Repairable and biocompatible transparent conductive hydrogel with water response shrinkage and preparation method and application thereof

Abstract

The invention provides transparent conductive hydrogel with water response shrinkage, repairability and biocompatibility as well as a preparation method and application of the transparent conductive hydrogel. The conductive hydrogel is formed by taking a dual network formed by polyethylene glycol (PEG)-alpha-cyclodextrin (alpha-CD) and polyethylene oxide (PEO) as a basis and taking polyvinyl alcohol (PVA) as a skeleton as an auxiliary material. Wherein water, as mild stimulation, can destroy directional arrangement of a crystal domain and a molecular chain in PEO so as to trigger efficient contraction, and excellent mechanical repeatability is ensured by combination between alpha-CD and PVA. In addition, the ionic liquid is added, so that the conductive strain sensing requirement is met. By adding glycerol, the gel is endowed with good water-retaining property, and the loss of water is reduced, so that the structural stability and flexibility are maintained. Meanwhile, the glycerin-water binary solvent researched and developed by the research can effectively repair dehydrated gel after long-term use, so that the performance of the gel can be completely recovered. The hydrogel can be used as a dressing for wound healing to promote wound healing. The hydrogel can tightly wrap the surfaces of soft epidermal skin, heart, tendon and other visceral organs in a conformal shape self-adaptive mode, and is used for monitoring physiological signals and motion signals, and meanwhile, the health condition of covered tissues can be visually observed.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensor technology, and in particular relates to a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, its preparation method, and its application. Background Technology

[0002] In recent years, conformal electronic devices capable of encapsulating the complex surfaces of soft tissue have attracted considerable attention due to their innovative application potential in wearable devices, electronic skin, and soft robotics. However, existing technologies require the shape and size of the devices to be pre-customized in a mold to adapt to the specific size requirements of different target organs. This not only complicates the process but also limits the ability to freely deform during implantation. In contrast, thin film materials with stimulus-responsive contraction properties (e.g., triggered by stimuli such as temperature, light, and chemicals) offer a feasible solution for shape-adaptive encapsulation of target objects. However, these stimuli may cause damage to biological tissues, posing a high risk and thus requiring extreme caution. Furthermore, the contraction effect may not be fully achieved. Therefore, there is an urgent need to develop a water-stimuli-responsive contraction sensor, which is crucial for achieving shape-adaptive encapsulation for health monitoring. Summary of the Invention

[0003] In view of this, to solve the above-mentioned technical problems, this invention proposes a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, and provides its preparation method and applications. It is prepared by a simple one-pot free radical polymerization method. First, PEG and α-CD form an inclusion gel through host-guest supramolecular interactions, and then crosslink with oriented water-soluble semi-crystalline PEO. Stretching induces the formation of ordered fiber bridges within the PEO, orienting its crystalline domains and molecular chains. These structures are subsequently temporarily fixed by recrystallization of the PEO crystalline domains. A binary solvent composed of glycerol and water destroys and dissolves these PEO crystalline domains, thereby inducing hydrogel shrinkage. Introducing PVA molecular chains into PEG / α-CD / PEO not only maintains the structural stability of the hydrogel in the binary solvent, but also promotes the adsorption of water molecules into the hydrogel network by forming hydrogen bonds with water molecules through the numerous hydrophilic hydroxyl groups in the PVA molecular chains. Subsequently, ionic liquids were added to the PEG / α-CD / PEO / PVA hydrogel to prepare ion-conductive PEG / α-CD / PEO / PVA / IL hydrogels, laying the foundation for flexible electronic wearable devices. Glycerol, as a non-volatile hydrophilic solvent, was added to the PEG / α-CD / PEO / PVA / IL hydrogel, imparting excellent water retention properties and reducing rapid water loss, thereby maintaining structural stability and flexibility. Conductive hydrogel film sensors, through water stimulation, achieve shape-adaptive conformal and tight encapsulation on soft epidermal skin and the surfaces of internal organs such as the heart and tendons, for monitoring physiological and motion signals, while also allowing for direct observation of the health status of the covered tissues.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows: This invention provides a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, comprising: The gel is based on a dual network formed by polyethylene glycol (PEG)-α-cyclodextrin (α-CD) and polyethylene oxide (PEO), supplemented with polyvinyl alcohol (PVA) as the backbone. Ionic liquids are added to meet the requirements for conductive strain sensing. The addition of glycerol imparts good water retention, maintaining structural stability and flexibility. In some preferred embodiments of the water-responsive, repairable, and biocompatible transparent conductive hydrogel of the present invention, after pre-stretching, the PEO polymer chains of the conductive hydrogel will align in a specific direction. Water, as a stimuli, can disrupt the directional alignment of the internal crystalline domains and molecular chains of PEO, thereby triggering efficient shrinkage. The combination between α-CD and PVA ensures excellent mechanical repeatability and stability in water.

[0005] In some preferred embodiments of the water-responsive, repairable, and biocompatible transparent conductive hydrogel of the present invention, the glycerol-water binary solvent can effectively repair the conductive gel that has dehydrated after long-term use, restoring its properties almost completely.

[0006] In some preferred embodiments of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel of the present invention, the mass ratio of polyethylene glycol, α-cyclodextrin, and water is 10–15:50–70:1000, the mass ratio of polyethylene oxide and water is 0.5–1.5:20, the mass ratio of polyvinyl alcohol and water is 5–7:100, and the mass ratio of ionic liquid and glycerol is 0.8–1.5:0.9–1.2.

[0007] Another aspect of the present invention provides a method for preparing a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, comprising the following steps: S1. Preparation of PEG / α-CD / PEO gel Polyethylene glycol (PEG) and polyethylene oxide (PEG) were dissolved separately in deionized water. Then, α-cyclodextrin was slowly added to the PEG solution and dispersed evenly in an ultrasonic water bath. The white mixture was cooled to room temperature to obtain a white PEG / α-CD inclusion complex gel. Next, an aqueous PEO solution was added and mixed with the PEG / α-CD white inclusion complex gel by mechanical stirring to obtain a viscous PEG / α-CD / PEO mixed gel. S2, Preparation of PEG / α-CD / PEO / PVA / IL / G gel Polyvinyl alcohol was dissolved in deionized water, and then an aqueous PVA solution was added to the above PEG / α-CD / PEO system. Mechanical stirring was performed to obtain a viscous PEG / α-CD / PEO / PVA mixed gel. An ionic liquid was added, and mechanical stirring was continued to obtain a PEG / α-CD / PEO / PVA / IL mixed gel. Glycerin was then added, and mechanical stirring continued to obtain a PEG / α-CD / PEO / PVA / IL / G gel. Next, the gel was allowed to stand at room temperature to remove internal air bubbles. Finally, it was poured into a petri dish and dried in an oven. After peeling it from the petri dish, the PEG / α-CD / PEO / PVA / IL / G hydrogel was obtained, the thickness of which could be adjusted according to the total amount of the casting mixture.

[0008] PEG / α-CD / PEO gel is formed by the inclusion complex gel of PEG and α-CD through host-guest supramolecular interactions, and crosslinked with oriented water-soluble semi-crystalline PEO. Stretching induces the formation of ordered fiber bridges within the PEO, orienting its crystalline domains and molecular chains. These structures are subsequently temporarily fixed through recrystallization of the PEO crystalline domains. A binary solvent composed of glycerol and water disrupts and dissolves these PEO crystalline domains, thereby inducing hydrogel shrinkage. PEG / α-CD / PEO / PVA / IL / G hydrogels are created by introducing PVA molecular chains into PEG / α-CD / PEO hydrogels. This not only maintains the hydrogel's structural stability in binary solvents but also facilitates water adsorption into the hydrogel network through hydrogen bonding formed by the numerous hydrophilic hydroxyl groups in the PVA molecular chains. Subsequently, ionic liquids are added to the PEG / α-CD / PEO / PVA hydrogels to prepare ionically conductive PEG / α-CD / PEO / PVA / IL hydrogels, laying the foundation for flexible electronic wearable devices. The addition of glycerol, a non-volatile hydrophilic solvent, to the PEG / α-CD / PEO / PVA / IL hydrogels imparts excellent water retention properties, reducing rapid water loss and thus maintaining structural stability and flexibility.

[0009] In some preferred embodiments of the water-responsive, repairable, and biocompatible transparent conductive hydrogel of the present invention, after pre-stretching, the PEO polymer chains of the conductive hydrogel will align in a specific direction. Water, as a stimuli, can disrupt the directional alignment of the internal crystalline domains and molecular chains of PEO, thereby triggering efficient shrinkage. The combination between α-CD and PVA ensures excellent mechanical repeatability and stability in water.

[0010] In some preferred embodiments of the water-responsive, repairable, and biocompatible transparent conductive hydrogel of the present invention, the glycerol-water binary solvent can effectively repair the conductive gel that has dehydrated after long-term use, restoring its properties almost completely.

[0011] In some preferred embodiments of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel of the present invention, the mass ratio of polyethylene glycol, α-cyclodextrin, and water is 10–15:50–70:1000, the mass ratio of polyethylene oxide and water is 0.5–1.5:20, the mass ratio of polyvinyl alcohol and water is 5–7:100, and the mass ratio of ionic liquid and glycerol is 0.8–1.5:0.9–1.2.

[0012] In another aspect, the present invention provides the use of a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel. The conductive hydrogel film sensor can conformally and tightly wrap around soft epidermal skin and the surface of internal organs such as the heart and tendons in a shape-adaptive manner for monitoring physiological and motion signals, while also allowing for direct observation of the health status of the covered tissues.

[0013] Compared with existing technologies, the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, its preparation method, and its applications described in this invention have the following advantages: (1) The water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel of this invention is prepared through a simple one-pot free radical polymerization method, focusing on both structural design and material selection. First, PEG and α-CD form an inclusion gel through host-guest supramolecular interactions and crosslink with oriented water-soluble semi-crystalline PEO. Stretching induces the formation of ordered fiber bridges within the PEO, orienting its crystalline domains and molecular chains. These structures are then temporarily fixed through recrystallization of the PEO crystalline domains. The binary solvent composed of glycerol and water destroys and dissolves these PEO crystalline domains, thereby inducing hydrogel shrinkage. Introducing PVA molecular chains into PEG / α-CD / PEO not only maintains the structural stability of the hydrogel in the binary solvent but also promotes the adsorption of water molecules into the hydrogel network by forming hydrogen bonds with water molecules through the large number of hydrophilic hydroxyl groups in the PVA molecular chains. Subsequently, ionic liquids were added to the PEG / α-CD / PEO / PVA hydrogel to prepare ion-conductive PEG / α-CD / PEO / PVA / IL hydrogels, laying the foundation for flexible electronic wearable devices. Glycerol, as a non-volatile hydrophilic solvent, was added to the PEG / α-CD / PEO / PVA / IL hydrogel, which endowed it with good water retention properties, reduced rapid water loss, and thus maintained structural stability and flexibility. (2) The conductive hydrogel of the present invention achieves conformal adhesion to biological tissues or organs through water stimulation, avoiding the damage that traditional stimulation methods such as light and chemicals may cause to biological tissues, and has both gentleness and biosafety. Based on the conformal mechanism of water stimulation, it provides a new idea for the safe and efficient integration of bioelectronic devices and living tissues, and is especially suitable for medical scenarios with high sensitivity to stimulation (such as monitoring of soft tissues such as the heart and tendons), showing significant advantages in the fields of smart wearables and clinical diagnosis; (3) The conductive hydrogel described in this invention has good adhesion, water retention, repairability, and biocompatibility. Based on its adhesion and biocompatibility, the conductive hydrogel film sensor can conformally adhere to the skin surface for the detection of physiological and limb signals. Based on the conformal mechanism of water stimulation, the conductive hydrogel film sensor can be tightly wrapped around the surface of internal organs such as the heart and tendons in a shape-adaptive manner for monitoring physiological and motor signals, while also allowing for direct observation of the health status of the covered tissues. In addition, the hydrogel can be used as a wound healing dressing to promote wound healing.

[0014] (4) The conductive hydrogel described in this invention can be effectively repaired by an oil-water binary solvent after long-term use and dehydration, so that its performance remains almost completely unchanged. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel described in this invention. Figure 2 Electron micrographs of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel and PEO structure changes in Example 1 of the present invention. Figure 3 Photographs of the structural stability and resistance to dissolution of a transparent conductive hydrogel that is water-responsive, shrinkable, repairable, and biocompatible; Figure 4 middle, Figure 4 a is a photograph showing the adhesion properties of the hydrogel; Figure 4 b is a photograph of the process by which the skin is forced to contract after the hydrogel is moistened (participant, young woman, BMI ~19). Figure 4 c is a photograph of the autonomous wound closure process (ex vivo pig skin) forced by the shrinkage of the wet hydrogel; Figure 4 d represents the corresponding shape and size traces during the autonomous wound closure process; Figure 4 e is a photograph of a pre-stretched hydrogel adaptively wrapping around a piece of pork with an irregular curved surface after water stimulation. Figure 4 A photo of hydrogel used as a wound dressing to promote wound healing; Figure 5 middle, Figure 5 a is a photograph showing the water retention properties of the hydrogel; Figure 5 b is the test result of the hydrogel's water retention capacity; Figure 5 c is a photograph showing the hydrogel repaired using a binary solvent; Figure 5 d is a graph showing the repair time of the hydrogel in a binary solvent; Figure 5 e is a performance test graph after hydrogel repair; Figure 6 middle, Figure 6 a represents the biocompatibility cell viability test. Figure 6b is a graph showing the cell viability assay using CCK-8. Figure 7 For the detection of human physiological signals and limb signals on the body surface of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel described in this invention; Figure 7 Image a shows a photo taken using hydrogel to detect heart rate. Figure 7 b is a graph showing the heart rate after multiple hydrogel repairs; Figure 7 c is the detection image for detecting finger bending; Figure 7 d is the detection image for wrist flexion; Figure 8 For the detection of implantable physiological and limb signals of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel described in this invention; Figure 8 a is a schematic diagram of epicardial monitoring and machine learning. Figure 8 b shows the detection graphs under different heart rate states. Figure 8 c is a photograph of the sensor implanted in the tendon. Figure 8 d is a test image showing different bending angles of the tendon in mice, and 8e is a test image showing the tendon bending 90 degrees 14 days after implantation. Detailed Implementation

[0016] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0017] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0018] A method for preparing a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel includes the following steps: S1. Preparation of PEG / α-CD / PEO gel Polyethylene glycol (PEG) and polyethylene oxide (PEG) were dissolved separately in deionized water. Then, α-cyclodextrin was slowly added to the PEG solution and dispersed evenly in an ultrasonic water bath. The white mixture was cooled to room temperature to obtain a white PEG / α-CD inclusion complex gel. Next, an aqueous PEO solution was added and mixed with the PEG / α-CD white inclusion complex gel by mechanical stirring to obtain a viscous PEG / α-CD / PEO mixed gel; the mass ratio of PEG, α-cyclodextrin, and water was 10–15:50–70:1000, and the mass ratio of PEG and water was 0.5–1.5:20. S2, Preparation of PEG / α-CD / PEO / PVA / IL / G gel Polyvinyl alcohol was dissolved in deionized water at a mass ratio of 5–7:100. Then, an aqueous PVA solution was added to the PEG / α-CD / PEO system, and mechanical stirring was performed to obtain a viscous PEG / α-CD / PEO / PVA mixed gel. An ionic liquid was added, and mechanical stirring was continued to obtain a PEG / α-CD / PEO / PVA / IL mixed gel. Glycerol was then added, and mechanical stirring continued to obtain a PEG / α-CD / PEO / PVA / IL / G gel. The mass ratio of the ionic liquid to glycerol was 0.8–1.5:0.9–1.2. Next, the gel was allowed to stand at room temperature to remove internal air bubbles. Finally, it was poured into a petri dish and dried in an oven. After peeling from the petri dish, the PEG / α-CD / PEO / PVA / IL / G hydrogel was obtained, and its thickness could be adjusted according to the total amount of the casting mixture.

[0019] like Figure 1 As shown, the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel was prepared via a simple one-pot free radical polymerization. PEG, α-CD, PEO, PVA, and IL were mixed in a binary solvent of deionized water and glycerol, then transferred to a mold and gelled by drying. PEG and α-CD formed an inclusion complex gel through host-guest supramolecular interactions and crosslinked with oriented water-soluble semi-crystalline PEO. Introducing PVA molecular chains into the PEG / α-CD / PEO system not only maintains the structural stability of the hydrogel in the binary solvent but also facilitates the adsorption of water molecules into the hydrogel network through hydrogen bonding with water molecules via the numerous hydrophilic hydroxyl groups in the PVA molecular chains. Adding ionic liquids to the PEG / α-CD / PEO / PVA hydrogel yielded an ion-conductive PEG / α-CD / PEO / PVA / IL hydrogel, laying the foundation for flexible electronic wearable devices. Meanwhile, adding glycerol to the hydrogel can give it good water retention properties, reduce rapid water loss, and thus maintain structural stability and flexibility.

[0020] like Figure 2 As shown, the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, when stretched, induces the formation of ordered fiber bridges within the PEO, orienting its crystal domains and molecular chains. Subsequently, these oriented structures are temporarily fixed by recrystallized PEO domains. Figure 2(ai). The binary solvent of glycerol and water disrupts and dissolves these PEO domains, causing the hydrogel to shrink. Due to the strong non-covalent interactions between water, IL, glycerol, and the polymer network, the hydrogel exhibits a uniform wrinkled structure (Fig. 2j, left). The hydrogel surface is pore-free, reflecting good compatibility between the polymer chains and other filler materials. In its cross-section, inclusion complexes forming sheet-like structures are clearly visible. After 60% stretching, some of the wrinkled structure of the hydrogel flattens out, forming scattered small bubbles (Fig. 2j, middle). With increasing stretching, the number and volume of bubbles increase. When the hydrogel is stretched, its network structure deforms, leading to changes in the internal pressure distribution and the expulsion of dissolved gas, thus promoting the formation of bubbles. After shrinking and drying, the 60% stretched hydrogel spontaneously recovers to its initial appearance and internal structure (Fig. 2j, right).

[0021] like Figure 3 As shown, the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel exhibits excellent structural stability and anti-dissolution ability in an aqueous environment. This is because the introduction of α-CD and PVA ensures structural stability. It does not dissolve after being immersed in a binary solvent for 15 days, laying a good foundation for repeated stretching repair.

[0022] Example 1: The preparation of a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel includes the following steps: S1. Preparation of PEG / α-CD / PEO gel 0.125 g of polyethylene glycol and 0.5 g of polyethylene oxide were dissolved in 10 g of deionized water. Then, 0.6 g of α-cyclodextrin was slowly added to the PEG solution and dispersed evenly in an ultrasonic water bath at 80 °C. The white mixture was cooled to room temperature to obtain a white PEG / α-CD inclusion complex gel. Next, an aqueous solution of PEO was added and mechanically stirred for 1 hour to mix with the PEG / α-CD white inclusion complex gel, resulting in a viscous PEG / α-CD / PEO mixed gel. S2, Preparation of PEG / α-CD / PEO / PVA / IL / G gel 0.6 g of polyvinyl alcohol was dissolved in 10 g of deionized water in a 95°C water bath. Then, an aqueous PVA solution was added to the mixture, and the mixture was mechanically stirred for 1 hour to obtain a viscous PEG / α-CD / PEO / PVA mixed gel. 1.2 g of ionic liquid was added, and the mixture was mechanically stirred for 1 hour to obtain a PEG / α-CD / PEO / PVA / IL mixed gel. Subsequently, 1.2 g of glycerol was added, and the mixture was mechanically stirred for another 1 hour to obtain a PEG / α-CD / PEO / PVA / IL / G mixed gel. Next, the mixed gel was allowed to stand at room temperature for 24 hours to remove internal air bubbles. Finally, it was poured into a petri dish and dried in a 60°C oven for 4 hours. After peeling from the petri dish, the PEG / α-CD / PEO / PVA / IL / G hydrogel was obtained, the thickness of which can be adjusted according to the total amount of the casting mixture. Typically, casting 7 g of the mixture into a 60 mm diameter petri dish yields a hydrogel with a thickness of approximately 0.6 mm.

[0023] Comparative Example 2: Based on Example 1, the difference from Example 1 is that the ionic liquid content is different (0.8g) and the glycerol content is different (0g) when preparing the PEG / α-CD / PEO / PVA / IL / G gel.

[0024] Comparative Example 3: Based on Example 1, the difference from Example 1 is that the ionic liquid content is 1g and the glycerol content is 0g when preparing the PEG / α-CD / PEO / PVA / IL / G gel.

[0025] Comparative Example 4: Based on Example 1, the difference from Example 1 is that the ionic liquid content is 1.2g and the glycerol content is 0g when preparing the PEG / α-CD / PEO / PVA / IL / G gel.

[0026] Comparative Example 5: Based on Example 1, the difference from Example 1 is that the ionic liquid content is 1.4g and the glycerol content is 0g when preparing the PEG / α-CD / PEO / PVA / IL / G gel.

[0027] Comparative Example 6: Based on Example 1, the difference from Example 1 is that when preparing the PEG / α-CD / PEO / PVA / IL / G gel, the contents of PVA, ionic liquid and glycerol are different and are 0g.

[0028] Comparative Example 7: Based on Example 1, the difference from Example 1 is that the content of ionic liquid and glycerol is 0g when preparing PEG / α-CD / PEO / PVA / IL / G gel.

[0029] Comparative Example 8: Based on Example 1, the difference from Example 1 is that the glycerol content is 0g when preparing the PEG / α-CD / PEO / PVA / IL / G gel.

[0030] Mechanical properties were tested on Examples 1 and Comparative Examples 2-8 to investigate the effects of different components and ionic liquid content in the PEG / α-CD / PEO / PVA / IL / G gel on the mechanical properties of the prepared hydrogels. The data are shown in Table 1.

[0031] Table 1

[0032] Table 1 shows that PVA molecular chains and ionic liquids as conductive components can improve the mechanical properties of PEG / α-CD / PEO. Compared with hydrogels without ionic liquids, the mechanical properties of the hydrogel are significantly improved after the introduction of IL. However, the study found that excessively high ion concentrations weaken the interactions between polymer chains, leading to a decrease in the mechanical properties of the hydrogel. When the ion concentration increases from 0.8 to 1.2, the modulus, strength, and toughness of the hydrogel gradually increase; when the ion concentration exceeds 1.2, the mechanical properties show a downward trend. Therefore, IL-1.2g is considered the best choice for subsequent experiments. However, due to its poor water retention (more than 25 wt.% water evaporation within two days), it is not suitable for long-term wearable applications. Adding glycerol to the PEG / α-CD / PEO / PVA / IL (i.e., PEG / α-CD / PEO / PVA / IL-1.2g) hydrogel can impart excellent water retention properties, making it suitable for long-term use.

[0033] Performance testing was performed on the prepared water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel. 1. For example Figure 4 As shown, the water-responsive, repairable, and biocompatible transparent conductive hydrogel prepared by this invention has good adhesion properties and can conformally adhere to human skin. Figure 4 a) The stretched hydrogel combines with VHB tape to form a hydrogel tape, which adheres to the skin surface. Upon contact with moisture, it immediately contracts and exerts pressure on the skin, causing skin displacement of more than 18% within 2 minutes. Figure 4b). After drying for 30 minutes, the hydrogel tape further compressed the skin, eventually displacing by 25%. These findings indicate that the hydrogel tape can generate sufficient pressure to compress human skin, potentially achieving effective wound closure through its contractile properties. The wound-closure properties of the hydrogel tape were demonstrated on a moist ex vivo porcine skin surface with an elliptical defect (10 mm × 2 mm). A binary solvent was added to the hydrogel tape to induce rapid contraction, and the wound closure process within 80 seconds could be clearly observed using its translucent properties. Figure 4 c and 4d). The pre-stretched hydrogel initially forms a loose encapsulation with the pork tissue, subsequently achieving complete tissue adhesion by triggering its water-responsive shrinkage properties. Figure 4 e). In addition, conductive hydrogels can be used as wound dressings to promote wound healing (4f).

[0034] 2. For example Figure 5 As shown, the water-responsive, repairable, and biocompatible transparent conductive hydrogel prepared by this invention exhibits good water retention properties. Figure 5 a and Figure 5 (b is the water retention diagram of the sensor), it was found that the conductive hydrogel could quickly recover its performance after water loss by soaking in a binary solvent. Figure 5 ce).

[0035] 3. For example Figure 6 As shown, the water-responsive, repairable, and biocompatible transparent conductive hydrogel prepared by this invention has excellent biocompatibility and its toxicity is negligible.

[0036] 4. For example Figure 7 As shown, the water-responsive, repairable, and biocompatible transparent conductive hydrogel prepared in this invention is used for the detection of physiological and motion signals in vitro. It can be used as a bioelectric sensor to detect human heart rate (…). Figure 7 a), and after gel dehydration, it can be repaired with a binary solvent and then used again to detect heart rate. Figure 7 b). It can be conformally applied to the skin surface of human fingers and wrists as a strain sensor to detect bending signals. Figure 7 c and Figure 7 d).

[0037] 5. For example Figure 8 As shown, the water-responsive, repairable, and biocompatible transparent conductive hydrogel prepared in this invention is used for implantable in vivo signal monitoring. It can serve as a bioelectric sensor to monitor heart rate signals in the epicardium. With the assistance of machine learning, it can perform diagnosis and early warning based on the monitored heart rate signals in different states (normal, hypoxic, myocardial infarction). Figure 8 a and Figure 8b) can also be used as a strain sensor to detect tendon flexion signals in mice. Figure 8 ce).

[0038] The water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel prepared in this invention exhibits excellent adhesion, water retention, repairability, and biocompatibility. Water can stimulate the pre-stretched hydrogel to achieve conformal shrinkage. Therefore, using water stimulation to achieve conformal adhesion to biological tissues or organs avoids the potential damage to biological tissues caused by traditional stimulation methods such as light and chemicals, combining gentleness and biosafety. Based on the conformal mechanism of water stimulation, conductive hydrogel film sensors can be tightly wrapped in soft epidermal skin and the surface of internal organs such as the heart and tendons in a shape-adaptive manner for monitoring physiological and motion signals, while also allowing for direct observation of the health status of the covered tissue. This provides a new approach for the safe and efficient integration of bioelectronic devices with living tissues, and is particularly suitable for medical scenarios with high stimulation sensitivity (such as monitoring soft tissues like the heart and tendons), demonstrating significant advantages in fields such as smart wearables and clinical diagnostics.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, characterized in that, include: The gel is based on a dual network formed by polyethylene glycol (PEG)-α-cyclodextrin (α-CD) and polyethylene oxide (PEO), supplemented with polyvinyl alcohol (PVA) as the backbone. Ionic liquids are added to meet the requirements for conductive strain sensing. The addition of glycerol imparts good water retention, maintaining structural stability and flexibility.

2. The water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel according to claim 1, characterized in that: After pre-stretching, the PEO polymer chains of the conductive hydrogel will align in a specific direction. Water, as a stimuli, can disrupt the directional alignment of the internal crystalline domains and molecular chains of PEO, thereby triggering efficient shrinkage. The combination between α-CD and PVA ensures excellent mechanical repeatability and stability in water.

3. The water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel according to claim 1, characterized in that: Glycerol-water binary solvents can effectively repair conductive gels that have dehydrated after long-term use, restoring their properties almost completely.

4. The water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel according to claim 1, characterized in that: The mass ratio of polyethylene glycol, α-cyclodextrin, and water is 10–15:50–70:1000; the mass ratio of polyethylene oxide and water is 0.5–1.5:20; the mass ratio of polyvinyl alcohol and water is 5–7:100; and the mass ratio of ionic liquid and glycerol is 0.8–1.5:0.9–1.

2.

5. A method for preparing a water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel, characterized in that, Includes the following steps: S1. Preparation of PEG / α-CD / PEO gel Polyethylene glycol (PEG) and polyethylene oxide (PEG) were dissolved separately in deionized water. Then, α-cyclodextrin was slowly added to the PEG solution and dispersed evenly in an ultrasonic water bath. The white mixture was cooled to room temperature to obtain a white PEG / α-CD inclusion complex gel. Next, an aqueous PEO solution was added and mixed with the PEG / α-CD white inclusion complex gel by mechanical stirring to obtain a viscous PEG / α-CD / PEO mixed gel. S2, Preparation of PEG / α-CD / PEO / PVA / IL / G gel Polyvinyl alcohol was dissolved in deionized water, and then an aqueous PVA solution was added to the above PEG / α-CD / PEO system. Mechanical stirring was performed to obtain a viscous PEG / α-CD / PEO / PVA mixed gel. An ionic liquid was added, and mechanical stirring was continued to obtain a PEG / α-CD / PEO / PVA / IL mixed gel. Glycerin was then added, and mechanical stirring continued to obtain a PEG / α-CD / PEO / PVA / IL / G gel. Next, the gel was allowed to stand at room temperature to remove internal air bubbles. Finally, it was poured into a petri dish and dried in an oven. After peeling it from the petri dish, the PEG / α-CD / PEO / PVA / IL / G hydrogel was obtained, the thickness of which could be adjusted according to the total amount of the casting mixture.

6. The method for preparing the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel according to claim 5, characterized in that: The mass ratio of polyethylene glycol, α-cyclodextrin, and water is 10–15:50–70:1000; the mass ratio of polyethylene oxide and water is 0.5–1.5:20; the mass ratio of polyvinyl alcohol and water is 5–7:100; and the mass ratio of ionic liquid and glycerol is 0.8–1.5:0.9–1.

2.

7. The use of the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel according to any one of claims 1 to 4, or the water-responsive, shrinkable, repairable, and biocompatible transparent conductive hydrogel prepared by the preparation method according to any one of claims 5 to 6, characterized in that: The conductive hydrogel film sensor can conformally and tightly wrap around soft epidermal skin and the surface of internal organs such as the heart and tendons in a shape-adaptive manner for monitoring physiological and motion signals, while also allowing for direct observation of the health status of the covered tissues.

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