Bionic movement and sensing difunctional fish tendon based on hydrogel material

Abstract

The invention provides a bionic movement and sensing bifunctional fish tendon based on hydrogel, which is prepared by the following steps: adding a PEDOT: PSS solution into a PVA solution, and uniformly stirring to obtain a PVA-PEDOT: PSS mixed solution; then adding the sodium citrate solution into the PVA-PEDOT: PSS mixed solution, fully stirring and separating out flocculent precipitate; and putting the flocculent precipitate into a mold, reacting at room temperature, freezing at low temperature, taking out, unfreezing at room temperature, and repeatedly freezing and thawing for multiple times to obtain the hydrogel-based bionic movement and sensing bifunctional fish tendon. According to the fish tendon, the sensing function is integrated into hydrogel, the motion and sensing functions are achieved, the underwater bionic robotic fish can sense the state of the robot fish in real time during motion, intelligent adjustment is conducted according to environment changes, the flexibility and autonomy of the robotic fish are remarkably improved, the adaptive capacity of the robotic fish in the complex underwater environment is enhanced, and the underwater bionic robotic fish is suitable for being used in the underwater environment. The method is suitable for manufacturing the tendon of the underwater robotic fish.

Description

Technical Field

[0001] The invention relates to a bionic motion and sensing dual-function fish tendon based on a hydrogel material, belonging to the technical field of bionic materials. Background Art

[0002] Bionics is a technology developed under the inspiration of biology, aiming to imitate the structure, function and behavior of biological systems. Through bionics, humans can draw inspiration from biological systems to create new materials, devices and systems to solve real-world problems. Bionics has broad application prospects in new materials, sensors, biomedical engineering, robotics and environmental monitoring.

[0003] After about 500 million years of evolution, fish have continuously evolved biological characteristics that are increasingly adapted to aquatic life. For example, tuna has body curves and proportions suitable for long-term high-speed swimming underwater, and catfish's pectoral fins have proprioception functions. These evolutions have endowed fish with excellent underwater movement and perception capabilities, becoming an important source of inspiration for bionics research. Based on the biological characteristics of fish, an underwater bionic robot fish has been developed. The robot fish is mainly used in underwater detection operations, environmental monitoring, military reconnaissance, etc., showing multiple advantages such as high propulsion efficiency, strong maneuverability, strong concealment, and outstanding environmental friendliness.

[0004] However, existing underwater bionic robot fish still have limitations in technical implementation. For example, fish tendons are dense fibrous connective tissues that connect muscles to bones. Muscles are attached to bones through tendons to achieve normal movement functions. Traditional underwater bionic robot fish often use rigid materials as tendons. Although they can provide certain support and movement capabilities, they cannot achieve effective sensing functions. This limitation causes the robot fish to lack real-time perception of its own state during movement, and it is difficult to make timely adjustments according to environmental changes. In addition, the existing technology still lacks bionic fish tendons that have both movement and sensing functions, which reduces the overall coordination and flexibility of the system and makes it impossible to work efficiently in complex environments. Summary of the invention

[0005] The present invention provides a bionic motion and sensing dual-function fish tendon based on hydrogel material, which can effectively solve the above problems.

[0006] The present invention is achieved in that:

[0007] A method for preparing a bionic motion and sensing dual-function fish tendon based on hydrogel comprises the following steps:

[0008] S1, adding PEDOT:PSS solution to the PVA solution and stirring evenly to obtain a PVA-PEDOT:PSS mixed solution;

[0009] S2, then adding the sodium citrate solution into the PVA-PEDOT:PSS mixed solution, stirring thoroughly and precipitating a flocculent precipitate;

[0010] S3, then putting the flocculent precipitate into a mold, leaving it to react at room temperature, freezing it at low temperature, then taking it out and thawing it at room temperature, repeating the freeze-thaw cycle for many times, and obtaining the hydrogel-based bionic motion and sensing dual-function fish tendon.

[0011] In some embodiments, in step S1, the mass fraction of the PVA is 5-20 wt%.

[0012] In some embodiments, in step S1, the mass fraction of the PEDOT:PSS solution is 1.0-1.3 wt %.

[0013] In some embodiments, in step S2, the concentration of the sodium citrate solution is 1-3 mol / L.

[0014] In some embodiments, in step S1, the volume ratio of the PEDOT:PSS solution to the PVA solution is 1:3-1:10.

[0015] In some embodiments, in step S2, the volume ratio of the sodium citrate solution to the PVA solution is 1:10-5:10.

[0016] In some embodiments, in step S3, the freezing temperature is -30°C to -20°C, the time is 8-12 hours, and the thawing time is 3-4 hours.

[0017] In some embodiments, in step S3, the number of freeze-thaw cycles is 2-5 times.

[0018] A bionic fish tendon with dual functions of motion and sensing based on hydrogel prepared by the above method.

[0019] An application of the above-mentioned hydrogel-based bionic motion and sensing dual-function fish tendon in the preparation of a robotic fish.

[0020] The beneficial effects of the present invention are:

[0021] The present invention ingeniously achieves an optimal balance between the electrical and mechanical properties of the hydrogel by carefully adding a high-performance conductive material, poly(3,4-ethylenedioxythiophene): polyphenylsulfonic acid (PEDOT:PSS), to a polyvinyl alcohol (PVA) solution, and combining it with the synergistic effect of a sodium citrate solution. This innovative design enables the hydrogel to maintain its excellent stability and conductivity under complex mechanical conditions such as stretching and deformation. During the movement of the robot fish, this special hydrogel can sense and accurately capture its own posture and state changes in real time, and then generate corresponding and diverse electrical signals. These electrical signals are received by the control system inside the robot fish as important feedback information, enabling it to autonomously adjust and optimize its own movement mode according to these real-time signals to adapt to different underwater environments. This unique self-sensing function is inspired by the muscle perception system in the body. By imitating the perception mechanism of the organism, it gives the robot fish higher flexibility and autonomy in complex and changeable underwater environments, and significantly improves its movement efficiency and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a flow chart for the preparation of the hydrogel-based bionic motion and sensing dual-functional fish tendon in Example 1.

[0024] Figure 2 The stress-strain relationship curves of the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 and the hydrogel prepared in Comparative Examples 1-2.

[0025] Figure 3 The conductivity characterization diagram of the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 and the hydrogel prepared in Comparative Examples 1-2.

[0026] Figure 4 This is a relative resistance change curve of the bionic motion and sensing dual-function fish tendon of Example 1 of the present invention prepared in Example 1 after being used as a proprioceptor on a robotic fish. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The embodiment of the present invention provides a method for preparing a bionic motion and sensing dual-function fish tendon based on hydrogel, and the method comprises the following detailed steps:

[0029] S1, first, add PEDOT:PSS solution to PVA solution, and stir it thoroughly to make it uniformly mixed, so as to obtain PVA-PEDOT:PSS mixed solution. Specifically, the preparation process of PVA solution is to add PVA (polyvinyl alcohol) monomer into deionized water, and then stir it under the condition of water bath heating until PVA is completely dissolved in pure water to form a uniform PVA solution.

[0030] S2, then, add the pre-prepared sodium citrate solution to the above-mentioned PVA-PEDOT:PSS mixed solution, stir it thoroughly to make it evenly mixed, and in the process, flocculated precipitates are precipitated. The preparation method of the sodium citrate solution is to add sodium citrate powder to deionized water, stir it to completely dissolve it, and form a uniform sodium citrate solution.

[0031] S3, then, the flocculent precipitate precipitated after stirring is placed in a pre-prepared mold, placed in a room temperature for reaction, and then placed in a low temperature environment for freezing treatment. After the freezing is completed, it is taken out and placed in room temperature for thawing. The freeze-thaw cycle treatment is repeated multiple times to finally obtain the bionic motion and sensing dual-function fish tendon based on the hydrogel.

[0032] The embodiment of the present invention cleverly balances the electrical and mechanical properties of the hydrogel by adding PEDOT:PSS, a conductive material, and sodium citrate solution to the PVA solution, so that the hydrogel can still maintain stable performance under stretching and deformation. This special hydrogel material can sense its own posture and state in real time during movement and generate different electrical signals. These electrical signals can be received by the robot fish, and its movement mode can be adjusted autonomously according to these signals, thereby achieving more flexible and autonomous movement control. The design inspiration of this self-sensing function comes from the muscle perception system in the body. By imitating this system, the robot fish can show higher flexibility and autonomy in complex and changeable underwater environments, greatly improving its performance and reliability in practical applications.

[0033] In some specific embodiments, during the operation of step S1, the mass fraction of the PVA (polyvinyl alcohol) solution used is strictly controlled between 5wt% and 20wt% to ensure its stability and effectiveness in subsequent reactions.

[0034] In some specific embodiments, during the operation of step S1, the mass fraction of the PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(benzenesulfonic acid)) solution used is also precisely set in the range of 1.0wt% to 1.3wt% to optimize its electrical conductivity and uniformity of the solution.

[0035] In some detailed embodiments, during the operation of step S2, the concentration of the sodium citrate solution used is precisely adjusted between 1 mol / L and 3 mol / L to ensure that it can effectively play a buffering and stabilizing role in the reaction.

[0036] In some specific embodiments, during the operation of step S1, the volume ratio of the PEDOT:PSS solution to the PVA solution is carefully controlled within a range of 1:3 to 1:10 to achieve optimal mixing effect and performance of the two solutions.

[0037] In some specific embodiments, during the operation of step S2, the volume ratio of the sodium citrate solution to the PVA solution is also carefully set within the range of 1:10-5:10 to ensure that the two solutions can achieve the expected reaction effect and stability after mixing, thereby improving the overall process reliability and product quality.

[0038] In some specific embodiments, during the operation of step S3, the set freezing temperature range is strictly controlled between -30°C and -20°C to ensure the stability and consistency of the experimental conditions. At the same time, the freezing time is also clearly specified as 8 to 12 hours. The selection of this time period is intended to ensure that the sample can be fully frozen to achieve the expected experimental effect. In addition, in the thawing process, the set thawing time is precisely controlled between 3 and 4 hours. The arrangement of this time period is intended to ensure that the sample can be thawed evenly and thoroughly, thereby laying the foundation for the smooth progress of subsequent experimental steps.

[0039] In some specific embodiments, during the operation of step S3, the number of freeze-thaw cycles performed is clearly limited to between 2 and 5. The setting of this number of cycles is based on the results of multiple experimental verifications, and aims to achieve the processing effect of the sample through a moderate number of freeze-thaw cycles, while avoiding unnecessary damage or influence on the sample caused by too many cycles, thereby ensuring the accuracy and reliability of the experimental results.

[0040] The embodiment of the present invention provides a bionic movement and sensing dual-function fish tendon based on a hydrogel prepared by the above method. The fish tendon cleverly integrates the sensing function into the hydrogel material, so that the underwater bionic robot fish can sense its own state in real time during the movement and make intelligent adjustments according to the changes in the surrounding environment. This innovative design has great practical significance and application value. This dual-function tendon not only significantly improves the flexibility and autonomy of the robot fish, allowing it to swim more freely in the underwater environment, but also greatly enhances the adaptability of the robot fish in the complex and changeable underwater environment, ensuring that it can still operate efficiently under various complex conditions.

[0041] The embodiment of the present invention further provides a specific application of a bionic motion and sensing dual-function fish tendon based on a hydrogel material in the preparation of a robotic fish. By applying this dual-function tendon to the manufacture of a robotic fish, not only the motion performance and perception ability of the robotic fish are improved, but also a solid technical guarantee is provided for its stable operation in a complex underwater environment. This innovative application not only broadens the application field of hydrogel materials, but also opens up a new path for the development of underwater bionic robots.

[0042] Example 1 Preparation of hydrogel-based bionic motion and sensing dual-function fish tendon

[0043] (1) Weigh 6 g of PVA (polyvinyl alcohol, 1799 type) and add it to 54 ml of deionized water. Heat and stir in a water bath at 95° C. for 3-4 h until the PVA is completely dissolved in the pure water to prepare a PVA solution with a mass fraction of 10 wt %;

[0044] (2) The PVA solution obtained in step (1) was cooled to room temperature, and then 12 ml of commercially available PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid) solution was added to the PVA solution, and the mixture was stirred for 0.5 h to form a uniform PVA-PEDOT:PSS mixed solution;

[0045] Adding PEDOT:PSS solution can improve the conductivity of the solution. The mass fraction of PEDOT:PSS solution is 1.0wt%, the model is PH1000, purchased from Heraeus, and the volume ratio of PEDOT:PSS solution to PVA solution is 1:5;

[0046] (3) Weigh 9.3 g of sodium citrate powder and add it to deionized water, stirring for 0.5 h until completely dissolved to form 18 ml of sodium citrate solution;

[0047] The concentration of sodium citrate solution is 2 mol / L, and the volume ratio of sodium citrate solution to PVA solution is 3:10;

[0048] (4) pouring the sodium citrate solution obtained in step (3) into the PVA-PEDOT:PSS mixed solution, stirring and mixing immediately to precipitate a certain amount of flocculent precipitate, and obtaining a clear solution;

[0049] (5) The flocculent precipitate is placed in a mold, reacted at room temperature for 12 h, then frozen at -25 °C for 8 h, taken out, and thawed at room temperature for 3.5 h. The freeze-thaw process is cycled twice to obtain a bionic motion and sensing dual-function fish tendon based on a hydrogel material.

[0050] Preparation process Figure 1 shown.

[0051] Comparative Example 1 Preparation of PVA-sodium citrate hydrogel

[0052] The PVA solution of step (1) in Example 1 and the sodium citrate solution of step (3) were mixed, and a certain amount of flocculent precipitate was precipitated after stirring and mixing. The flocculent precipitate was placed in a mold, reacted at room temperature for 12 hours, then frozen at -25°C for more than 8 hours, taken out, and thawed at room temperature for 3.5 hours. The freeze-thaw process was cycled twice to obtain PVA-sodium citrate hydrogel.

[0053] Comparative Example 2 Preparation of PVA-PEDOT:PSS Hydrogel

[0054] The PVA-PEDOT:PSS mixed solution in step (2) of Example 1 was stirred and mixed to precipitate a certain amount of flocculent precipitate, and the flocculent precipitate was placed in a mold, reacted at room temperature for 12 hours, then frozen at -25°C for 8 hours, taken out, and thawed at room temperature for 3.5 hours. The freeze-thaw process was cycled twice to obtain a PVA-PEDOT:PSS hydrogel.

[0055] Test Example 1 Stress-strain relationship test

[0056] In this test experiment, the hydrogel prepared in Example 1 and Comparative Examples 1-2 of Example 1 is used as the test sample. The sample is clamped on a tensile test instrument by a clamp. Before applying the load, the initial length (L0) and cross-sectional area (A0) of the sample are recorded; then a tensile force (F) is gradually applied at a constant rate of 20 mm / min, and the corresponding sample length change (ΔL) is recorded. The tensile instrument continuously records stress (σ=F / A0) and strain (ε=ΔL / L0), and the tensile force is continuously applied until the sample breaks, and the maximum stress and the corresponding strain value are recorded; finally, a curve graph is drawn based on the recorded stress and strain data, with strain (ε) as the x-axis and stress (σ) as the y-axis, and Young's modulus (E=σ / ε) is calculated in the initial stage of the linear interval of the stress-strain relationship curve (the strain range of 5-15% is taken in this experiment).

[0057] The tensile testing instrument used in the test experiment is an E43.104 microcomputer-controlled electronic universal testing machine and is calibrated before the test to ensure that the equipment operates normally and the measurement results are accurate; the fixture is tested for adaptability before use to ensure that the sample can be fixed so that both ends of the sample are evenly stressed and no lateral sliding occurs; the test must ensure that the ambient temperature and humidity are appropriate to avoid changes in the properties of the hydrogel material; in order to improve the reliability of the test results, the test should be performed at least 3 times and the average and standard deviation should be calculated. The test results are as follows: Figure 2 shown.

[0058] Figure 2 The stress-strain relationship curves of the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 and the hydrogel prepared in Comparative Examples 1-2 are shown. It can be seen from the curve that within the elastic limit of the test sample, the stress and strain present an approximately linear relationship, that is, as the strain increases, the stress increases almost proportionally.

[0059] The Young's modulus was calculated in the initial stage of the linear interval of the stress-strain curve (with a strain range of 5-15%). The results show that the maximum strain of the bionic tendon prepared in Example 1 exceeds 300%, and the Young's modulus is 2.051MPa; the maximum strain of the PVA-sodium citrate hydrogel in Control Example 1 exceeds 250%, and the Young's modulus is 3.409MPa. However, the PVA-PEDOT:PSS composite hydrogel in Control Example 2 is difficult to be firmly clamped on the stretching device due to its significantly insufficient toughness and modulus, and its performance has not been significantly improved after multiple freeze-thaw cycles, so it was not subjected to stress-strain testing.

[0060] The research results show that the bionic tendon prepared in Example 1 has excellent performance in toughness and modulus, can withstand large loads without breaking, and meets the mechanical property requirements for use as a tendon.

[0061] Test Example 2 Conductivity Characterization Test

[0062] Conductivity is usually represented by the symbol σ. It is a physical quantity that describes the material's ability to conduct electricity, that is, the material's ability to pass current per unit volume and unit length. It is defined as: σ = L / (R*S), where L represents the original length of the measurement, R represents the material's resistance, and S represents the material's cross-sectional area. Generally, the higher the conductivity, the better the material's conductivity.

[0063] In this test experiment, the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 and the hydrogel prepared in Comparative Examples 1-2 were used as test samples, and the original length (L) and cross-sectional area (S) of the samples were measured respectively; then, a resistance measuring instrument was used to directly contact the hydrogel with electrodes using a two-point probe method to measure the resistance (R) of the sample; finally, the conductivity was calculated.

[0064] The resistance measuring instrument used in the test experiment is a VC4092C LCR desktop digital bridge meter, which is calibrated before measurement to ensure the normal operation of the equipment and accurate measurement results; a vernier caliper is used to measure the sample length and cross-sectional area; the test environment temperature and humidity must be appropriate to avoid changes in the properties of the hydrogel material; to improve the reliability of the test results, the test should be performed at least 3 times and the average and standard deviation should be calculated. The test results are as follows: Figure 3 shown.

[0065] Figure 3 The conductivity characterization diagram of the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 and the hydrogel prepared in Comparative Examples 1-2 is shown. According to the measurement, the conductivity of the PVA-PEDOT:PSS-sodium citrate hydrogel prepared in Example 1 is 0.883S / m, the conductivity of the PVA-sodium citrate hydrogel prepared in Comparative Example 1 is 0.017S / m, and the conductivity of the PVA-PEDOT:PSS hydrogel prepared in Comparative Example 2 is 0.101S / m.

[0066] The results show that the conductivity of the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 is significantly higher than that of the PVA-sodium citrate hydrogel prepared in Comparative Example 1 and the PVA-PEDOT:PSS hydrogel prepared in Comparative Example 2, which are 51.9 times and 8.7 times of Comparative Examples 1 and 2, respectively. The bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 of the present invention has the best conductivity, and far exceeds Comparative Examples 1 and 2, which shows that PVA, PEDOT:PSS and sodium citrate play a synergistic role and jointly improve the conductivity of the hydrogel.

[0067] Test Example 3: Application effect test of bionic motion and sensing dual-function tendon

[0068] In this test experiment, the bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 is used as a test sample, multiple turns of wire are wrapped around both ends of the sample, and the sample is fixed with insulating black tape to ensure good electrical contact; a robotic fish test model is designed and manufactured, and rectangular channels are set on both sides of the robotic fish, the size of which is slightly larger than the sample size; the tendon sample is loaded into the channel set in advance in the robotic fish, and the electrode clamp external to the resistance measuring instrument is clamped at different positions of the unilateral tendon, and the program debugged in advance is run at the same time, so that the bionic motion and sensing dual-function fish tendon based on hydrogel material can drive the tail of the robotic fish to swing, and the swing amplitude is 0-±60° to achieve different movement postures of turning left and right. The bionic motion and sensing dual-function fish tendon based on hydrogel material has a certain prestress when the tail of the robotic fish is straight, and the resistance at this time is used as the initial resistance (R0), and the relative resistance change (ΔR / R0=(R-R0) / R0) when it swings in the posture of turning left and right is recorded.

[0069] The resistance measuring instrument used in the test experiment is a VC4092C LCR desktop digital bridge meter and is calibrated before measurement to ensure the normal operation of the equipment and accurate measurement results. The test must ensure that the ambient temperature and humidity are appropriate to avoid changes in the properties of the hydrogel material. To improve the reliability of the test results, the test should be performed at least 3 times and the average value and standard deviation should be calculated. The test results are as follows: Figure 4 shown.

[0070] Figure 4The bionic motion and sensing dual-function fish tendon based on hydrogel material prepared in Example 1 is shown, and the electrical signal characteristic diagram after being applied as a proprioceptor on a robot fish (the electrical signal of the unilateral tendon is measured). It can be observed that in the straight state, the swing amplitude of the fish tail is basically the same, and the waveform shows periodic fluctuations near the value of 0. When the robot fish turns right, the fish tail bends more to the right, which leads to a decrease in the strain of the bionic motion and sensing dual-function fish tendon based on hydrogel material, and then causes an overall decrease in the relative resistance change. On the contrary, in the left turn state, the fish tail bends more to the left, increasing the strain of the tendon, so that the relative resistance change increases as a whole. Through the changes in the up and down movement of the waveform, the swimming posture of the robot fish can be reflected in real time, and immediate adjustments can be made accordingly, thereby realizing the proprioceptive function.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a bionic motion and sensing dual-function fish tendon based on hydrogel, characterized in that: The following steps are involved: S1, adding PEDOT:PSS solution to the PVA solution and stirring evenly to obtain a PVA-PEDOT:PSS mixed solution; S2, then adding the sodium citrate solution into the PVA-PEDOT:PSS mixed solution, stirring thoroughly and precipitating a flocculent precipitate; S3, then putting the flocculent precipitate into a mold, leaving it to react at room temperature, freezing it at low temperature, then taking it out and thawing it at room temperature, repeating the freeze-thaw cycle for many times, and obtaining the hydrogel-based bionic motion and sensing dual-function fish tendon.

2. The method for preparing the hydrogel-based bionic motion and sensing dual-function fish tendon according to claim 1, characterized in that: In step S1, the mass fraction of the PVA is 5-20wt%.

3. The method for preparing the hydrogel-based bionic motion and sensing dual-function fish tendon according to claim 1, characterized in that: In step S1, the mass fraction of the PEDOT:PSS solution is 1.0-1.3 wt%.

4. The method for preparing the hydrogel-based bionic motion and sensing dual-function fish tendon according to claim 1, characterized in that: In step S2, the concentration of the sodium citrate solution is 1-3 mol / L.

5. The preparation method according to claim 1, characterized in that: In step S1, the volume ratio of the PEDOT:PSS solution to the PVA solution is 1:3-1:

10.

6. The preparation method according to claim 1, characterized in that: In step S2, the volume ratio of the sodium citrate solution to the PVA solution is 1:10-5:

10.

7. The preparation method according to claim 2, characterized in that: In step S3, the freezing temperature is -30°C to -20°C, the time is 8-12 hours, and the thawing time is 3-4 hours.

8. The preparation method according to claim 2, characterized in that: In step S3, the number of freeze-thaw cycles is 2-5 times.

9. A bionic motion and sensing dual-function fish tendon based on hydrogel prepared according to the method described in any one of claims 1 to 8.

10. Use of the hydrogel-based bionic motion and sensing dual-function fish tendon according to claim 9 in the manufacture of a robotic fish.

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