Soft robotic arms and their usage

Abstract

This invention relates to a soft robotic hand, comprising at least one gripping part. The gripping part includes a body and a thermally responsive layer covering the surface of the body. The elastic modulus of the body is less than that of the thermally responsive layer. The body contains photothermal conversion fillers. The thermally responsive layer is made of a thermally responsive polymer and a crosslinking agent. The molecular chain of the thermally responsive polymer contains furan groups, and the molecular chain of the crosslinking agent contains maleimide groups. This invention also relates to a method of using the soft robotic hand. The surface roughness of the gripping part of the soft robotic hand can be reversibly adjusted. When gripping a target object, the surface roughness of the soft robotic hand can be further controlled by adjusting the temperature of the soft robotic hand by changing the infrared illumination time, thus enabling the gripping and release of fragile and easily damaged items of different weights and surface roughnesses.

Description

Technical Field

[0001] This invention relates to the field of robotic arm technology, and in particular to soft robotic arms and methods of using them. Background Technology

[0002] Soft robotic arms are robotic hands made of soft materials, and compared with traditional robotic arms or grippers, they are more capable of manipulating small or fragile objects. However, traditional methods of controlling soft robotic arms to grasp objects mainly include electrical stimulation, pneumatic actuation, or magnetic field control. When grasping smooth, fragile, or easily damaged items, it is inconvenient to precisely control the grasping and releasing, which can easily cause damage to the grasped object. Summary of the Invention

[0003] Therefore, it is necessary to provide a soft robotic arm and its usage method to address the above problems. The surface roughness of the gripping part of the soft robotic arm can be reversibly adjusted. When the soft robotic arm is used to grip a target object, the temperature of the soft robotic arm can be adjusted by changing the infrared illumination time, which can further control the surface roughness of the soft robotic arm, thereby realizing the gripping and release of fragile and easily damaged items with different weights and surface roughnesses.

[0004] A soft robotic hand includes at least one gripping part, the gripping part comprising a body and a thermally responsive layer covering the surface of the body, the elastic modulus of the body being less than the elastic modulus of the thermally responsive layer, wherein the body contains photothermal conversion filler that can absorb infrared light and convert it into heat energy, and the material of the thermally responsive layer comprises a thermally responsive polymer and a crosslinking agent, the molecular chain of the thermally responsive polymer containing furan groups, and the molecular chain of the crosslinking agent containing maleimide groups.

[0005] In one embodiment, the thermally responsive polymer has the structural formula shown in formula (1):

[0006]

[0007] In formula (1), R1 is selected from hydrogen atoms or methyl groups, R2 is selected from alkanes with a carbon chain length of 3-20, R3 is selected from halogen atoms, and x, y and z are all integers from 5000 to 20000.

[0008] In one embodiment, the crosslinking agent has the structural formula shown in formula (2) or formula (3):

[0009] In equation (2), n is an integer between 20 and 1000.

[0010] In one embodiment, the molar ratio of the thermally responsive polymer to the crosslinking agent is 2:1 to 4:1.

[0011] In one embodiment, the thickness of the thermally responsive layer is 2mm-10mm.

[0012] In one embodiment, the photothermal conversion filler has an absorption rate of infrared light greater than or equal to 75%.

[0013] In one embodiment, the photothermal conversion filler is selected from at least one of graphene, carbon nanotubes, or carbon black.

[0014] In one embodiment, the photothermal conversion filler has a mass fraction of 0.01%-5% in the bulk.

[0015] In one embodiment, the material of the body is selected from polydimethylsiloxane, polyurethane, or a copolymer of butylene adipate and butylene terephthalate.

[0016] A method of using the aforementioned soft robotic arm includes:

[0017] The soft robotic hand is irradiated with infrared light to raise the temperature of its gripping part to 70°C-75°C. After cooling, the surface roughness of the thermal response layer in the gripping part increases, enabling the gripping part to grasp the target object.

[0018] The soft robotic arm is irradiated with infrared light to raise the temperature of its gripping part to 120°C-130°C. After cooling, the surface roughness of the thermal response layer in the gripping part decreases, enabling the gripping part to release the target object.

[0019] In the soft manipulator of the present invention, the photothermal conversion filler in the body can absorb infrared light and convert it into heat energy to heat the gripping part. When the temperature of the gripping part reaches 70°C-75°C, the thermally responsive polymer and crosslinking agent in the thermally responsive layer undergo a crosslinking reaction to generate a three-dimensional crosslinked network, which increases the modulus of the thermally responsive layer. Therefore, after cooling, the thermally responsive layer generates a wrinkled structure, which increases the surface roughness of the gripping part. When the temperature of the gripping part reaches 120°C-130°C, the three-dimensional crosslinked network in the thermally responsive layer undergoes a decrosslinking reaction, which decreases the modulus of the thermally responsive layer. Therefore, after cooling, the wrinkled structure of the thermally responsive layer disappears, which reduces the surface roughness of the gripping part and even restores it to a flat state.

[0020] Therefore, the surface roughness of the gripping part of the soft robotic arm of the present invention can be reversibly adjusted, and can be precisely controlled by heating temperature. Thus, when using the soft robotic arm of the present invention to grip a target object, the friction between the gripping part and the target object can be adjusted by controlling the surface roughness of the gripping part, achieving controllable gripping and release of the target object. Furthermore, by adjusting the surface roughness of the soft robotic arm, it is possible to grip and release fragile and easily damaged items of different weights and surface roughnesses, thus broadening its applicability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the gripping part of the soft robotic arm of the present invention;

[0022] Figure 2 This is a schematic diagram of the use of the soft robotic arm of the present invention, wherein (a) is a schematic diagram of the gripping part gripping the target object, and (b) is a schematic diagram of the gripping part releasing the target object.

[0023] In the diagram: 10, gripping part; 20, target object; 101, body; 102, thermal response layer; 103, photothermal conversion filler. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the soft robotic arm and its usage method of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0026] like Figure 1 As shown, the soft robotic arm provided by the present invention includes at least one gripping part 10, the gripping part 10 including a body 101 and a thermal response layer 102 covered on the surface of the body 101.

[0027] The body 101 contains a photothermal conversion filler 103, which can absorb infrared light and convert it into heat energy. Therefore, the photothermal conversion filler 103 can heat the gripping part 10. The material of the thermal response layer 102 includes a thermal response polymer and a crosslinking agent. The molecular chain of the thermal response polymer contains furan groups, and the molecular chain of the crosslinking agent contains maleimide groups. Therefore, by controlling the temperature, the thermal response polymer and the crosslinking agent can undergo a reversible Diels-Alder (DA) reaction.

[0028] Specifically, the process of the reversible Diels-Alder reaction between the thermally responsive polymer and the crosslinking agent in the thermally responsive layer 102 of the present invention is as follows: the photothermal conversion filler 103 distributed in the body 101 absorbs infrared light and converts it into heat energy to heat the gripping part 10. When the temperature of the gripping part 10 reaches 70℃-75℃, the thermally responsive polymer and the crosslinking agent in the thermally responsive layer 102 undergo a crosslinking reaction to generate a three-dimensional crosslinked network, thereby increasing the modulus of the thermally responsive layer 102. Since the elastic modulus of the body 101 is less than that of the thermally responsive layer 102, the thermally responsive layer 102 generates a wrinkled structure after cooling, which in turn increases the surface roughness of the gripping part 10. When the temperature of the gripping part 10 reaches 120℃-130℃, the three-dimensional crosslinked network in the thermally responsive layer 102 undergoes a decrosslinking reaction, which decreases the modulus of the thermally responsive layer 102. Therefore, the wrinkled structure of the thermally responsive layer 102 disappears after cooling, thereby reducing the surface roughness of the gripping part 10, or even restoring it to a flat state.

[0029] In the process of crosslinking and decrosslinking reactions between the thermally responsive polymer and the crosslinking agent, the degree of crosslinking and decrosslinking reactions can be controlled by temperature, thereby controlling the wrinkled structure of the thermally responsive layer 102 and achieving precise and flexible control of the surface roughness of the gripping part 10. Therefore, the surface roughness of the gripping part 10 of the soft robotic arm of the present invention can be reversibly adjusted by the thermally responsive layer 102, and can be precisely controlled by heating temperature.

[0030] like Figure 2 The diagram shows the process of using the soft robotic arm of the present invention. When using the soft robotic arm of the present invention, the soft robotic arm relies on the gripping part 10 to grasp and release the target object 20. Specifically, the friction between the gripping part 10 and the target object 20 is adjusted by controlling the surface roughness of the gripping part 10, so as to realize the controllable grasping and release of the target object 20.

[0031] More specifically, when the surface roughness of the gripping part 10 of the soft robotic arm increases, the friction between the gripping part 10 and the target object 20 increases, and the target object 20 can be gripped; when the surface roughness of the gripping part 10 of the soft robotic arm decreases, the friction between the gripping part 10 and the target object 20 decreases, and the target object 20 can be released.

[0032] It is understood that the thermal response layer 102 can be applied to one or more surfaces of the body 101, or it can completely cover the body 101, so as to adjust the operable area.

[0033] In addition, the soft robotic hand may also include components such as a support part. The number of gripping parts 10 can be one or more. When the number of gripping parts 10 is multiple, for example, it can be a symmetrical structure composed of two parts, a V-shaped structure, or a ring structure composed of three or more parts, or it can be a biomimetic structure, such as a biomimetic hand.

[0034] Therefore, the material of the body 101 is preferably polydimethylsiloxane (PDMS), polyurethane (TPU), or a copolymer of butylene adipate and butylene terephthalate (Ecoflex).

[0035] In the soft robotic hand of the present invention, the degree of cross-linking and de-cross-linking reactions of the thermally responsive polymer and the cross-linking agent can be controlled by the temperature of the gripping part 10, which in turn can be controlled by the photothermal conversion filler 103 distributed in the body 101. Therefore, in order to better control the temperature and improve the heating efficiency, the photothermal conversion filler 103 is preferably a carbon-based filler with an infrared light absorption rate greater than or equal to 75%. Optionally, the photothermal conversion filler 103 is selected from at least one of graphene, carbon nanotubes, or carbon black.

[0036] In order to control the heating temperature more precisely and efficiently, the photothermal conversion filler 103 is uniformly distributed in the body 101. The particle size of the photothermal conversion filler 103 is preferably 0.05μm-15μm, and the shape is not limited. The mass fraction of the filler in the body 101 is preferably 0.01%-5%.

[0037] It is understandable that different thermally responsive polymers have different thermal responsiveness, that is, the rates of cross-linking and de-cross-linking reactions are different, and the required reaction times are different. Similarly, different thermally responsive polymers have different moduli after cross-linking, which makes the adjustable range of surface roughness different, and thus the range of target objects 20 that can be grasped are also different, including the mass, shape, surface roughness, and whether the target object 20 is a fragile object.

[0038] To improve the grasping efficiency and grasping range of the soft robotic arm of the present invention, in one embodiment, the thermally responsive polymer has the structural formula as shown in formula (1):

[0039]

[0040] In formula (1), R1 is selected from hydrogen atoms or methyl groups, R2 is selected from alkanes with a carbon chain length of 3-20, R3 is selected from halogen atoms, and x, y and z are all integers from 5000 to 20000.

[0041] The thermally responsive polymer shown in formula (1) has a certain rigidity. After crosslinking with the crosslinking agent, it has a large modulus and can produce larger surface wrinkles. The adjustable range of surface roughness is larger. Therefore, the range of target objects 20 that can be grasped is larger, the controllability is better, and the grasping efficiency is higher.

[0042] Optionally, the thermally responsive polymer has the structural formula shown in formula (1-1) or formula (1-2):

[0043]

[0044] It should be noted that the thermo-responsive polymer shown in formula (1-1) can be prepared by the following steps: dissolving chloromethylstyrene and n-butyl acrylate in dioxane, followed by free radical polymerization with azobisisobutyronitrile to obtain an intermediate, and then branching furfuryl thiol onto the side of the intermediate to obtain the thermo-responsive polymer shown in formula (1-1).

[0045] The thermo-responsive polymer shown in formula (1-2) can be prepared by the following steps: dissolving chloromethylstyrene and n-butyl acrylate in dioxane, followed by free radical polymerization with azobisisobutyronitrile to obtain an intermediate, and then branching 5-methyl-2-furanthiol onto the side of the intermediate to obtain the thermo-responsive polymer shown in formula (1-2).

[0046] The structural formula of the intermediate is shown in formula (a):

[0047]

[0048] Alternatively, in one embodiment, the crosslinking agent has the structural formula shown in formula (2) or formula (3):

[0049] In equation (2), n is an integer between 20 and 1000.

[0050] It should be noted that the crosslinking agents shown in formulas (2) and (3) can be prepared by the following steps: maleic anhydride and molecules containing amino groups at both ends are dissolved in toluene, and the crosslinking agent is synthesized by azeotropic distillation dehydration. When the amino group at both ends is polyetheramine D-230, the crosslinking agent shown in formula (2) is obtained. When the amino group at both ends is 1,4-butanediol bis(3-aminopropyl) ether, the thermoresponsive polymer shown in formula (3) is obtained.

[0051] In particular, when the material of the thermal response layer 102 is selected from the thermal response polymer shown in formula (1) and the crosslinking agent shown in formula (2), or selected from the thermal response polymer shown in formula (1) and the crosslinking agent shown in formula (3), the grasping effect on the target object 20 is more prominent, and it can grasp and release fragile and easily damaged items of different weights and different surface roughness, and has a wider range of applications.

[0052] It should be noted that the step of preparing the thermally responsive layer 102 on the body 101 includes: mixing the thermally responsive polymer and the crosslinking agent, and applying the mixture to the surface of the body 101 by spin coating or blade coating.

[0053] Optionally, the molar ratio of the thermally responsive polymer to the crosslinking agent is 2:1-4:1, and the thickness of the thermally responsive layer 102 can be 2mm-10mm.

[0054] Therefore, the present invention also provides a method of using the aforementioned soft robotic arm, comprising:

[0055] S1, the soft robotic hand is irradiated with infrared light to raise the temperature of the gripping part 10 of the soft robotic hand to 70℃-75℃. After cooling, the surface roughness of the thermal response layer 102 in the gripping part 10 increases so that the gripping part 10 can grip the target object 20.

[0056] S2, the soft robotic hand is irradiated with infrared light to raise the temperature of the gripping part 10 of the soft robotic hand to 120℃-130℃. After cooling, the surface roughness of the thermal response layer 102 in the gripping part 10 is reduced, so that the gripping part 10 can release the target object 20.

[0057] In step S1, when the soft manipulator is irradiated with infrared light, the photothermal conversion filler 103 distributed in the body 101 can absorb the infrared light and convert it into heat energy to heat the gripping part 10. This allows the thermally responsive polymer and crosslinking agent in the thermally responsive layer 102 to undergo a crosslinking reaction, generating a three-dimensional crosslinked network. This increases the modulus of the thermally responsive layer 102. Since the elastic modulus of the body 101 is less than that of the thermally responsive layer 102, the thermally responsive layer 102 generates a wrinkled structure after cooling. This increases the surface roughness of the gripping part 10 and the friction between the gripping part 10 and the target object 20, enabling the gripping part 10 to grasp the target object 20.

[0058] Optionally, the target object 20 may be a chip or the like.

[0059] In step S2, when the temperature of the gripping part 10 reaches 120℃-130℃, the three-dimensional cross-linked network in the thermal response layer 102 undergoes a de-cross-linking reaction, causing the modulus of the thermal response layer 102 to decrease. Therefore, after cooling, the wrinkled structure of the thermal response layer 102 disappears, thereby reducing the surface roughness of the gripping part 10, or even restoring it to a flat state. The friction between the gripping part 10 and the target object 20 decreases, and the target object 20 can be released.

[0060] Therefore, the soft robotic arm of the present invention can adjust the friction between the gripping part 10 and the target object 20 by controlling the surface roughness of the gripping part 10, so as to realize the controllable gripping and release of the target object 20. In particular, it can realize the gripping and release of fragile and easily damaged items with different weights and different surface roughnesses. The method is simple and can repeatedly realize controllable gripping and release, and can be applied to a wider range.

[0061] Meanwhile, during this process, the degree of cross-linking and de-cross-linking reactions can be adjusted according to the infrared light irradiation time and the photothermal conversion filler 103 distributed in the body 101, thereby precisely controlling the surface roughness of the gripping part 10. It is understood that in step S1, it is not necessary to make the surface roughness of the gripping part 10 reach the maximum value, and in step S2, it is not necessary to restore the gripping part 10 to a completely flat plane. It is sufficient to ensure that the gripping part 10 can stably grip and release the target object 20, thereby improving the gripping and releasing efficiency.

[0062] The following specific embodiments will further illustrate the soft robotic arm and its usage.

[0063] The materials in the soft manipulators of the following embodiments are shown in Table 1, wherein x = 6000, y = 7000, z = 5000 in equation (1-1), x = 8000, y = 5000, z = 6000 in equation (1-2), and n = 50 in equation (2).

[0064] Table 1

[0065]

[0066]

[0067] The soft robotic arms of Examples 1-9 were irradiated with infrared light, first heated to 75°C and then heated to 125°C. The changes in the elastic modulus and surface roughness of the thermal response layer 102 are shown in Table 2.

[0068] Table 2

[0069]

[0070] It should be noted that the thermal response time of the thermal response layer 102 during decrosslinking is basically the same as that during crosslinking. After decrosslinking, the elastic modulus of the thermal response layer 102 is basically restored to the elastic modulus before crosslinking, and the surface roughness is basically restored to the surface roughness before crosslinking.

[0071] The soft robotic arms of Examples 1-9 were used to grasp ultra-thin chips (smooth surface, very light weight, and easily broken), and the results are shown in Table 3.

[0072] Table 3

[0073]

[0074]

[0075] As shown in Table 3, when the weight of the ultrathin chip is the same, the greater the surface roughness of the cross-linked thermal response layer 102, the smaller the surface roughness of the ultrathin chip that the soft robot can grasp.

[0076] 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.

[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. 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 protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A soft robot hand, comprising: The device includes at least one gripping part, which includes a body and a thermally responsive layer coated on the surface of the body. The elastic modulus of the body is less than that of the thermally responsive layer. The body contains photothermal conversion filler that can absorb infrared light and convert it into heat energy. The thermally responsive layer is made of a thermally responsive polymer and a crosslinking agent. The molecular chain of the thermally responsive polymer contains furan groups, and the molecular chain of the crosslinking agent contains maleimide groups. The structural formula of the thermally responsive polymer is shown in formula (1): ； In formula (1), R1 is selected from hydrogen atoms or methyl groups, R2 is selected from alkanes with a carbon chain length of 3-20, R3 is selected from halogen atoms, and x, y and z are all integers from 5000 to 20000. The crosslinking agent has the structural formula shown in formula (2) or formula (3): 、 ； In equation (2), n is an integer between 20 and 1000.

2. The soft manipulator according to claim 1, wherein The molar ratio of the thermally responsive polymer to the crosslinking agent is 2:1 to 4:

1.

3. The soft manipulator of claim 1, wherein The thickness of the thermally responsive layer is 2mm-10mm.

4. The soft robot hand of claim 1, wherein, The photothermal conversion filler has an absorption rate of infrared light greater than or equal to 75%.

5. The soft robot hand of claim 4, wherein, The photothermal conversion filler is selected from at least one of graphene, carbon nanotubes, or carbon black.

6. The soft robot hand of claim 1, wherein, The mass fraction of the photothermal conversion filler in the body is 0.01%-5%.

7. The soft robot hand of claim 1, wherein, The material of the body is selected from polydimethylsiloxane, polyurethane, or a copolymer of butylene adipate and butylene terephthalate.

8. A method of using a soft robot hand as claimed in any one of claims 1 to 7, characterised in that, include: The soft robotic hand is irradiated with infrared light to raise the temperature of its gripping part to 70°C-75°C. After cooling, the surface roughness of the thermal response layer in the gripping part increases, enabling the gripping part to grasp the target object. The soft robotic arm is irradiated with infrared light to raise the temperature of its gripping part to 120°C-130°C. After cooling, the surface roughness of the thermal response layer in the gripping part decreases, enabling the gripping part to release the target object.

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