitated electrode by photocuring, and the hydrogel layer is tightly adhered to the surface of the interdigitated electrode; the interdigitated electrode is two coplanar nested interdigitated electrodes prepared using a flexible circuit board; the hydrogel layer is a hydrogel layer with different cross-linking density and height; the hydrogel layer comprises a high cross-linking density hydrogel region and a low cross-linking degree hydrogel region.

[0008] In some exemplary embodiments, the high cross-linking density hydrogel region is located at the center of the hydrogel layer, and the low cross-linking density hydrogel region is surrounded by the high cross-linking density hydrogel region; the high cross-linking density hydrogel region does not deform during the pressure process and is only affected by temperature; the low cross-linking density hydrogel region can be affected by temperature and pressure at the same time, and achieves single pressure perception by decoupling from the high cross-linking density hydrogel region.

[0009] In some exemplary embodiments, the hydrogel layer has a cross-linked network structure, and ionic components are doped in the cross-linked network structure to form ion paths; the network main material of the cross-linked network structure includes one or more of acrylamide, hydroxyethyl methacrylate, acrylic acid, isooctyl methacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, and N,N-methylenebisacrylamide hydrogel monomers; the ionic component is an ionic liquid or an anionic and cationic polyelectrolyte with a polymerizable functional group structure; the ionic component includes: vinyl imidazole sulfonyl imide salt, vinyl imidazole phosphate, allyl imidazole sulfonyl imide salt, allyl imidazole phosphate, and one or more of sodium alginate, sodium polystyrene sulfonate, sodium polyacrylate, and polydiallyldimethylammonium chloride.

[0010] In some exemplary embodiments, the hydrogel layer further comprises a solvent and a photoinitiator; the solvent is deionized water or a doping system of deionized water and a polyol; the polyol comprises one or more of ethylene glycol, 1,3-propylene glycol, glycerol, n-butanol, and 1,2-butanediol; and the photoinitiator comprises one or more of benzil, acetophenone, α-hydroxyketone, and acylphosphine oxide.

[0011] In some exemplary embodiments, the mass ratio of the network host material to the ionic component is (1-100):1; the mass ratio of the solvent to the network host material is (0.5-10):1; and the mass ratio of the photoinitiator to the network host material is (0-0.5):1.

[0012] In some exemplary embodiments, the sensor array unit is connected to an array module acquisition system, and the sensor array unit performs row and column scanning through the array module acquisition system to acquire array image information under temperature and pressure changes.

[0013] In some exemplary embodiments, the flexible circuit board is one of a single-sided, double-sided or multi-layer circuit; the flexible circuit board includes a flexible substrate and an electrode material arranged on the flexible substrate; the flexible substrate includes one of polyimide and polyethylene terephthalate; and the electrode material includes one of gold, platinum, copper and silver.

[0014] On the second aspect, an embodiment of the present application also provides a method for preparing a pressure-temperature integrated hydrogel array sensor, comprising the following steps: first, providing a mold; then, forming a hydrogel material layer on the mold; next, using a photocuring mask, photocuring the hydrogel material layer once; then, covering the hydrogel material layer after the first photocuring treatment with interdigital electrodes, and performing a second photocuring to obtain a hydrogel layer with cross-linking density differences and height differences that is tightly fitted with the interdigital electrodes; the hydrogel layer includes a high cross-linking density hydrogel area and a low cross-linking degree hydrogel area; finally, removing the mold to obtain a hydrogel sensing structure.

[0015] In some exemplary embodiments, the high cross-linking density hydrogel region is located at the center of the hydrogel layer, and the low cross-linking degree hydrogel region surrounds the high cross-linking density hydrogel region.

[0016] In some exemplary embodiments, the time for the primary light curing and the secondary light curing is 0.1 min to 10 min.

[0017] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0018] The embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor and a preparation method thereof, wherein the hydrogel array sensor comprises: a plurality of sensor array units arranged in an array; each sensor array unit comprises an interdigital electrode and a hydrogel layer covering the surface of the interdigital electrode; the hydrogel layer is fixed to the interdigital electrode by photocuring, and the hydrogel layer is tightly adhered to the surface of the interdigital electrode; the interdigital electrode is two coplanar nested interdigital electrodes prepared using a flexible circuit board; the hydrogel layer is a hydrogel layer with different cross-linking densities and heights; the hydrogel layer comprises a high cross-linking density hydrogel region and a low cross-linking degree hydrogel region. The present application simultaneously realizes pressure and temperature perception through ion sensing, adopts a hydrogel material component, and can realize perception differences in different regions only by changing the structural design. Based on the double layer theory, it can simultaneously monitor changes in pressure and temperature signals, and can perform arrayed sensing structure design to realize signal acquisition of temperature and pressure distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily described by the pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute proportional limitations.

[0020] Figure 1 This is a schematic structural diagram of the pressure-temperature integrated hydrogel array sensor provided in an embodiment of the present application.

[0021] Figure 2 A schematic diagram of the structure of the array electrode provided in an embodiment of the present application.

[0022] Figure 3 This is a schematic flow chart of a method for preparing a pressure-temperature integrated hydrogel array sensor provided in an embodiment of the present application.

[0023] Figure 4 This is a top view of the hydrogel layer provided in an embodiment of the present application.

[0024] Figure 5 Schematic diagram of the integrated hydrogel sensing principle provided in the embodiments of the present application.

[0025] Figure 6 and Figure 7 This is a schematic diagram of the temperature and pressure integrated sensing response curve provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] As can be seen from the background technology, in the prior art zwitterion-based ionic skin sensor system, N-isopropylacrylamide hydrogel may cause overall buckling deformation due to temperature changes when in an asymmetric structure, which may interfere with the overall capacitive sensing signal.

[0027] To solve the above technical problems, the embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor and a preparation method thereof, wherein the hydrogel array sensor comprises: a plurality of sensor array units arranged in an array; each sensor array unit comprises an interdigital electrode and a hydrogel layer covering the surface of the interdigital electrode; the hydrogel layer is fixed to the interdigital electrode by photocuring, and the hydrogel layer is tightly adhered to the surface of the interdigital electrode; the interdigital electrode is two coplanar nested interdigital electrodes prepared using a flexible circuit board; the hydrogel layer is a hydrogel layer with different cross-linking densities and heights; the hydrogel layer comprises a high cross-linking density hydrogel region and a low cross-linking degree hydrogel region. The present application realizes simultaneous pressure and temperature sensing through ion sensing, adopts a hydrogel material component, and can achieve sensing differences in different regions only by changing the structural design. Based on the double-layer theory, it can simultaneously monitor changes in pressure and temperature signals, and can perform arrayed sensing structure design to realize signal acquisition of temperature and pressure distribution. The embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor and a preparation method thereof. Based on the ionization sensing and diffusion layer effect of the double-layer theory, a flexible sensing structure based on photocurable hydrogel is designed. Through the array electrode design and the array module acquisition system, the pressure signal and temperature signal changes can be monitored simultaneously.

[0028] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0029] See Figure 1 The embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor, comprising: a plurality of sensor array units arranged in an array; each sensor array unit comprises an interdigitated electrode 101 and a hydrogel layer 102 covering the surface of the interdigitated electrode 101; the hydrogel layer 102 is fixed on the interdigitated electrode 101 by photocuring, and the hydrogel layer 102 is tightly adhered to the surface of the interdigitated electrode 101; the interdigitated electrode 101 is two coplanar nested interdigitated electrodes prepared using a flexible circuit board; the hydrogel layer 102 is a hydrogel layer with different cross-linking densities and heights; the hydrogel layer 102 comprises a high cross-linking density hydrogel region 102a and a low cross-linking degree hydrogel region 102b.

[0030] This application innovatively proposes a new integrated pressure and temperature sensing structure, based on the ionization sensing and diffusion layer effect of the double layer theory, and designs a flexible sensing structure based on photocurable hydrogel. The flexible sensing structure consists of two coplanar nested interdigitated electrodes made of a flexible circuit board, and a hydrogel material with height differences and cross-linking density differences covered thereon. The electrodes in the array sensor structure are obtained by arraying the above-mentioned interdigitated electrodes, and the hydrogel material covered thereon is a repetition of the above-mentioned unit. The hydrogel is fixed on the interdigitated electrodes by photocuring, and there is no gap or other material between the two.

[0031] This application uses ion sensing to simultaneously realize pressure and temperature perception, and uses hydrogel material components to design an array sensor structure. Figure 1 The integrated hydrogel array sensing structure, using a 5x5 array as an example, demonstrates the double-sided routing design of the interdigitated electrodes. Row and column traces are located on the front and back sides, respectively. Holes are drilled at specific locations, and metallization is used on the hole walls to connect the circuits on both sides. The hydrogel layer has 25 repeating units.

[0032] It should be noted that Figure 1 The integrated hydrogel array sensing structure is shown as an example of a 5*5 array, but is not limited thereto. Figure 2 As shown, Figure 2 The figure shows the interdigital electrodes and array design of an integrated sensing structure taking 3*3 as an example.

[0033] The sensor array unit is connected to the array module acquisition system. During data acquisition, the integrated sensor's temperature and pressure channel testing can be performed by connecting two single-point interdigital electrodes to the same excitation signal. Capacitance changes are then converted into output voltage changes via an op amp circuit. The array module acquisition system then scans the sensor array row and column, capturing array image information under varying temperature and pressure. Data processing yields pressure and temperature distribution.

[0034] In some embodiments, the flexible electrodes are prepared by conventional printing conductive materials or laser etching methods. The prepared flexible circuit board can be single-sided, double-sided or multi-layer circuit. The flexible substrate includes but is not limited to polyimide and polyethylene terephthalate, and the electrode materials include but are not limited to inert metals such as gold, platinum, copper, silver, etc.

[0035] In some embodiments, the thickness of the flexible substrate is 1 to 1000 microns, further 10 to 500 microns. The line width of the interdigitated stripe electrodes is specifically 0.1 to 1000 microns, further 10 to 300 microns; the spacing between adjacent two interdigitated stripe electrodes is 0.1 to 1000 microns, further 10 to 300 microns; and the spacing between each unit of the array electrode is 1 to 10,000 microns, further 50 to 5,000 microns.

[0036] The hydrogel layer with different cross-linking density and height differences has a cross-linked network structure and an ion path, and its composition is a photocurable gel system. In some embodiments, the hydrogel layer has a cross-linked network structure, and ionic components are doped in the cross-linked network structure to form an ion path; the network main material of the cross-linked network structure includes one or more of acrylamide, hydroxyethyl methacrylate, acrylic acid, isooctyl methacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, and N,N-methylenebisacrylamide hydrogel monomers; the ionic component is an ionic liquid or anionic and cationic polyelectrolyte with a polymerizable functional group structure; the ionic component includes: vinyl imidazole sulfonyl imide salt, vinyl imidazole phosphate, allyl imidazole sulfonyl imide salt, allyl imidazole phosphate, and one or more of sodium alginate, sodium polystyrene sulfonate, sodium polyacrylate, and polydiallyldimethylammonium chloride.

[0037] In some embodiments, the hydrogel layer further comprises a solvent and a photoinitiator; the solvent is deionized water or a doping system of deionized water and a polyol; the polyol comprises one or more of ethylene glycol, 1,3-propylene glycol, glycerol, n-butanol, and 1,2-butanediol; and the photoinitiator comprises one or more of benzil, acetophenone, α-hydroxy ketone, and acylphosphine oxide.

[0038] In some embodiments, the mass ratio of the network host material to the ionic component is (1-100):1; the mass ratio of the solvent to the network host material is (0.5-10):1; and the mass ratio of the photoinitiator to the network host material is (0-0.5):1. Preferably, the mass ratio of the network host material to the ionic component is (5-50):1; the mass ratio of the solvent to the network host material is (1-5):1; and the mass ratio of the photoinitiator to the network host material is (0.01-0.1):1.

[0039] Specifically, the hydrogel preparation process is as follows Figure 3As shown, first, the network host material, ionic components, solvent, and photoinitiator are uniformly mixed and oxygen is removed to obtain a hydrogel prepolymer 111. The height difference of the hydrogel is prepared by casting, wherein the mold 110 is obtained by mechanical processing, including but not limited to a PDMS mold, a polytetrafluoroethylene mold, or a stainless steel mold, and the height difference is controlled to be 0.1mm to 2mm. The hydrogel prepolymer 111 is poured into the mold 110. The crosslink density difference of the hydrogel is controlled by covering it with a photocuring mask 112, where the black area is shielded from light and the transparent area is preferentially cured. After the area is exposed to ultraviolet light, the photocuring mask 112 is removed. Then, the interdigital electrode 1θ1 is covered on the hydrogel and the entire body is subjected to a secondary photocuring, with the curing time of both times controlled to be between 0.1 and 10 minutes. Finally, one side of the hydrogel layer 102 is removed from the mold 110, while the other side remains directly attached to the interdigital electrode 101, resulting in a hydrogel layer 102 with different crosslinking density and height.

[0040] In some embodiments, as Figure 4 As shown, the high cross-linking density hydrogel region 102a is located at the center of the hydrogel layer 102, and the low cross-linking density hydrogel region 102b is surrounded by the high cross-linking density hydrogel region 102a; the high cross-linking density hydrogel region 102a does not deform during the pressure process and is only affected by temperature; the low cross-linking density hydrogel region 102b can be affected by temperature and pressure at the same time, and achieves single pressure sensing by decoupling from the high cross-linking density hydrogel region 102a. The sensing principle diagram is shown in FIG. Figure 5 shown.

[0041] Figure 5 The pressure and temperature sensing principle is demonstrated. The high cross-linking density hydrogel region (region I) does not deform during the pressure process and is only affected by temperature. The low cross-linking density hydrogel region (region II) is affected by both temperature and pressure, but can achieve single pressure sensing by decoupling from region I. Principle description: According to Stern theory, the double-layer capacitance is mainly composed of the Helmholtz layer capacitance (C H ) and diffusion layer capacitance (C D ), where C H It is only related to the ion contact area and the capacitance per unit area. Since the ion material and the electrode are in full contact in this application, C H It is only related to the capacitance per unit area, that is, temperature. D It is positively correlated with the thickness of the ionic material. The increase in pressure causes the thickness to decrease, resulting in C D The value is reduced, and the empirical formula can be obtained by collecting experimental data. The capacitance of region I and region II are expressed as:

[0042] C I =C H(I) =UAC×S I (1)

[0043]

[0044] In the formula, C I and C II The capacitance values ​​collected in two areas are C H(I) and C H(II) is the Helmholtz layer capacitance of the two regions, UAC is the unit area capacitance, and the two regions are assumed to be consistent. I and S II The effective contact areas of the sensing electrodes in the two regions are fixed constants in this application. It can be seen that after the capacitance decoupling of region I, region II can be transformed into a region only affected by C D , that is, pressure influence.

[0045] In addition, the present invention also provides a method for preparing a pressure-temperature integrated hydrogel array sensor. Figure 3 , specifically including the following steps: first, providing a mold; then, forming a hydrogel material layer on the mold; next, using a photocuring mask to perform a primary photocuring on the hydrogel material layer; then, covering the hydrogel material layer after the primary photocuring treatment with interdigital electrodes, and performing a secondary photocuring to obtain a hydrogel layer with different cross-linking density and height differences that is tightly fitted with the interdigital electrodes; the hydrogel layer includes a high cross-linking density hydrogel area and a low cross-linking degree hydrogel area; finally, removing the mold to obtain a hydrogel sensing structure.

[0046] In some embodiments, the high cross-linking density hydrogel region is located in the center of the hydrogel layer, and the low cross-linking degree hydrogel region surrounds the high cross-linking density hydrogel region.

[0047] In some embodiments, the time for the primary photocuring and the secondary photocuring is 0.1 min to 10 min.

[0048] This application realizes simultaneous pressure and temperature perception through ion sensing, adopts a hydrogel material component, and can achieve perception differences in different areas only by changing the structural design. Based on the double layer theory, it can simultaneously monitor the changes in pressure signals and temperature signals, and can perform arrayed sensing structure design to realize signal acquisition of temperature and pressure distribution.

[0049] The preparation method of the pressure-temperature integrated hydrogel array sensor provided by the present application is described in detail below through specific examples.

[0050] First, prepare a hydrogel prepolymer. Acrylamide and polyethylene glycol diacrylate are selected as the main hydrogel components, with sodium alginate as the dopant ionic component. Pure water is used as the solvent, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is selected as the photoinitiator. The mass ratio of acrylamide: polyethylene glycol diacrylate: sodium alginate: water: photoinitiator is controlled to be 1:0.05:0.1:3:0.03. Stir thoroughly, remove oxygen, and set aside.

[0051] Next, electrode selection was performed. A flexible printed circuit board (PCB) with a polyimide substrate was used to print dual-channel interdigitated electrodes. The interdigitated electrode line width and line spacing were both 200 microns, and the overall electrode size was a 10mm diameter circle. The temperature sensing portion of the electrode was a 5mm diameter circle, and the pressure sensing portion was the remaining area.

[0052] Next, the integrated sensing structure is constructed. A circular polytetrafluoroethylene mold is machined to have overall dimensions of 15mm diameter, 1mm depth, a 5mm diameter center cone, and 0.5mm height. The hydrogel prepolymer is poured into the mold. A mask is added, with a 5mm diameter central circular area for light transmission. The prepolymer is cured with 365nm UV light for 1 minute. The mask is removed, and interdigital electrodes are placed over the gel. A second photocuring step is performed for 30 seconds. Finally, one side of the hydrogel is removed from the mold, while the other side remains directly attached to the interdigital electrodes, resulting in an integrated sensing structure.

[0053] Finally, performance characterization was performed. An inductance-capacitance-resistance detection system was used to deduce the pressure applied at a specific moment. A data acquisition card detection system was used to measure the change in dual-channel capacitance under different underwater water pressures and contact forces. Figure 6 and Figure 7 Figure 2 shows a schematic diagram of the temperature and pressure integrated sensing response curve, where: Figure 6 and Figure 7 The horizontal axis represents the temperature change of the sensor and the thickness change of the hydrogel after being compressed, and the vertical axis represents the output capacitance of the sensor.

[0054] Based on the above technical solutions, the embodiment of the present application provides a pressure-temperature integrated hydrogel array sensor and a preparation method thereof, wherein the hydrogel array sensor comprises: a plurality of sensor array units arranged in an array; each sensor array unit comprises an interdigital electrode and a hydrogel layer covering the surface of the interdigital electrode; the hydrogel layer is fixed to the interdigital electrode by photocuring, and the hydrogel layer is tightly adhered to the surface of the interdigital electrode; the interdigital electrode is two coplanar nested interdigital electrodes prepared using a flexible circuit board; the hydrogel layer is a hydrogel layer with different cross-linking densities and heights; the hydrogel layer comprises a high cross-linking density hydrogel region and a low cross-linking degree hydrogel region. The present application realizes simultaneous pressure and temperature perception through ion sensing, adopts a hydrogel material component, and can achieve perception differences in different regions only by changing the structural design. Based on the double-layer theory, it can simultaneously monitor changes in pressure and temperature signals, and can perform arrayed sensing structure design to realize signal acquisition of temperature and pressure distribution.

[0055] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A pressure-temperature integrated hydrogel array sensor, characterized in that: include: A plurality of sensor array units arranged in an array; Each sensing array unit includes an interdigital electrode and a hydrogel layer covering the surface of the interdigital electrode; The hydrogel layer is fixed on the interdigital electrode by light curing, and the hydrogel layer is closely attached to the surface of the interdigital electrode; The interdigital electrodes are two coplanar nested interdigital electrodes made of a flexible circuit board; The hydrogel layer is a hydrogel layer with different cross-linking density and height; the hydrogel layer includes a high cross-linking density hydrogel area and a low cross-linking degree hydrogel area.

2. The pressure-temperature integrated hydrogel array sensor according to claim 1, characterized in that: The high cross-linking density hydrogel region is located at the center of the hydrogel layer, and the low cross-linking degree hydrogel region is surrounded by the high cross-linking density hydrogel region; The high cross-linking density hydrogel area does not deform during the pressure process and is only affected by temperature; the low cross-linking degree hydrogel area can be affected by temperature and pressure at the same time, and achieves single pressure perception by decoupling from the high cross-linking density hydrogel area.

3. The pressure-temperature integrated hydrogel array sensor according to claim 1, characterized in that: The hydrogel layer has a cross-linked network structure, and ion components are doped into the cross-linked network structure to form ion pathways; The main network material of the cross-linked network structure includes one or more of acrylamide, hydroxyethyl methacrylate, acrylic acid, isooctyl methacrylate, ethylene glycol diacrylate, polyethylene glycol diacrylate, and N,N-methylenebisacrylamide hydrogel monomers; The ionic component is an ionic liquid or anionic and cationic polyelectrolyte with a polymerizable functional group structure; the ionic component includes: vinyl imidazole sulfonyl imide salt, vinyl imidazole phosphate, allyl imidazole sulfonyl imide salt, allyl imidazole phosphate, and one or more of sodium alginate, sodium polystyrene sulfonate, sodium polyacrylate, and polydiallyldimethylammonium chloride.

4. The pressure-temperature integrated hydrogel array sensor according to claim 3, characterized in that: The hydrogel layer further includes a solvent and a photoinitiator; The solvent is deionized water or a doping system of deionized water and polyols; the polyols include one or more of ethylene glycol, 1,3-propylene glycol, glycerol, n-butanol, and 1,2-butanediol; The photoinitiator includes one or more of benzil, acetophenone, α-hydroxyketone and acylphosphine oxide.

5. The pressure-temperature integrated hydrogel array sensor according to claim 4, characterized in that: The mass ratio of the network main material to the ionic component is (1-100):1; The mass ratio of the solvent to the network main material is (0.5-10):1; The mass ratio of the photoinitiator to the network main material is (0~0.5):

1.

6. The pressure-temperature integrated hydrogel array sensor according to claim 1, characterized in that: The sensor array unit is connected to the array module acquisition system. The sensor array unit performs row and column scanning through the array module acquisition system to acquire array image information under temperature and pressure changes.

7. The pressure-temperature integrated hydrogel array sensor according to claim 1, characterized in that: The flexible circuit board is a single-sided, double-sided or multi-layer circuit; The flexible circuit board includes a flexible substrate and an electrode material arranged on the flexible substrate; The flexible substrate comprises one of polyimide and polyethylene terephthalate; The electrode material includes one of gold, platinum, copper and silver.

8. A method for preparing a pressure-temperature integrated hydrogel array sensor, applied to the pressure-temperature integrated hydrogel array sensor according to claim 1, characterized in that: The following steps are involved: Provide molds; forming a layer of hydrogel material on the mold; Using a photocuring mask, the hydrogel material layer is photocured once; The interdigital electrodes are covered on the hydrogel material layer after the primary photocuring treatment, and a secondary photocuring is performed to obtain a hydrogel layer with different cross-linking densities and heights that is closely attached to the interdigital electrodes; the hydrogel layer includes a high cross-linking density hydrogel region and a low cross-linking degree hydrogel region; The mold was removed to obtain the hydrogel sensing structure.

9. The method for preparing the pressure-temperature integrated hydrogel array sensor according to claim 8, characterized in that: The high cross-linking density hydrogel region is located at the center of the hydrogel layer, and the low cross-linking degree hydrogel region surrounds the high cross-linking density hydrogel region.

10. The method for preparing the pressure-temperature integrated hydrogel array sensor according to claim 8, characterized in that: The time for primary light curing and secondary light curing is 0.1min~10min.

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