Polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode as well as preparation method and application thereof
By preparing composite hydrogel electrodes of polyvinyl alcohol, silk fibroin peptide and phosphoric acid, the mechanical strength, water retention and transparency of conductive hydrogels are solved, and high-performance bioelectric signal acquisition and flexible sensing applications are achieved.
Patent Information
- Application Number
- CN202411939333.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-07-25
AI Technical Summary
Existing conductive hydrogels have problems such as insufficient mechanical strength, moisture dependence, weak water retention ability, poor self-adhesion and low transparency in flexible sensor applications, and commonly used chemical methods may cause harm to the tissue and the environment.
A composite hydrogel electrode of polyvinyl alcohol, silk fibroin peptide and phosphoric acid is prepared by freeze-thaw cycle method, combining natural polymers and synthetic polymers to ensure biocompatibility, while imparting excellent mechanical properties, conductivity, adhesion properties, water retention ability and high transparency.
It realizes a non-toxic and harmless high-performance conductive hydrogel, with excellent mechanical properties, conductivity, adhesion and water retention, and is suitable for a variety of substrates, used in bioelectric signal acquisition and flexible sensing, providing stable signal acquisition and long-term working ability.
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Figure CN120365589A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of biomaterials and relates to a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode and its preparation method and application. Background Art
[0002] With the progress of flexible electronics technology, people are committed to developing soft and stretchable flexible materials to replace traditional rigid materials. Flexible materials have unique advantages such as light weight, portability, strong flexibility, bendability, foldability, and high adaptability, and can meet different application requirements. Flexible materials can be used to manufacture flexible sensors with multifunctionality and excellent performance stability, and have a wide range of applications in the fields of wearable devices, medical diagnosis, electronic skin, human-computer interaction, and soft robotics.
[0003] Among many flexible materials, hydrogels have great potential in the field of constructing flexible sensing elements due to their unique similarity to biological tissues and their versatility and flexibility in customizing properties. In addition to excellent biocompatibility, hydrogels also have unique structural and functional advantages such as hierarchical porous structures, viscoelasticity, and tissue-like properties. The mechanical properties of hydrogels such as toughness, stretchability, and fluidity can be adjusted during synthesis. Introducing conductive components such as ionizable salts, ionic liquids, polyelectrolytes, conductive polymers, and conductive fillers into hydrogels can construct conductive hydrogels, and conductive hydrogels with high conductivity are ideal choices for developing personalized flexible sensing devices.
[0004] However, existing conductive hydrogels still have certain defects, which limit their partial applications in flexible sensing. Many conductive hydrogels themselves lack sufficient mechanical strength, and their fragile and brittle characteristics greatly limit the application scenarios of conductive hydrogels. Moreover, most conductive hydrogels are moisture-dependent, and their conductivity will decrease significantly when moisture is lost. The weak water retention ability limits the application scenarios and continuous working time of conductive hydrogels. Secondly, some conductive hydrogels do not have self-adhesion and require other aids to help them be installed on the tissue surface, which will make the application process cumbersome and vulnerable to external interference, resulting in signal distortion. In addition, in order to ensure that the conductive hydrogel has various properties such as mechanical properties, adhesion properties, and water retention properties, chemical methods and chemical reagents are often involved in the synthesis of hydrogels ([1] Zhang Y, Jing X, Zou J, et al. Mechanically Robust and Anti-Swelling Anisotropic Conductive Hydrogel with Fluorescence for Multifunctional Sensing[J]. Advanced Functional Materials, 2024, 2410698.). Some toxic chemical reagents will harm the surrounding tissues and environment, causing inflammation or irritant reactions.
[0005] To avoid toxic chemical methods, many strategies for obtaining high-performance conductive hydrogels relying solely on physical methods have been proposed. Among them, polyvinyl alcohol-based hydrogels have attracted extensive attention due to their good biocompatibility and the ability to obtain high mechanical properties through repeated freeze-thaw cycles. However, due to the interaction of polymer chains and the existence of crystalline structures in polyvinyl alcohol-based hydrogels, light scattering or refraction is likely to occur, often resulting in low transparency of polyvinyl alcohol-based hydrogels, which may limit their application in optical sensors ([2] Zhou Yiyang, Zhang Lei, Xiangyu Lin, et al. Dual-network polyvinyl alcohol / polyacrylamide / xanthan gum ionic conductive hydrogels for flexible electronic devices [J]. International Journal of Biological Macromolecules, 2023, 233, 123573.; [3] Li Xunzhang, Wang Ziquan, Bi Weiyu, et al. Tough and conductive PVA-based double-network ionic hydrogels for flexible sensors [J]. Polymer, 2024, 309, 127465.). On the premise of ensuring the high biocompatibility of the hydrogel, it is still challenging to endow the hydrogel with multiple specific functions and prepare a conductive hydrogel with excellent mechanical properties, adhesion properties, water retention properties, and high transparency. Summary of the Invention
[0006] The object of the present invention is to provide a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode, a preparation method thereof, and an application thereof. The present invention combines natural polymers and synthetic polymers and, relying entirely on physical methods, endows the composite hydrogel electrode with excellent mechanical properties, electrical conductivity, adhesion properties, long-term water retention ability, and high transparency on the premise of ensuring the high biocompatibility of the hydrogel.
[0007] The technical solution for achieving the object of the present invention is as follows:
[0008] A method for preparing a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode, comprising the following steps:
[0009] (1) Heat polyvinyl alcohol and dissolve it in water to obtain a colorless and transparent polyvinyl alcohol solution; dissolve silk fibroin peptide in water to obtain a silk fibroin peptide solution; successively mix the polyvinyl alcohol solution, silk fibroin peptide solution, phosphoric acid solution and glycerol in proportion to prepare a hydrogel pre-gel solution.
[0010] (2) Pour the hydrogel pre-gel solution into a mold, and obtain a composite polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode after freeze-thaw cycling.
[0011] Further, in step (1), the heating temperature is 50-100 °C, and the heating time is 1-5 hours until all the polyvinyl alcohol solids are dissolved.
[0012] Further, in step (1), in the mixed solution, the mass concentration of polyvinyl alcohol is 3-15 wt%, preferably 9 wt%.
[0013] Further, in step (1), the molecular weight of polyvinyl alcohol is 9000-205000, preferably 74800-80000.
[0014] Further, in step (1), the molecular weight of silk fibroin peptide is 1000-200000, preferably 100000.
[0015] Further, in step (1), in the mixed solution, the mass concentration of silk fibroin peptide is 3-15 wt%, preferably 5 wt%.
[0016] Further, in step (1), the mass concentration of phosphoric acid in the phosphoric acid solution is 5-85 wt%; the volume of the phosphoric acid solution is 2-30% of the volume of the mixed solution. In a specific embodiment of the present invention, 20% is taken as an example.
[0017] Further, in step (1), the volume of glycerol is 2-30% of the volume of the mixed solution. In a specific embodiment of the present invention, 20% is taken as an example.
[0018] Further, in step (2), the freeze-thaw cycling method is: first freeze at a low temperature of -10 °C to -80 °C, and then thaw at 4-25 °C, and cycle repeatedly more than 2 times.
[0019] Further, in step (2), the mold material includes but is not limited to glass material, acrylic material, polytetrafluoroethylene material, etc., and the mold morphology includes but is not limited to cylindrical, square, triangular pyramid type, etc., which is suitable for preparing hydrogel electrodes with different morphologies.
[0020] The present invention provides a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode prepared by the above preparation method.
[0021] Furthermore, the present invention provides an application of the above-mentioned polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode in bioelectrical signal acquisition or flexible sensing.
[0022] Specifically, the bioelectrical signals include, but are not limited to, electrocardiogram signals, electromyogram signals, electroencephalogram signals, etc.
[0023] Compared with the prior art, the present invention has the following advantages:
[0024] (1) The present invention adopts a strategy of combining polyvinyl alcohol and silk fibroin peptide with phosphoric acid and glycerol to prepare a composite hydrogel electrode with excellent mechanical properties, high conductivity, high water retention ability, strong adhesion performance, and high transparency. The introduction of the hydrophilic polymer polyvinyl alcohol improves the biocompatibility and mechanical properties of the hydrogel electrode; the introduction of silk fibroin peptide improves the adhesion and biocompatibility of the hydrogel electrode; the addition of the phosphoric acid electrolyte solution improves the conductivity of the hydrogel electrode. The addition of phosphoric acid also makes the molecular chain arrangement in the hydrogel more uniform, reduces the crystalline region, and improves the transparency of the hydrogel; the addition of the water retention agent glycerol enhances the hydration of the hydrogel electrode and improves the water retention performance of the hydrogel electrode.
[0025] (2) The present invention does not involve any toxic chemical reagents, and there is no need to add any chemical initiators and cross-linking agents. The prepared polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode has high cell and tissue compatibility, mild preparation conditions, simple operation, low cost, and is easy to industrialize.
[0026] (3) The polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode of the present invention has excellent reversible adhesion ability on common substrates such as wood, acrylic, iron, glass, polyurethane, and polytetrafluoroethylene. There is no need for other viscous substances to assist in use during application, which greatly broadens the application field of the hydrogel electrode.
[0027] (4) When the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode of the present invention is applied to bioelectrical signal acquisition, it has the advantages of convenient operation, stable signal, and long normal working time. Compared with the existing dry electrodes, the hydrogel electrode provided by the present invention can better fit the tissue surface, has higher wearing comfort and smaller contact impedance, and the collected signal quality is higher; compared with the existing wet electrodes, the hydrogel electrode provided by the present invention does not require complex installation operations, does not require smearing conductive glue or salt solution, will not cause skin discomfort during use, and there will be no residual conductive glue after use.
[0028] (5) The polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode provided by the present invention has excellent biocompatibility, mechanical properties, electrical conductivity, adhesion properties, water retention properties, and high transparency. When subjected to external forces, its conductivity changes stably and always maintains strong electrical conductivity. After working normally for a long time, it still maintains strong adhesion properties and high electrical conductivity, and has application prospects in the fields of wearable devices, electronic skin, nerve signal sensing, soft robots, etc. For example, the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode provided by the present invention can be applied to the acquisition of electrocardiogram signals, which can sensitively capture the skin surface potential changes caused by cardiac electrical activities to acquire electrocardiogram signals, helping to achieve clinical diagnosis and the development of some electrocardiogram portable devices; at the same time, the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode provided by the present invention can be applied to the acquisition of electromyogram signals. Through good contact with the skin, the hydrogel can reliably capture the electrical signals generated during muscle fiber activities and conduct them to the signal processor, helping to achieve medical diagnosis or human-computer interaction; in addition, the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode provided by the present invention can also be applied to the acquisition of electroencephalogram signals, which can capture the potential fluctuations generated during synchronous activities of brain neurons to detect abnormal electroencephalogram fluctuations and apply them to brain-computer interfaces. Description of the Drawings
[0029] Figure 1 Schematic diagram of the preparation process of the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode;
[0030] Figure 2 Result diagram of the adhesion of the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode to various substrates;
[0031] Figure 3 Real-time electrocardiogram result diagram collected when the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode is used for electrocardiogram signal detection;
[0032] Figure 4 Result diagram of electromyogram signals corresponding to different gestures collected when the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode is used for electromyogram signal detection;
[0033] Figure 5 Result diagram of the stress-strain curves of hydrogels prepared using silk fibroin peptide, porcine gelatin, and fish gelatin respectively;
[0034] Figure 6 Result diagram of the transparency comparison of composite hydrogels prepared by adding different electrolyte solutions. Detailed Embodiments
[0035] The present invention will be further described in detail below through specific embodiments and accompanying drawings. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. The implementation conditions not specified in the embodiments are usually the conditions in conventional experiments.
[0036] Example 1
[0037] (1) Polyvinyl alcohol with a molecular weight of 74,800 - 80,000 was added to water and heated in a water bath at 90 °C for 3 hours to obtain a colorless and transparent polyvinyl alcohol solution. Silk fibroin peptide with a molecular weight of 100,000 was dissolved in water to obtain a silk fibroin peptide solution. The polyvinyl alcohol solution, silk fibroin peptide solution, phosphoric acid solution, and glycerol were successively mixed in proportion to obtain five groups of different mixed solutions. The mass concentration of polyvinyl alcohol in each group was 7 wt%, 8 wt%, 9 wt%, 10 wt%, and 11 wt% respectively. The mass concentration of silk fibroin peptide in each group was 5 wt%. The volume of the phosphoric acid solution in each group accounted for 20% of the mixed solution, and the mass concentration of the phosphoric acid solution was 85 wt%. The volume of glycerol in each group accounted for 20% of the mixed solution, and five groups of hydrogel pre-gel solutions were prepared.
[0038] (2) The obtained hydrogel pre-gel solution was poured into a mold, frozen at -20 °C for 8 - 12 hours, then thawed at room temperature for 3 - 5 hours, and demolded after repeating the cycle 3 times to obtain a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode.
[0039] (3) Keeping the other conditions in steps (1) and (2) unchanged, silk fibroin peptides with molecular weights of 50,000 and 1,000 were used instead to obtain two other groups of polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrodes.
[0040] Polyvinyl alcohol can provide excellent biocompatibility, viscoelasticity, and mechanical properties for hydrogel electrodes. However, too high a polyvinyl alcohol content may lead to a decrease in the flexibility of the hydrogel electrodes, which is not conducive to matching with softer tissues. Specifically, the hydrogel electrodes in the groups with polyvinyl alcohol concentrations of 7wt% and 8wt% have relatively weak overall strength and toughness and are more likely to deform under stress, while the hydrogel electrodes in the groups with polyvinyl alcohol concentrations of 10wt% and 11wt% have stronger toughness but weaker tensile properties. Therefore, when preparing the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode, the preferred polyvinyl alcohol concentration is 9wt%. Silk fibroin peptide can improve the biocompatibility, mechanical properties, and adhesion ability of the hydrogel electrode. Silk fibroin peptides with a large molecular weight usually have longer amino acid chains and stronger intermolecular hydrogen bond interactions, which can enhance the mechanical strength, elasticity, and toughness of the hydrogel electrode; silk fibroin amino acids with a small molecular weight have shorter chains and better solution dispersibility, which can improve the flexibility of the hydrogel electrode. After comprehensively comparing the hydrogel electrodes prepared from three different molecular weight silk fibroin peptides, the preferred molecular weight of the silk fibroin peptide is 100,000.
[0041] The polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode prepared based on the preferred strategy has excellent adhesion ability and excellent reversible adhesion ability on common substrates such as wood, acrylic, iron, glass, polyurethane, and polytetrafluoroethylene, as Figure 2 shown.
[0042] Example 2
[0043] 1. Preparation of polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode
[0044] (1) Add polyvinyl alcohol with a molecular weight of 74,800 - 80,000 to water and heat it in a water bath at 90°C for 3 hours to obtain a colorless and transparent polyvinyl alcohol solution. Dissolve silk fibroin peptide with a molecular weight of 100,000 in water to obtain a silk fibroin peptide solution. Then mix the polyvinyl alcohol solution, silk fibroin peptide solution, phosphoric acid solution, and glycerol in proportion, where the concentration of polyvinyl alcohol is 9wt%, the concentration of silk fibroin peptide is 5wt%, the volume of the phosphoric acid solution is 20% of the volume of the mixed solution, the mass concentration of the phosphoric acid solution is 85wt%, and the volume of glycerol is 20% of the volume of the mixed solution to prepare a hydrogel pre-gel solution.
[0045] (2) Pour the obtained hydrogel pre-gel solution into an oblate mold with a diameter of 5 cm and a depth of 3 mm, freeze it at -20 °C for 8 - 12 hours, then thaw it at room temperature for 3 - 5 hours. After repeating the cycle 3 times, demold it to finally obtain a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode for the detection experiment of electrocardiogram signals. Pour the obtained hydrogel pre-gel solution into an oblate mold with a diameter of 2 cm and a depth of 2 mm, freeze it at -20 °C for 8 - 12 hours, then thaw it at room temperature for 3 - 5 hours. After repeating the cycle 3 times, demold it to obtain a polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode for the detection experiment of electromyogram signals.
[0046] 2. Detection of electrocardiogram signals by polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode:
[0047] Take three demolded polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrodes, each connected to an electrode buckle. Attach the three composite hydrogel electrodes to the first intercostal space along the midclavicular line on the right side of the upper right sternum, the first intercostal space along the midclavicular line on the left side of the upper left sternum, and the xiphoid process level along the midclavicular line on the lower left side respectively. The electrode buckles are connected to a rapid electrocardiogram detector through lead wires to collect electrocardiogram signals.
[0048] The hydrogel electrode prepared by the present invention can collect high-quality real-time electrocardiogram signals as Figure 3 shown. Clear PQRST waveforms can be observed from the collected real-time electrocardiogram detection results, and there is no obvious difference in the signal quality compared with that collected by commercial electrodes. Moreover, the quality of the electrocardiogram signals obtained after using the hydrogel electrode for a long time does not decline. The above results indicate that the composite hydrogel electrode prepared by the present invention can provide a comfortable and effective electrocardiogram detection solution.
[0049] 3. Detection of electromyogram signals by polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode:
[0050] Take five demolded polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrodes and connect them to five electrode buckles respectively. Take two of the composite hydrogel electrodes and place them on the elbow as the common reference electrode and the ground electrode, and the other three composite hydrogel electrodes as the acquisition electrodes, and place them on the upper side of the forearm to simultaneously collect the electromyogram activities of three target muscles. Connect the five electrodes to the corresponding channels of the OpenBCI Cyton board through electrode wires, and the OpenBCI Cyton board can collect the signals generated by the contraction of muscle fibers. When making different gestures, the composite hydrogel electrodes placed on the upper side of the forearm can collect strong and repeatable electromyogram signals. Figure 4The surface electromyogram signals collected when making five different gestures are shown, and the electromyogram signals of different gestures can be subjected to feature extraction for subsequent applications. The above results indicate that the composite hydrogel electrode prepared by the present invention can detect the electrical signals generated by muscles, record and analyze muscle activities, and provide information about muscle function, nerve control, and movement patterns.
[0051] Comparative Example 1
[0052] This comparative example is basically the same as Example 2, except that the silk fibroin peptide solution is replaced with porcine gelatin and fish gelatin solutions respectively. The obtained hydrogels are respectively subjected to mechanical property tests.
[0053] The prepared polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel, polyvinyl alcohol / porcine gelatin / phosphoric acid composite hydrogel, and polyvinyl alcohol / fish gelatin / phosphoric acid composite hydrogel are respectively cut into dumbbell shapes with a width of 4 mm, a length of 16 mm, and a thickness of 1 mm in the middle narrow part, and they are respectively placed on a universal tensile testing machine for mechanical property testing to obtain the stress-strain curves of each hydrogel sample.
[0054] The results are as Figure 5 shown. Compared with the polyvinyl alcohol / porcine gelatin / phosphoric acid composite hydrogel and the polyvinyl alcohol / fish gelatin / phosphoric acid composite hydrogel, the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel has a greater elongation at break and can maintain higher ductility under tensile action. At the same time, the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel can withstand greater external pressure without rupture and deformation compared with the other two groups. On the other hand, the biocompatibility of the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel is better than that of the hydrogel electrodes added with porcine gelatin and fish gelatin.
[0055] Comparative Example 2
[0056] This comparative example is basically the same as Example 2, except that the phosphoric acid solution is replaced with sodium dihydrogen phosphate solution, disodium hydrogen phosphate solution, sodium chloride solution, and calcium chloride solution respectively. The transparency of the obtained hydrogel electrodes is compared.
[0057] The hydrogel electrodes prepared with different electrolyte solutions are respectively placed on the pattern printed with "NJUST", and their transparency is compared. It can be seen that the composite hydrogel electrode added with phosphoric acid has the highest transparency, as Figure 6 shown. The reason may be that phosphoric acid has strong hydrophilicity. The addition of phosphoric acid can increase the degree of hydration of the polyvinyl alcohol hydrogel, make the arrangement of polyvinyl alcohol molecular chains more uniform, and at the same time reduce the crystalline regions in the hydrogel, thereby reducing light scattering and increasing the transparency of the hydrogel.
Claims
1. Preparation method of polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode, characterized in that, It includes the following steps: (1) Heat polyvinyl alcohol and dissolve it in water to obtain a colorless and transparent polyvinyl alcohol solution; Dissolve silk fibroin peptide in water to obtain a silk fibroin peptide solution; successively mix the polyvinyl alcohol solution, silk fibroin peptide solution, phosphoric acid solution and glycerol in proportion to prepare a hydrogel pre-gel solution; (2) Pour the hydrogel pre-gel solution into a mold, and obtain a composite polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode after freeze-thaw cycles.
2. The preparation method according to claim 1, wherein, In step (1), the heating temperature is 50~100 °C, and the heating time is 1~5 hours.
3. The preparation method according to claim 1, characterized in that, In step (1), the molecular weight of polyvinyl alcohol is 9000~205000, and the molecular weight of silk fibroin peptide is 1000~200000.
4. The preparation method according to claim 1, wherein In step (1), in the mixed solution, the mass concentration of polyvinyl alcohol is 3~15 wt%, and the mass concentration of silk fibroin peptide is 3~15 wt%; the mass concentration of phosphoric acid in the phosphoric acid solution is 5~85 wt%; the volume of the phosphoric acid solution is 2~30% of the volume of the mixed solution; the volume of glycerol is 2~30% of the volume of the mixed solution.
5. The preparation method according to claim 1, wherein In step (1), the molecular weight of polyvinyl alcohol is 74800~80000, and the molecular weight of silk fibroin peptide is 100000; in the mixed solution, the mass concentration of polyvinyl alcohol is 9 wt%, and the mass concentration of silk fibroin peptide is 5 wt%; the volume of the phosphoric acid solution is 20% of the volume of the mixed solution, and the mass concentration of the phosphoric acid solution is 85 wt%; the volume of glycerol is 20% of the volume of the mixed solution.
6. The preparation method according to claim 1, characterized in that, In step (2), the freeze-thaw cycle method is: first freeze at a low temperature of -10 °C~-80 °C, and then thaw at 4~25 °C, and repeat the cycle more than 2 times.
7. The preparation method according to claim 1, characterized in that, In step (2), the mold material is glass material, acrylic material or polytetrafluoroethylene material, and the morphology of the mold is cylindrical, square or triangular pyramid type.
8. A polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode prepared by the preparation method according to any one of claims 1~7.
9. Application of the polyvinyl alcohol / silk fibroin peptide / phosphoric acid composite hydrogel electrode according to claim 8 in bioelectric signal acquisition or flexible sensing.
10. The application according to claim 9, characterized in that, The bioelectric signal is an electrocardiogram signal, an electromyogram signal or an electroencephalogram signal.