A fast-response multimodal shape memory alloy soft actuator

Abstract

The present invention relates to a fast-response multi-modal shape memory alloy soft driver, comprising a gel wrapping layer, a driving module, and a flexible wrapping layer, wherein the driving module is encapsulated inside the gel wrapping layer, and the flexible wrapping layer is adhered to the bottom end of the gel wrapping layer. The driving module comprises a fixed plate, an elastic substrate, a heat-conducting insulating film, and a shape memory alloy wire. There are four fixed plates, which are respectively arranged at the two ends of the upper and lower surfaces of the elastic substrate, and each fixed plate is provided with two positioning holes. The shape memory alloy wire is constrained between the two positioning holes and arranged in an X-shape as a whole in the same horizontal plane, and the heat-conducting insulating film is wrapped around the surface of the shape memory alloy wire. Based on the shape memory effect, the present invention can realize the bending, torsion and bending-torsion combined modal motion of the driver, and accelerate the heat dissipation of the driver through the evaporation and dehydration of hydrogel. It has the characteristics of high driving efficiency, low manufacturing cost, and various motion forms. It is suitable for soft manipulators, flexible manufacturing and other fields.

Description

Technical Field

[0001] The present invention relates to the fields of soft manipulators, flexible manufacturing, space exploration, and more specifically, to a fast-response multi-modal shape memory alloy soft actuator. Background Art

[0002] Traditional rigid robots have been widely used in industrial production, medical services, military reconnaissance, and other fields. However, their inherent limitations, such as poor environmental adaptability, high noise levels, and poor biocompatibility, make them difficult to apply in specialized environments such as grasping fragile objects and working in confined spaces. In recent years, with the development of new intelligent materials, soft robots have garnered widespread attention and research. Soft robots are made of stable flexible materials, capable of continuous deformation, theoretically possessing unlimited degrees of freedom, and can maintain high integrity and stability under extreme and complex conditions. Their excellent biocompatibility and compliance also offset the shortcomings of rigid robots.

[0003] As one of the smart materials developed in recent years, shape memory alloy has many excellent properties, specifically, including superelasticity, shape memory effect, high damping and other characteristics, and can produce a certain degree of expansion and contraction deformation. Based on the above properties, shape memory alloys are widely used in the field of soft actuators. Soft actuators made of shape memory alloys can integrate drive and structure, and have advantages such as high energy density and large load-to-weight ratio. However, since shape memory alloys are based on thermal drive, it takes a long time to completely cool after heating. Therefore, the cooling rate of shape memory alloys directly restricts the response speed of the actuator. In addition, although soft actuators can produce a variety of motion types, including linear motion, bending motion and torsional motion, few soft actuators currently under research can achieve multiple motion states.

[0004] Patent CN11991184A discloses a variable-stiffness soft pneumatic rehabilitation hand that uses an air pump to inflate and pressurize the cavity, thereby actuating the palm. However, the air pressure required for this pressurization requires an external air pump, which increases the complexity of the system and limits the application scope of this technology.

[0005] Patent CN111264948A discloses a shape-memory alloy-driven soft rehabilitation glove. This glove generates driving force by energizing and / or de-energizing shape-memory alloy wires at different locations, enabling bending and lateral movement of different joints. However, this patent fails to address heat dissipation issues associated with the shape-memory alloy wires, resulting in poor response speed.

[0006] The patented technology of patent CN108622352A discloses an autonomous underwater vehicle diving and floating device based on a shape memory alloy driver, which mainly drives the piston to move through a shape memory alloy spring. However, the driver can only output one-dimensional linear motion, and the motion form is single, which limits the application range of the driver.

[0007] Patent CN113459077A discloses a shape memory alloy soft actuator that primarily utilizes a flexible substrate and a heat dissipation coating to cool the shape memory alloy wire, thereby improving the actuator's response speed. First, the flexible substrate is mostly made of a polymer, such as silicone rubber, which inherently has poor heat dissipation performance. Even with the addition of thermally conductive fillers, the thermal conductivity remains limited. Poly(N-isopropylacrylamide) hydrogel contains over 90% water in its swollen state. Water has a significant latent heat, far exceeding that of typical phase change materials. When the hydrogel is heated, the water within it evaporates, removing a significant amount of heat. During cooling, it absorbs the lost water from the air, resulting in significant stability and high cooling performance. Compared to a flexible substrate composed of a polymer, the gel coating composed of poly(N-isopropylacrylamide) hydrogel exhibits superior cooling performance. Furthermore, during the evaporation heat dissipation process, the gel coating loses water, resulting in volume contraction. By adhering to flexible coatings with varying thermal response properties, a bending force can be generated, thereby providing driving force for the actuator. Secondly, the shape memory alloy soft actuator proposed in the patent can only output bending motion, which has a single motion form and limits the actuator's application range. Finally, the patent uses a continuous 5V voltage to activate the shape memory alloy wire. Compared with pulse activation, the activation time is longer and the heat generated is greater. Summary of the Invention

[0008] The present invention provides a fast-response multi-modal shape memory alloy soft actuator, which aims to solve the above-mentioned technical problems, improve the problems of slow response speed, insufficient driving force, and single movement form of shape memory alloy actuators, realize multi-modal movement of the actuator, and provide a new idea for the design of shape memory alloy soft actuators.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] A fast-response multi-modal shape memory alloy soft driver comprises a gel wrapping layer, a driving module, and a flexible wrapping layer, wherein the driving module is encapsulated inside the gel wrapping layer; and the flexible wrapping layer is adhered to the bottom end of the gel wrapping layer.

[0011] The driving module includes a fixed plate, an elastic substrate, a thermally conductive insulating film, and a shape memory alloy wire; the elastic substrate is arranged on the median surface of the driving module; there are four fixed plates in total, which are respectively arranged at the two ends of the upper and lower surfaces of the elastic substrate and fixedly connected by bonding, and each fixed plate is provided with two positioning holes; the positioning holes are located on the median surface of the fixed plate; the shape memory alloy wire starts from one positioning hole of the fixed plate, passes through the distance between the two positioning holes along the length of the elastic substrate, and is connected to the positioning hole of the other fixed plate, and is arranged in an X-shape as a whole in the same horizontal plane; the thermally conductive insulating film is wrapped around the surface of the shape memory alloy wire.

[0012] There are four shape memory alloy wires, and the eccentricity of each shape memory alloy wire to the elastic substrate is the same; the shape memory alloy wire one is fixed between positioning hole one and positioning hole three; the shape memory alloy wire two is fixed between positioning hole two and positioning hole four; the shape memory alloy wire three is fixed between positioning hole five and positioning hole seven; and the shape memory alloy wire four is fixed between positioning hole six and positioning hole eight.

[0013] The surface of the gel wrapping layer is provided with grid grooves, which effectively increases the surface roughness.

[0014] Preferably, the material of the gel wrapping layer is poly (N-isopropylacrylamide) hydrogel with high heat dissipation ratio, soft texture and good thermal response performance.

[0015] Preferably, the material of the flexible wrapping layer is silicone with soft texture and good mechanical properties.

[0016] Preferably, the fixing plate is made of a printed circuit board.

[0017] Preferably, the elastic substrate is made of polyvinyl chloride board.

[0018] Preferably, the thermally conductive insulating film has good flexibility, high electrical insulation and high thermal conductivity, and the material of the thermally conductive insulating film is fluorinated graphene film.

[0019] By turning on and off the power to the shape memory alloy wires at different positions, the shape memory alloy wires undergo phase change and generate driving force, thereby realizing multimodal driving of the soft drive; when the shape memory alloy wire one and the shape memory alloy wire two are energized, their temperature rises, their length shrinks and a deformation force is generated, and the torque of the deformation force cancels each other out, and the generated bending moment causes the drive to bend toward the top surface; when the shape memory alloy wire three and the shape memory alloy wire four are energized, the torque generating the deformation force cancels each other out, and the drive bends toward the bottom surface under the action of the bending moment; when the shape memory alloy wire one and the shape memory alloy wire four or the shape memory alloy wire two and the shape memory alloy wire three are energized, the bending moment generating the deformation force cancels each other out, and the drive performs a torsional motion under the action of the torque of the deformation force; when a single shape memory alloy wire is energized, the drive will perform a combined bending and torsional motion under the combined action of the bending moment and torque of the deformation force; when the heating of the shape memory alloy wire is stopped, the temperature of the shape memory alloy wire decreases, the deformation force disappears, and the drive gradually returns to its initial state. In addition, since the elastic substrate has a certain elasticity, it can provide a certain restoring force during the cooling process, accelerating the transition of the driver from other states to the initial state.

[0020] The soft driver uses millisecond-level electric pulses for power-on heating. During the heating process, part of the energy of the shape memory alloy wire is converted into the internal energy and latent heat of phase change of the shape memory alloy wire, and the other part of the energy is dissipated through heat exchange with the environment. With rapid pulse heating, that is, using a given power supply voltage to generate electric pulses within the millisecond range to power-on and heat the driver, the shape memory alloy wire can quickly reach the phase change temperature and start driving, reducing the energy dissipated by heat exchange with the environment, saving energy while improving the response speed of the driver.

[0021] When the shape memory alloy wire is heated by electricity, part of the energy is converted into the internal energy of the shape memory alloy wire and the latent heat of phase change, while the remaining energy is dissipated through heat exchange with the gel coating. This heat exchange causes the temperature of the gel coating to rise sharply. When the temperature exceeds the critical solution temperature, the gel coating releases free water in the form of evaporation, removing a large amount of heat. This effectively increases the cooling rate of the shape memory alloy wire and, in turn, the response speed of the actuator. During the evaporative dehydration process, the gel coating undergoes a sudden change in volume due to water loss, while the volume of the flexible coating remains relatively unchanged. The difference in volume change between the upper and lower coatings causes the actuator to bend to one side, further improving the response speed and increasing the degree of deformation of the actuator based on the shape memory alloy wire drive. When the actuator stops working, the gel coating can replenish the evaporated water from the surrounding air, restoring the actuator to its initial state.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention is a soft driver that integrates drive and structure into one, has a simple and compact structure, is noiseless in driving, has strong environmental adaptability, and has good biocompatibility.

[0024] 2. The present invention uses shape memory alloy as a driving element, which has high energy density, large output force, and large load-to-weight ratio.

[0025] 3. The present invention can realize multi-modal driving, including bending, torsion and bending-torsion combination, which expands the application range of the driver.

[0026] 4. The present invention utilizes a hydrogel as the gel coating, which is soft and stable, enabling efficient evaporative heat dissipation. It also absorbs lost moisture from the surrounding air, significantly increasing the cooling rate of the shape memory alloy and, in turn, improving the actuator's response speed. During evaporative heat dissipation, water loss causes the gel coating to shrink in volume. Since the volume of the flexible coating adhered to the bottom remains relatively unchanged, the difference in volume between the two coatings causes the actuator to bend to one side. Therefore, the gel coating also provides a certain amount of driving force for the actuator.

[0027] 5. The present invention uses fluorinated graphene film as a thermally conductive insulating film with high electrical insulation and high thermal conductivity. Wrapping it on the surface of the shape memory alloy wire can accelerate the heat dissipation of the shape memory alloy wire while ensuring safe use, thereby improving the response speed of the driver.

[0028] 6. The present invention has low production cost, simple production process and is easy to produce and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0030] Figure 1 This is a diagram of the initial state of the multi-modal shape memory alloy soft actuator of the present invention.

[0031] Figure 2 This is a diagram of the wrapping layer of the multimodal shape memory alloy soft actuator of the present invention.

[0032] Figure 3 This is a diagram of a driving module of the multi-modal shape memory alloy soft driver of the present invention.

[0033] Figure 4 It is a side view of the driving module of the multi-modal shape memory alloy soft driver of the present invention.

[0034] Figure 5 This is a manufacturing flow chart of the multi-modal shape memory alloy soft actuator of the present invention.

[0035] Figure 6 This is a mold frame diagram of the multi-modal shape memory alloy soft actuator of the present invention.

[0036] Figure 7 This is a diagram showing the top surface bending state of the multi-modal shape memory alloy soft actuator of the present invention.

[0037] Figure 8 This is a bottom bending state diagram of the multi-modal shape memory alloy soft actuator of the present invention.

[0038] Figure 9 It is a torsional state diagram of the multi-modal shape memory alloy soft actuator of the present invention.

[0039] Figure 10 This is a diagram of the bending and torsion combination state of the multi-modal shape memory alloy soft actuator of the present invention.

[0040] The figure shows: 1-gel wrapping layer, 2-driving module, 3-flexible wrapping layer, 21-fixing plate, 211-positioning hole, 2111-positioning hole one, 2112-positioning hole two, 2113-positioning hole three, 2114-positioning hole four, 2115-positioning hole five, 2116-positioning hole six, 2117-positioning hole seven, 2118-positioning hole eight, 22-elastic substrate, 23-thermal conductive insulating film, 24-shape memory alloy wire, 241-shape memory alloy wire one, 242-shape memory alloy wire two, 243-shape memory alloy wire three, 244-shape memory alloy wire four. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that, for those skilled in the art, several changes and improvements can be made without departing from the concept of the present invention. These all fall within the scope of protection of the present invention. In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0042] The shape memory alloy soft actuator and its manufacturing method of the present invention are described below with reference to the accompanying drawings.

[0043] Example 1

[0044] See also Figure 1A fast-response multi-modal shape memory alloy soft driver includes a gel wrapping layer 1, a driving module 2, and a flexible wrapping layer 3; the driving module 2 is encapsulated inside the gel wrapping layer 1; and the flexible wrapping layer 3 is adhered to the bottom end of the gel wrapping layer 1.

[0045] The driving module 2 includes a fixed plate 21, an elastic substrate 22, a thermally conductive insulating film 23, and a shape memory alloy wire 24; the elastic substrate 22 is arranged on the median surface of the driving module 2; there are four fixed plates 21, which are respectively arranged at the two ends of the upper and lower surfaces of the elastic substrate 22 and fixedly connected by bonding. Each fixed plate 21 is provided with two positioning holes 211; the positioning holes 211 are located on the median surface of the fixed plate 21; the shape memory alloy wire 24 starts from one positioning hole 211 of the fixed plate 21, passes through the distance between the two positioning holes 211 along the length of the elastic substrate 22, and is connected to the positioning hole 211 of the other fixed plate 21, and is arranged in an X-shape as a whole in the same horizontal plane; the thermally conductive insulating film 23 is wrapped around the surface of the shape memory alloy wire 24.

[0046] The shape memory alloy soft actuator of this embodiment is suitable for soft manipulators, flexible manufacturing and other fields. It can realize bending, torsion and bending-torsion combined modal motion of the actuator, and accelerate the heat dissipation of the actuator through hydrogel evaporation and dehydration. It has the characteristics of high driving efficiency, low manufacturing cost, and diverse motion forms.

[0047] Example 2

[0048] See also Figure 1 and Figure 2 In the above embodiment, the material of the gel wrapping layer 1 is poly (N-isopropylacrylamide) hydrogel with high heat dissipation ratio, soft texture and good thermal response performance.

[0049] The material of the flexible wrapping layer 3 is silicone with soft texture and good mechanical properties.

[0050] The fixing plate 21 is made of a printed circuit board.

[0051] The elastic substrate 22 is made of polyvinyl chloride.

[0052] The thermally conductive insulating film 23 has good flexibility, high electrical insulation and high thermal conductivity. The material of the thermally conductive insulating film 23 is a fluorinated graphene film.

[0053] The soft driver uses millisecond-level electric pulses for power-on heating. During the heating process, part of the energy of the shape memory alloy wire 24 is converted into the internal energy and phase change latent heat of the shape memory alloy wire 24, and the other part of the energy is dissipated through heat exchange with the environment. By relying on rapid pulse heating, that is, using a given power supply voltage to generate electric pulses within the millisecond range to power-on heating the driver, the shape memory alloy wire 24 can quickly reach the phase change temperature and start driving, reducing the energy dissipated by heat exchange with the environment, and improving the response speed of the driver while saving energy.

[0054] During use, the shape memory alloy soft actuator in this embodiment utilizes millisecond-level electrical pulses to heat the soft actuator, accelerating the actuator's response while improving energy efficiency and reducing excess heat generation. During this heating process, accumulated heat is dissipated through the gel coating. This embodiment utilizes poly(N-isopropylacrylamide) hydrogel as the gel coating, releasing free water through evaporation and removing a significant amount of heat. This effectively increases the cooling rate of the shape memory alloy wire, thereby accelerating the actuator's response.

[0055] Example 3

[0056] A fast-response multimodal shape memory alloy soft actuator, such as Figure 1 As shown, it includes a gel wrapping layer 1, a driving module 2, and a flexible wrapping layer 3; the driving module 2 is encapsulated inside the gel wrapping layer 1; and the flexible wrapping layer 3 is adhered to the bottom end of the gel wrapping layer 1.

[0057] The driving module 2 includes a fixed plate 21, an elastic substrate 22, a thermally conductive insulating film 23, and a shape memory alloy wire 24; the elastic substrate 22 is arranged on the median surface of the driving module 2; there are four fixed plates 21, which are respectively arranged at the two ends of the upper and lower surfaces of the elastic substrate 22 and fixedly connected by bonding. Each fixed plate 21 is provided with two positioning holes 211; the positioning holes 211 are located on the median surface of the fixed plate 21; the shape memory alloy wire 24 starts from one positioning hole 211 of the fixed plate 21, passes through the distance between the two positioning holes 211 along the length of the elastic substrate 22, and is connected to the positioning hole 211 of the other fixed plate 21, and is arranged in an X-shape as a whole in the same horizontal plane; the thermally conductive insulating film 23 is wrapped around the surface of the shape memory alloy wire 24.

[0058] See also Figure 2The material of the gel wrapping layer 1 can be poly (N-isopropylacrylamide) hydrogel with high heat dissipation ratio, soft texture, and good thermal response performance, or other gel materials with good mechanical properties, good stability, soft texture, excellent thermal response performance, and high heat dissipation ratio. The surface of the gel wrapping layer 1 is provided with grid grooves, which can effectively increase the surface roughness of the driver, providing favorable conditions for the application of the driver in soft mobile robots and flexible gripping.

[0059] The flexible wrapping layer 3 has a soft texture, good mechanical properties and good stability. The material of the flexible wrapping layer 3 can be silicone or other suitable materials.

[0060] The fixing plate 21 is used to constrain the shape memory alloy wire 24 . The fixing plate 21 is made of a printed circuit board, or other materials that meet the requirements, such as an acrylic board.

[0061] The elastic substrate 22 has a certain elasticity and can provide a restoring force when the shape memory alloy wire 24 cools down. The elastic substrate 22 can be made of a polyvinyl chloride plate or any other suitable material.

[0062] The thermally conductive insulating film 23 has good flexibility, high electrical insulation and high thermal conductivity. The material of the thermally conductive insulating film 23 can be a fluorinated graphene film, or other flexible film materials with good thermal conductivity and insulation.

[0063] See also Figure 3 and Figure 4 The number of the shape memory alloy wires 24 is four, and the eccentricity of each shape memory alloy wire 24 to the elastic substrate 22 is the same; the shape memory alloy wire 1 241 is fixed between the positioning hole 1 2111 and the positioning hole 3 2113; the shape memory alloy wire 2 242 is fixed between the positioning hole 2112 and the positioning hole 4 2114; the shape memory alloy wire 3 243 is fixed between the positioning hole 5 2115 and the positioning hole 7 2117; the shape memory alloy wire 4 244 is fixed between the positioning hole 6 2116 and the positioning hole 8 2118.

[0064] See also Figure 5 The manufacturing process of the fast-response multi-modal shape memory alloy soft actuator can be divided into five parts.

[0065] First, four fixing plates 21 of the same size are bonded to both ends of the upper and lower surfaces of the elastic base plate 22 .

[0066] Secondly, the position of the shape memory alloy wire 24 is arranged. The shape memory alloy wire 24 starts from a positioning hole 211 of the fixed plate 21, passes through the distance between two positioning holes 211 along the length of the elastic substrate 22, and is connected to the positioning hole 211 of another fixed plate 21. The overall arrangement is X-shaped in the same horizontal plane, and a single shape memory alloy wire 24 is fixed and constrained at both ends of the positioning hole 211.

[0067] Next, place the manufactured drive module 2 on the Figure 6 In the mold shown, N-isopropylacrylamide mixed solution is added into the mold until the driving module 2 is completely immersed, and the mold is left to stand for a period of time at room temperature to wait for the formation of the gel coating layer 1.

[0068] Next, the silicone liquid that has been fully stirred and de-bubbled in a vacuum box is poured into the mold, and the silicone is allowed to solidify at room temperature to form a flexible wrapping layer 3 .

[0069] Finally, demolding is performed, and the desired multimodal shape memory alloy soft actuator can be obtained after demolding.

[0070] The following combination Figure 7-10 This section introduces the different driving states of software drivers.

[0071] When the multimodal shape memory alloy soft driver of the present invention is in use, current is passed through the shape memory alloy wires 24 at different positions to change the temperature of the shape memory alloy wires 24, causing the shape memory alloy wires 24 to undergo phase change and generate corresponding driving force. Since the shape memory alloy wires 24 are constrained between the fixed plates 21 through the positioning holes 211, the driving force generated drives the elastic substrate 22 adhered to the middle surface of the fixed plate 21 to produce deformation movement under the restriction of the fixed plate 21, thereby realizing the multimodal drive of the soft driver; when the shape memory alloy wire 1 241 and the shape memory alloy wire 2 242 are energized, the shape memory alloy wire 1 241 and the shape memory alloy wire 2 242 generate a large amount of Joule heat, causing the temperature to rise, and the internal phase gradually changes from the martensite phase to the austenite phase, the length shrinks and a deformation force is generated, and the torque of the deformation force offsets each other, and the bending moment generated causes the driver to bend toward the top surface, presenting as shown in the figure. Figure 7 When the shape memory alloy wire 3 243 and the shape memory alloy wire 4 244 are energized, the internal structure thereof gradually transforms from the martensite phase to the austenite phase, the length shrinks and a deformation force is generated. The torque of the deformation force offsets each other, and the bending moment generated causes the driver to bend toward the bottom surface, showing as shown. Figure 8 When the shape memory alloy wire 241 and the shape memory alloy wire 244 or the shape memory alloy wire 242 and the shape memory alloy wire 243 are energized, the deformation force and bending moment produced offset each other, and the driver performs a torsional motion under the action of the deformation force torque, showing as Figure 9When a single shape memory alloy wire 24 is energized, the driver performs a combined bending and twisting motion under the combined action of deformation force, bending moment, and torque, showing the state shown in FIG. Figure 10 The state shown; stop heating the shape memory alloy wire 24. During the cooling process, the interior of the shape memory alloy wire 24 gradually recovers from the austenite phase to the martensite phase, and the length of the shape memory alloy wire 24 recovers to the initial state. The deformation force generated by heating disappears, and the driver gradually returns to its initial state. In addition, since the elastic substrate 22 has a certain elasticity, it can provide a certain restoring force during the cooling process, accelerating the transition of the driver from other states to the initial state, and finally presents as shown. Figure 1 The status shown.

[0072] The multimodal shape memory alloy soft actuator of the present invention uses millisecond-level electric pulses for electrical heating. During the heating process, a portion of the energy of the shape memory alloy wire 24 is converted into the internal energy of the shape memory alloy wire 24 and the latent heat of phase change, while the remaining energy is dissipated through heat exchange with the environment. By utilizing rapid pulse heating, that is, using a given power supply voltage to generate electric pulses within milliseconds to heat the actuator, the shape memory alloy wire 24 can quickly reach the phase change temperature and begin driving, reducing the energy dissipated by heat exchange with the environment, thereby increasing the driving speed of the actuator while saving energy. Specifically, the voltage and duty cycle of the electric pulse signal are determined based on the phase change temperature of the shape memory alloy wire 24 and the output force of the actuator.

[0073] Furthermore, when the shape memory alloy wire 24 is electrically heated, a portion of the energy is converted into its internal energy and latent heat of phase change, while the remaining energy is dissipated through heat exchange with the gel coating 1. This heat exchange causes the temperature of the gel coating 1 to rise sharply. When the temperature exceeds the critical solution temperature, the gel coating 1 releases free water through evaporation, removing a significant amount of heat. This effectively increases the cooling rate of the shape memory alloy wire 24 and, in turn, the actuator's response speed. During the evaporative dehydration process, the gel coating 1 undergoes a sudden volume change due to water loss, while the volume of the flexible coating 3 remains relatively unchanged. This difference in volume change between the upper and lower coatings causes the actuator to bend to one side, further improving the actuator's response speed and increasing the degree of deformation, in addition to the shape memory alloy wire 24's drive. When the actuator stops functioning, the gel coating 1 replenishes the evaporated water from the surrounding air, restoring the actuator to its initial state.

[0074] According to the above combination Figures 1-10As can be seen from the introduction, the shape memory alloy soft actuator of this embodiment is based on the shape memory effect of the shape memory alloy wire. The deformation movement of the shape memory alloy wire is restricted by a fixed plate. The shape memory alloy wire is heated by power on and / or cooled by power off at different positions, causing the drive module to deform, thereby driving the gel coating to move, and realizing the bending, torsion, and combined bending and torsion modal motion of the soft actuator. The shape memory alloy soft actuator of this embodiment uses millisecond-level electric pulses to heat the actuator. With the rapid pulse heating, the shape memory alloy wire can quickly reach the phase transition temperature and start driving, reducing the generation of excess heat, while improving the response speed of the actuator. At the same time, poly (N-isopropylacrylamide) hydrogel is used as the gel coating, which releases free water in the form of evaporation and removes a large amount of heat, thereby accelerating the cooling of the shape memory alloy wire. During the evaporation and dehydration process, the volume of the gel coating changes suddenly. Due to the poor thermal responsiveness of the flexible coating, its volume remains relatively unchanged. The difference in volume change between the upper and lower coatings will cause the actuator to bend to one side. On the basis of the shape memory alloy wire drive, the response speed is further improved and the deformation degree of the actuator is increased. As the actuator cools, the gel coating replenishes the lost moisture from evaporation from the surrounding air, restoring the actuator to its initial state. This embodiment of the shape memory alloy soft actuator offers high drive efficiency, low manufacturing cost, and diverse motion forms, making it suitable for applications in soft robotic arms, flexible manufacturing, and other fields.

[0075] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A fast-response multi-modal shape memory alloy soft actuator, comprising a gel wrapping layer (1), a driving module (2), and a flexible wrapping layer (3), characterized in that: The driving module (2) is encapsulated inside the gel wrapping layer (1); the flexible wrapping layer (3) is adhered to the bottom end of the gel wrapping layer (1); The driving module (2) comprises a fixing plate (21), an elastic substrate (22), a heat-conducting insulating film (23), and a shape memory alloy wire (24); the elastic substrate (22) is arranged on the middle surface of the driving module (2); there are four fixing plates (21), which are respectively arranged at the two ends of the upper and lower surfaces of the elastic substrate (22) and fixedly connected by bonding, and each fixing plate (21) is provided with two positioning holes (211); the positioning holes (211) are located on the middle surface of the fixing plate (21); the shape memory alloy wire (24) starts from one positioning hole (211) of the fixing plate (21), passes through the distance between the two positioning holes (211) along the length of the elastic substrate (22), and is connected to the positioning hole (211) of another fixing plate (21), and is arranged in an X-shape as a whole in the same horizontal plane; the heat-conducting insulating film (23) is wrapped around the surface of the shape memory alloy wire (24).

2. The fast-response multi-modal shape memory alloy soft actuator according to claim 1, characterized in that: The number of the shape memory alloy wires (24) is four, and the eccentricity of each shape memory alloy wire (24) relative to the elastic substrate (22) is the same; the first shape memory alloy wire (241) is fixed between the first positioning hole (2111) and the third positioning hole (2113); the second shape memory alloy wire (242) is fixed between the second positioning hole (2112) and the fourth positioning hole (2114); the third shape memory alloy wire (243) is fixed between the fifth positioning hole (2115) and the seventh positioning hole (2117); and the fourth shape memory alloy wire (244) is fixed between the sixth positioning hole (2116) and the eighth positioning hole (2118).

3. The fast-response multi-modal shape memory alloy soft actuator according to claim 1, characterized in that: The surface of the gel wrapping layer (1) is provided with grid grooves, which effectively increases the surface roughness.

4. The fast-response multi-modal shape memory alloy soft actuator according to any one of claims 1 to 3, characterized in that: The material of the gel wrapping layer (1) is poly (N-isopropylacrylamide) hydrogel.

5. The fast-response multi-modal shape memory alloy soft actuator according to any one of claims 1 to 3, characterized in that: The material of the flexible wrapping layer (3) is silica gel.

6. The fast-response multi-modal shape memory alloy soft actuator according to any one of claims 1 to 3, characterized in that: The material of the fixing plate (21) is a printed circuit board.

7. The fast-response multi-modal shape memory alloy soft actuator according to any one of claims 1 to 3, characterized in that: The elastic substrate (22) is made of a polyvinyl chloride board.

8. The fast-response multi-modal shape memory alloy soft actuator according to any one of claims 1 to 3, characterized in that: The thermally conductive insulating film (23) has good flexibility, high electrical insulation and high thermal conductivity, and the material of the thermally conductive insulating film (23) is a fluorinated graphene film.

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