Underwater transparent flexible drive device

Abstract

This invention discloses an underwater transparent flexible actuation device, belonging to the field of underwater soft robot technology. The device includes a flexible support frame, a composite actuation film, and conductive connectors. The flexible support frame is a monolithic polymer film with multiple cantilevered support ribs evenly distributed outwards from the center. The composite actuation film is attached and fixed to the flexible support frame and includes two equiaxed pre-stretched dielectric elastomer film layers and a flexible conductive layer sandwiched between them. The two dielectric elastomer film layers self-encapsulate the flexible conductive layer, which is connected to an external power source via conductive connectors. Both the flexible support frame and the composite actuation film are made of transparent materials. By controlling the on / off state of the flexible conductive layer, the flexible support frame is driven to expand and contract to generate buoyancy thrust. This invention solves the problems of complex encapsulation and opacity inherent in traditional DE actuator technology.

Description

Technical Field

[0001] This invention relates to the field of underwater soft robot technology, specifically to an underwater transparent flexible drive device, which is an underwater transparent flexible drive device based on dielectric elastomer drive. Background Technology

[0002] With the increasing demand for marine resource development, underwater vehicles are being used more and more widely. However, traditional rigid drive methods suffer from drawbacks such as high noise, strong disturbance, and poor stealth. Dielectric elastomers, due to their large deformation and high energy density, have become ideal materials for constructing flexible biomimetic robots. However, current technologies still face the following bottlenecks in fully transparent underwater applications: 1. Insulation versus efficiency: Traditional DE actuators (dielectric elastomer actuators) are prone to short circuits in conductive water media, and additional insulating encapsulation not only complicates the process, but the parasitic stiffness it introduces also hinders deformation and significantly reduces actuation efficiency.

[0003] 2. Transparency and material constraints: Mature carbon-based electrodes are opaque and cannot meet the needs of covert reconnaissance; while transparent electrodes such as silver nanowires are expensive and have poor underwater stability, making them difficult to use on a large scale.

[0004] Therefore, there is an urgent need to develop a transparent, efficient, and flexible drive device that has a simplified structure, requires no complex packaging, and can utilize the properties of water as a medium. Summary of the Invention

[0005] The technical problem to be solved: To avoid the shortcomings of the prior art, the present invention provides an underwater transparent flexible actuation device. Both the flexible support frame and the composite actuation film attached to the flexible support frame are made of transparent materials. The composite actuation film is self-encapsulated by two pre-stretched dielectric elastomer films sandwiching a transparent flexible conductive layer. The flexible conductive layer, as an electrode, uses ion hydrogel to solve the problems of complex encapsulation and opacity in traditional DE actuator technology.

[0006] The technical solution of this invention is: an underwater transparent flexible driving device, comprising: The flexible support frame has a spherical crown-shaped connector at its center. Multiple cantilever support ribs are evenly distributed around the connector. The multiple cantilever support ribs are structures that radiate outward from the connector along the spherical surface of the connector. A spherical fan-shaped hollow area is formed between two adjacent cantilever support ribs. The composite actuation film layer is attached and fixed to the upper surface of the flexible support frame with the connector as the center position. The composite actuation film layer includes two dielectric elastomer film layers and a flexible conductive layer sandwiched between the two dielectric elastomer film layers. The two dielectric elastomer film layers have the same structure and are both in an equiaxial pre-stretched state. The edges of the two dielectric elastomer film layers are bonded and sealed to each other to encapsulate the flexible conductive layer. And conductive connectors, including wires, one end of which extends into the interior of the composite actuation membrane layer and is electrically connected to the flexible conductive layer, and the other end is connected to an external power source; the connection end between the wire and the flexible conductive layer is sealed with sealant for waterproofing. Both the flexible support frame and the composite actuation membrane are made of transparent materials; by controlling the on and off of the flexible conductive layer, the flexible support frame is driven to expand and contract to generate buoyancy thrust.

[0007] A further technical solution of the present invention is that the flexible support frame is a single-piece integrated structure.

[0008] A further technical solution of the present invention is: it also includes a flexible passive tentacle, the end of the cantilever support rib away from the connecting seat is a free end, the flexible passive tentacle is bonded to the free end, the stiffness of the flexible passive tentacle is less than the stiffness of the cantilever support rib, and the flexible passive tentacle is used to swing with the cantilever support rib to improve the floating stability of the driving device.

[0009] A further technical solution of the present invention is: the flexible passive tentacle is a trapezoidal sheet structure, the upper bottom side of the trapezoid is bonded to the cantilever support rib, and the waist angle of the trapezoid is 30°-60°.

[0010] A further technical solution of the present invention is that both the flexible support frame and the flexible passive tentacles are made of polyethylene terephthalate film.

[0011] A further technical solution of the present invention is: the outer diameter of the two dielectric elastomer film layers is larger than the outer diameter of the flexible conductive layer, the three-layer structure is concentric, and the outer portions of the two dielectric elastomer film layers that extend beyond the flexible conductive layer contact each other and are bonded and sealed to form an annular insulating sealing edge.

[0012] A further technical solution of the present invention is: the material of the two dielectric elastomer film layers is an acrylic elastomer, and the equiaxial pre-stretch ratio of the two dielectric elastomer film layers is in the range of 1.5×1.5 to 3.0×3.0; the flexible conductive layer is a patterned ion hydrogel layer.

[0013] A further technical solution of the present invention is: when the driving device is applied in a conductive water medium, it forms a single-electrode driving circuit, the flexible conductive layer is connected to the positive terminal of an external high-voltage power supply through a wire, the external water medium of the driving device is grounded as the negative terminal, and the dielectric elastomer film layer between the water medium and the flexible conductive layer serves as an insulating layer.

[0014] A further technical solution of the present invention is that the conductive connector further includes a conductive silver paste layer, which is used to electrically connect the wire and the flexible conductive layer.

[0015] A method for preparing the underwater transparent flexible actuation device includes the following steps: Fabrication of a flexible support frame: Multiple fan-shaped cutouts are laser-cut into a circular sheet of polyethylene terephthalate film. The multiple fan-shaped cutouts are evenly distributed and their central corners all face the center of the circular sheet of film. Ribs are formed between two adjacent fan-shaped cutouts to connect the center of the circular sheet of film and the annular frame. Clean the completed flexible support frame; After the first dielectric elastomer film layer is subjected to equiaxial pre-stretching, it is attached to the cleaned flexible support frame using its own adhesiveness, and its shape is trimmed so that its edges are consistent with the flexible support frame. The upper surface of the first dielectric elastomer film layer is subjected to hydrophilic modification treatment, and then the flexible conductive layer is attached to the center position of the upper surface of the first dielectric elastomer film layer. One end of the wire is introduced into the first dielectric elastomer film layer, and the wire and the flexible conductive layer are electrically connected by conductive silver paste. The other end of the wire is used to connect to an external power source. A waterproof curing adhesive layer is set in the section where the wire is introduced into the film layer. After the second dielectric elastomer film layer undergoes the same equiaxial pre-stretching treatment as the first dielectric elastomer film layer, it is attached to the flexible conductive layer, so that its edges are bonded to the first dielectric elastomer film layer. Its shape is then trimmed so that its edges are consistent with the flexible support skeleton frame. Thus, the encapsulation of the electrode in the composite actuation film layer is completed. Cut away the annular frame area opposite each fan-shaped hollow part in the flexible support frame, so that the annular frame breaks the restraint on the ribs, and each rib forms a cantilever support rib. The central area is the connecting seat. When cutting, the two layers of dielectric elastomer film attached to the area to be removed on the annular frame are also cut away. After cutting, under the mechanical coupling effect between the pre-stretching force of the two dielectric elastomer film layers and the stiffness of the flexible support frame structure, each cantilever support rib naturally curls from the initial planar shape toward the central axis, resulting in the spherical crown-shaped flexible drive device shape when not energized.

[0016] The beneficial effects of this invention are as follows: This invention provides an underwater transparent flexible actuation device. A flexible support frame serves as the flexible support body, with multiple cantilevered support ribs evenly distributed around its circumference that can flexibly retract and expand. A self-encapsulated composite actuation membrane layer is bonded to this frame. The composite actuation membrane layer adopts a sandwich structure, encapsulating a flexible conductive electrode layer through two layers of dielectric elastomer films. Simultaneously, the wires connecting the flexible conductive layer to the external power supply are sealed to the composite actuation membrane layer with a waterproof curing adhesive layer, achieving a waterproof seal for the electrodes and improving the stability of the underwater working environment. Both the flexible support frame and the composite actuation membrane layer are made of transparent materials, meeting the concealment requirements. The flexible support frame expands and contracts to generate propulsion by switching the flexible conductive layer on and off. The overall structure is simple and highly operable.

[0017] Specifically, compared with traditional underwater propulsion devices, the present invention has the following advantages: 1. Flexible and transparent design, suitable for covert underwater scenarios: This invention has optical transparency in the visible light band, which can complete tasks such as covert movement and biological observation without affecting the normal activities of organisms.

[0018] 2. Waterproof self-sealing structure, simplified design and reliable sealing: This invention achieves reliable sealing through a dual waterproof design: firstly, the annular insulating sealing edge of the composite actuation membrane layer forms a self-sealing waterproof structure; secondly, the waterproof curing adhesive layer of the wire interface seals the gaps to prevent liquid infiltration. No additional sealing components are required, simplifying the structure and improving adaptability to underwater environments and long-term stability.

[0019] 3. Integrated mechanical coupling design, with movement patterns closer to natural organisms: This invention adopts a single-piece integrated flexible support skeleton, combined with a pre-stretched composite actuation membrane layer. Through the "mechanical coupling of pre-stretch stress and skeleton structural stiffness", it achieves biomimetic movement of naturally curling when not energized and expanding outward when energized. In addition, the passive follow-up swing of the flexible passive tentacles with lower stiffness makes the propulsion smoother and more flexible.

[0020] 4. Single-electrode drive circuit, adapted to underwater conductive medium environment: The present invention is specifically designed with a single-electrode drive circuit: a transparent flexible conductive layer is connected to the positive electrode of the power supply, the water medium is used as the negative electrode, and the second dielectric elastomer film layer located on the outside of the device serves as an isolation insulating layer. This simplifies the drive circuit structure and solves the short circuit problem in the underwater conductive environment, thereby improving the adaptability and safety of the device in underwater scenarios.

[0021] 5. Stable interlayer adhesion and extended service life: This invention significantly enhances interlayer adhesion by hydrophilically modifying the contact interface between the first dielectric elastomer film layer and the transparent flexible conductive layer. This effectively prevents film peeling during repeated curling and unwinding movements, extending the service life and improving operational stability.

[0022] 6. Simple materials and easy processing: The polyethylene terephthalate film, acrylic elastomers, and ion hydrogels selected in this invention are all common materials that are easy to purchase; the processing only requires laser cutting, heat sealing and bonding, and conventional bonding, and the integrated flexible support frame does not require complex assembly, which is convenient for engineering implementation and mass application. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is an exploded view of the overall structure of an underwater transparent flexible driving device (adhesive flexible passive tentacle) according to the present invention; Figure 2 This is a three-dimensional view of the overall shape of an underwater transparent flexible driving device (adhesive flexible passive tentacle) according to the present invention; Figure 3 This is an exploded view of the structure before trimming the annular frame during the fabrication of an underwater transparent flexible driving device according to the present invention. Figure 4 This is a structural diagram of an underwater transparent flexible driving device of the present invention before trimming the annular frame during the manufacturing process. Figure 5 This is an exploded view of the underwater transparent flexible actuation device of the present invention after trimming the annular frame (without the flexible passive tentacles attached). Figure 6 This is a graph showing the vertical displacement and time relationship of the flexible drive device of the present invention.

[0025] In the figure: 1. Flexible support frame, 11. Connector, 12. Cantilever support rib, 2. Composite actuation film layer, 21. First dielectric elastomer film layer, 22. Flexible conductive layer, 23. Second dielectric elastomer film layer, 3. Wire, 4. Flexible passive tentacle, 10. Flexible support frame, 101. Fan-shaped hollow part, 102. Rib, 103. Annular frame, 104. Cutting area of ​​the annular frame. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 An embodiment of the underwater transparent flexible actuation device of the present invention, such as... Figure 1 , Figure 2 As shown, it includes a flexible support frame 1, a composite actuation membrane layer 2, a conductive connector, and a flexible passive tentacle 4.

[0028] The flexible support frame 1 has a spherical crown-shaped connecting seat 11 at its center. Eight cantilevered support ribs 12 are evenly distributed around the connecting seat 11, forming a structure that radiates outwards from the connecting seat 11 along its spherical surface. This ensures balanced force distribution and stable movement of the device. A spherical fan-shaped hollow area is formed between adjacent cantilevered support ribs 12. The end of each cantilevered support rib 12 furthest from the connecting seat 11 is a free end, allowing for large-angle curling deformation.

[0029] In this embodiment, the flexible support frame 1 is a single-piece integrated structure, and its material is a polyethylene terephthalate film, which is transparent and has a thickness of 0.5 mm.

[0030] The composite actuation film layer 2 is attached and fixed to the upper surface of the flexible support frame 1 with the connecting seat 11 as the center. The composite actuation film layer 2 and the flexible support frame 1 are coaxial and completely cover the flexible support frame 1. The composite actuation film layer 2 includes two dielectric elastomer film layers and a flexible conductive layer 22 sandwiched between the two dielectric elastomer film layers. The two dielectric elastomer film layers have the same structure, namely the first dielectric elastomer film layer 21 and the second dielectric elastomer film layer 23, both in an equiaxial pre-stretched state, and both have the same stretching ratio, which is in the range of 1.5×1.5 to 3.0×3.0. The outer diameter of the two dielectric elastomer film layers is larger than the outer diameter of the flexible conductive layer. The three layers are concentric. The portions of the two dielectric elastomer film layers that extend beyond the outer periphery of the flexible conductive layer 22 are in contact with each other and are bonded and sealed. The bonded portions of the edges of the two dielectric elastomer film layers form an annular insulating sealing edge, constituting a waterproof self-sealing structure, thereby encapsulating the intermediate flexible conductive layer 22 as an electrode. When the composite actuation membrane 2 is bonded to the flexible support frame 1, such as Figure 1 As shown, the first dielectric elastomer film layer 21 and the flexible support skeleton 1 in the composite actuation film layer 2 are bonded and fixed.

[0031] The first dielectric elastomer film layer 21 and the second dielectric elastomer film layer 23 are made of acrylic elastomers, and the flexible conductive layer 22 is a patterned transparent ionic hydrogel. Both dielectric elastomer film layers and the flexible conductive layer 22 are transparent materials.

[0032] To enhance interlayer adhesion, the contact interface between the first dielectric elastomer film layer 21 and the flexible conductive layer 22 is modified with hydrophilicity.

[0033] The conductive connector enables electrical connection between the flexible conductive layer 22 and an external power source. The connector includes a wire 3 and a conductive silver paste layer. One end of the wire 3 extends into the composite actuation membrane layer 2 and is electrically connected to the flexible conductive layer 22 via the conductive silver paste layer. The other end of the wire extends outside the device to connect to an external power source. To ensure the airtightness of the flexible conductive layer 22 and prevent water from entering the composite actuation membrane layer 2 through the connection point of the wire 3, the wire 3 is introduced through the mating surface of two dielectric elastomer film layers. Simultaneously, the gap between the wire 3 and the two dielectric elastomer film layers is sealed with a waterproof curing adhesive layer to prevent liquid infiltration.

[0034] When the conductive connector is electrically connected, the drive device forms a single-electrode drive circuit when applied in a conductive water medium. The flexible conductive layer 22 is connected to the positive terminal of an external high-voltage power supply through the wire 3. The external water medium of the drive device is grounded as the negative terminal. The second dielectric elastomer film layer 23 between the water medium and the flexible conductive layer 22 serves as an insulating layer.

[0035] To improve the underwater stability of the drive unit, a flexible passive tentacle 4 is bonded to the free end of each cantilever support rib 12. The flexible passive tentacle 4 is a trapezoidal sheet structure. The upper base of the trapezoid is bonded and fixed to the cantilever support rib 12, with the width of the upper base being the same as the width of the cantilever support rib 12. The width of the lower base is greater than the upper base, and the waist angle of the trapezoid is 30°-60°. The flexible passive tentacle 4 is made of the same material as the flexible support frame 1—polyethylene terephthalate film—but its stiffness is less than that of the cantilever support rib 12. The flexible passive tentacle 4 passively swings with the cantilever support rib 12 to optimize the underwater stability of the drive unit.

[0036] By using polyethylene terephthalate film for the flexible support frame 1 and the flexible passive tentacles 4, using acrylic elastomer for the two dielectric elastomer film layers, and using transparent ionic hydrogel for the flexible conductive layer 22, the entire device has optical transparency in the visible light band (400-780nm).

[0037] The specific working principle is as follows: The device operates at a driving voltage range of 0 to 5 kV. When not energized, the pre-tension stress of the dielectric elastomer film layer 2 of the composite actuation membrane 2 is mechanically coupled with the structural stiffness of the flexible support frame 1, causing the entire device to naturally curl towards the central axis in a three-dimensional contraction shape. When energized, Maxwell stress drives the deformation of the composite actuation membrane layer 2, causing the flexible support frame 1 to expand outward. This achieves the reciprocating motion of the biomimetic jellyfish through the cycle of switching the power on and off. Specifically, in the driven state, the positive terminal of the external high-voltage power supply is connected to the internal flexible conductive layer 22 via the wire 3, while the negative terminal is the conductive water surrounding the device. When an excitation voltage is applied, an electric field is formed on both sides of the dielectric elastomer film between the internal flexible conductive layer 22 (i.e., the hydrogel electrode) and the external water. The electric field generates Maxwell stress, compressing the dielectric elastomer film and causing it to expand in area. Since the film adheres to the surface of the frame, the expansion force of the film overcomes the bending stiffness and pre-stress of the frame, driving the cantilevered support ribs of the flexible support frame 1 to expand outward. After the voltage is removed, the Maxwell stress disappears, and the device quickly rebounds to its initial curled shape under the pre-tension stress. By periodically controlling the on and off of the excitation voltage, the device achieves repeated expansion and contraction, generating net thrust through fluid interaction to achieve underwater floating motion. Therefore, this invention provides a highly transparent, flexible, and efficient underwater transparent flexible actuation device.

[0038] Figure 6 The vertical displacement and velocity curves of this invention over time are shown. In this embodiment, the experimental environment was 25℃, pure water (density 1g / cm³), and an external power supply applied a 2Hz pulse excitation signal to the device, with the voltage amplitude switching between 4kV and 0kV. Experimental data shows that under the drive of this pulse signal, the device exhibits a clear upward floating trend. During the 30-second test period, the device accumulated an upward floating distance of 20.36cm in the vertical direction, and the average vertical velocity was measured to be 0.68cm / s. From the motion process, in the initial stage of startup, the device mainly overcomes water resistance and its own weight, exhibiting a relatively slow up-and-down fluctuation state; around the 5th second, the device overcomes resistance and begins to move upward significantly.

[0039] Example 2 This embodiment provides a method for preparing the underwater transparent flexible actuation device described in Embodiment 1, the method comprising the following steps: Step 1. Fabricate the flexible support frame 10: as shown Figure 3As shown, eight fan-shaped cutouts 101 are laser-cut into a circular polyethylene terephthalate (PET) film. The eight cutouts 101 are evenly distributed, with their central angles all pointing towards the center of the circular film. A rectangular rib 102 is formed between adjacent cutouts 101, connecting the center of the circular film to an annular frame 103. The annular frame 103 is retained to maintain the tension and positioning of the structure during fabrication.

[0040] In this embodiment, the thickness of the circular polyethylene terephthalate film is 0.5 mm, the outer diameter is 13 cm, and the radius of the fan-shaped cutout 101 is 4.2 cm.

[0041] Step 2. Clean the flexible support frame 10 fabricated in Step 1 and place it in a ventilated environment to dry, in order to ensure the reliability of the subsequent bonding process.

[0042] Step 3. After performing equiaxial pre-stretching on the first dielectric elastomer film layer 21, it is adhered to the cleaned flexible support frame 10 using its own adhesive properties. The shape of the first dielectric elastomer film layer 21 is trimmed so that its edges are consistent with the flexible support frame 10. The first dielectric elastomer film layer 21 is a transparent VHB4910 acrylic tape film. Before bonding, it is subjected to 2.5×2.5 times equiaxial pre-stretching on the pre-stretching device. The pre-stretching treatment provides necessary pre-stress support for the subsequent deformation of the structure.

[0043] Step 4. Perform hydrophilic modification treatment on the upper surface of the first dielectric elastomer film layer 21, and then attach the flexible conductive layer 22 to the center position of the upper surface of the first dielectric elastomer film layer 21. The flexible conductive layer 22 is a patterned transparent ionic hydrogel. The first dielectric elastomer film layer 21 is hydrophilic modified by plasma cleaning to introduce active groups and increase polarity, thereby significantly enhancing the interfacial bonding strength between the hydrogel and the dielectric elastomer.

[0044] Step 5. Introduce one end of the wire 3 into the first dielectric elastomer film layer 21, and electrically connect the wire 3 and the flexible conductive layer 22 with conductive silver paste. The other end of the wire 3 is used to connect to an external power source. A waterproof curing adhesive layer is set in the section of the wire 3 that is introduced into the film layer to seal the gap between the wire and the film layer and prevent liquid from seeping in.

[0045] Step 6. After performing the same equiaxial pre-stretching treatment as the first dielectric elastomer film layer 21 on the second dielectric elastomer film layer 23, it is attached to the flexible conductive layer 22, so that the second dielectric elastomer film layer 23 extends beyond the periphery of the flexible conductive layer 22 and adheres to the first dielectric elastomer film layer 21. Utilizing the self-adhesive properties of the dielectric elastomer material, self-encapsulation of the internal hydrogel electrode is achieved, forming a reliable insulating and waterproof structure. Simultaneously, the waterproof cured adhesive layer at the wire 3 forms a seal. The shape of the second dielectric elastomer film layer 23 is trimmed so that its edges align with the flexible support frame 10. At this point, the encapsulation of the flexible conductive layer 22, i.e., the hydrogel electrode, in the composite actuation film layer 2 is complete, and the structure is now... Figure 4 The sheet-like shape is shown.

[0046] Step 7. Figure 4 As shown, after step 6 is completed, the annular border area opposite each fan-shaped hollow portion 101 in the flexible support frame 10 is cut off, i.e. Figure 4 The cropping area 104 of the ring-shaped border shown by the dashed line ( Figure 4 Only one cutting area 104 of the central ring-shaped frame is shown. During cutting, a total of 8 cutting areas 104 of the ring-shaped frame corresponding to 8 fan-shaped cutouts 101 are cut, so that the ring-shaped frame breaks the constraint on the ribs 102, releasing the boundary constraint force. Each rib 102 forms a cantilever support rib 12, and the central area of ​​each rib 102 is the connecting seat 11. It should be noted that during cutting, the two layers of dielectric elastomer film attached to the cutting area 104 of the ring-shaped frame are cut off together. The cutting of the two layers of dielectric elastomer film does not exceed the annular insulating sealing edge formed by the two layers beyond the outer periphery of the flexible conductive layer 22, and does not affect the sealing of the flexible conductive layer 22.

[0047] When cutting the annular frame 103, the initial planar shape of the flexible support skeleton 1 and the composite actuation film layer 2 is obtained (e.g., Figure 4 As shown in the figure, after cutting, under the mechanical coupling effect between the pre-stretching force of the two dielectric elastomer film layers and the stiffness of the flexible support frame structure, each cantilever support rib 11 naturally curls from its initial planar shape toward the central axis, obtaining the spherical crown-shaped flexible drive device shape when not energized, i.e., the minimum energy body state. Figure 5 This is an exploded view of the drive unit's naturally curled shape after cutting.

[0048] It should be noted that, in order to make the flexible support frame 10 structure clearer, Figure 3 and Figure 4 Inverted, meaning the actual assembly is rotated 180° vertically.

[0049] Step 8. To optimize device stability and thrust effect according to usage requirements, flexible passive tentacles 4 are bonded to the free ends of each cantilever support rib 11. In this embodiment, the flexible passive tentacles 4 are independent trapezoidal polyethylene terephthalate sheets, prepared by laser cutting. The length of the flexible passive tentacles 4 is 30mm (i.e., the height of the trapezoidal structure), the thickness is 0.3mm, and the waist angle is 30°-60°. The stiffness of the flexible passive tentacles 4 is less than that of the flexible support frame 1, and they are used to generate passive follow-up oscillation during device movement to enhance the propulsion effect.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An underwater transparent flexible actuation device, characterized in that, include: The flexible support frame has a spherical crown-shaped connector at its center. Multiple cantilever support ribs are evenly distributed around the connector. The multiple cantilever support ribs are structures that radiate outward from the connector along the spherical surface of the connector. A spherical fan-shaped hollow area is formed between two adjacent cantilever support ribs. The composite actuation film layer is attached and fixed to the upper surface of the flexible support frame with the connector as the center position. The composite actuation film layer includes two dielectric elastomer film layers and a flexible conductive layer sandwiched between the two dielectric elastomer film layers. The two dielectric elastomer film layers have the same structure and are both in an equiaxial pre-stretched state. The edges of the two dielectric elastomer film layers are bonded and sealed to each other to encapsulate the flexible conductive layer. And conductive connectors, including wires, one end of which extends into the interior of the composite actuation film layer and is electrically connected to the flexible conductive layer, and the other end is connected to an external power source; The connection between the wire and the flexible conductive layer is sealed with waterproof sealant. Both the flexible support frame and the composite actuation membrane are made of transparent materials; by controlling the on and off of the flexible conductive layer, the flexible support frame is driven to expand and contract to generate buoyancy thrust.

2. The underwater transparent flexible actuation device according to claim 1, characterized in that, The flexible support frame is a single-piece integrated structure.

3. The underwater transparent flexible actuation device according to claim 1, characterized in that, It also includes a flexible passive tentacle. The end of the cantilever support rib away from the connector is a free end. The flexible passive tentacle is bonded to the free end. The stiffness of the flexible passive tentacle is less than that of the cantilever support rib. The flexible passive tentacle is used to swing with the cantilever support rib to improve the floating stability of the drive device.

4. The underwater transparent flexible actuation device according to claim 3, characterized in that, The flexible passive tentacle has a trapezoidal sheet structure, with the upper bottom side of the trapezoid bonded to the cantilevered support rib, and the waist angle of the trapezoid is 30°-60°.

5. The underwater transparent flexible actuation device according to claim 3, characterized in that, Both the flexible support frame and the flexible passive tentacles are made of polyethylene terephthalate film.

6. The underwater transparent flexible actuation device according to claim 1, characterized in that, The outer diameter of the two dielectric elastomer film layers is larger than the outer diameter of the flexible conductive layer. The three-layer structure is concentric. The outer portions of the two dielectric elastomer film layers that extend beyond the flexible conductive layer contact each other and are bonded and sealed to form an annular insulating sealing edge.

7. The underwater transparent flexible actuation device according to claim 1, characterized in that, The two dielectric elastomer film layers are made of acrylic elastomers, and the equiaxial pre-stretch ratio of the two dielectric elastomer film layers is in the range of 1.5×1.5 to 3.0×3.0; the flexible conductive layer is a patterned ion hydrogel layer.

8. The underwater transparent flexible actuation device according to claim 1, characterized in that, When the driving device is applied in a conductive water medium, it forms a single-electrode driving circuit. The flexible conductive layer is connected to the positive terminal of an external high-voltage power supply through a wire. The external water medium of the driving device is grounded as the negative terminal. The dielectric elastomer film layer between the water medium and the flexible conductive layer serves as an insulating layer.

9. The underwater transparent flexible driving device according to claim 1, characterized in that, The conductive connector also includes a conductive silver paste layer, which is used to electrically connect the wires and the flexible conductive layer.

10. A method for preparing an underwater transparent flexible actuation device according to any one of claims 1-9, characterized in that, Includes the following steps: Fabrication of a flexible support frame: Multiple fan-shaped cutouts are laser-cut into a circular sheet of polyethylene terephthalate film. The multiple fan-shaped cutouts are evenly distributed and their central corners all face the center of the circular sheet of film. Ribs are formed between two adjacent fan-shaped cutouts to connect the center of the circular sheet of film and the annular frame. Clean the completed flexible support frame; After the first dielectric elastomer film layer is subjected to equiaxial pre-stretching, it is attached to the cleaned flexible support frame using its own adhesiveness, and its shape is trimmed so that its edges are consistent with the flexible support frame. The upper surface of the first dielectric elastomer film layer is subjected to hydrophilic modification treatment, and then the flexible conductive layer is attached to the center position of the upper surface of the first dielectric elastomer film layer. One end of the wire is introduced into the first dielectric elastomer film layer, and the wire and the flexible conductive layer are electrically connected by conductive silver paste. The other end of the wire is used to connect to an external power source. A waterproof curing adhesive layer is set in the section where the wire is introduced into the film layer. After the second dielectric elastomer film layer undergoes the same equiaxial pre-stretching treatment as the first dielectric elastomer film layer, it is attached to the flexible conductive layer, so that its edges are bonded to the first dielectric elastomer film layer. Its shape is then trimmed so that its edges are consistent with the flexible support skeleton frame. Thus, the encapsulation of the electrode in the composite actuation film layer is completed. Cut away the annular frame area opposite each fan-shaped hollow part in the flexible support frame, so that the annular frame breaks the restraint on the ribs, and each rib forms a cantilever support rib. The central area is the connecting seat. When cutting, the two layers of dielectric elastomer film attached to the area to be removed on the annular frame are also cut away. After cutting, under the mechanical coupling effect between the pre-stretching force of the two dielectric elastomer film layers and the stiffness of the flexible support frame structure, each cantilever support rib naturally curls from the initial planar shape toward the central axis, resulting in the spherical crown-shaped flexible drive device shape when not energized.

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