Conductive organic hydrogel with wrinkle structure as well as preparation method and application of conductive organic hydrogel
By constructing a conductive organic hydrogel with a wrinkled structure on the conductive coating, the problem of insufficient reconstruction of the conductive network during the stretching process is solved, high sensitivity and stable sensing performance are achieved, and the application range of sensors is expanded.
Patent Information
- Application Number
- CN202510711718.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-07-29
AI Technical Summary
The existing nanocomposite conductive hydrogels are not fully reconstructed during the stretching process, which makes it difficult to optimize the sensitivity and response range in a coordinated manner, limiting the application field of sensors.
By constructing a conductive organic hydrogel with a wrinkled structure on the conductive coating, combining a dynamic crosslinking network and a pre-stretching control strategy, a conductive organic hydrogel with a wrinkled structure is prepared to enhance the interface combination between the flexible matrix and the rigid conductive layer.
It achieves high sensitivity and excellent sensing stability within a wide sensing response range, improves the mechanical performance and long-term cycle stability of the sensor, and expands the application range of the sensor.
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Figure CN120383743A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of sensors, and particularly relates to a conductive organic hydrogel with a wrinkled structure, a preparation method thereof, and an application thereof. Background Art
[0002] In the field of sports health, sensors are indispensable. The most basic function of motion sensors is to monitor motion data in real time, such as the number of steps, distance, and speed, etc., providing users with clear feedback on their motion states, thereby helping to reasonably formulate exercise plans and adjust exercise rhythms to ensure exercise effects. As people's awareness of sports health gradually improves, monitoring physiological indicators such as electrocardiogram and electromyogram signals has also developed into a demand for motion sensors. Especially during exercise, heart rate data can reflect the body's state and exercise intensity, helping users avoid over-exercise and at the same time ensuring that the exercise achieves the expected effect. At the same time, through continuous dynamic signal acquisition, the sensor can effectively analyze the exercise posture, timely detect incorrect postures and provide corrective suggestions, prevent sports injuries, and improve exercise effects. In the field of sports rehabilitation, it can track the rehabilitation process in real time, provide accurate data support for doctors and rehabilitation therapists, and assist in formulating appropriate rehabilitation plans. The data collected by the sensor can be synchronized to intelligent devices for users to view and analyze at any time. Through long-term monitoring and data analysis, potential health risks can be discovered and personalized health suggestions can be provided to improve living habits. Therefore, it is very necessary to design a sensor that can detect motion for a long time, stably, and sensitively.
[0003] Due to characteristics such as tissue-like flexibility and excellent biocompatibility, hydrogel materials have received much attention in the field of flexible electronic devices. By compounding nano-conductive fillers such as MXene, graphene, and CNTs with the hydrogel polymer network, effective regulation of conductive properties and mechanical properties can be achieved, showing significant application potential in the field of wearable sensing technology. However, due to the insufficient reconstruction of the conductive network during the stretching process in the uniformly doped nano-composite conductive hydrogel, there is a trade-off problem between sensitivity and response range, which limits the application fields of the sensor. Therefore, developing a new type of nano-composite conductive hydrogel that maintains high sensitivity within a wide response range has become an important research direction in this field.
[0004] Loading nanoconductive coatings on hydrogel surfaces can help improve sensor sensitivity. However, if the conductive coating is directly applied to the hydrogel surface, the mismatch in Young's modulus between the rigid conductive coating and the flexible gel matrix can lead to delamination and / or localized fracture of the material under external forces. This results in a narrow sensor response range, limiting its application in wearable devices. To address the difficulty in co-optimizing sensitivity and operating range, researchers have exploited the difficulty of constructing microstructures (such as "cracks" and "wrinkles") on the conductive coating to manipulate sensing performance. Currently, loading rigid conductive coatings on commercial flexible substrates (such as polyurethane and dimethylsiloxane) and then microstructuring the coating is a common and feasible method for improving sensor response performance. However, research on constructing microstructures on conductive coatings on hydrogels as flexible substrates to optimize strain sensing performance is rare.
[0005] The construction of a "wrinkled" structure can greatly increase the surface area of the sensor, allowing the conductive layer to generate more contact area and conductive path changes when subjected to force, thereby giving the sensor better sensing performance. However, under continuous mechanical deformation, the weak interface bonding between the flexible gel layer and the rigid conductive layer will cause displacement and sliding of the microstructure, and also affect the stability of the sensing signal. Therefore, the development of a nanocomposite conductive hydrogel system with strong interface bonding is of great scientific significance for achieving high-performance sensing. Summary of the Invention
[0006] In order to solve the problem that the sensitivity and response range of hydrogels in the prior art are difficult to coordinately optimize, the purpose of the present invention is to provide a conductive organic hydrogel with a wrinkled structure and its preparation method and application.
[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a conductive organic hydrogel with a wrinkled structure, comprising the following steps: (1) Stir phytic acid, glycerol and water at room temperature to obtain a mixed solution A; (2) Heat the mixture A to 80-90°C, add chitosan and 1# polyvinyl alcohol thereto in sequence, stir evenly, and obtain a mixture B; wherein the alcoholysis degree of 1# polyvinyl alcohol is 98-99 mol%; (3) After the mixed solution B is cooled, acrylamide and a cross-linking agent are added thereto in sequence, and the mixture is stirred until the acrylamide is completely dissolved. After vacuum degassing, an initiator is added, and the mixture is stirred evenly. Then, a free radical polymerization reaction is carried out. After the reaction is completed, the reaction solution is freeze-thawed to obtain a conductive organic hydrogel matrix. (4) Add 2# polyvinyl alcohol to the aqueous dispersion of MXene and stir until the polyvinyl alcohol is completely dissolved to obtain a mixed solution C; wherein, the degree of alcoholysis of 2# polyvinyl alcohol is 87-89 mol%. (5) Apply a pre-tensile stress to the conductive organic hydrogel matrix obtained in step (3) for unidirectional stretching. After fixing with a clamp, spray the mixed solution C obtained in step (4) onto the surface of the conductive organic hydrogel matrix obtained after stretching, and then perform freeze-thaw treatment to release the pre-tensile stress to obtain a conductive organic hydrogel with a wrinkled structure.
[0008] Preferably, in step (1), by mass ratio, phytic acid∶glycerol∶water = (10-40) g∶(2.5-10) g∶(2.5-10) g; Preferably, in steps (2) and (3), by mass ratio, chitosan∶1# polyvinyl alcohol∶acrylamide∶mixed solution A = (0.1-0.4)∶(0.4-1.6)∶(2-8)∶(15-60); based on the percentage of the molar amount of acrylamide, the molar amount of the crosslinking agent is 0.03-0.04%, and the molar amount of the initiator is 0.05-0.1%.
[0009] Preferably, in the method for preparing a conductive organic hydrogel with a wrinkled structure as described in claim 1, characterized in that: in step (3), the mixed solution B is cooled to 35-40 °C, and the temperature of the free radical polymerization reaction is 50-60 °C and the time is 6-12 h.
[0010] Preferably, in the method for preparing a conductive organic hydrogel with a wrinkled structure as described in claim 1, characterized in that: in step (3), the crosslinking agent is N,N'-methylenebisacrylamide, and the initiator is azobisisobutyronitrile (AIBN) or ammonium persulfate (APS).
[0011] Preferably, in step (4), by mass ratio, 2# polyvinyl alcohol∶aqueous dispersion of MXene = (2-4)∶100, and the concentration of the aqueous dispersion of MXene is 6-8 mg / mL.
[0012] Preferably, in step (5), the unidirectional stretching is performed until the stretching ratio is 100-200%. The unidirectional stretching means stretching only in one direction, either horizontally or vertically; the stretching ratio refers to the ratio of the length change before and after stretching to the original length before stretching. For example, if the original length before stretching is 2 cm and the length after stretching is 4 cm, the corresponding stretching ratio is 100%.
[0013] Preferably, in step (5), the spraying pressure is 1-2 MPa and the spraying distance is 10-15 cm.
[0014] Preferably, in step (3) and step (5), the freeze-thaw treatment is first freezing treatment and then thawing treatment at room temperature, and in step (3), the freezing treatment temperature is -20~-30℃, the freezing treatment time is 8~12h, and the thawing treatment time is 2~6h; in step (5), the freezing treatment temperature is -20~-30℃, the freezing treatment time is 3~6h, and the thawing treatment time is 2~6h.
[0015] A conductive organic hydrogel with a wrinkled structure prepared by the preparation method.
[0016] An application of the conductive organic hydrogel with a wrinkled structure in a pressure sensor.
[0017] In the present invention, MXene (Mikeene), a two-dimensional transition metal carbide / nitride material, has the general chemical formula M n+1 X n T x , where M is a transition metal, X is carbon or nitrogen, T x is a surface functional group (-OH, -O or -F).
[0018] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The preparation method of the present invention is simple to operate and low in cost. It is based on the design concept of a dynamic cross-linked network, with a network composed of polyacrylamide / polyvinyl alcohol / chitosan as the basic skeleton. At the same time, phytic acid, glycerol and water ternary solvents constitute the liquid environment of the hydrogel skeleton. The water retention capacity of the hydrogel is improved by the combination of phytic acid and glycerol. Finally, a wrinkle structure is successfully constructed in the MXene / polyvinyl alcohol conductive layer by combining freeze-thaw technology with a pre-stretching control strategy. (2) The conductive organic hydrogel with a wrinkled structure prepared by the present invention has excellent mechanical properties. The compression can reach about 60% of the original length, the compressive strength can reach 1.0 MPa, and the elastic modulus can reach 1.8 MPa; (3) The present invention proposes an innovative hydrogel flexible matrix - polyacrylamide / polyvinyl alcohol / chitosan composite matrix, which directly introduces glycerol and phytic acid into the hydrogel during the polymerization process, thereby enhancing the environmental tolerance of the organic hydrogel; (4) The conductive organic hydrogel with a wrinkled structure prepared by the present invention has high sensitivity, excellent sensing stability and long-term cycle stability in a wide sensing response range; (5) The conductive organic hydrogel with a wrinkled structure prepared by the present invention can be used in pressure sensors. Due to its unique structural design and excellent performance, it has broad application prospects in the field of sensors. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 : Schematic diagram of the preparation process of the conductive organic hydrogel with a wrinkled structure of the present invention.
[0020] Figure 2 : Organic hydrogels PVCM obtained in Examples 1 to 3 and Comparative Example 1 of the present invention 200 、PVCM 100 、PVCM 150 and stress-strain curve diagrams (a) of PVCM at a compression rate of 8 mm / min, as well as statistical diagrams (b) of elastic modulus and compressive strength.
[0021] Figure 3 : Organic hydrogel PVCM obtained in Example 1 200 and sensitivity (S) of the organic hydrogel PVCM obtained in Control Example 1 as a pressure sensor. In the figure, wrinkled PVCM represents the organic hydrogel PVCM obtained in Example 1 200 , and planar PVCM represents the organic hydrogel PVCM obtained in Control Example 1.
[0022] Figure 4 : Organic hydrogel PVCM obtained in Example 1 200 Time-current change rate response curves under different large compression strains (20%, 40%, 60%).
[0023] Figure 5 : Organic hydrogel PVCM obtained in Example 1 200 Time-current change rate response curves under different small compression strains (1%, 5%, 10%).
[0024] Figure 6 : Organic hydrogel PVCM obtained in Example 1 200 Long-term cyclic stability test curve under a 50% compression strain.
[0025] Figure 7 : Organic hydrogel PVCM obtained in Example 1 200 Response signal curve at an environmental temperature of 50 °C and a compression strain of 50%.
[0026] Figure 8 : Organic hydrogel PVCM obtained in Example 1 200 Actual application signal curve as a sensor. Specific implementation mode
[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present invention.
[0028] Example 1
[0029] A preparation method of a conductive organic hydrogel with a wrinkled structure, the schematic diagram of the preparation process is as Figure 1 shown, and the preparation steps are as follows: (1) Add 20 g of phytic acid, 5 g of glycerol and 5 g of deionized water into a glass bottle, stir at room temperature for 30 min to obtain a mixed solution A; (2) Place the mixed solution A under a water bath condition of 90 °C, and sequentially add 0.2 g of chitosan and 0.8 g of polyvinyl alcohol 1799 (degree of alcoholysis: 98 - 99 mol%), stir magnetically for 2 h to obtain a mixed solution B; (3) After the mixed solution B is cooled to 40 °C, add 4 g of acrylamide and 0.325 mL of an aqueous solution of N,N'-methylenebisacrylamide with a concentration of 1 wt% thereto, continuously stir for 2 h until the acrylamide is completely dissolved. After vacuum degassing treatment, slowly add 0.08 mL of an aqueous solution of APS with a concentration of 10 wt%, stir for 30 s, then quickly inject the mixed solution into a self-made mold, place it at 60 °C for 8 h, then put it into a low-temperature refrigerator at -30 °C and freeze for 8 h, and then take it out and place it at room temperature for 2 h to obtain a conductive organic hydrogel matrix; (4) Add 0.2 g of polyvinyl alcohol 1788 (degree of alcoholysis: 87 - 89 mol%) into 10 g of an aqueous solution of MXene (Ti3C2T x ) with a concentration of 6 mg / mL, stir magnetically until the polyvinyl alcohol is completely dissolved to obtain a mixed solution C; (5) Apply a pre-tensile stress to the conductive organic hydrogel matrix along its length direction for unidirectional stretching until the stretching ratio is 200%. After fixing with a clamp, use an airbrush equipped with an air compressor to spray 0.5 mL of the mixed solution C onto the gel surface at a pressure of about 1 MPa and a spraying distance of 10 cm, place it in a refrigerator at -30 °C and freeze for 3 h, thaw at room temperature for 4 h, and then release the pre-tensile stress to obtain the target product, labeled as PVCM 200 .
[0030] Example 2
[0031] The difference from Example 1 is that in step (5), the conductive organic hydrogel matrix is stretched to a stretching ratio of 100%; the others are the same as in Example 1.
[0032] The obtained product is labeled as PVCM 100 。
[0033] Example 3
[0034] It is different from Example 1 in that: in step (5), the conductive organic hydrogel matrix is stretched to a stretch ratio of 150%; the others are the same as in Example 1
[0035] The obtained product is labeled as PVCM 150 。
[0036] Comparative Example 1 It is different from Example 1 in that: in step (5), the conductive organic hydrogel matrix is not stretched, but the mixed solution C is directly sprayed on its surface and frozen and thawed; the others are the same as in Example 1
[0037] The obtained product is labeled as PVCM
[0038] Comparative Example 2 It is different from Example 1 in that: in step (4), polyvinyl alcohol 1788 is not added to the mixed solution C; the others are the same as in Example 1
[0039] It is found that: in step (5), after spraying the mixed solution C, the rigid MXene layer on the surface of the conductive organic hydrogel matrix is weakly bonded to the gel matrix and is very easy to fall off
[0040] Performance test (1) At room temperature, the hydrogels PVCM 200 , PVCM 100 , PVCM 150 and PVCM obtained in Examples 1 to 3 and Comparative Example 1 of the present invention are respectively fixed on an electronic universal testing machine for relevant tensile tests
[0041] Figure 2 are the stress-strain curve diagrams (a) and the statistical diagrams of elastic modulus and compressive strength (b) of the organic hydrogels PVCM 200 , PVCM 100 , PVCM 150 and PVCM obtained in Examples 1 to 3 and Comparative Example 1 of the present invention at a compression rate of 8 mm / min. It can be seen from Figure 2 that as the stretching ratio increases, the compressive elastic modulus and compressive strength of the material are significantly improved, the compression can reach about 60% of the original length, the compressive strength can reach 1.0 MPa, and the elastic modulus can reach 1.8 MPa
[0042] (2) Sensor fabrication: The organic hydrogel PVCM obtained in Example 1 of the present invention 200For the organic hydrogel PVCM obtained in Example 1 or Comparative Example 1, carbon cloth was attached to both ends with conductive tape, and the carbon cloth was led out with wires to obtain the corresponding sensor.
[0043] (2.1) At room temperature, the sensor was fixed on an electronic universal testing machine, and at the same time, the other end of the wire was connected to a CHI660E electrochemical workstation. The relevant tensile test was started, and the CHI660E electrochemical workstation was used to record the output signal at both ends of the sensor in real time.
[0044] Figure 3 It is the organic hydrogel PVCM obtained in Example 1 200 and the sensitivity (S) of the organic hydrogel PVCM obtained in Comparative Example 1 as a pressure sensor. The wrinkled PVCM in the figure represents the organic hydrogel PVCM obtained in Example 1 200 , and the planar PVCM represents the organic hydrogel PVCM obtained in Comparative Example 1. It can be seen from Figure 3 that: PVCM shows sensitivities of 1.16 kPa -1 and 0.55 kPa -1 respectively in the stress ranges of 0 - 65 kPa and 65 - 600 kPa, while PVCM 200 shows sensitivities of 1.97 kPa -1 and 1.01 kPa -1 respectively in the stress ranges of 0 - 100 kPa and 100 - 600 kPa, indicating that the organic hydrogel PVCM with a wrinkled structure prepared by the present invention 200 has high sensitivity and wide linear response characteristics compared to the organic hydrogel PVCM with a planar structure.
[0045] Figure 4 It is the organic hydrogel PVCM obtained in Example 1 200 The time - current change rate response curves of the organic hydrogel PVCM obtained in Example 1 under different large compression strains (20%, 40%, 60%). It can be seen from Figure 4 that: the resistance signal shows highly consistent repeatability in different compression strain cycles, proving that the PVCM 200 organic hydrogel has excellent strain sensing reversibility and reliability under large compression strain conditions.
[0046] Figure 5 It is the organic hydrogel PVCM obtained in Example 1 200 The time - current change rate response curves of the organic hydrogel PVCM obtained in Example 1 under different small compression strains (1%, 5%, 10%). It can be seen from Figure 5 that: the material can show a low detection limit of 1%, indicating that the sensor has potential applications in sensing subtle human movements.
[0047] Figure 6The organic hydrogel PVCM obtained in Example 1 200 Long-term cyclic stability test curve under 50% compressive strain. It can be seen from Figure 6 that under 50% compressive strain, the organic hydrogel PVCM 200 can maintain excellent sensing signal stability and reproducibility in a long-term loading-unloading test of more than 8000 s.
[0048] (2.2) In a temperature control box at 50 °C, the sensor was placed and fixed on an electronic universal testing machine, and at the same time, the other end of the wire was connected to a CHI660E electrochemical workstation. The relevant tensile test was started, and the CHI660E electrochemical workstation was used to record the output signal at both ends of the sensor in real time.
[0049] Figure 7 The organic hydrogel PVCM obtained in Example 1 200 Response signal curve under the conditions of an environmental temperature of 50 °C and a compressive strain of 50%. The results show that the organic hydrogel PVCM 200 still has stable sensing performance at an environmental temperature of 50 °C, indicating its excellent environmental stability and sensing reliability.
[0050] (2.3) At room temperature, when the sensor was attached to the human finger joint, at different bending angles of 30°, 60°, and 90°, the other end of the wire was connected to a CHI660E electrochemical workstation, and the CHI660E electrochemical workstation was used for real-time dynamic monitoring.
[0051] Figure 8 The organic hydrogel PVCM obtained in Example 1 200 As the actual application signal curve of the sensor. The results show that the rate of change of its resistance is significantly positively correlated with the bending angle, and this sensor has both angle resolution accuracy and long-term working reliability in human motion monitoring.
Claims
1. A preparation method of a conductive organic hydrogel with a wrinkled structure, characterized in that The steps are as follows: (1) Stir phytic acid, glycerol and water evenly at room temperature to obtain mixture A; (2) Heat mixture A to 80 - 90 °C, and successively add chitosan and 1# polyvinyl alcohol thereto, and stir evenly to obtain mixture B; wherein, the alcoholysis degree of 1# polyvinyl alcohol is 98 - 99 mol%; (3) After mixture B is cooled, successively add acrylamide and a crosslinking agent thereto, stir until acrylamide is completely dissolved, after vacuum degassing treatment, add an initiator, stir evenly, and then carry out a free radical polymerization reaction. After the reaction ends, subject the reaction solution to freeze-thaw treatment to obtain a conductive organic hydrogel matrix; (4) Add 2# polyvinyl alcohol to the aqueous dispersion of MXene, and stir until the polyvinyl alcohol is completely dissolved to obtain mixture C; wherein, the alcoholysis degree of 2# polyvinyl alcohol is 87 - 89 mol%; (5) Apply a pre-tensile stress to the conductive organic hydrogel matrix obtained in step (3) for unidirectional stretching. After fixing with a clamp, spray mixture C obtained in step (4) onto the surface of the conductive organic hydrogel matrix obtained after stretching, and then carry out freeze-thaw treatment to release the pre-tensile stress to obtain a conductive organic hydrogel with a wrinkled structure.
2. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, wherein: In step (1), by mass ratio, phytic acid∶glycerol∶water = (10 - 40) g∶(2.5 - 10) g∶(2.5 - 10) g; In steps (2) and (3), by mass ratio, chitosan∶1# polyvinyl alcohol∶acrylamide∶mixture A = (0.1 - 0.4)∶(0.4 - 1.6)∶(2 - 8)∶(15 - 60); by the percentage of the molar amount of acrylamide, the molar amount of the crosslinking agent is 0.03 - 0.04%, and the molar amount of the initiator is 0.05 - 0.1%.
3. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In step (3), mixture B is cooled to 35 - 40 °C, and the temperature of the free radical polymerization reaction is 50 - 60 °C and the time is 6 - 12 h.
4. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In step (3), the crosslinking agent is N,N'-methylenebisacrylamide, and the initiator is azobisisobutyronitrile or ammonium persulfate.
5. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In step (4), by mass ratio, 2# polyvinyl alcohol∶aqueous dispersion of MXene = (2 - 4)∶100, and the concentration of the aqueous dispersion of MXene is 6 - 8 mg / mL.
6. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In step (5), unidirectional stretching is carried out to a stretching ratio of 100 - 200%.
7. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In step (5), the spraying pressure is 1 - 2 MPa, and the spraying distance is 10 - 15 cm.
8. The preparation method of the conductive organic hydrogel with a wrinkled structure according to claim 1, characterized in that: In steps (3) and (5), the freeze-thaw treatment is first freezing treatment and then thawing treatment at room temperature. In step (3), the temperature of the freezing treatment is -20 - -30 °C, the time of the freezing treatment is 8 - 12 h, and the time of the thawing treatment is 2 - 6 h; in step (5), the temperature of the freezing treatment is -20 - -30 °C, the time of the freezing treatment is 3 - 6 h, and the time of the thawing treatment is 2 - 6 h.
9. A conductive organic hydrogel with a wrinkled structure prepared by the preparation method according to any one of claims 1 - 8.
10. Application of the conductive organic hydrogel with a wrinkled structure as described in claim 9 in a pressure sensor.