Ultraviolet-cured high-viscoelasticity ionic conductive hydrogel as well as preparation method and application thereof
The highly viscoelastic ion-conductive hydrogel prepared by ultraviolet curing technology, combined with covalent cross-linking and electrostatic interaction, solves the problem of balancing the stretchability, adhesion and conductivity of hydrogel materials in flexible bioelectrodes, and realizes high-performance bioelectric signal acquisition.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-29
- Publication Date
- 2026-04-14
AI Technical Summary
Existing hydrogel materials cannot simultaneously possess high tensile strength, strong adhesion, and high ionic conductivity, resulting in discomfort when worn in flexible bioelectrodes and unstable signal acquisition.
A highly viscoelastic ionic conductive hydrogel was prepared using ultraviolet light curing technology. By combining covalent cross-linking networks with dynamic electrostatic interactions, and using methacryloyl ethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate, and α-ketoglutaric acid as raw materials, a balance between high tensile strength, strong adhesion, and high ionic conductivity was formed.
It achieves high tensile strength (>500%), strong adhesion (>140kPa) and high ionic conductivity (2.24 S/m), low interfacial impedance, strong resistance to motion artifacts, rapid preparation and low cost, and is suitable for long-term dynamic bioelectric signal monitoring.
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Figure CN121851245A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a UV-curable highly viscoelastic ion-conductive hydrogel, its preparation method, and its applications, belonging to the fields of functional polymer materials and bioelectronics technology. Background Technology
[0002] With the development of wearable electronics and personalized medicine, there is an increasingly urgent need for flexible bioelectrodes that can monitor human physiological signals long-term, stably, and comfortably. Traditional commercial electrodes (such as Ag / AgCl electrodes) have good conductivity, but the gel is prone to drying out, and long-term wear can cause skin irritation. Furthermore, collecting electrophysiological signals during human movement can easily produce motion artifacts, leading to signal distortion.
[0003] Ion-conductive hydrogels, as an emerging flexible electronic material, are considered ideal novel bioelectrode materials due to their mechanical modulus similar to that of human skin. However, most hydrogels currently face the challenge of simultaneously achieving optimal mechanical properties (such as tensile strength and toughness), interfacial adhesion, and conductivity. Hydrogels with strong adhesion often have high modulus and poor ductility, resulting in discomfort when worn; while soft, highly tensile hydrogels struggle to form a stable, low-impedance interfacial contact with the skin, easily detaching or generating noise during dynamic monitoring. Therefore, developing a hydrogel material that combines excellent mechanical properties, strong tissue adhesion, and high ionic conductivity is of great significance for promoting the development of next-generation high-performance flexible bioelectronic devices. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a UV-curable highly viscoelastic ionic conductive hydrogel, its preparation method, and its applications. This hydrogel undergoes rapid polymerization initiated by UV light, combining a covalent cross-linked network with a dynamic electrostatic interaction network, achieving a balance between high tensile strength, strong adhesion, and high ionic conductivity.
[0005] This invention is achieved using the following technical solution: A UV-curable, highly viscoelastic, ionicly conductive hydrogel is formed by UV-initiated crosslinking polymerization of raw materials comprising the following components: a zwitterionic monomer, a high-density cationic monomer, a crosslinking agent, and a photoinitiator; wherein the zwitterionic monomer is methacryloyl ethyl sulfobetaine (SBMA), the high-density cationic monomer is methacryloyloxyethyl trimethylammonium chloride (DADMAC), the crosslinking agent is polyethylene glycol diacrylate (PEGDA), and the photoinitiator is α-ketoglutaric acid.
[0006] The contents of each component are as follows: 70-90% methacryloyl ethyl sulfobetaine, 10-30% methacryloyl oxyethyl trimethyl ammonium chloride, the sum of methacryloyl ethyl sulfobetaine and methacryloyl oxyethyl trimethyl ammonium chloride is 100%, the amount of polyethylene glycol diacrylate added is 3-7% of the sum of the two, and the amount of α-ketoglutaric acid added is 2-5% of the sum of the two.
[0007] The ultraviolet-cured, highly viscoelastic, ion-conductive hydrogel exhibits a tensile strain greater than 600% at break, an adhesion strength to skin tissue greater than 140 kPa, an ionic conductivity of up to 2.24 S / m, and a contact impedance 1-3 orders of magnitude lower than that of commercial Ag / AgCl electrodes.
[0008] A method for preparing a UV-curable highly viscoelastic ion-conductive hydrogel includes the following preparation steps: S1. Preparation of precursor solution: Methacrylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate and α-ketoglutaric acid are dissolved in deionized water and stirred evenly at room temperature to obtain hydrogel precursor solution. S2. UV curing: The hydrogel precursor solution obtained in step S1 is placed in a molding mold or directly dripped onto the substrate surface, and cross-linking polymerization reaction is carried out under UV irradiation to obtain a highly viscoelastic ion-conductive hydrogel.
[0009] The total content of solid components in the hydrogel precursor solution in S1 is 60-80 wt%.
[0010] The molding die in S2 is a polytetrafluoroethylene (PTFE) die.
[0011] The substrate surface in S2 is human skin or a flexible substrate.
[0012] The ultraviolet light source in S2 has a wavelength of 365nm, a power of 25W, and an irradiation time of 60-90 seconds.
[0013] A flexible bioelectrode is formed by preparing a highly viscoelastic ion-conducting hydrogel using the above-mentioned method, with additional conductive leads.
[0014] The aforementioned flexible bioelectrode, with its highly viscoelastic ion-conductive hydrogel, can be formed in situ on the skin surface and used for bioelectrical signal monitoring, particularly for long-term, dynamic, and high signal-to-noise ratio electromyography (EMG) signal monitoring.
[0015] The beneficial effects of this invention are: 1. Excellent comprehensive performance: Through molecular design, covalent cross-linking and electrostatic interaction are cleverly combined, enabling the hydrogel to simultaneously possess high tensile strength (>500%), strong tissue adhesion (>140kPa) and high ionic conductivity (2.24 S / m), solving the problem of balancing tensile strength, toughness, adhesion and conductivity.
[0016] 2. Low interfacial impedance: Hydrogels can form a tight and stable conformal contact with the skin, and through the strong electrostatic interaction between them and the skin, they adhere tightly to the skin surface. Their skin-electrode contact impedance is 1-3 orders of magnitude lower than that of commercial Ag / AgCl gel electrodes, which is beneficial for collecting weak bioelectric signals.
[0017] 3. Strong resistance to motion artifacts: The high flexibility and strong adhesion of the material ensure the stability of the contact interface between the electrode and the skin during body movement, effectively suppressing motion artifacts.
[0018] 4. Rapid preparation and low cost: Using ultraviolet curing technology, the molding process can be completed within tens of seconds. The raw materials for bioelectrodes are abundant, inexpensive, and the process is simple.
[0019] 5. High scalability: The ultraviolet light sensitivity of this gel electrode makes it highly promising in the field of bioelectronics (such as the development of customized bioelectrode arrays). Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the preparation process in the preparation method of the present invention; Figure 2 These are photographs of the tensile properties of the hydrogel prepared in Example 1 of this invention, demonstrating its high tensile strength.
[0021] Figure 3 This is a schematic diagram and adhesion strength data of the hydrogel prepared in Example 1 of the present invention adhering to various substrate materials.
[0022] Figure 4 This is a comparison chart of the conductivity of the hydrogel prepared in Example 1 of this invention as an electrode and a commercial Ag / AgCl electrode.
[0023] Figure 5 This is a comparison diagram of the skin-electrode interface impedance of the hydrogels prepared as electrodes in Examples 1-2 and Comparative Examples 3-5 of this invention and commercial Ag / AgCl electrodes.
[0024] Figure 6 This is a comparison diagram of electromyographic signals collected by the hydrogel electrode prepared in Example 1 of the present invention during the dynamic bending of the human arm and signals from commercial electrodes. Detailed Implementation
[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0026] This UV-curable highly viscoelastic ionic conductive hydrogel is formed by UV-initiated crosslinking polymerization of raw materials containing the following components: zwitterionic monomer, high-density cationic monomer, crosslinking agent, and photoinitiator; the zwitterionic monomer is methacryloyl ethyl sulfobetaine (SBMA), the high-density cationic monomer is methacryloyloxyethyl trimethylammonium chloride (DADMAC); the crosslinking agent is polyethylene glycol diacrylate (PEGDA); and the photoinitiator is α-ketoglutaric acid.
[0027] In some embodiments, the contents of each component are as follows: 70-90% of methacryloylethyl sulfobetaine, for example: 70%, 75%, 80%, 85% or 90%; 10%-30% of methacryloyloxyethyl trimethylammonium chloride, for example: 10%, 15%, 20%, 25% or 30%; the sum of methacryloylethyl sulfobetaine and methacryloyloxyethyl trimethylammonium chloride is 100%; the amount of polyethylene glycol diacrylate added is 3-7% of the sum of the two, for example: 3%, 4%, 5%, 6% or 7%; and the amount of α-ketoglutaric acid added is 2-5% of the sum of the two, for example: 2%, 3%, 4% or 5%.
[0028] The ultraviolet-cured, highly viscoelastic, ion-conductive hydrogel exhibits a tensile strain greater than 600% at break, an adhesion strength to skin tissue greater than 140 kPa, an ionic conductivity of up to 2.24 S / m, and a contact impedance 1-3 orders of magnitude lower than that of commercial Ag / AgCl electrodes.
[0029] The preparation method of this UV-curable highly viscoelastic ion-conductive hydrogel includes the following preparation steps: S1. Preparation of precursor solution: Methacrylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate and α-ketoglutaric acid are dissolved in deionized water and stirred evenly at room temperature to obtain hydrogel precursor solution. S2. UV curing: The hydrogel precursor solution obtained in step S1 is placed in a molding mold or directly dripped onto the substrate surface, and cross-linking polymerization reaction is carried out under UV irradiation to obtain a highly viscoelastic ion-conductive hydrogel.
[0030] In some embodiments, the total content of the solid components of the hydrogel precursor solution in S1 is 60-80 wt%, for example, 60 wt%, 65 wt%, 70 wt%, 75 wt%, or 80 wt%.
[0031] In some implementations, the molding die in S2 is a polytetrafluoroethylene (PTFE) die.
[0032] In some implementations, the substrate surface in S2 is human skin or a flexible substrate.
[0033] In some implementations, the ultraviolet light source in S2 has a wavelength of 365nm, a power of 25W, and an irradiation time of 60-90 seconds, such as 60 seconds, 70 seconds, 80 seconds, or 90 seconds. Example 1
[0034] like Figure 1 As shown, the preparation of the three-component hydrogel (SBMA-DADMAC-PEGDA) The preparation method of this UV-curable highly viscoelastic ion-conductive hydrogel includes the following preparation steps: S1. Preparation of the precursor solution: Methacrylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate, and α-ketoglutaric acid are dissolved in deionized water and stirred until homogeneous at room temperature to obtain a hydrogel precursor solution; wherein methacryloylethyl sulfobetaine is 70%, methacryloyloxyethyl trimethylammonium chloride is 30%, the sum of methacryloylethyl sulfobetaine and methacryloyloxyethyl trimethylammonium chloride is 100%, the amount of polyethylene glycol diacrylate added is 5% of the sum of the two, and the amount of α-ketoglutaric acid added is 2% of the sum of the two; the solid content of the hydrogel precursor solution is 70%. S2. UV curing: The hydrogel precursor solution obtained in step S1 is placed in a polytetrafluoroethylene mold and crosslinked polymerization reaction is carried out under UV irradiation (365nm, 25W, 60 seconds) to obtain a highly viscoelastic ion-conductive hydrogel (SDP hydrogel).
[0035] The tensile properties test photos of the hydrogel prepared in Example 1 are shown below. Figure 2 As shown, from Figure 2 As can be seen from this embodiment, the hydrogel prepared in this embodiment has a tensile strength of 600%, demonstrating its high tensile properties.
[0036] Schematic diagrams and adhesion strength data of the hydrogel prepared in Example 1 adhering to various substrate materials are shown below. Figure 3 As shown, from Figure 3 As can be seen from the results, the hydrogel prepared in this embodiment has an adhesion strength of 144.18 kPa, demonstrating its high adhesion.
[0037] The conductivity comparison graph of the hydrogel prepared in Example 1 of this invention as an electrode and the commercial Ag / AgCl electrode is shown in Figure 1. Figure 4 As shown, from Figure 4 As can be seen from this example, the hydrogel prepared in this embodiment has a higher conductivity than Ag / AgCl, demonstrating its high conductivity. Example 2
[0038] like Figure 1 As shown, the preparation of the three-component hydrogel (SBMA-DADMAC-PEGDA) The preparation method of this UV-curable highly viscoelastic ion-conductive hydrogel includes the following preparation steps: S1. Preparation of the precursor solution: Methacrylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate, and α-ketoglutaric acid are dissolved in deionized water and stirred until homogeneous at room temperature to obtain a hydrogel precursor solution; wherein methacryloylethyl sulfobetaine is 90%, methacryloyloxyethyl trimethylammonium chloride is 10%, the sum of methacryloylethyl sulfobetaine and methacryloyloxyethyl trimethylammonium chloride is 100%, the amount of polyethylene glycol diacrylate added is 5% of the sum of the two, and the amount of α-ketoglutaric acid added is 2% of the sum of the two; the solid content of the hydrogel precursor solution is 70%. S2. UV curing: The hydrogel precursor solution obtained in step S1 is placed in a polytetrafluoroethylene mold and crosslinked polymerization reaction is carried out under UV irradiation (365nm, 25W, 60 seconds) to obtain a highly viscoelastic ion-conductive hydrogel (SDP hydrogel).
[0039] Comparative Example 1 Preparation of two-component hydrogel (SBMA-PEGDA) 1) Add SBMA (70%), PEGDA (5% of the mass of SBMA), and α-ketoglutarate (2% of the mass of SBMA) sequentially to deionized water. Stir with a magnetic stirrer for 4 hours at room temperature to obtain a hydrogel precursor solution with a solid content of 70%.
[0040] 2) The hydrogel precursor solution was transferred into a polytetrafluoroethylene mold and crosslinked and polymerized under ultraviolet light exposure conditions (365nm, 25W, 60s) to obtain SP conductive hydrogel.
[0041] The SP hydrogel prepared in this comparative example has an elongation at break of 320%, a Young's modulus of 0.75 MPa, a tensile strength of 2.8 MPa, and an adhesion strength of 87 kPa.
[0042] Comparative Example 2 Preparation of two-component hydrogel (DADMAC-PEGDA) 1) Add DADMAC (70%), PEGDA (5% of the mass of DADMAC), and α-ketoglutarate (2% of the mass of DADMAC) sequentially to deionized water. Stir with a magnetic stirrer for 4 hours at room temperature to obtain a hydrogel precursor solution with a solid content of 70%.
[0043] 2) The hydrogel precursor solution was transferred into a polytetrafluoroethylene mold and crosslinked and polymerized under ultraviolet light exposure conditions (365nm, 25W, 1min) to obtain DP hydrogel.
[0044] The DP hydrogel prepared in this comparative example is a transparent jelly-like substance with poor tensile strength and no adhesiveness. The mechanical properties of this hydrogel have obvious defects.
[0045] Comparative examples 3 to 5 Comparative Examples 3 to 5 also prepared three-component hydrogels (SBMA-DADMAC-PEGDA), but the difference from Examples 1 to 2 was the different formulation, as shown in Table 1 below. Table 1. Hydrogel formulations of Examples 1-2 and Comparative Examples 1 to 5
[0046] Two-component comparative hydrogels (Comparative Examples 1-2) and three-component inventive hydrogels with different ratios (Examples 1-2 and Comparative Examples 3-5) were tested, and their key properties were evaluated. The test results are shown in Table 2. Table 2
[0047] As can be seen from Examples 1-2 and Comparative Examples 1-2, the two-component hydrogels (Comparative Examples 1 and 2) have weaker tensile strength, modulus and adhesion properties compared with the three-component hydrogels of Examples 1-2.
[0048] For the three-component hydrogel, different component ratios in Examples 1-2 and Comparative Examples 3-5 show that as the SBMA content increases from 10% (Comparative Example 3) to 90% (Example 2), the tensile strength (from 180% to 600%) and adhesiveness (from 32.75 kPa to 238.71 kPa) of the hydrogel exhibit a significant and continuous increasing trend. Simultaneously, its Young's modulus gradually increases from an extremely low <0.05 MPa to 0.15 MPa, indicating that the material maintains high flexibility while enhancing its mechanical integrity.
[0049] As can be seen from the above, SBMA, as a viscoelastic matrix provider, ensures the material's basic strength, flexibility, and tissue adhesion potential through its zwitterionic structure; DADMAC, as a contributor to ionic conductivity and intermolecular electrostatic interaction forces, yields a hydrogel with excellent comprehensive performance through a specific ratio of SBMA, DADMAC, and PEGDA combined with photopolymerization.
[0050] Example 3 The hydrogels prepared in Examples 1-2 and Comparative Examples 3-5 were used as flexible bioelectrodes, with external leads connected to an electromyography (EMG) detection device for EMG signal monitoring. Test results showed that the skin-electrode interface impedance of this flexible bioelectrode (Example 1) was one order of magnitude lower than that of commercial Ag / AgCl electrodes, effectively suppressing motion artifacts and achieving high signal-to-noise ratio (43.47 dB) EMG signal monitoring.
[0051] The skin-electrode interface impedance comparison diagrams of the hydrogels prepared in Examples 1-2 and Comparative Examples 3-5 of this invention as electrodes and commercial Ag / AgCl electrodes are shown below. Figure 5 As shown, from Figure 5 As can be seen from the results, the skin-electrode interface impedance of the hydrogels prepared in Examples 1-2 and Comparative Examples 3-5 is lower than that of commercial Ag / AgCl electrodes, and the interface impedance of the hydrogels decreases with the increase of DADMAC content.
[0052] The comparison image of the electromyographic signals collected by the hydrogel electrode prepared in Example 1 of this invention during the dynamic flexion of the human arm with those of commercial electrodes is shown below. Figure 6 As shown, from Figure 6 As can be seen from this embodiment, the electromyography signal signal with a signal-to-noise ratio of the hydrogel electrode prepared in this embodiment is higher than that of the electromyography signal with Ag / AgCl electrode, demonstrating its excellent bioelectric signal acquisition capability.
[0053] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A UV-curable, highly viscoelastic, ion-conductive hydrogel, characterized in that: It is produced by crosslinking polymerization of raw materials containing the following components under ultraviolet light initiation: zwitterionic monomer, high-density cationic monomer, crosslinking agent and photoinitiator; wherein the zwitterionic monomer is methacryloylethyl sulfobetaine, the high-density cationic monomer is methacryloyloxyethyl trimethylammonium chloride, the crosslinking agent is polyethylene glycol diacrylate, and the photoinitiator is α-ketoglutaric acid.
2. The UV-curable highly viscoelastic ion-conducting hydrogel according to claim 1, characterized in that: The contents of each component are as follows: 70-90% methacryloylethyl sulfobetaine, 10-30% methacryloyloxyethyl trimethylammonium chloride, the sum of methacryloylethyl sulfobetaine and methacryloyloxyethyl trimethylammonium chloride is 100%, the amount of polyethylene glycol diacrylate added is 3-7% of the sum of the two, and the amount of α-ketoglutaric acid added is 2-5% of the sum of the two.
3. The UV-curable highly viscoelastic ion-conducting hydrogel according to claim 1 or 2, characterized in that: The ultraviolet-cured highly viscoelastic ion-conductive hydrogel exhibits a tensile strain greater than 600% at break, an adhesion strength to skin tissue greater than 140 kPa, an ionic conductivity of up to 2.24 S / m, and a contact impedance 1-3 orders of magnitude lower than that of commercial Ag / AgCl electrodes.
4. A method for preparing a UV-curable highly viscoelastic ion-conductive hydrogel according to any one of claims 1 to 3, characterized in that, The preparation steps include the following: S1. Preparation of precursor solution: Methacrylethyl sulfobetaine, methacryloyloxyethyl trimethylammonium chloride, polyethylene glycol diacrylate and α-ketoglutaric acid are dissolved in deionized water and stirred evenly at room temperature to obtain hydrogel precursor solution. S2. UV curing: The hydrogel precursor solution obtained in step S1 is placed in a molding mold or directly dripped onto the substrate surface, and cross-linking polymerization reaction is carried out under UV irradiation to obtain a highly viscoelastic ion-conductive hydrogel.
5. The method for preparing the ultraviolet-curable highly viscoelastic ion-conductive hydrogel according to claim 4, characterized in that: The total content of solid components in the hydrogel precursor solution in S1 is 60-80 wt%.
6. The method for preparing the ultraviolet-curable highly viscoelastic ion-conductive hydrogel according to claim 4, characterized in that: The molding die in S2 is a polytetrafluoroethylene (PTFE) die.
7. The method for preparing the ultraviolet-curable highly viscoelastic ion-conductive hydrogel according to claim 4, characterized in that: The substrate surface in S2 is human skin or a flexible substrate.
8. The method for preparing the ultraviolet-curable highly viscoelastic ion-conductive hydrogel according to claim 4, characterized in that: The ultraviolet light source in S2 has a wavelength of 365nm, a power of 25W, and an irradiation time of 60-90 seconds.
9. A flexible bioelectrode, characterized in that: The highly viscoelastic ion-conductive hydrogel prepared by any one of claims 4 to 8 is further provided with conductive leads.
10. A flexible bioelectrode according to claim 9, wherein the highly viscoelastic ion-conductive hydrogel on the flexible bioelectrode can be formed in situ on the skin surface and used for bioelectric signal monitoring.