High-brightness bionic soft actuator based on double-layer hydrogel structure and preparation method thereof

Abstract

The invention discloses a preparation method and application of a high-brightness bionic soft actuator based on a double-layer hydrogel structure, and belongs to the field of bionic soft robots. The bionic soft actuator is composed of double layers of hydrogel, wherein a luminous layer PT4B-N is prepared by adopting a freeze thawing method, and tetra (4-boric acid phenyl) ethylene (TPE-4BA) and polyvinyl alcohol (PVA) are subjected to covalent crosslinking; the driving layer PNPC is prepared through a photo-initiation polymerization method and a freeze thawing method, and the main components of the driving layer PNPC comprise PT4B-N and polyacrylic acid (PAAc). The bionic soft actuator prepared by the invention has excellent fluorescent brightness, the preparation method is simple, the bionic soft actuator has an acid-base response characteristic, and underwater deformation can be realized by adjusting the pH value of the environment. The preparation method is efficient, simple and convenient, and a new thought is provided for design and application of bionic soft robots and intelligent materials.

Description

Technical Field

[0001] The present invention relates to the field of bionic soft robots, and specifically to a preparation method and potential application of a high-brightness bionic soft actuator based on a double-layer hydrogel structure. Background Art

[0002] In the past few decades, biologists have gradually realized that, similar to the way terrestrial organisms use sound, deep-sea organisms also use bioluminescence to complete survival behaviors such as attracting prey, deterring enemies, and finding mates. For example, organisms such as the fluorescent squid, firefly squid, and deep-sea anglerfish have evolved complex organ structures to achieve specific bioluminescence in order to adapt to the environment. These marine organisms with bioluminescence characteristics provide innovative research ideas for bionic engineering. In view of the detection requirements for the deep-sea dark environment, the development of bionic soft robots with high-brightness bioluminescence characteristics is of great significance for realizing long-term in-situ observation. In the low-temperature and high-pressure environment of the deep sea, humans cannot directly observe the state of the robot and can only rely on camera equipment for real-time monitoring. In the visible light range of 400-700 nm, the human eye can detect a weak bioluminescence signal of about 100 photons, and this sensitivity far exceeds that of traditional underwater camera equipment. In application scenarios that require long-term in-situ observation, it is necessary to increase the brightness of the light source of the underwater bioluminescence robot to ensure that the sensor can receive more light signals, so as to meet the requirements of the CCD / CMOS image sensor for the signal-to-noise ratio.

[0003] By adjusting the hydration state, the shape, hardness, and mechanical properties of hydrogels can be regulated in response to environmental changes (such as humidity, temperature, pH value, etc.), enabling them to flexibly adapt to external stimuli under different conditions. Their excellent tunability and reversibility make them ideal materials for fabricating bionic soft actuators. Currently, many researchers have incorporated luminescent materials such as carbon quantum dots, perovskites, and rare-earth ions into hydrogels to achieve the preparation of highly bright fluorescent hydrogels. For example, Wang incorporated all-inorganic PVSK (all-inorganic PVSK) crystals into the gel matrix, and the obtained PVSK gel composite exhibited a PLQY value of 43.2% (Wang D, Cui J, Yang F, et al. A Universal Approach Toward Intrinsically Flexible All-Inorganic Perovskite-Gel Composites with Full-Color Luminescence[J]. Research 2024, 2024(7)). Cheng reported a PVA / QD composite humidity-sensing gel with high sensitivity, stretchability, and self-healing properties. By modifying different ligands on the luminescent quantum dots, the PLQY of this gel reached 60.5% (Cheng Y, Li L, Meredith C.H, et al. Photoluminescent Humidity Sensors Based on Droplet-Enabled Porous Composite Gels[J]. ACS Materials Letters, 2023, 5(8), 2074-2083). Liu successfully encapsulated CsPbBr3 perovskite nanocrystals in the shell of PDMS by the emulsification method. Due to the protection of hydrophobic PDMS, the PLQY of CsPbBr3@PDMS-hydrogel reached 22% (Liu G, Li Z, Lai Z, et al. Flexible, Stretchable, and Luminescent Hydrogels Based on a Polydimethylsiloxane-Coated CsPbBr3 Nanostructure for Elastomers[J]. ACS Applied Nano Materials, 2023, 6(11), 9588-9597).Jiang prepared a high-performance hydrogel made of boric acid-doped silicon nanoparticles and a polyvinyl alcohol matrix, with excellent fluorescence intensity and a PLQY reaching 22.4% (Jiang X, Wu M, Zhang L, et al. Multi-Functional Hydrogels Simultaneously Featuring Strong Fluorescence, Ultralong Phosphorescence, and Excellent Self-Healing Properties and Their Use for Advanced Anti-counterfeiting [J]. Analytical Chemistry, 2022, 94(20), 7264-7271.). Introducing high-performance fluorescent molecules to improve the fluorescence intensity of hydrogels is a direct and effective method. However, fluorescent hydrogels prepared by physical cross-linking usually rely on weak intermolecular forces (van der Waals forces, hydrogen bonds) to promote luminescence, which makes it prone to the problem of fluorescent molecule leakage during long-term underwater use. In addition, the structural instability also makes the hydrogel vulnerable to external factors (such as metal ions, strong acids and bases, temperature, etc.), which is not conducive to continuous operation in complex environments.

[0004] As a classic aggregation-induced emission (AIE) fluorophore, tetraphenylethylene (TPE) exhibits excellent fluorescence properties in a polymer hydrogel matrix. Compared with physical crosslinking, introducing TPE molecules by covalent crosslinking to prepare fluorescent hydrogels has certain advantages. Li designed and fabricated a multi-stimuli responsive fluorescent hydrogel by introducing TPE derivatives as non-aggregating crosslinkers into the gel network. The prepared hydrogel showed good fluorescence responses to temperature, pH, metal ions, and hydrogen bond agents (Li B, Yan B, Wang J, et al. A multistimuli-responsive fluorescent hydrogel based on a fluorescence response to macromolecular segmental motion [J]. NanoResearch, 2023, 16(10), 12098-12105.). Dr. Chandrasekaran reported a novel star-shaped fluoranthene-tetraphenylethylene conjugated emitter. The bulky fluoranthene units on the periphery of the emitter blocked the intramolecular rotation of the phenyl rings and induced a blue shift in enhanced emission (Chandrasekaran, Y, Venkatramaiah, N, Patil, S. Tetraphenylethene-Based Conjugated Fluoranthene: A Potential Fluorescent Probe for Detection of Nitroaromatic Compounds [J]. Chemistry-A European Journal, 2016, 22(15), 5288-5294.). We note that, on the one hand, covalent crosslinking connects the matrix and the fluorescent molecules by chemical bonds, which can greatly enhance the structural stability of the fluorescent hydrogel. On the other hand, since the luminescence mechanism of TPE originates from restricted intramolecular rotation and restricted intramolecular vibration, strong intermolecular forces are expected to fully limit the non-radiative dissipation of energy and enhance the fluorescence emission intensity. Summary of the Invention

[0005] Aiming at the existing technical problems, the present invention designs a high-brightness bionic soft actuator based on a double-layer hydrogel structure. The bionic soft actuator is composed of a double-layer hydrogel: the light-emitting layer PT4B-N is prepared by the freeze-thaw method, in which tetra(4-boronic acid phenyl)ethylene (TPE-4BA) and polyvinyl alcohol (PVA) undergo covalent cross-linking; the driving layer PNPC is prepared by the photoinitiated polymerization method and the freeze-thaw method, and its main components include PT4B-N and polyacrylic acid (PAAc). It should be noted that the photoluminescence quantum yield (PLQY) of the light-emitting layer is up to 63.66%. PAAc in the driving layer exhibits different swelling abilities under different acid-base conditions. By virtue of the swelling difference of the double-layer hydrogel, we can precisely control the deformation of the bionic soft actuator, thereby realizing complex bio-like behaviors including grasping and releasing. Without the need for an interface layer or an adhesive layer, the connection between the double-layer hydrogels is good, and a specific mold can be used to cut out the target shape to meet different needs. This method for preparing the bionic soft actuator is simple and efficient, providing ideas for the design and application of bionic soft robots and intelligent materials.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-brightness bionic soft actuator based on a double-layer hydrogel structure, the main body of which is a double-layer hydrogel and is carried out in several steps. First, the precursor solutions of the PT4B-N light-emitting layer and the PNPC driving layer are prepared respectively. A circular glass culture dish of a certain specification is taken as a mold, and the culture dish is placed in a suitable position to keep the solution in the dish horizontal and stable. Then, the PNPC precursor solution is poured in, and the solution is cured with an ultraviolet lamp to obtain the deformation layer PNPC. After the curing is completed, the PT4B-N precursor solution is added to the upper layer of the PNPC. After being uniformly stable, it is placed in a refrigerator at -20°C and repeatedly freeze-thawed to obtain an initial sample. According to different application scenarios, various shapes of hydrogels can be cut out with a mold.

[0008] The preparation method of the above high-brightness bionic soft actuator based on a double-layer hydrogel structure specifically includes the following steps:

[0009] (1) Weigh a certain amount of polyvinyl alcohol PVA and add it to deionized water, and add ammonia water to make the solution alkaline. Then, take the powder of tetra(4-boronic acid phenyl)ethylene TPE-4BA and place it in a beaker, add 1 mL of absolute ethanol and ultrasonically dissolve it for 30 min. After that, add it to the PVA solution. Then, place the above mixed solution in a water bath, control the pH of the reaction solution > 10, heat it at 90°C to fully dissolve PVA and carry out the B-O click reaction with TPE-4BA for 90 min to prepare the PT4B-N precursor solution.

[0010] (2) Add acrylic acid (AAc) and N,N'-methylenebisacrylamide (Bis) to deionized water at 55 °C and dissolve them thoroughly for 20 min to obtain a PAAc solution. Then add the precursor solution of PT4B-N. After continuing to stir for 10 min, add 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) to the mixed solution and stir for 3 min to obtain a PNPC precursor solution.

[0011] (3) After obtaining the PNPC precursor solution, quickly transfer it to a round glass petri dish. Place the petri dish in a suitable position to keep the solution in the dish level and stable. Then use a 365 nm ultraviolet lamp with a power of 300 W to cure the solution (for 5 min) to obtain a deformed layer of PNPC. After the deformed layer of PNPC is cured, add the PT4B-N solution to the upper layer of PNPC. After it is evenly stable, place it in a refrigerator at -20 °C and freeze-thaw it more than 5 times to obtain an initial sample of the double-layer hydrogel. According to different application scenarios, a hydrogel actuator with a target shape can be cut out using a mold.

[0012] Preferably, in the step (1), the weight ratio of PVA to deionized water for preparing the PT4B-N precursor solution is 2:18.

[0013] Preferably, in the step (1), the addition amount of TPE-4BA accounts for 0.25 wt% of the PT4B-N precursor solution.

[0014] Preferably, in the step (1), 0.2 mL of ammonia water is added, and the purity > 25%.

[0015] Preferably, in the step (2), the mass ratio of Bis:AIBA:AAc in the PNPC precursor solution is 1:1:100.

[0016] Preferably, in the step (2), the volume ratio of PT4B-N to PAAc in the preparation of the PNPC precursor solution is 8:20.

[0017] In the step (2), the mass ratio of AAc to deionized water is 3:17.

[0018] In the step (2), the mass ratio of Bis:AIBA:AAc in the PNPC precursor solution is 1:1:100.

[0019] In the step (3), the volume ratio of the PT4B-N precursor solution to the PNPC precursor solution for preparing the double-layer hydrogel is 1:1.

[0020] Preferably, in the step (3), the diameter of the round glass petri dish used is 95 mm.

[0021] A high-brightness bionic soft actuator based on a double-layer hydrogel structure prepared by the above method.

[0022] The remarkable advantages of the present invention are as follows:

[0023] (1) Fluorescent molecules are introduced into the light-emitting layer by the covalent cross-linking method, thus realizing high-brightness fluorescence performance.

[0024] (2) Stable bonding can be achieved between the double-layer hydrogels without the need for adhesives or intermediate materials, significantly simplifying the manufacturing process.

[0025] (3) Based on the pH-responsive characteristics of polyacrylic acid, the driving layer (PNPC) regulates the precise deformation of the actuator through swelling differences.

[0026] (4) The dual response of the light-emitting layer and the driving layer to acid-base stimuli endows the bionic soft actuator with the ability of "light-force" cooperative control. Description of the Drawings

[0027] Figure 1 It is the preparation route of the bionic software actuator, including the main structure composed of the light-emitting layer PT4B-N and the driving layer PNPC, and models of different shapes can be designed according to specific application requirements.

[0028] Figure 2 It is the schematic diagram of the B-O click reaction between PVA and TPE-4BA.

[0029] Figure 3 It is the actual photo of the color change of the PT4B-N solution before and after the B-O click reaction.

[0030] Figure 4 It is the fluorescence quantum yield diagram (PLQY) of the light-emitting layer PT4B-N.

[0031] Figure 5 It is the infrared spectrum diagram (FT-IR) of the light-emitting layer PT4B-N after acid-base treatment.

[0032] Figure 6 It is the fluorescence spectrum diagram of PT4B-N at pH = 1 and pH = 13.

[0033] Figure 7 It is the fluorescence cycle response diagram of PT4B-N at pH = 1 and pH = 13.

[0034] Figure 8 It is the infrared spectrum diagram (FT-IR) of PNPC, PAAc and PT4B-N.

[0035] Figure 9 It is the high-resolution X-ray photoelectron spectrum (XPS) of PNPC before and after acid-base treatment.

[0036] Figure 10 It is a cross-sectional view (SEM) of the double-layer hydrogel interface taken by a scanning electron microscope.

[0037] Figure 11 It is the pH-responsive bending deformation curve of the bar-shaped PT4B-N / PNPC hydrogel.

[0038] Figure 12 It is the pH-responsive swelling curve and swelling difference curve of PT4B-N and PNPC in the double-layer hydrogel.

[0039] Figure 13 It is a top view of the deformation and color-changing behavior of the PT4B-N / PNPC simulated starfish model when stimulated.

[0040] Figure 14 It is a photo of the PT4B-N / PNPC hydrogel tentacles grasping and releasing an object under 365 nm ultraviolet light. Detailed implementation mode

[0041] The present invention discloses a high-brightness bionic soft actuator based on a double-layer hydrogel structure. The preparation materials include: polyvinyl alcohol (PVA), acrylic acid (AAc), tetrakis(4-boronic acid phenyl) ethylene (TPE-4BA), N,N'-methylenebisacrylamide (Bis), 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA), ammonia water, absolute ethanol, deionized water. The main structure of the hydrogel bionic software actuator and its application schematic diagrams under different shape models are as Figure 1 shown.

[0042] In order to make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific implementation modes, but the present invention is not limited thereto.

[0043] Example 1:

[0044] Step 1: Weigh 2.0 g of PVA and add it to 18 mL of deionized water, and add 0.2 mL of ammonia water to make the solution alkaline. Take 5.07 mg of TPE-4BA powder and place it in a beaker, add 1 mL of absolute ethanol and ultrasonically dissolve it for 30 min. After that, add it to the PVA solution. Then, place the above mixed solution in a water bath, control the pH of the reaction solution > 10, and heat it at 90 °C to fully dissolve PVA and react with TPE-4BA for 90 min to prepare a PT4B-N precursor solution.

[0045] Step 2: Add 3 g of AAc and 30 mg of Bis to 17 mL of deionized water, fully dissolve at 55 ° C for 20 minutes to obtain a PAAc solution, and then add the PT4B-N precursor solution in step 1 (the volume ratio of PT4B-N precursor solution: PAAc precursor solution = 8:20); continue stirring for 10 minutes, add 30 mg of AIBA to the mixed solution, and continue stirring to obtain a PNPC precursor solution.

[0046] Step 3: Transfer 10mL of the PNPC precursor solution in step 2 to a round glass culture dish; place the culture dish in a suitable position to keep the solution in the dish horizontal and stable, and then use a 365nm ultraviolet lamp with a power of 300W to cure the solution (5min) to obtain a deformable layer PNPC. After curing, add 10mL of the PT4B-N solution in step 1 to the upper layer of PNPC, and place it in a refrigerator at -20°C after it is evenly stabilized. Repeat freezing and thawing for more than 5 times to obtain a double-layer hydrogel initial sample. Depending on the application scenario, a hydrogel actuator of the target shape can be cut out with a mold.

[0047] Figure 2 This is a schematic diagram of the BO click reaction of PVA and TPE-4BA. Since the ammonia added to the reaction solution makes the environment alkaline (pH>pKa), TPE-4BA and the ortho-hydroxyl groups on the side chain of PVA undergo a BO click reaction, and the borate ester bond formed is a covalent bond.

[0048] Figure 3 This is a real shot of the color change of PT4B-N solution before and after the BO click reaction. The color of the PT4B-N solution changes from cyan to blue, indicating the occurrence of the reaction.

[0049] Figure 4 This is the fluorescence quantum yield diagram (PLQY) of the light-emitting layer PT4B-N. It can be seen from the figure that under 365nm excitation, the fluorescence emission peak of PT4B-N is located near 450nm, indicating that this is a typical blue fluorescence, and the PLQY reaches 63.66%, which has the characteristics of high-efficiency and high-brightness fluorescence.

[0050] Figure 5 This is the infrared spectrum (FT-IR) of the light-emitting layer PT4B-N after acid-base treatment. The FT-IR results show that the characteristic peak attributed to the C-OH bond in PT4B-N is located at 1088cm -1 After acid treatment, a large shift to 1041 cm -1 It is found that after alkali treatment, the hydroxyl groups on PVA are protonated. -1The stretching characteristic peak of the B-O-C bond weakens because after the formation of the charged borate ester, the geometric configuration changes from sp 2 triangular plane to sp 3 tetrahedron, weakening the B-O bond. The above results indicate that under acid-base stimulation, the strength of the borate ester bond of PT4B-N will be affected.

[0051] Figure 6 are the fluorescence spectra of PT4B-N at pH = 1 and pH = 13. After alkali treatment, the fluorescence emission peak intensity of PT4B-N decreases and can recover after acid treatment.

[0052] Figure 7 is the fluorescence cyclic response diagram of PT4B-N at pH = 1 and pH = 13. It can be seen from the figure that under acid-base cyclic stimulation, the change in the fluorescence intensity of PT4B-N is highly reversible. The above results indicate that PT4B-N has fluorescence acid-base response characteristics.

[0053] Figure 8 are the infrared spectra of PNPC, PAAc, and PT4B-N. As shown in the figure, in FT-IR, 1700 cm -1 corresponds to the O-C=O characteristic peak of the carboxyl group in PAAc, and around 3300 cm -1 and at 1090 cm -1 represent C-OH and -OH in PVA, indicating the effective composition of PAAc and PT4B-N in PNPC.

[0054] Figure 9 is the high-resolution XPS C 1s spectrum of the driving layer PNPC before and after acid-base treatment. PAAc hydrogel is a typical acid-base responsive hydrogel. In an acidic environment, the pH value is low, and there are a large number of hydrogen bond attractive forces between -COOH groups. The electrostatic repulsive force between PAAc segments is weak, and the structure of the hydrogel is relatively compact and difficult to absorb a large amount of water. When the pH increases, the -COOH groups in PAAc are deprotonated and become negatively charged -COO- groups. This deprotonation phenomenon triggers the electrostatic repulsive force between polymer chains, resulting in the swelling of the hydrogel network structure. As Figure 7 shown, the peaks at 286.3 eV and 289.1 eV correspond to the C-O bond and C=O bond respectively. After alkaline treatment, the intensity of the C-O characteristic peak weakens, and the intensity of the C=O characteristic peak weakens and shifts to 288.3 eV, indicating that the carboxyl group has been deprotonated at this time and electrostatic repulsive force has been generated.

[0055] Figure 10It is a SEM cross-sectional view of the double-layer hydrogel interface. As shown in the figure, there are significant changes in the internal pores of the driving layer PNPC before and after acid-base treatment, indicating a change in its swelling ability. This result is in line with the design expectations.

[0056] Figure 11 It is a pH-responsive bending deformation curve graph of the strip-shaped PT4B-N / PNPC hydrogel. As shown in the figure, under acid-base control, the bending behavior of the strip-shaped double-layer hydrogel can be well controlled, indicating that it has excellent pH-responsive bending deformation ability.

[0057] Figure 12 It is the pH-responsive swelling curve and swelling difference curve of PT4B-N and PNPC in the double-layer hydrogel, corresponding to λ PT4B-N 、λ PNPC and Δλ respectively. The swelling difference curve is highly similar to the Figure 11 bending deformation curve, further illustrating the regulation of swelling on deformation.

[0058] Application Example

[0059] Many starfish and jellyfish have the ability to change their body color. Some species of starfish will change color when threatened, and their tentacles will gradually stretch or contract during predation or defense. Inspired by this color-changing behavior, we prepared a pentagram hydrogel model that can well simulate the stress behavior of starfish. As can be seen from the Figure 13 top view, the deformation and color-changing process of the pentagram hydrogel can be completed synergistically under acid-base stimulation, successfully simulating the complex behavior of starfish after being stimulated. In addition, PT4B-N / PNPC has excellent bending performance and can achieve behaviors similar to those of living organisms, such as grasping and releasing objects. As Figure 14 shown, the hydrogel tentacle begins to bend and deform in an environment with pH = 12, adjusts its position to catch the depression of the green toy nut, and then realizes the unscrewing and pulling of the nut. When it is necessary to put down the nut, just place the hydrogel tentacle in a solution with pH = 2 to complete the release. The entire grasping and releasing process is completed within 16 minutes. Since this process is carried out under the excitation of 365nm ultraviolet light, thanks to the excellent fluorescence performance of PT4B-N, the entire operation process can be clearly observed in the dark and the position can be accurately adjusted.

[0060] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure, characterized in that: It includes the following steps: (1) Weigh a certain amount of polyvinyl alcohol (PVA) and add it to deionized water. Then add ammonia water to make the solution alkaline. Next, take tetrakis(4-boronic acid phenyl)ethylene (TPE-4BA) powder and place it in a beaker. Add 1 mL of absolute ethanol and ultrasonically dissolve it for 30 min. After that, add it to the PVA solution. Then, place the above mixed solution in a water bath, control the pH of the reaction solution > 10, and heat it at 90 °C to fully dissolve PVA and carry out the B–O click reaction with TPE-4BA for 90 min to prepare the PT4B-N precursor solution. (2) Add acrylic acid (AAc) and N,N'-methylenebisacrylamide (Bis) to deionized water at 55 °C and fully dissolve them for 20 min to obtain the PAAc solution. Then add the PT4B-N precursor solution. After continuously stirring for 10 min, add 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) to the mixed solution and stir for 3 min to obtain the PNPC precursor solution. (3) After obtaining the PNPC precursor solution, quickly transfer it to a round glass petri dish. Place the petri dish in a suitable position to keep the solution in the vessel horizontally stable. Then use a 365 nm ultraviolet lamp with a power of 300 W to cure the solution for 5 min to obtain the deformed layer PNPC. After the deformed layer PNPC is cured, add the PT4B-N solution to the upper layer of PNPC. After it is uniformly stable, place it in a refrigerator at -20 °C and freeze-thaw it more than 5 times to obtain the initial sample of the double-layer hydrogel.

2. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (1), the mass ratio of PVA to deionized water is 1:

9.

3. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (1), the addition amount of TPE-4BA accounts for 0.25 wt% of the PT4B-N precursor solution.

4. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (1), 0.2 mL of ammonia water is added, and the purity > 25%.

5. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (2), the mass ratio of AAc to deionized water is 3:

17.

6. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (2), the mass ratio of Bis:AIBA:AAc in the PNPC precursor solution is 1:1:

100.

7. The preparation method of a high-brightness bionic soft actuator based on a double-layer hydrogel structure according to claim 1, characterized in that: In the step (3), the volume ratio of the PT4B-N precursor solution to the PNPC precursor solution for preparing the double-layer hydrogel is 1:

1.

8. A bionic soft actuator prepared by the preparation method according to any one of claims 1 to 7.

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