Reprogrammable flexible actuators and methods of making and driving the same

Abstract

The present application relates to a kind of reprogrammable flexible actuator and its preparation and driving method.The flexible actuator includes flexible double-layer film formed by carbon nanotube and polydimethylsiloxane upside down, and paraffin structure.Flexible double-layer film is mirror image symmetry with a symmetry plane parallel to actuation direction.Flexible double-layer film includes opposite parallel head and tail, and the extension direction of head and tail is perpendicular to symmetry plane.Flexible double-layer film is in the form of curling along the extension direction of symmetry plane in natural state, to form the "C" type structure with opening downward.Paraffin structure is in the form of strip and is attached to the surface of carbon nanotube layer.When flexible double-layer film is in flat state, there is a preset angle α between the extension direction of paraffin structure and the extension direction of head or tail, and α ∈ [-30 °, 60 °], and the length of head and tail is greater than the width of paraffin structure.The movement form of the flexible actuator is more abundant, and can be reprogrammed without destroying the original material structure.

Description

Technical Field

[0001] This invention relates to the field of flexible actuator technology, and in particular to a reprogrammable flexible actuator, a method for manufacturing the reprogrammable flexible actuator, and a method for driving the reprogrammable flexible actuator. Background Technology

[0002] In recent years, biomimetic soft actuators have been widely studied due to their excellent flexibility and manipulation, demonstrating enormous potential and broad application prospects. With the continuous development of biomimetic research, this field has achieved fruitful results, promoting progress in biomimetic research, especially in biomimetic robots. By imitating various biological models, many biomimetic robots have emerged, such as hard robots, continuum robots, and flexible robots. Among them, flexible robots can easily exhibit muscle-like movements, better mimicking the movement of soft biological systems, thus enabling complex movements and the completion of specific tasks based on the inherent properties of the materials themselves.

[0003] Current flexible robotics technologies often utilize bilayer membrane structures as photothermal actuators, converting external photothermal stimuli into mechanical deformation outputs to achieve various actuation functions. However, existing flexible actuators often employ a single bilayer membrane structure. This type of structure has limited motion capabilities, sometimes requiring surface damage to create grooves to achieve the desired motion. Therefore, without damaging the material itself, a single bilayer membrane exhibits fixed motion patterns, failing to meet the diverse actuation requirements of practical applications. Furthermore, actuators cannot be reprogrammed after membrane damage, presenting significant limitations in non-destructive programming and reprogramming. Summary of the Invention

[0004] Therefore, in view of the technical problem that the motion mode of a single flexible actuator is limited and cannot be reprogrammed in the prior art, this invention provides a reprogrammable flexible actuator and its preparation and driving method.

[0005] This invention discloses a reprogrammable flexible actuator, comprising a flexible bilayer membrane formed by stacking carbon nanotubes and polydimethylsiloxane, and at least one paraffin structure. The flexible bilayer membrane is mirror-symmetrical about a plane of symmetry parallel to the actuation direction. The flexible bilayer membrane includes a relatively parallel head and tail, and the extension directions of the head and tail are both perpendicular to the plane of symmetry. In its natural state, the flexible bilayer membrane is curled along the extension direction of the plane of symmetry, thereby forming a downward-opening "C"-shaped structure. The paraffin structure is a strip-shaped band attached to the upper surface of the carbon nanotube layer. When the flexible bilayer membrane is in a flat state, there is a preset angle α ∈ [-30°, 60°] between the extension direction of the paraffin structure and the extension direction of the head or tail, and the length of the head and tail is greater than the width of the paraffin structure.

[0006] As a further improvement to the above scheme, the flexible double-layer membrane is rectangular or isosceles trapezoidal when it is laid flat.

[0007] When the flexible double-layer membrane is rectangular in its flat state, the shorter opposite sides of the rectangle constitute the beginning and the end, respectively. When the flexible double-layer membrane is an isosceles trapezoid in its flat state, the lower base and the upper base of the isosceles trapezoid constitute the beginning and the end, respectively.

[0008] As a further improvement to the above scheme, when the flexible double-layer film in the flat state is rectangular, the ratio between the width of the paraffin structure and the length of the shorter side of the rectangle is 1:8.

[0009] When the flexible double-layer membrane in its flat state is an isosceles trapezoid, the ratio between the width of the paraffin structure and the length of the lower base of the isosceles trapezoid is 1:8.

[0010] As a further improvement to the above scheme, the thickness of the paraffin structure is 48-54 μm.

[0011] This invention also discloses a method for fabricating a reprogrammable flexible actuator, which is used to fabricate any of the above-mentioned reprogrammable flexible actuators. The fabrication method includes the following steps:

[0012] S1. Provides a flexible bilayer membrane of a specific shape and size. The flexible bilayer membrane is composed of carbon nanotubes and polydimethylsiloxane stacked on top of each other.

[0013] S2. A preset amount of molten paraffin is attached to the surface of the carbon nanotube layer of a flexible double-layer film in a flat state, and after cooling, it solidifies into a solid paraffin layer.

[0014] S3. Obtain the target paraffin pattern and scan the paraffin layer with an infrared nanosecond laser to evaporate and remove the paraffin layer outside the target paraffin pattern, thereby generating the paraffin structure of the target pattern on the surface of the carbon nanotube layer.

[0015] As a further improvement to the above scheme, in S1, a double-layer film tiling pattern of a specific shape and size is drawn in the operation interface of a nanosecond laser processing system and imported into the marking software. Then, the laser of the system emits a laser beam to the flexible double-layer film substrate in the tiling state to cut and process a flexible double-layer film of a specific shape and size.

[0016] As a further improvement to the above scheme, in S1, the laser pulse width of the laser is 10ns, the wavelength is 1064nm, and the processing frequency is 100KHz.

[0017] As a further improvement to the above scheme, in S3, the infrared nanosecond laser has a laser pulse width of 10ns, a wavelength of 1064nm, a processing frequency of 100KHz, a laser power of 24W, a processing speed of 3500mm / s, and a scanning spacing of 1μm.

[0018] As a further improvement to the above scheme, in S2, before attaching paraffin to the surface of the carbon nanotube layer, black paraffin pigment is mixed into the molten paraffin and stirred. The mass ratio of black paraffin pigment to molten paraffin is 1:8.

[0019] This invention also discloses a driving method for a flexible actuator, used to drive any of the above-mentioned reprogrammable flexible actuators to perform crawling motion. The driving method includes the following steps:

[0020] The flexible actuator is placed on the stage in a natural state with its "C"-shaped structure facing downwards.

[0021] The flexible actuator is scanned and irradiated using a near-infrared laser. The laser spot falls on the upper surface of the carbon nanotube layer and moves from the midpoint of the end of the flexible bilayer film along the curve formed by the projection of the plane of symmetry onto the upper surface of the carbon nanotube layer to the midpoint of the beginning end, thus achieving a single scan irradiation.

[0022] Compared with the prior art, the technical solution disclosed in this invention has the following beneficial effects:

[0023] 1. The reprogrammable flexible actuator provided by this invention can change the motion trajectory of the flexible actuator by applying an anisotropic structure (i.e., paraffin structure) to the flexible structure. Compared with the traditional single double-layer membrane with fixed motion law, which is difficult to meet the various needs of actual operation without damaging the flexible double-layer membrane material itself, this invention, by applying anisotropic structure to the flexible material without damaging its own structure, better enables programmable manipulation while protecting the flexible structure. Furthermore, the high-temperature removal and room-temperature solidification characteristics of paraffin make the actuator's reprogrammability even more advantageous. By adding or removing paraffin to the actuator, the same actuator can achieve different motion modes, greatly improving both programming efficiency and work efficiency. This has significant implications for research in the field of soft actuators.

[0024] 2. The method proposed in this invention for fabricating flexible actuators by bonding a soft shell structure onto a photothermal responsive material using nanosecond laser processing is characterized by low cost, simplicity, and non-destructive operation. This actuator can achieve crawling functionality; the crawling speed and offset direction can be controlled by adjusting the width and tilt angle of the paraffin structure, thus changing its original single motion strategy. Compared with traditional actuators, it can more actively respond to complex environmental changes, and through fully optically controlled contactless manipulation, programming efficiency is greatly improved. This will pave a new path for reprogrammable, self-healing, and optically driven soft robots with multiple functions and complex deformations, and has significant inspirational significance and applications in the future fields of intelligent robotics and bionics. Attached Figure Description

[0025] Figure 1 This is a three-dimensional structural diagram of the reprogrammable flexible actuator in Embodiment 1 of the present invention;

[0026] Figure 2 for Figure 1 A top view of a flexible actuator in a flat state;

[0027] Figure 3 This is a schematic diagram of the nanosecond laser processing system in Embodiment 2 of the present invention;

[0028] Figure 4 This is a schematic diagram of the processing of the flexible bilayer film in Embodiment 2 of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating the preparation of paraffin wax in Example 2 of the present invention;

[0030] Figure 6 This is a schematic diagram of the removal of excess paraffin layer using a nanosecond laser in Embodiment 2 of the present invention;

[0031] Figure 7 This is a schematic diagram of the driving mechanism of the flexible actuator in Embodiment 2 of the present invention;

[0032] Figure 8 This is a schematic diagram of the motion trajectories of different flexible actuators in Embodiment 2 of the present invention;

[0033] Figure 9 This is a comparison diagram of the original motion trajectory and the crawling motion trajectory along a straight line in Embodiment 2 of the present invention.

[0034] Explanation of main component symbols

[0035] 1. Flexible bilayer film; 11. Carbon nanotube layer; 12. Polydimethylsiloxane layer; 2. Paraffin structure; 31. First lens; 32. Second lens; 33. Third lens; 34. Computer; 35. Nanosecond laser; 36. Attenuator; 37. Reflector; 38. CCD image sensor; 39. Dichroic mirror; 310. High-magnification objective lens; 311. Processing material; 312. Processing platform; 4. Glass slide; 5. Heating stage; 6. Burette; 7. Paraffin pigment; 8. Molten paraffin; 9. Two-dimensional moving stage.

[0036] The above description of the main component symbols, together with the accompanying drawings and specific embodiments, provides a more detailed explanation of the present invention. Detailed Implementation

[0037] 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.

[0038] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] Example 1

[0041] Please see Figure 1 This embodiment provides a reprogrammable flexible actuator, which includes a flexible bilayer film 1 formed by stacking a carbon nanotube layer 11 and a polydimethylsiloxane layer 12, and a paraffin structure 2.

[0042] The flexible bilayer membrane 1 is mirror-symmetrical about a plane of symmetry parallel to the actuation direction. The flexible bilayer membrane 1 includes a front end and a rear end that are relatively parallel, and the extension directions of the front end and the rear end are both perpendicular to the plane of symmetry. Here, the actuation direction refers to the direction of the line connecting the front end and the rear end of the flexible bilayer membrane.

[0043] The flexible bilayer membrane 1 is curled up along the direction of its symmetry plane in its natural state, thus forming a downward-opening "C"-shaped structure. When the flexible bilayer membrane 1 is laid flat, it can be rectangular or isosceles trapezoidal.

[0044] In this embodiment, the flexible bilayer membrane 1 is rectangular, 24 mm long and 4 mm wide. The shorter opposite sides of the rectangle constitute the beginning and the end, respectively.

[0045] Please combine Figure 2 The paraffin structure 2 is a strip-shaped band attached to the upper surface of the carbon nanotube layer 11. When the flexible bilayer membrane 1 is in a flat state, there is a preset angle α ∈ [-30°, 60°] between the extension direction of the paraffin structure 2 and the extension direction of its first or last end, and the lengths of both the first and last ends of the flexible bilayer membrane 1 are greater than the width of the paraffin structure 2. In this embodiment, the paraffin structure 2 is a parallelogram when flat, and the width of the paraffin structure 2 is 0.5 mm, that is, the ratio between the width of the paraffin structure 2 and the length of the shorter side of the flexible bilayer membrane 1 is 1:8. In addition, the thickness of the paraffin structure 2 can be 48-54 μm.

[0046] Of course, in other embodiments, when the flexible double-layer membrane 1 in the flat state is an isosceles trapezoid, the lower base (longer side) and the upper base (shorter side) of the isosceles trapezoid constitute the beginning and end, respectively, and the ratio between the width of the paraffin structure 2 and the length of the lower base of the isosceles trapezoid is 1:8.

[0047] Example 2

[0048] This embodiment provides a method for fabricating a reprogrammable flexible actuator, which is used to fabricate the reprogrammable flexible actuator in Embodiment 1. The fabrication method includes the following steps:

[0049] S1. A flexible bilayer membrane 1 with a specific shape and size is provided. The flexible bilayer membrane 1 is composed of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) stacked on top of each other.

[0050] S2. A preset amount of molten paraffin 8 is attached to the surface of the carbon nanotube layer 11 of the flexible double-layer film 1 in a flat state, and after cooling, it solidifies into a solid paraffin layer.

[0051] S3. Obtain the target paraffin pattern and scan the paraffin layer with an infrared nanosecond laser to evaporate and remove the paraffin layer outside the target paraffin pattern, thereby generating the paraffin structure 2 of the target pattern on the surface of the carbon nanotube layer 11.

[0052] In this embodiment, the paraffin layer is made by fusing microcrystalline wax and black paraffin pigment 7. The shapes of the flexible bilayer film 1 and the paraffin structure 2 are both prepared using a nanosecond laser processing system.

[0053] like Figure 3 The nanosecond laser processing system includes: a computer 34, a nanosecond laser 35, an attenuator 36, a reflector 37, a first lens 31, a second lens 32, a CCD image sensor 38, a third lens 33, a dichroic mirror 39, a high-magnification objective lens 310, processing materials 311, and a processing platform 312.

[0054] The nanosecond laser 35 is an infrared nanosecond pulsed fiber laser. A computer 34 controls the shutter of the nanosecond laser 35 to emit a laser beam. The laser beam then passes through an attenuator 36, which adjusts the laser beam power. The beam reaches a reflector 37, which alters the laser path. The laser then passes through a first lens 31 and a second lens 32 before reaching a dichroic mirror 39. Finally, it is focused by a high-powered objective lens 310 and vertically illuminates the processing material 311 placed on a processing platform 312. The sample is fixed on a movable precision displacement platform, whose displacement is controlled by the computer 34. Visible light passes through the dichroic mirror 39 to filter out excess red light before entering the CCD image sensor for real-time observation of the processing.

[0055] In S1, the shape of the flexible bilayer film is prepared as follows: Figure 4 As shown, a rectangular structure (24mm long and 4mm wide) is drawn in the operation interface of the nanosecond laser processing system, imported into the marking software, and then processed by emitting a laser beam through the nanosecond laser 35.

[0056] In this embodiment, the flexible bilayer film 1 is a CNTs / PDMS flexible bilayer film, with the CNTs layer and the PDMS layer being a single unit. The laser pulse width is 10 ns, the wavelength is 1064 nm, and the processing frequency is 100 kHz. A nanosecond laser 35 emits a laser beam onto the flat flexible bilayer film 1 substrate to cut and process the flexible bilayer film 1 into a specific shape and size.

[0057] In S2, paraffin is prepared as follows: Figure 5As shown, a suitable amount of microcrystalline wax is weighed and placed on a glass slide 4. The glass slide 4 is then placed on a heating stage 5 set at 100°C, and the microcrystalline wax quickly melts into a liquid state. To improve the heat absorption performance of the wax layer during laser processing, two drops of black paraffin pigment 7 are added to the molten paraffin using a burette 6, and stirred evenly with a glass rod to ensure that the paraffin pigment 7 and the molten paraffin 8 are fully mixed.

[0058] like Figure 6 As shown, in step S2, the flexible bilayer film 1 prepared in step S1 is placed flat on another glass slide and fixed on a two-dimensional moving stage 9. The carbon nanotube layer 11 of the flexible bilayer film structure is quickly dipped into and removed from the surface of the molten paraffin 8, parallel to the surface of the CNTs layer. At room temperature, the molten paraffin 8 attached to the surface of the CNTs layer quickly solidifies into a solid. In this embodiment, the paraffin layer that has not yet fully solidified can be pressed onto a clean glass slide to make the thickness of the paraffin layer more uniform.

[0059] In step S3, the excess portion of the paraffin layer is removed again by the nanosecond laser 35, leaving paraffin of the desired shape. The nanosecond laser 35 has a laser pulse width of 10 ns, a wavelength of 1064 nm, a processing frequency of 100 kHz, a laser power of 24 W, a processing speed of 3500 mm / s, and a scanning spacing of 1 μm. In this embodiment, the flexible bilayer film 1 has a rectangular structure, therefore the paraffin structure 2 formed on its surface has a parallelogram shape.

[0060] In this embodiment, driving experiments were also conducted on different flexible actuators. For example... Figure 7 As shown, the flexible actuator can be placed on the graduated paper. Using an 808nm near-infrared laser as the driving source, with an output power range of 0 to 300mW, it can be focused to illuminate a 3×1.5mm area. 2 A rectangular area was defined. Before irradiating the actuator, the output power was measured using a power meter and fixed at 250mW to ensure the material was not damaged by heat and to maintain good driving performance. The laser spot scanned along the long axis of the actuator's center, sequentially scanning at positions I, II, and III to drive the flexible actuator to crawl along the forward direction (IV) shown in the figure. Since the actuator initially bent downwards, when the laser scanned along the actuator's centerline, due to the difference in friction between the actuator's head and tail, the actuator would move towards the side with greater friction. To improve the actuator's maneuverability, an isosceles trapezoidal actuator was used to generate greater asymmetric friction; the lengths of the upper and lower bases were 2mm and 4mm respectively, with a straight-line distance of 10mm between the two bases. Three sets of control experiments were provided below.

[0061] (a) When the actuator does not apply any paraffin structure 2, the following driving method is used to obtain the following result: Figure 8The trajectory of motion of a. Within 160s, the flexible actuator has a horizontal forward displacement of 13.5mm and a vertical leftward displacement of 5mm.

[0062] (b) When a paraffin structure with a width of 0.5 mm and an inclination angle of 30° is applied to the actuator, the same driving method described above yields the following result: Figure 8 The trajectory of motion b. Within 160s, the flexible actuator exhibits a horizontal forward linear displacement of 13mm, with a very small vertical displacement. (The tilt angle α is the angle between the hypotenuse of the paraffin and the horizontal direction.)

[0063] (c) When a paraffin structure with a width of 0.5 mm and an inclination angle of 45° is applied to the actuator, the same driving method described above yields the following result: Figure 8 The trajectory of motion of C. Within 56 seconds, the flexible actuator has a horizontal forward linear displacement of 9 mm and a vertical rightward displacement of 4 mm.

[0064] Analysis showed that setting the width of the attached paraffin structure to 0.5 mm minimized its impact on the actuator's crawling speed. Tilting angles of 30° and 45° were chosen to compensate for the actuator's initial offset angle and achieve significant turning. With a paraffin structure tilt angle of 30°, the actuator crawled 13 mm horizontally within 160 seconds, with minimal vertical displacement. At a tilt angle of 45°, the actuator's movement began to shift to the right. The increased tilt angle increased the initial contraction of the actuator and decreased the distance between its ends. This increased the step size per light cycle, significantly increasing the crawling speed; thus, a horizontal displacement of 9 mm and a vertical displacement of 4 mm were achieved within 56 seconds.

[0065] like Figure 9 As shown, with the lower right corner of the actuator as the observation point, the original motion trajectory and the crawling trajectory along a straight line are recorded using horizontal and vertical displacements as the horizontal and vertical coordinates, respectively. Experimental results show that by adding a specific paraffin soft shell structure to the actuator, the direction and speed of the actuator's motion can be well controlled.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for fabricating a reprogrammable flexible actuator, characterized in that, It is used to prepare a reprogrammable flexible actuator; the reprogrammable flexible actuator includes a flexible bilayer film formed by stacking carbon nanotubes and polydimethylsiloxane; the flexible bilayer film is mirror-symmetrical about a plane of symmetry parallel to the actuation direction; the flexible bilayer film includes a relatively parallel head end and a tail end, and the extension direction of the head end and the tail end is perpendicular to the plane of symmetry; the flexible bilayer film is curled up along the extension direction of the plane of symmetry in its natural state, thereby forming a downward-opening "C"-shaped structure; the reprogrammable flexible actuator also includes at least one paraffin structure; the paraffin structure is a strip-shaped band attached to the upper surface of the carbon nanotube layer; wherein, when the flexible bilayer film is in a flat state, there is a preset angle α ∈ [-30°, 60°] between the extension direction of the paraffin structure and the extension direction of the head end or the tail end, and the length of the head end and the tail end is greater than the width of the paraffin structure. The preparation method includes the following steps: S1. A flexible bilayer membrane of a specific shape and size is provided; wherein the flexible bilayer membrane is composed of carbon nanotubes and polydimethylsiloxane stacked one on top of the other; S2. A preset amount of molten paraffin is attached to the surface of the carbon nanotube layer of the flexible double-layer film in a flat state, and solidified into a solid paraffin layer after cooling. S3. Obtain the target paraffin pattern and scan the paraffin layer with an infrared nanosecond laser to evaporate and remove the paraffin layer outside the target paraffin pattern, thereby generating the paraffin structure of the target pattern on the surface of the carbon nanotube layer.

2. The method for fabricating a reprogrammable flexible actuator according to claim 1, characterized in that, In S1, a double-layer film pattern of a specific shape and size is drawn in the operation interface of a nanosecond laser processing system and imported into the marking software. Then, the laser of the system emits a laser beam to the flexible double-layer film substrate in the flat state to cut and process the flexible double-layer film of a specific shape and size.

3. The method for fabricating a reprogrammable flexible actuator according to claim 2, characterized in that, In S1, the laser pulse width of the laser is 10ns, the wavelength is 1064nm, and the processing frequency is 100KHz.

4. The method for fabricating a reprogrammable flexible actuator according to claim 1, characterized in that, In S3, the infrared nanosecond laser has a laser pulse width of 10ns, a wavelength of 1064nm, a processing frequency of 100KHz, a laser power of 24W, a processing speed of 3500mm / s, and a scanning spacing of 1μm.

5. The method for fabricating a reprogrammable flexible actuator according to claim 1, characterized in that, In step S2, before attaching paraffin to the surface of the carbon nanotube layer, black paraffin pigment is mixed into the molten paraffin and stirred; wherein the mass ratio of the black paraffin pigment to the molten paraffin is 1:

8.

6. A driving method for a flexible actuator, characterized in that, It is used to drive a reprogrammable flexible actuator prepared by the method of preparing a reprogrammable flexible actuator as described in any one of claims 1 to 5 to perform crawling motion; the driving method includes the following steps: The flexible actuator is placed on the platform in its natural state with the "C"-shaped structure opening facing downwards; The flexible actuator is scanned and irradiated using a near-infrared laser; wherein the spot of the near-infrared laser falls on the upper surface of the carbon nanotube layer, and moves from the midpoint of the end of the flexible bilayer film along the curve formed by the projection of the symmetry plane onto the upper surface of the carbon nanotube layer to the midpoint of the beginning end, thereby achieving a single scan irradiation.

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