Solvent vapor fast response Janus flexible driver and preparation method and application thereof

Abstract

The present application relates to a kind of solvent vapor fast response Janus flexible driver and its preparation method and application, flexible driver has asymmetric wetting, including passive layer and the polydimethylsiloxane-based active layer of passive layer with glue one side of passive layer, passive layer is used to limit active layer free expansion, active layer is cured by including polydimethylsiloxane prepolymer, curing agent and inorganic filler, surface is provided with laser etching orientation texture structure, for inducing deformation, can be absorbed and diffused organic solvent molecule when being stimulated by organic solvent vapor, and swelling occurs, after the removal of organic solvent vapor stimulation, organic solvent molecule is desorbed, make flexible driver occur reversible bending, curl, spiral bending or winding deformation, with non-contact response, response speed is fast, deformation is controllable, reversibility is good, cycle stability is good and can be repeatedly used and the like, can be used in soft body driving and flexible execution, sensing and detection and the like field.

Description

Technical Field

[0001] This invention belongs to the field of smart response materials and soft actuators, specifically relating to a PDMS / PI flexible actuator with oriented texture, capable of rapid solvent vapor response and controllable deformation, as well as its preparation method and application. Background Technology

[0002] With the development of flexible robots, intelligent sensors, bionic actuators, and wearable devices, flexible actuators capable of controllable deformation under external stimuli have attracted widespread attention. Compared to traditional rigid actuators, flexible actuators can undergo bending, curling, twisting, or contraction under the influence of light, heat, electricity, magnetism, humidity, or chemical stimuli. They can be used in scenarios such as grasping, handling, opening and closing, crawling, and entanglement, and have advantages such as lightweight and thin structure, flexible deformation, strong environmental adaptability, and high operational safety. Therefore, developing flexible actuators that are easy to manufacture, have fast response, are reversible and stable, and have adjustable bending direction will help expand the application range of flexible actuators in practical scenarios such as soft actuation and flexible execution, sensing and detection.

[0003] Solvent-responsive actuators primarily rely on the adsorption, diffusion, and swelling of solvent molecules in polymer materials to achieve deformation. Polydimethylsiloxane (PDMS), due to its good flexibility, ease of film formation, high chemical stability, and sensitivity to various organic solvents, is often used in solvent-responsive flexible actuators. Existing solvent-responsive actuators mostly employ direct contact with liquid organic solvents, allowing the solvent to enter the polymer network and induce volume changes in the material, thereby producing bending or curling deformation. However, direct contact with liquid organic solvents still has shortcomings: on the one hand, liquid solvents easily remain on the actuator surface, causing contamination and making cleaning difficult; on the other hand, the high intensity of liquid solvent stimulation can easily cause localized excessive swelling, making it difficult to stably control the deformation rate and degree of bending. Simultaneously, some solvent molecules desorb slowly within the polymer network, leading to prolonged actuator recovery time, reduced reversibility and recycling efficiency, and repeated stimulation may also cause degradation of the material's mechanical properties.

[0004] Organic solvent vapor-driven processes can achieve non-contact driving by utilizing the adsorption, diffusion, swelling, and desorption processes of volatile solvent molecules in polymers. This can reduce contamination, residues, and structural damage caused by liquid contact to some extent. However, ordinary PDMS films have a simple surface structure, limited specific surface area, and limited mass transfer channels. Under vapor stimulation, they usually still have the following problems: (1) Limited response speed and bending output capability: The driving mechanism of PDMS thin film is the volume strain caused by the swelling of solvent vapor. However, the mass transfer path of vapor molecules adsorption and diffusion into the interior of the material is long and the resistance is large, which leads to the lag in the swelling response under vapor stimulation. The flexible actuator takes a long time to reach the maximum bending deformation. At the same time, the overall bending curvature is small and the deformation output force is weak, which cannot meet the application requirements of fast response and large deformation output.

[0005] (2) Single bending mode: Although the diffusion of solvent vapor into the PDMS film causes non-uniform expansion of the flexible actuator, which can cause macroscopic deformation and directional movement of the film, the swelling behavior is isotropic. It can only generate a single bending deformation by relying on the overall strain mismatch between the layers. It is impossible to programmatically control the direction and shape of the deformation, making it difficult to achieve diversified driving modes and limiting application scenarios.

[0006] (3) Insufficient reversibility and cycle stability: The interfacial bonding stability of PDMS film is insufficient. After a single cycle, residual strain is easily generated. After multiple cycles, the residual strain continues to accumulate, resulting in a decrease in deformation reversibility. At the same time, repeated swelling and contraction cycles will cause fatigue damage such as microcracks and interfacial relaxation inside the material. The slow solvent desorption rate of the single-structure surface further aggravates the solvent residue, ultimately causing the cycle stability to deteriorate and the life of the flexible actuator to be limited. The flexible actuator is not hydrophobic enough, which is also not conducive to its stable operation in humid and other harsh environments.

[0007] (4) Complex preparation methods and difficulty in achieving the desired performance: To improve driving performance, existing technologies usually adopt methods such as constructing porous structures, multi-layer structures or surface modification to enhance the response capability of the actuator. However, these methods have the problems of complex overall processes, long preparation cycles, and high equipment and consumable costs. Furthermore, it is still difficult to simultaneously meet the requirements of simple preparation, fast response, reversible stability and adjustable bending direction. For example, although reducing the film thickness can achieve a faster response speed and a larger bending curvature, it will cause a decrease in the service life, load-bearing capacity or rigidity of the flexible actuator in practical applications, making it difficult to meet the application requirements of scenarios such as soft gripping, intelligent switching, directional crawling and lightweight execution. Summary of the Invention

[0008] This invention aims to at least partially solve one of the problems mentioned above regarding the insufficient response speed and bending output capability of flexible actuators, easy contamination from direct contact with liquid solvents, limited bending modes, insufficient cycle stability, and limited application modes. This invention provides a Janus flexible actuator with rapid solvent vapor response, its preparation method, and its application. The flexible actuator has Janus wetting properties and can produce rapid, reversible, and directionally controllable bending, curling, helical bending, or winding deformation under the stimulation and removal of organic solvent vapor. It also has a superhydrophobic surface, large deformation range, simple structure, stable cycle, and convenient preparation, thereby meeting the application requirements of rapid, reversible, programmable deformation, and humid environments.

[0009] The technical solution adopted by this invention to solve its technical problem is: A first aspect of the present invention is to provide a solvent vapor fast-response Janus flexible actuator, comprising a passive layer and a polydimethylsiloxane active layer disposed on the adhesive side of the passive layer. The polydimethylsiloxane active layer comprises a polydimethylsiloxane prepolymer, a curing agent, and an inorganic filler, wherein the mass ratio of the polydimethylsiloxane prepolymer, the curing agent, and the inorganic filler is 100:(5-15):(0.6-8). The side of the polydimethylsiloxane active layer away from the passive layer is provided with an orientation texture structure that induces deformation of the flexible actuator, and the polydimethylsiloxane active layer is located away from the passive layer. The surface of this side of the layer has hydrophobic or superhydrophobic properties; the passive layer is used to restrict the free expansion of the polydimethylsiloxane active layer. The side of the passive layer away from the polydimethylsiloxane active layer has hydrophilic properties and together with the side of the polydimethylsiloxane active layer, it forms an asymmetric wetting gradient across the layer, giving the flexible actuator asymmetric wetting properties in the thickness direction, i.e., Janus wetting properties. The polydimethylsiloxane active layer can adsorb and diffuse organic solvent molecules and swell when stimulated by organic solvent vapor, and can desorb organic solvent molecules after the organic solvent vapor stimulation is removed, thereby causing the flexible actuator to undergo reversible deformation.

[0010] This invention differs from traditional direct contact actuation methods using liquid solvents. Instead, it utilizes volatile organic solvent vapors as a stimulus source. The organic solvent vapors do not require the actuator to be completely immersed in the liquid solvent, reducing issues such as solvent residue, surface contamination, and excessive swelling. This flexible actuator uses a polydimethylsiloxane (PDMS)-based active layer with an oriented textured surface as the active layer, which, combined with a passive layer, forms an asymmetric wetting Janus bilayer structure. The PDMS active layer, after being constructed with an oriented textured structure, exhibits superhydrophobic properties on its outer surface, demonstrating a strong affinity for and adsorption capacity for organic solvent molecules. The passive layer's outer surface is hydrophilic, exhibiting extremely weak adsorption capacity for organic solvent vapors. This creates a significant asymmetric wetting gradient and adsorption capacity difference on both sides of the flexible actuator, allowing for the directional guidance of organic solvent vapors towards the active layer side for mass transfer and enrichment, further enhancing the directionality and efficiency of the actuation process. Its actuation mechanism includes: Under the stimulation of organic solvent vapor, the active layer, due to its superhydrophobic surface properties, adsorbs and diffuses organic solvent molecules, inducing swelling of the active layer after these molecules enter the polydimethylsiloxane polymer network. By adding inorganic fillers, the surface roughness, structural stability, and functional expansion capability of the polydimethylsiloxane active layer can be improved, allowing the oriented textured structure to maintain good morphological integrity even after repeated organic solvent vapor stimulation. This also makes it more suitable for processing oriented textured structures using methods such as laser etching, thus enhancing vapor response driving performance. Simultaneously, the passive layer, due to its hydrophilic properties, hardly adsorbs organic solvents and does not undergo swelling deformation, complementing the passive layer... The rigid constraint of the passive layer restricts the free swelling of the active layer, creating a strain mismatch between the active and passive layers. This results in an uneven strain distribution within the bilayer structure, which in turn transforms the molecular-scale swelling behavior into macroscopic bending deformation output. Under the induction of the oriented texture structure, controllable deformations such as bending, curling, spiral bending, or entanglement are generated. After the removal of the organic solvent vapor stimulus, the organic solvent molecules are desorbed and reset, enabling the flexible actuator to achieve rapid response and reversible deformation. In addition, the oriented texture structure also changes the surface properties of PDMS, achieving superhydrophobicity. This superhydrophobicity is beneficial for stable operation in harsh environments such as humidity.

[0011] In a preferred embodiment, the passive layer is a polyimide (PI) layer with an adhesive layer, forming a PDMS / PI flexible actuator. Polyimide possesses excellent flexibility, dimensional stability, and chemical stability, thus maintaining the integrity of the bilayer structure during repeated steam stimulation and recovery cycles. The polydimethylsiloxane active layer and the polyimide layer are bonded together by a self-adhesive layer of polyimide tape. The bonding strength between the active and passive layers directly affects the conversion efficiency of swelling strain to macroscopic bending deformation. If the interfacial bonding is insufficient, the active layer is prone to local debonding after being stimulated by solvent vapor, which reduces the bending output of the actuator and may even lead to a decrease in cycle stability. Therefore, the bonding method should ensure that the active and passive layers do not undergo significant delamination during organic solvent vapor stimulation and repeated bending. By improving the interfacial bonding stability of the bilayer, the reversibility and long-term performance of the flexible actuator can be further improved.

[0012] In a preferred embodiment, the thickness of the passive layer is 25–100 μm, preferably 50 μm; the thickness of the polydimethylsiloxane active layer is 100–500 μm, preferably 200 μm; and the total thickness of the flexible actuator is 150–550 μm. These thickness ranges achieve a balance between bending output and operational stability. If the overall thickness of the active and passive layers is too small, the actuator can achieve a large curvature, but its stability is poor during cutting, clamping, and repeated use. If the overall thickness is too large, the bending stiffness of the double-layer structure increases, and the curvature output decreases under the same steam stimulation. Therefore, by controlling the thickness of the active and passive layers, the flexible actuator can possess both high bending curvature and good reusability stability.

[0013] In a preferred embodiment, the inorganic filler includes a conductive / reinforcing filler, which can impart a certain conductivity to the active layer, enabling the flexible actuator to have further application possibilities in scenarios such as switch closure, flexible electronic contact, or electrical signal triggering.

[0014] In a preferred embodiment, the inorganic filler is composed of silica and graphene in a mass ratio of (0.5-5):(0.1-3). The silica particles are used to improve the surface roughness of the active layer and the texture retention ability after laser etching. After the silica particles are dispersed in the polydimethylsiloxane network, on the one hand, they can form a certain inorganic filling skeleton inside the active layer, reducing the excessive deformation of polydimethylsiloxane during repeated swelling and recovery. On the other hand, they can promote the formation of a more stable micro-undulation structure on the surface during laser etching, so that the oriented texture structure can still maintain good morphological integrity after multiple organic solvent vapor stimulations. The conductive / reinforcing filler is preferably graphene, whose layered structure can enhance the mechanical stability of the polydimethylsiloxane composite layer and impart a certain conductivity to the active layer. The mass ratio of polydimethylsiloxane prepolymer, curing agent, silica and graphene can be further preferred to be 100:10:2:1.

[0015] In a preferred embodiment, the oriented texture structure includes several striped, grooved, or ridged textures with an adjacent texture spacing of 0.05–0.5 mm. This allows the flexible sensor to have a higher water contact angle and a more complete surface texture structure, avoiding local texture overlap caused by excessively small adjacent texture spacing and reduced texture coverage and lifespan caused by excessively large adjacent texture spacing. Further preferred embodiment is a striped texture formed by laser etching with an adjacent texture spacing of 0.10 mm.

[0016] In a preferred embodiment, the oriented texture structure includes several parallel stripe-like textures. The angle between the stripe-like textures and the width direction of the flexible actuator is -90° to 90°. An angle of 0° is used to induce bending or curling deformation, which is mainly bending along the length direction of the flexible actuator. Textures with an angle of 45° or -45° are used to induce helical bending or winding deformation in the opposite direction. Thus, by changing the orientation of the stripe-like textures, the bending direction and deformation mode of the actuator can be controlled under the same material system and the same steam stimulation conditions, thereby improving the programmability and application adaptability of the actuator.

[0017] In a preferred embodiment, the organic solvent vapor is one or more of n-hexane, n-pentane, dichloromethane, acetone, ethanol, or methanol, and is more preferably n-hexane vapor. The polydimethylsiloxane active layer has a strong swelling response to non-polar or low-polarity organic solvents, thus achieving higher bending curvature and faster response speed under n-hexane vapor stimulation. For water vapor or strongly polar solvent vapor, due to their weak compatibility with polydimethylsiloxane, the active layer has a lower degree of swelling, resulting in a smaller actuator bending output. This difference can be used to achieve selective response to different solvent vapors.

[0018] In preferred technical solutions, the organic solvent vapor stimulation method includes one or more of static vapor stimulation, heated vapor evaporation stimulation, and atomized vapor stimulation. Static vapor stimulation refers to placing the organic solvent in a container or localized space for natural evaporation, exposing the flexible actuator to its vapor environment. Heated vapor evaporation stimulation refers to heating the organic solvent at a temperature below or close to its boiling point to obtain a more stable vapor supply. Atomized vapor stimulation refers to atomizing the organic solvent using a spray device and applying it to the surface of the flexible actuator to quickly trigger local bending or continuous movement. None of the above stimulation methods require the flexible actuator to be completely immersed in the liquid solvent, thus reducing liquid residue and excessive material swelling, and facilitating functional actions such as switch triggering, directional crawling, clamping, and entanglement.

[0019] In a preferred embodiment, after the organic solvent vapor stimulation is removed, the flexible actuator desorbs the organic solvent through one or more methods, including natural evaporation, airflow, heating, or negative pressure suction. Natural evaporation, airflow, low-temperature heating, or negative pressure suction can promote the desorption of solvent molecules in the active layer, allowing the actuator to return to its initial state or near-initial state. The recovery process does not require an external mechanical reset structure; it relies on the desorption of solvent molecules in the polydimethylsiloxane active layer and the elastic recovery of the polyimide passive layer. By controlling the active layer thickness, texture depth, solvent type, and ambient temperature, the response time and recovery time of the actuator can be adjusted, making it suitable for different working modes such as single triggering, periodic triggering, or continuous cycle driving.

[0020] A second aspect of the present invention is to provide a method for preparing a Janus flexible actuator with fast solvent vapor response according to any one of the preceding claims, the method comprising the following steps: S1. Mix the components including polydimethylsiloxane prepolymer, curing agent and inorganic filler evenly and degas them under vacuum to prepare polydimethylsiloxane composite slurry. S2. The polydimethylsiloxane composite slurry obtained in step S1 is prepared into a polydimethylsiloxane composite film and cured. S3. Cut the polydimethylsiloxane composite film obtained in step S2 into a preset size as the polydimethylsiloxane active layer, and attach the polydimethylsiloxane active layer to the adhesive side of the passive layer to form a double-layer structure film. S4. An oriented texture structure is processed on the surface of the polydimethylsiloxane active layer of the bilayer structure film obtained in step S3 to obtain the flexible actuator.

[0021] In a preferred embodiment, in step S1, the PDMS prepolymer is first mixed with a curing agent, and then silica and graphene are added and stirred evenly to disperse the silica powder and graphene powder as evenly as possible in the polydimethylsiloxane body.

[0022] In the preferred technical solution, the degassing time in step S1 can be determined according to the slurry volume and bubble content, preferably 10 to 30 minutes, so that the polydimethylsiloxane composite slurry is uniform, continuous and without obvious large bubbles, so as to ensure uniform film thickness and stable driving response in the subsequent process.

[0023] In a preferred embodiment, in step S2, a polydimethylsiloxane composite film is prepared by a thickness-limited film-forming method. The polydimethylsiloxane composite slurry is placed between two thickness-limiting plates, and the film thickness is controlled by a gap ruler. The thickness-limited film-forming method can improve the uniformity of the active layer thickness, thereby enhancing the consistency of the actuator's bending response. The thickness-limiting plate can be a polypropylene plate, a glass plate, or other flat substrate, and the gap ruler can be a metal gap ruler or a gasket. It is further preferred that the thickness-limited film-forming method uses two PP plates and a manganese steel gap ruler to control the film thickness.

[0024] In the preferred technical solution, step S2 involves heating and curing at a temperature of 60–100°C for 0.5–2 hours, preferably at 80°C for 1 hour, to fully crosslink and cure the polydimethylsiloxane composite slurry and form a polydimethylsiloxane composite film.

[0025] In the preferred technical solution, the orientation texture structure is processed by laser marking or laser etching in step S3. Laser marking or laser etching can be completed in a normal temperature air environment without the need for a mask and complex wet processing. It has the advantages of flexible processing, designable patterns, and suitability for mass production.

[0026] In the preferred technical solution, the scanning speed of laser etching in step S3 is 100-500 mm / s, the laser power is 5%-30% of the rated power, and the number of scans is 3-15. The above laser parameters can form a stable and continuous orientation texture on the surface of the active layer, while avoiding surface damage caused by excessive etching. As the number of laser etchings increases, the bending curvature of the driver increases and gradually tends to stabilize. When the number of etchings is too high, thermal damage or structural defects are easily generated on the surface of the active layer. It is further preferred that the laser scanning speed is 200 mm / s, the laser power is 20% of the rated power of the equipment, the number of laser scans is 9, and the spacing between adjacent textures is 0.1 mm, which can balance response performance and structural integrity.

[0027] In a preferred embodiment, the bending direction, curvature, response time, and spiral winding method of the flexible actuator under organic solvent vapor stimulation are controlled by changing the angle between the texture and the width direction of the flexible actuator and / or the spacing between adjacent textures and / or the number of scans.

[0028] A third aspect of the present invention is to provide an application of the Janus flexible actuator with rapid solvent vapor response according to any one of the preceding claims, including using the flexible actuator in the fields of soft actuation and flexible execution, sensing and detection, and causing the flexible actuator to undergo reversible deformation by stimulating or removing desorption of organic solvent vapor.

[0029] In a preferred embodiment, the flexible actuator is used to fabricate soft grippers, smart switches, directional crawlers, spiral winding grippers, organic solvent vapor detectors, small load lifting devices, or flexible electronic actuators. By combining one or more of the flexible actuators with clamps, conductive electrodes, support rods, or objects to be gripped, functions such as object gripping, circuit closure and conduction, continuous crawling, lifting heavy objects, and winding fixation can be achieved. By changing the orientation texture direction of laser etching, different bending directions, different spiral directions, and different motion modes can be further controlled.

[0030] In preferred technical solutions, the flexible actuator can be cut into strip, sheet, and rectangular structures according to application requirements. Strip actuators are suitable for unidirectional bending, switch closure, directional crawling, and wrapping clamping; sheet actuators are suitable for large-area bending, covering response, and soft object grasping; multiple sheet actuators can be symmetrically arranged around a support rod or fixed end to form a multi-finger soft gripper; by changing the length, width, thickness, and orientation of the texture structure of the flexible actuator, the bending curvature, response speed, contact area, and load capacity can be further controlled. Shorter actuators have the characteristics of fast response and structural stability; longer actuators can generate greater displacement or wrapping stroke; narrower actuators are suitable for crawling and switch triggering; wider actuators are suitable for lifting and clamping lightweight objects.

[0031] In a preferred embodiment, the flexible actuator bends and contacts the opposite conductive terminal under the stimulation of hexane vapor, thereby achieving circuit closure and conduction; or, the flexible actuator curls or spirals under the stimulation of hexane vapor, thereby achieving target object grasping, load lifting, or directional movement.

[0032] Compared with the prior art, the beneficial effects of the present invention are at least as follows: (1) Non-contact response: The present invention uses a polydimethylsiloxane active layer and a polyimide passive layer to form a double-layer flexible actuator. The active layer is induced to swell by organic solvent vapor, and the swelling strain is converted into macroscopic bending deformation by the constraint of the passive layer. Compared with direct contact drive by liquid solvent, the present invention can reduce solvent residue, surface contamination and excessive swelling, and achieve a more gentle and controllable non-contact drive.

[0033] (2) Possesses Janus wetting properties, fast response speed, and large deformation range: In this invention, inorganic fillers are introduced into the polydimethylsiloxane active layer. The inorganic fillers can be further selected as silica particles and graphene conductive / reinforcing fillers. An oriented texture structure is constructed on the surface of the active layer by laser etching. This oriented texture can increase the surface roughness, improve the interaction efficiency between organic solvent vapor and the active layer, and provide a structural anisotropy basis for the control of bending direction, exhibiting hydrophobic or superhydrophobic properties. It forms an asymmetric wetting gradient and adsorption capacity difference with the hydrophilic passive layer, thereby improving the response speed and bending output of the actuator. The flexible actuator described in this invention has a fast response speed and high bending curvature under the stimulation of organic solvent vapors such as hexane. Under preferred conditions, the actuator with a thickness of 250 μm and 9 laser etchings can achieve a large bending deformation within 4.3 seconds, with an average bending curvature of 0.563 mm. -1 It can meet application requirements such as rapid response, target object grasping, and lightweight execution.

[0034] (3) Deformation controllable: The present invention can control the deformation mode of the flexible actuator by changing the orientation of the orientation texture structure. When the texture orientation is different, the flexible actuator can produce axial bending, helical bending or winding deformation in opposite directions. Compared with the traditional double-layer actuator which can only produce a single bending mode, the present invention realizes programmable control of bending direction and deformation mode under the same material system.

[0035] (4) Good reversibility, cycle stability and reusability: The flexible actuator described in this invention has good reversibility and cycle stability. After being stimulated by organic solvent vapor, the actuator can recover its deformation through solvent desorption. It has been tested and can maintain a relatively stable bending response in multiple stimulation and recovery cycles. It is suitable for flexible switches, crawling drives and soft clamping scenarios that require repetitive actions. At the same time, it achieves superhydrophobic surface, which is beneficial for stable operation in harsh environments such as humid environments.

[0036] (5) Simple preparation method: No complex molds, masks or wet micro-nano processing technology is required. The active layer can be obtained by mixing, degassing, thickness limiting film formation and heating curing. The oriented texture structure is formed by direct laser processing. The process flow is short and the parameters are adjustable. It is suitable for preparing flexible actuators with different thicknesses, sizes and texture directions, and is suitable for mass production.

[0037] (6) It has good functional expandability: by combining the flexible actuator with electrodes, clamps, support rods or light loads, it can realize functions such as circuit closure and conduction, soft grasping, directional crawling, lifting heavy objects and spiral winding; by changing the laser etching angle and pattern, it can be further expanded to multi-directional motion, selective winding and complex path execution. Attached Figure Description

[0038] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the flexible actuator structure and steam response mechanism described in this invention.

[0039] Figure 2 This is a schematic diagram of the fabrication process of the flexible actuator described in this invention.

[0040] Figure 3 This is a comparison diagram of the flexible actuator before and after laser etching and the water contact angle on the PI side in Embodiment 11 of the present invention.

[0041] Figure 4 Figure 11 shows the surface and cross-sectional morphology of the flexible actuator after laser etching. Figure (a) shows the cross-sectional morphology of the flexible actuator, Figure (b) shows the SEM image with the oriented stripe texture at an angle of 0° relative to the width direction of the flexible actuator, Figure (c) shows the SEM image with the oriented stripe texture at an angle of 45° relative to the width direction of the flexible actuator, and Figure (d) shows the SEM image with the oriented stripe texture at an angle of -45° relative to the width direction of the flexible actuator.

[0042] Figure 5 This is a real-life photograph of the flexible actuator driven by organic solvent vapor in Embodiment 11 of the present invention.

[0043] Figure 6 This is a schematic diagram of the deformation modes corresponding to different texture directions of the flexible actuator in Embodiment 11 of the present invention.

[0044] Figure 7 This is a graph showing the cyclic stability and reversible recovery test data of the flexible actuator in Embodiment 11 of the present invention. Detailed Implementation

[0045] To address the problems of insufficient response speed, easy contamination from direct contact with liquid solvents, unidirectional deformation, insufficient cycle stability, and limited application modes of existing solvent-responsive actuators, this invention considers amplifying the bending output through strain mismatch between the active and passive layers of a bilayer structure. By combining surface microstructure to change the material's surface roughness, wetting state, and solvent mass transfer path, a Janus structure with thickness-direction asymmetric wetting is constructed. This invention develops an organic solvent vapor-responsive Janus flexible actuator and its fabrication method, which is simple in structure, easy to prepare, fast in response speed, has good reversibility, good cycle stability, and can control the bending direction and deformation mode through oriented texture structure.

[0046] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the scope of protection of the present invention. Without departing from the concept of the present invention, those skilled in the art can make appropriate adjustments to the active layer composition, passive layer material, film thickness, laser etching parameters, texture direction, solvent type, and application structure according to actual needs. These equivalent substitutions or conventional modifications should all be included within the scope of protection of the present invention.

[0047] The reagents used in the following examples and comparative examples came from the following sources: Polydimethylsiloxane prepolymer and its matching curing agent (DC184) were purchased from Kunshan Development Zone Wanbotong New Materials Business Department; nano silica powder (particle size 15nm) was purchased from XFNANO Materials Technology Co., Ltd.; graphene powder was purchased from Shenzhen Suiheng Technology Co., Ltd.; polyimide tape (PI tape) was purchased from Shenzhen Changdasheng Electronics Co., Ltd.; and n-hexane, n-pentane, dichloromethane, acetone, ethanol, methanol and deionized water were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0048] The test methods for the following embodiments and comparative examples include: (1) Surface wettability test: The water contact angle of the sample on the PDMS side and the PI side was tested using an OCA20 water contact angle meter. During the test, water droplets were added to the sample surface and the water contact angle after the water droplets stabilized was recorded. Multiple different locations were selected for testing on the same sample, and the average value was taken as the water contact angle result of the sample to compare the changes in the wettability of the sample surface before and after laser etching.

[0049] (2) Solvent vapor driven test: Fix one end of the sample to the fixture so that the PDMS composite layer faces the solvent vapor environment; place a certain volume of organic solvent under the sample and provide solvent vapor stimulation by natural evaporation, heating evaporation, etc. Use a high-speed camera to record the bending deformation of the sample during the stimulation process; preferably use n-hexane as the main stimulation solvent to evaluate the response time and maximum bending curvature of the sample.

[0050] (3) Bending curvature test: The bending process of the sample is recorded by a high-speed camera, and the bending profile of the sample is fitted by ImageJ image processing software to calculate the bending curvature. The bending curvature is used to evaluate the driving output capability of the sample. The test content may include the comparison of the bending curvature of the sample before and after etching, and the comparison of the bending curvature under different laser etching times.

[0051] like Figures 1-2 The image shows a preferred embodiment of the method for fabricating the solvent vapor fast-response Janus flexible actuator according to the present invention. The fabrication method includes the following steps: Preparation of S1, polydimethylsiloxane composite slurry: Weigh 15g of polydimethylsiloxane prepolymer (PDMS prepolymer) and 1.5g of curing agent, place them in a clean container, and stir thoroughly to ensure uniform mixing of the prepolymer and curing agent, thus obtaining a polydimethylsiloxane mixture system. Then, weigh 0.3g of silica powder and 0.15g of graphene powder and add them to the above polydimethylsiloxane mixture system, and continue stirring to ensure that the silica powder and graphene powder are dispersed as uniformly as possible in the polydimethylsiloxane prepolymer, thus obtaining a polydimethylsiloxane composite slurry.

[0052] To reduce bubble defects in the slurry, the above-mentioned uniformly mixed polydimethylsiloxane composite slurry is placed in a vacuum environment for degassing treatment. The degassing time can be determined according to the slurry volume and bubble content. After degassing, the polydimethylsiloxane composite slurry should be uniform, continuous and free of obvious large bubbles to ensure uniform film thickness and stable driving response in the subsequent process.

[0053] S2, Thickness-limited film formation and curing of polydimethylsiloxane composite films: The degassed polydimethylsiloxane composite slurry from step S1 is transferred between two clean polypropylene plates. A manganese steel gap gauge is placed between the two polypropylene plates to control the thickness of the polydimethylsiloxane composite film, resulting in a thickness-limited film structure. The thickness of the manganese steel gap gauge can be selected according to the thickness of the target flexible actuator, preferably 100-500 μm. In this embodiment, a 200 μm gap gauge is used to control the thickness of the polydimethylsiloxane composite layer.

[0054] The assembled thickness-limited film structure is placed in a constant temperature drying oven for heating and curing. The curing temperature is preferably 60-100℃ and the curing time is preferably 0.5-2h. In this embodiment, the polydimethylsiloxane composite slurry is heated at 80℃ for 1h to fully crosslink and cure, forming a polydimethylsiloxane composite film (PDMS composite film).

[0055] S3, Composite of polydimethylsiloxane composite film and polyimide layer: After the polydimethylsiloxane composite film from step S2 has cured and cooled to room temperature, it is removed from between the polypropylene plates and cut into samples of a predetermined size as the active layer of polydimethylsiloxane. The samples can be cut into strips, rectangular sheets, arc shapes, or other irregular shapes. Strip samples are suitable for unidirectional bending, opening and closing, crawling, and winding experiments; sheet samples are suitable for large-area bending or soft-body grasping experiments. Polyimide tape (PI tape) is used as the passive layer, and the cut polydimethylsiloxane... An alkyl composite film is attached to the adhesive side of a polyimide tape, forming a tightly bonded bilayer structure between the polydimethylsiloxane composite film and the polyimide layer, i.e., a polydimethylsiloxane composite layer / polyimide layer (PDMS / PI) bilayer sample; the thickness of the polyimide tape is preferably 25-100 μm, and in this embodiment it is 50 μm; during bonding, obvious bubbles, wrinkles or local debonding should be avoided to ensure that the bilayer flexible actuator can bend stably under the stimulation of organic solvent vapor.

[0056] S4. Laser etching constructs oriented texture structures: The polydimethylsiloxane composite layer / polyimide layer bilayer sample obtained in step S3 is placed on the worktable of the laser etching equipment with the polydimethylsiloxane composite layer surface facing upward. Laser etching is performed on the surface of the polydimethylsiloxane composite layer according to the preset bending direction to form an orientation texture structure.

[0057] The laser etching parameters can be adjusted according to the equipment power, film thickness, and target texture depth. Preferably, the laser scanning speed is 100–500 mm / s, the laser power is 5%–30% of the equipment's rated power, the number of laser scans is 3–15, and the spacing between adjacent textures is 0.05–0.5 mm. In this embodiment, the laser scanning speed is 200 mm / s, the laser power is 20% of the equipment's rated power, the number of laser scans is 9, the spacing between adjacent textures is 0.1 mm, and the oriented texture structure includes several parallel oriented stripe textures. The angle between the oriented stripe textures and the width direction of the flexible actuator is 0°. After laser etching, anhydrous ethanol or clean airflow is used to remove surface impurity particles as needed, and the actuator is dried at room temperature to obtain a laser texture-controlled solvent vapor fast response Janus flexible actuator (PDMS / PI dual-layer actuator).

[0058] (1) To evaluate the effect of laser etching on the surface wettability, bending output, and deformation direction control capability of the flexible actuator, a comparative actuator without etching was prepared: A bilayer sample of a polydimethylsiloxane composite layer / polyimide layer without laser etching was prepared according to steps S1-S3 as the comparative actuator without etching. The comparative actuator without etching has the same material composition, active layer thickness, passive layer thickness, and sample size as the laser-etched actuator in Example 1, the only difference being that its polydimethylsiloxane composite layer surface does not have a laser-oriented texture structure. Figures 5-6 As shown, in the organic solvent vapor-driven test, one end of the flexible actuator is fixed so that the polydimethylsiloxane active layer faces the organic solvent vapor environment. After being stimulated by organic solvent vapors such as n-hexane, the polydimethylsiloxane active layer swells, and the PI tape passive layer restricts its free expansion, causing the actuator to gradually bend from the initial straight state. By recording the bending process of the actuator and performing image analysis on its bending profile, the response time and bending curvature can be obtained, which can be used to evaluate the vapor response speed and bending output capability of the actuator.

[0059] To investigate the effect of the mass ratio of PDMS prepolymer, curing agent, silica, and graphene in the polydimethylsiloxane active layer on the surface wetting properties of the flexible actuator, step S4 was omitted, and the basic mass ratio of PDMS prepolymer, curing agent, silica, and graphene in Example 1 was set to 100:10:2:1. Different PDMS composite films were prepared by changing the content of one component, and then these films were laminated with PI tape to form a PDMS / PI bilayer actuator. Specifically, Group 1: Comparative Examples 1-2 differed from Examples 1-3 in the mass ratio of the curing agent, used to investigate the effect of the curing agent content on the film formation state and surface hydrophobicity of the polydimethylsiloxane active layer; Group 2: Comparative Examples 3-4 differed from Examples 4-6 in the mass ratio of silica, used to investigate the effect of the inorganic filler content on surface roughness and water contact angle; Group 3: Comparative Examples 5-6 differed from Examples 7-9 in the mass ratio of graphene, used to investigate the effect of the conductive / reinforcing filler content on the film surface uniformity and wetting properties. To facilitate comparison of the various variable groups, the basic ratio of 100:10:2:1 was repeated in different variable groups. Water contact angle (WCA) tests were performed on each sample, and the results are shown in Table 1 below.

[0060] Table 1. Effect of polydimethylsiloxane active layer composition on water contact angle

[0061] Table 1 shows that when the curing agent content is too low, the PDMS composite film is under-cured, the surface is sticky, and the structural stability is poor, resulting in a low water contact angle. When the curing agent content is too high, the film cross-linking degree is too high, the film layer is too hard, and both the surface condition and hydrophobic properties are affected. When the silica content is too low, the surface roughness of the active layer is insufficient, making it difficult to form a surface structure conducive to hydrophobicity. When the silica content is too high, the filler is prone to agglomeration, leading to an increase in surface defects and a decrease in the water contact angle. When the graphene content is too low, its effect on the structural stability and surface modification of the film is limited. When the graphene content is too high, the sheet filler is prone to agglomeration, reducing the surface uniformity of the film. In summary, the mass ratio of PDMS prepolymer, curing agent, silica, and graphene is 100:10:2:1, resulting in a better sample surface condition and a higher water contact angle, which can be used as the preferred ratio for subsequent laser etching and steam-driven testing.

[0062] (2) To further investigate the effect of polydimethylsiloxane active layer components on the organic solvent vapor response performance of the flexible actuator, PDMS / PI bilayer actuators were prepared using the same component variable settings as in Table 1, and the maximum bending curvature of each sample was tested under the same n-hexane vapor stimulation conditions. That is, Group 1: The difference between Comparative Examples 1-2 and Examples 1-3 is the different mass fraction of curing agent, used to investigate the effect of the degree of PDMS crosslinking on the bending output and recovery stability of the actuator; Group 2: The difference between Comparative Examples 3-4 and Examples 4-6 is the different mass fraction of silica, used to investigate the effect of inorganic filler content on the swelling response and bending curvature of the active layer; Group 3: The difference between Comparative Examples 5-6 and Examples 7-9 is the different mass fraction of graphene, used to investigate the effect of conductive / reinforcing fillers on the bending output and structural stability of the actuator; To facilitate comparison of each variable group, the basic ratio 100:10:2:1 is repeated in different variable groups; n-hexane vapor drive tests were performed on each sample, and the results are shown in Table 2 below.

[0063] Table 2. Effect of polydimethylsiloxane active layer composition on bending curvature

[0064] Table 2 shows that when the curing agent content is too low, the polydimethylsiloxane active layer is not sufficiently cross-linked. Although the material is relatively soft, its recovery stability is poor, making it difficult to obtain a stable and reversible bending response. When the curing agent content is too high, the film stiffness increases, and the strain generated by the swelling of the active layer is difficult to effectively convert into macroscopic bending, resulting in a decrease in the maximum curvature. When the silica content is moderate, it is beneficial to improve the surface and internal structural stability of the active layer and improve the steam action efficiency. However, excessive silica will increase the film stiffness and cause filler agglomeration, thereby inhibiting bending output. When the graphene content is moderate, it can improve the mechanical stability and laser processing adaptability of the composite film. Excessive graphene will lead to increased film stiffness and increased local defects, reducing the bending curvature of the actuator. Combining Tables 1 and 2, it can be seen that the polydimethylsiloxane active layer with a mass ratio of 100:10:2:1 has good surface hydrophobicity, film quality, and bending response performance. Therefore, it is determined to be the preferred basic ratio for subsequent laser etching experiments.

[0065] (3) In order to investigate the influence of laser etching parameters on the surface wetting performance of PDMS / PI flexible actuator and the influence of laser etching parameters on the organic solvent vapor response performance of PDMS / PI flexible actuator, a polydimethylsiloxane active layer with a mass ratio of PDMS prepolymer, curing agent, silica and graphene of 100:10:2:1 was selected as the base sample. The proportion of this group was kept constant, and different etching samples were prepared by changing the laser scanning speed, laser power, number of scans and adjacent texture spacing in step S4. Group 1: The difference between Comparative Examples 7-8 and Examples 10-12 is the scanning speed, used to investigate the effect of laser action time per unit area on stripe formation and water contact angle, and the effect of scanning speed on bending curvature and response stability; Group 2: The difference between Comparative Examples 9-10 and Examples 13-15 is the laser power, used to investigate the effect of laser energy input on surface roughening and thermal damage, and the effect of laser power on the surface structure and curvature output of the active layer; Group 3: The difference between Comparative Examples 11-12 and Examples 16-20 is the number of scans, used to investigate the effect of repeated etching on surface wetting performance, and the effect of the number of etchings on the enhancement effect of bending output; Group 4: The difference between Comparative Examples 13-14 and Examples 21-24 is the spacing between adjacent textures, used to investigate the effect of texture density on the driver curvature output, and the effect of texture density on water contact angle. Water contact angle tests were performed on each sample, and the results are shown in Table 3. The response speed was calculated as the ratio of maximum curvature to response time, i.e., response speed = maximum curvature / response time; "—" indicates that the sample surface was severely damaged or that stable test results could not be obtained.

[0066] Table 3. Effects of laser etching parameters on the water contact angle and bending curvature of the preferred sample.

[0067] Table 3 shows that the unetched sample has some hydrophobicity, but has not yet reached a superhydrophobic state. After laser etching, directional stripe textures are formed on the surface of the polydimethylsiloxane active layer, and the water contact angle is significantly improved. When the scanning speed is too slow or the laser power is too high, the heat input per unit area is too large, which can easily cause local thermal damage, reduce surface uniformity, or even damage the sample. When the scanning speed is too fast or the laser power is too low, the texture formation is insufficient, and the improvement in water contact angle is limited. As the number of scans increases, the water contact angle of the sample first increases and then tends to stabilize. Although the water contact angle still increases after 12 scans or more, excessive scanning will cause surface damage and affect the service life. Too small a spacing between adjacent textures can easily cause local texture overlap, while too large a spacing between adjacent textures will reduce the texture coverage. In summary, the sample has a higher water contact angle and a more complete surface texture structure when the scanning speed is 200 mm / s, the laser power is 20%, the number of scans is 9, and the spacing between adjacent textures is 0.10 mm.

[0068] Table 3 shows that, compared with the unetched sample, appropriate laser etching can improve the maximum bending curvature of the PDMS / PI flexible actuator. This indicates that directional stripe texture is beneficial to enhancing the effect of organic solvent vapor on the polydimethylsiloxane active layer and promoting the transformation of active layer swelling mismatch into macroscopic bending output. When the scanning speed is too fast, the laser power is too low, or the number of scans is too few, the stripe texture is shallow, and the curvature improvement is limited. When the scanning speed is too slow, the laser power is too high, or the number of scans is too many, the local heat input is too large, which can easily lead to surface damage or structural defects, decreased bending stability, reduced sample lifespan, or sample damage. The spacing between adjacent textures also affects the driving performance. Too small a spacing may cause local etching overlap, while too large a spacing will result in insufficient effective texture coverage. Based on Table 3, a scanning speed of 200 mm / s, a laser power of 20%, 9 scans, and an adjacent texture spacing of 0.10 mm can achieve a good balance between surface wetting performance, bending curvature, and sample integrity, and can be used as the preferred laser etching parameters of this invention.

[0069] Overall, Tables 1-3 collectively demonstrate that a reasonable composite active layer ratio is fundamental to achieving stable driving performance, while appropriate laser texturing further enhances surface wettability and organic solvent vapor response; the synergistic effect of these two factors enables the PDMS / PI flexible actuator to achieve rapid, controllable, and stable bending response; for example... Figures 3-4As shown, laser etching can form directional stripes, grooves, or ridges on the surface of the polydimethylsiloxane active layer, changing the surface roughness and structural anisotropy of the sample. Under the stimulation of organic solvent vapor, the flexible actuator swells after the active layer adsorbs organic solvent molecules, and a strain mismatch is formed between it and the passive layer, resulting in reversible bending, curling, spiral bending, or winding deformation. The water contact angle before etching is about 116°, while the water contact angle after etching can reach 153°, which is a superhydrophobic state. For vapor-responsive flexible actuators, superhydrophobic properties are beneficial for stable operation in harsh environments such as humidity. The water contact angle of the back PI tape is only 72°. Laser etching changes the surface roughness and wetting state of the polydimethylsiloxane active layer and may improve the contact and diffusion process between organic solvent vapor and the active layer, thereby improving the bending response. The comparative experiments in Table 3 also show that laser etching can indeed improve vapor diffusion.

[0070] (4) To further verify the applicability of the polydimethylsiloxane active layer composition range to the vapor response performance of the laser texture-controlled flexible actuator, based on the formulation screening shown in Tables 1 and 2, representative ratios close to the endpoints of the composition range described in the claims were selected for supplementary experiments. Specifically, while keeping the preferred laser etching conditions of 200 mm / s laser scanning speed, 20% laser power, 9 scans, and 0.10 mm spacing between adjacent textures unchanged, the mass fractions of curing agent, silica, and graphene were adjusted to prepare different PDMS / PI bilayer flexible actuators, and their water contact angle, maximum bending curvature, response time, and response speed were tested. The difference between Examples 25-34 and Example 11 is that the contents of curing agent, silica, and graphene in the polydimethylsiloxane active layer are different, which are used to examine the vapor response capability of different boundary ratios within the active layer composition range described in this invention after laser etching. The results are shown in Table 4 below.

[0071] Table 4. Response performance of boundary samples with different active layer compositions under preferred laser etching conditions

[0072] As shown in Table 4, the present invention processes directional stripes on the PDMS surface by laser etching, actively creating anisotropy of solvent swelling. Combined with the uniform constraint of the PI layer, the strain mismatch of the two layers is released in a directional manner to control bending. When the mass ratio of PDMS prepolymer, curing agent, silica and graphene is in the range of 100:(5~15):(0.5~5):(0.1~3), after processing under the optimized laser etching conditions, the obtained PDMS / PI flexible actuator can form an effective bending response, indicating that this component range can support the organic solvent vapor response function of the present invention. Compared to the preferred ratio of 100:10:2:1, samples with ratios close to the endpoints still exhibit a certain water contact angle and curvature. However, when the curing agent content is low, the degree of film cross-linking is insufficient, and the recovery stability is relatively reduced. When the curing agent content is high or the filler content is high, the film stiffness increases, while the curvature and response speed decrease. When the silica and graphene contents are low, the surface roughness, texture retention, and composite reinforcement are insufficient, and the response performance is also lower than the preferred example. However, after preferred laser etching, the samples with the above boundary ratios are still higher than the unetched comparative example and the comparative example with out-of-range laser parameters, indicating that this component range can still support the rapid response function of the present invention. In summary, the samples within the component range all have usable steam response capabilities. Among them, the 100:10:2:1 ratio shows a better balance between water contact angle, maximum curvature, response time, and response speed, and can be used as a further preferred ratio of the present invention.

[0073] like Figure 7 As shown, the flexible actuator of the present invention can achieve a reversible response of bending and recovery during the stimulation and removal of organic solvent vapor. After 100 stimulation and recovery cycles, the actuator can still maintain a relatively stable bending deformation capability, indicating that there is good interfacial bonding stability between the polydimethylsiloxane active layer and the PI tape passive layer. The directional stripe texture formed by laser etching can remain basically intact during the cycle, thereby enabling the flexible actuator to be reused.

[0074] The flexible actuator described in this invention has advantages such as non-contact response, fast response speed, controllable deformation, good reversibility, good cycle stability, and reusability, achieving a balance of performance. It can be combined with electrodes, clamps, support rods, or lightweight loads according to application requirements. When the flexible actuator is used for circuit closure, it bends and contacts the conductive terminal on the opposite side under the stimulation of organic solvent vapor, realizing circuit conduction. When the flexible actuator is used for directional crawling, it can generate displacement by periodic bending and recovery. When the flexible actuator is used for lifting small loads, the supporting force or traction force generated by the bending of the actuator can drive the lightweight load to move. When the flexible actuator is used for helical winding, textured samples with an included angle of 45° or −45° can generate helical deformation under vapor stimulation, realizing the winding and clamping of rod-shaped or line-shaped targets.

[0075] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For example, the active layer composition, passive layer material, film thickness, laser etching parameters, texture direction, solvent type, and application form can be adjusted as needed. For example, the orientation texture structure is a striped, grooved, or ridged texture disposed on the surface of the polydimethylsiloxane composite layer. The striped texture is not limited to parallel stripes in a single direction, but can also be intersecting stripes, partitioned stripes, or gradient-spacing stripes. Parallel stripes in a single direction can be used to obtain stable directional bending; intersecting stripes can be used to enhance surface roughness and vapor contact area; partitioned stripes can be used to form different bending regions on the same actuator; gradient-spacing stripes can be used to generate non-uniform curvature distribution. Through the above texture design, the flexible actuator can achieve differentiated deformation in different regions under the same vapor stimulation, thereby obtaining more complex motion patterns and higher programmability. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Janus flexible actuator with fast solvent vapor response, characterized in that, The device includes a passive layer and a polydimethylsiloxane active layer disposed on the adhesive side of the passive layer. The passive layer is used to restrict the free expansion of the polydimethylsiloxane active layer. The polydimethylsiloxane active layer is composed of a polydimethylsiloxane prepolymer, a curing agent, and an inorganic filler. The mass ratio of the polydimethylsiloxane prepolymer, curing agent, and inorganic filler is 100:(5-15):(0.6-8). The side of the polydimethylsiloxane active layer away from the passive layer is provided with an oriented texture structure that induces deformation of the flexible actuator. The side surface of the polydimethylsiloxane active layer away from the passive layer has hydrophobic or superhydrophobic properties, while the passive layer has hydrophilic properties. Together, they form an asymmetric wetting gradient.

2. The Janus flexible actuator with fast solvent vapor response according to claim 1, characterized in that, The passive layer is a polyimide layer with an adhesive layer, and the thickness of the passive layer is 25-100 μm; the thickness of the polydimethylsiloxane active layer is 100-500 μm; and the total thickness of the flexible actuator is 150-550 μm.

3. The Janus flexible actuator with fast solvent vapor response according to claim 1, characterized in that, The inorganic filler is composed of silicon dioxide and graphene in a mass ratio of (0.5-5):(0.1-3).

4. The Janus flexible actuator with fast solvent vapor response according to claim 1, characterized in that, The oriented texture structure includes several striped, grooved, or ridge-like textures, with a spacing of 0.05 to 0.5 mm between adjacent textures.

5. The Janus flexible actuator with fast solvent vapor response according to claim 1, characterized in that, The orientation texture structure includes several parallel stripe-like textures. The angle between the stripe-like textures and the width direction of the flexible actuator is -90° to 90°. An angle of 0° is used to induce bending or curling deformation, which is mainly bending in the length direction of the flexible actuator. Textures with an angle of 45° or -45° are used to induce spiral bending or winding deformation in the opposite direction.

6. The Janus flexible actuator with fast solvent vapor response according to claim 1, characterized in that, The polydimethylsiloxane active layer can swell by adsorbing and diffusing organic solvent molecules when stimulated by organic solvent vapor, and can desorb organic solvent molecules after the organic solvent vapor stimulation is removed, thereby causing the flexible actuator to undergo reversible deformation; the organic solvent vapor is one or more of n-hexane, n-pentane, dichloromethane, acetone, ethanol or methanol; the organic solvent vapor stimulation method includes one or more of static vapor stimulation, heated volatilization vapor stimulation and atomized vapor stimulation; the organic solvent desorption method includes one or more of natural evaporation, air flow, heating or negative pressure extraction.

7. The method for preparing the Janus flexible actuator with fast solvent vapor response according to any one of claims 1 to 6, characterized in that, Its preparation method includes the following steps: S1. Mix the components including polydimethylsiloxane prepolymer, curing agent and inorganic filler evenly and degas them under vacuum to prepare polydimethylsiloxane composite slurry. S2. The polydimethylsiloxane composite slurry obtained in step S1 is prepared into a polydimethylsiloxane composite film and cured. S3. Cut the polydimethylsiloxane composite film obtained in step S2 into a preset size as the polydimethylsiloxane active layer, and attach the polydimethylsiloxane active layer to the adhesive side of the passive layer to form a double-layer structure film. S4. An oriented texture structure is processed on the surface of the polydimethylsiloxane active layer of the bilayer structure film obtained in step S3 to obtain the flexible actuator.

8. The method for preparing the Janus flexible actuator with fast solvent vapor response according to claim 7, characterized in that, In step S2, a polydimethylsiloxane composite film is prepared by a thickness-limited film formation method; it is cured by heating at a temperature of 60–100°C for a time of 0.5–2 hours.

9. The method for preparing the Janus flexible actuator with fast solvent vapor response according to claim 7, characterized in that, In step S3, the orientation texture structure is processed by laser marking or laser etching. The scanning speed of laser etching is 100-500 mm / s, the laser power is 5%-30% of the rated power, and the number of scans is 3-15.

10. The application of the Janus flexible actuator with fast solvent vapor response according to any one of claims 1 to 6, characterized in that, This includes using the flexible actuator in the fields of software actuation and flexible execution, sensing and detection, and causing the flexible actuator to undergo reversible deformation by stimulating or removing organic solvent vapors.

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