Photocuring hydrogel material, preparation method and application thereof, and bionic flexible grabber

Abstract

The invention provides a photocuring hydrogel material, a preparation method and application thereof and a bionic flexible grabber, and belongs to the technical field of bionic manufacturing. The preparation method comprises the following steps: mixing acrylic acid, acrylamide, N-acryloyl semicarbazide and a solvent to obtain a precursor solution; mixing the precursor solution, a photoinitiator and a photopolymerization inhibitor to obtain hydrogel ink; the hydrogel ink is subjected to light curing, and the light-cured hydrogel material is obtained. According to the preparation method, a series of poly (NASC-co-AAc-co-AAm) hydrogel with adjustable mechanical properties is prepared by combining the synergistic effect of strong hydrogen bonds and weak hydrogen bonds and controlling the mass ratio of acrylamide to acrylic acid to N-acryloyl semicarbazide to change the density of a hydrogen bond supramolecular network, so that the grabbing capacity of a soft gripper can be improved, and the mechanical properties of the soft gripper can be improved. And lossless grabbing and releasing of the ultra-soft object are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic manufacturing, and particularly relates to a photocurable hydrogel material, a preparation method and application thereof, and a bionic flexible gripper. Background Art

[0002] Flexible grippers have shown unique value in many fields such as industrial manufacturing, medical and health, agriculture and food industry due to their high adaptability, safety and flexibility. At present, with the breakthrough development of materials science, artificial intelligence and drive technology, flexible grippers are penetrating from industrial scenarios into broader fields such as medical and home, becoming one of the key technologies for human-machine collaboration.

[0003] However, when the flexible grippers in related technologies grasp some irregular, ultra-soft and fragile items, due to problems such as insufficient flexibility of the material and difficulty in controlling the grasping force, they cannot gently contact the surface of the item, thereby damaging the item. For flexible grippers, if the material is too soft, it is difficult for the gripper to firmly grasp an object; if the material is too hard, the gripper is difficult to be driven and easily damages the object. The traditional flexible gripper has a simple structure and mainly relies on the contact of several points or surfaces to apply pressure and uses friction to achieve the grasping function. For soft and fragile items, this type of gripper is very likely to cause damage to them. Therefore, the insufficient flexibility of the material mechanics performance severely restricts the practical application of flexible grippers. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a photocurable hydrogel material, a preparation method and application thereof, and a bionic flexible gripper. The photocurable hydrogel material prepared by the present invention has soft and tough mechanical properties and can be used for manufacturing an adaptive soft gripper.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a photocurable hydrogel material (poly(NASC-co-AAc-co-AAm) hydrogel), comprising the following steps:

[0007] Mix acrylic acid (AAc), acrylamide (AAm), N-acryloyl semicarbazide (NASC) and a solvent to obtain a precursor solution; the mass ratio of acrylic acid to acrylamide is 3:1 to 1:3, and the mass ratio of the sum of the masses of acrylic acid and acrylamide to N-acryloyl semicarbazide is 0.3 to 0.6:1;

[0008] Mix the precursor solution, a photoinitiator and a photopolymerization inhibitor to obtain a hydrogel ink;

[0009] Carry out photocuring on the hydrogel ink to obtain the photocurable hydrogel material.

[0010] Preferably, the solvent includes an organic solvent and water, and the volume ratio of the organic solvent to water in the solvent is 1:9 to 9:1.

[0011] Preferably, the organic solvent includes one or more of dimethyl sulfoxide, glycerol, and ethanol.

[0012] Preferably, the mass ratio of acrylamide, organic solvent, and water is 3.13:26.25:11.25.

[0013] Preferably, the mass of the photoinitiator is 0.1 to 1% of the mass of the monomers, and the monomers include acrylic acid, acrylamide, and N-acryloyl semicarbazide.

[0014] Preferably, the mass ratio of the photoinitiator to the photopolymerization inhibitor is 0.0625:0.015.

[0015] The present invention also provides a photocurable hydrogel material prepared by the preparation method described in the above technical solution. The tensile strength of the photocurable hydrogel material is 1 to 10 MPa, the elastic modulus is 0.05 to 1 MPa, the elongation at break is 800 to 1500%, and the tear toughness is 1 to 50 kJ·m -2 .

[0016] The present invention also provides an application of the photocurable hydrogel material described in the above technical solution in the field of flexible grippers.

[0017] The present invention also provides a bionic flexible gripper, including: a bionic hydrogel gripper unit, a first syringe pump, a second syringe pump, a robotic arm, a silicone tube, a syringe pump controller, and a robotic arm controller;

[0018] The bionic hydrogel gripper unit is connected to the first syringe pump and the second syringe pump through the silicone tube. The syringe pump controller is connected to the first syringe pump and the second syringe pump. The bionic hydrogel gripper unit is fixed on the robotic arm. The robotic arm controller is connected to the robotic arm. The bionic hydrogel gripper unit is made of the photocurable hydrogel material described in the above technical solution.

[0019] Preferably, the bionic hydrogel gripper unit includes a grasping main body, a first pipe, a second pipe, and a suction cup. The suction cup includes a suction cup air cavity and a suction cup membrane. The first pipe and the second pipe are not communicated with each other. The first pipe is connected to the suction cup air cavity. The suction cup membrane is connected to the suction cup air cavity. The suction cup is arranged inside the grasping main body.

[0020] The present invention provides a method for preparing a photocurable hydrogel material, comprising the following steps: mixing acrylic acid, acrylamide, N-acryloyl semicarbazide and a solvent to obtain a precursor solution; the mass ratio of acrylic acid to acrylamide is 3:1 to 1:3, and the mass ratio of the sum of the masses of acrylic acid and acrylamide to N-acryloyl semicarbazide is 0.3 to 0.6:1; mixing the precursor solution, a photoinitiator and a photopolymerization inhibitor to obtain a hydrogel ink; and subjecting the hydrogel ink to photocuring to obtain the photocurable hydrogel material.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Through the synergistic effect of strong hydrogen bonds (between NASC and NASC, and between NASC and AAc) and weak hydrogen bonds (between NASC and AAm), the present invention designs a photocurable hydrogel material with adjustable mechanical properties for the manufacture of adaptive soft grippers. The principle is as Figure 1 shown. Due to the strong hydrogen bond interaction between NASC and AAc, the PNASC hydrogel exhibits plastic mechanical properties. The introduction of AAc can effectively adjust the mechanical properties of the PNASC hydrogel from plastic to elastic, because there are non-synergistic hydrogen bond interactions between ureido groups and between ureido groups and carboxyl groups in the P(NASC-co-AAc) hydrogel. However, the modulus and toughness of the P(NASC-co-AAc) hydrogel are too high, making it unsuitable for the manufacture of soft fixtures. To achieve the preparation of a super-soft supramolecular hydrogel, AAm is introduced into NASC by utilizing the weak hydrogen bond interaction between ureido groups and amino groups to prepare the P(NASC-co-AAm) hydrogel. Due to the excessive presence of weak hydrogen bonds, the strength, modulus and toughness of the P(NASC-co-AAm) hydrogel are significantly reduced. By introducing AAc with strong hydrogen bonds and AAm with weak hydrogen bonds into NASC simultaneously, and controlling the mass ratios of acrylamide, acrylic acid and N-acryloyl semicarbazide, the density of the hydrogen bond supramolecular network is changed, and a series of poly(NASC-co-AAc-co-AAm) hydrogels with adjustable mechanical properties are prepared. They are soft and tough in mechanical properties, can be used to prepare a bionic flexible gripper for non-destructive manipulation of super-soft objects, have good molding, are soft and tough in mechanical properties and have high precision, can improve the grasping ability of the soft gripper, and achieve non-destructive grasping and releasing of super-soft objects.

[0023] The present invention also provides a bionic flexible gripper that can achieve non-destructive manipulation of super-soft objects. Through the control of the first injection pump and the second injection pump, the grasping main body is caused to bend to achieve the grasping function and the suction cup film contracts to achieve the adhesion function. Compared with the grippers in the related art, this gentle grasping and releasing mode and the special mechanical properties of the soft and tough hydrogel can achieve stable grasping and non-destructive releasing of super-soft objects. Brief Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the preparation principle of the photocurable hydrogel material;

[0025] Figure 2 It is a schematic diagram of the structure of the bionic flexible gripper of the present invention, where 201 is the bionic hydrogel gripper unit, 202 is the first syringe pump, 203 is the second syringe pump, 204 is the syringe pump controller, 205 is the silicone tube, 206 is the robotic arm, and 207 is the robotic arm controller;

[0026] Figure 3 It is a schematic diagram of the structure of the bionic hydrogel gripper unit, where 101 is the gripping body, 102 is the first pipeline, 103 is the second pipeline, 104 is the suction cup, 1041 is the suction cup air cavity, and 1042 is the suction cup membrane;

[0027] Figure 4 It is a schematic diagram of the process for preparing the photocurable hydrogel material of the present invention;

[0028] Figure 5 It is a physical diagram of using a combination of one or more bionic hydrogel gripper units in Example 3 to achieve the grasping and releasing of various objects;

[0029] Figure 6 It is a physical diagram of the driving gripper prepared from the hydrogel of Comparative Example 1. Detailed Description of the Invention

[0030] The present invention provides a method for preparing a photocurable hydrogel material, comprising the following steps:

[0031] Mix acrylic acid, acrylamide, N-acryloyl semicarbazide and a solvent to obtain a precursor solution; the mass ratio of acrylic acid to acrylamide is 3:1 to 1:3, and the mass ratio of the sum of the masses of acrylic acid and acrylamide to N-acryloyl semicarbazide is 0.3 to 0.6:1;

[0032] Mix the precursor solution, a photoinitiator and a photopolymerization inhibitor to obtain a hydrogel ink;

[0033] Carry out photocuring on the hydrogel ink to obtain the photocurable hydrogel material.

[0034] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0035] In the present invention, acrylic acid, acrylamide, N-acryloyl semicarbazide and a solvent are mixed to obtain a precursor solution; the mass ratio of acrylic acid to acrylamide is 3:1 to 1:3, and the mass ratio of the sum of the masses of acrylic acid and acrylamide to N-acryloyl semicarbazide is 0.3 to 0.6:1. By controlling the amounts of acrylamide, acrylic acid and NASC, the mechanical properties of the obtained photocurable hydrogel material can be suitable for the preparation of bionic flexible grippers.

[0036] In the present invention, the mass ratio of acrylamide, acrylic acid and N-acryloyl semicarbazide is preferably 3.13:1.04:8.33.

[0037] In the present invention, the solvent preferably includes an organic solvent and water, and the volume ratio of the organic solvent to water in the solvent is preferably 1:9 to 9:1, specifically it can be 26.25:11.25.

[0038] In the present invention, the organic solvent preferably includes one or more of dimethyl sulfoxide, glycerol and ethanol.

[0039] In the present invention, the mass ratio of acrylamide, organic solvent and water is preferably 3.13:26.25:11.25.

[0040] In the present invention, acrylamide, acrylic acid and N-acryloyl semicarbazide are preferably dissolved in the solvent by magnetic stirring at room temperature to obtain the precursor solution.

[0041] After obtaining the precursor solution, the precursor solution, a photoinitiator and a photopolymerization inhibitor are mixed in the present invention to obtain a hydrogel ink.

[0042] In the present invention, the mass of the photoinitiator is preferably 0.1 to 1% of the mass of the monomers, specifically it can be 0.1%, 0.5% or 1%, and the monomers include acrylic acid, acrylamide and N-acryloyl semicarbazide.

[0043] In the present invention, the photoinitiator preferably includes a water-soluble photoinitiator, and more preferably includes lithium phenyl-2,4,6-trimethylbenzoylphosphite (LAP).

[0044] In the present invention, the mass ratio of the photoinitiator to the photopolymerization inhibitor is preferably 0.0625:0.015.

[0045] In the present invention, the photopolymerization inhibitor preferably includes lemon yellow.

[0046] In the present invention, the mass percentage of the monomers in the hydrogel ink is preferably 25%, and the monomers include acrylic acid, acrylamide and N-acryloyl semicarbazide.

[0047] After obtaining the hydrogel ink, the present invention cures the hydrogel ink by light to obtain the photocured hydrogel material.

[0048] In the present invention, the photocuring is preferably photocuring 3D printing or direct ultraviolet curing. The present invention has no special limitation on the specific parameters of the photocuring, and a method well-known to those skilled in the art can be adopted.

[0049] In the present invention, the parameters of the photocuring 3D printing preferably include: the light source intensity of the 3D printer is 300 mW, the slice layer thickness is 0.1 mm, the exposure time of the bottom layer is 15 s, and the exposure time of the remaining layers is 10 s.

[0050] In the present invention, the wavelength of the direct ultraviolet curing is preferably 405 nm.

[0051] After the photocuring is completed, the present invention preferably immerses the obtained base gel in deionized aqueous solution for 3 days to obtain a supramolecular hydrogel material, which is the photocured hydrogel material.

[0052] Figure 4 It is a schematic flow chart for preparing the photocured hydrogel material of the present invention.

[0053] The present invention also provides a photocured hydrogel material prepared by the preparation method described in the above technical solution. The tensile strength of the photocured hydrogel material is 1-~10 MPa, preferably 1.30-3.87 MPa, the elastic modulus is 0.05-1 MPa, preferably 0.24-0.93 MPa, the elongation at break is 800-1500%, preferably 893.88-1482.28%, and the tear toughness is 1-50 kJ·m -2 , preferably 2.32-39.31 kJ·m -2 , the fracture toughness is preferably 6.87-34.53 MJ·m -3 , the tear strength is preferably 1.50-23.73 N / mm, having soft and tough mechanical properties, and at the same time having excellent high-precision photocuring 3D printing manufacturing ability. The prepared bionic flexible gripper can realize the non-destructive manipulation of ultra-soft objects.

[0054] The present invention also provides an application of the photocured hydrogel material described in the above technical solution in the field of flexible grippers.

[0055] The present invention also provides a bionic flexible gripper, comprising: a bionic hydrogel gripper unit, a first injection pump, a second injection pump, a robotic arm, a silicone tube, an injection pump controller and a robotic arm controller;

[0056] The bionic hydrogel gripper unit is connected to the first injection pump and the second injection pump through the silica gel tube. The injection pump controller is connected to the first injection pump and the second injection pump. The bionic hydrogel gripper unit is fixed on the robotic arm, and the robotic arm controller is connected to the robotic arm. The bionic hydrogel gripper unit is made of the photocurable hydrogel material described in the above technical solution.

[0057] Figure 2 FIG. 4 is a schematic structural diagram of the bionic flexible gripper of the present invention, where 201 is the bionic hydrogel gripper unit, 202 is the first injection pump, 203 is the second injection pump, 204 is the injection pump controller, 205 is the silica gel tube, 206 is the robotic arm, and 207 is the robotic arm controller. The following will be combined with Figure 2 to illustrate the bionic flexible gripper of the present invention.

[0058] In the present invention, the robotic arm controller 207 controls the movement of the robotic arm 206. The robotic arm 206 controls the bionic hydrogel gripper unit 201 to move near the object to be grasped. The injection pump controller 204 controls the first injection pump 202 to move forward, so as to control the bionic hydrogel gripper unit 201 to bend close to the object to be grasped through the silica gel tube 205. The injection pump controller 205 controls the second injection pump 203 to move backward, so as to control the suction cup of the bionic hydrogel gripper unit 201 to contract through the silica gel tube 205, thereby adhering to the object to be grasped. The robotic arm controller 207 controls the robotic arm 206 to move so that the object to be grasped is moved to the designated position. Then, the injection pump controller 204 controls the second injection pump 203 to move forward and the first injection pump 202 to move backward, so that the bionic hydrogel gripper unit 201 bends back and the suction cup expands, thereby releasing the object to be grasped. The bionic flexible gripper of the present invention can improve the grasping ability of the soft gripper and realize the non-destructive grasping and releasing of ultra-soft objects.

[0059] The bionic flexible gripper of the present invention is a bionic flexible gripper made of photocurable hydrogel material for non-destructive manipulation of ultra-soft objects. Based on the soft and tough mechanical properties of the photocurable hydrogel material and the excellent high-precision photocurable 3D printing manufacturing ability, the prepared bionic flexible gripper can realize the non-destructive manipulation of ultra-soft objects. Compared with other grippers, the gentle grasping and releasing mode of the present invention and the special mechanical properties of the photocurable hydrogel material being soft and tough can realize the stable grasping and non-destructive releasing of ultra-soft objects.

[0060] The bionic flexible gripper of the present invention includes a bionic hydrogel gripper unit 201, and the bionic hydrogel gripper unit 201 is made of the photocurable hydrogel material described in the above technical solution. Figure 3Schematic structural diagram of the bionic hydrogel gripper unit, where 101 is the gripping body, 102 is the first pipeline, 103 is the second pipeline, 104 is the suction cup, 1041 is the suction cup air cavity, and 1042 is the suction cup membrane. The following will be combined with Figure 3 to describe the bionic hydrogel gripper unit 201 of the present invention.

[0061] In the present invention, the bionic hydrogel gripper unit 201 preferably includes a gripping body 101, a first pipeline 102, a second pipeline 103, and a suction cup 104. The suction cup 104 includes a suction cup air cavity 1041 and a suction cup membrane 1042. The first pipeline 102 and the second pipeline 103 are not connected to each other. The first pipeline 102 is connected to the suction cup air cavity 1041, and the suction cup membrane 1042 is connected to the suction cup air cavity 1041. The suction cup 104 is arranged inside the gripping body 101.

[0062] In the present invention, the first pipeline 102 is preferably connected to the second injection pump 203 to control the contraction and relaxation of the suction cup membrane 1042, thereby adhering to and releasing the grasped target object.

[0063] In the present invention, the second pipeline 103 is preferably connected to the first injection pump 202 to control the bending and restoration of the gripping body, thereby wrapping the target object.

[0064] In the present invention, the interior of the suction cup 104 preferably contains a negative pressure cavity. The first pipeline 102 preferably controls the negative pressure cavity inside the suction cup 104 to achieve the expansion and contraction of the suction cup membrane 1042, and further controls the relaxation and contraction of the suction cup 104.

[0065] In the present invention, when the first injection pump 202 is started forward, it controls the bending of the gripping body 101 to wrap the target object. When the second injection pump 203 is started in reverse, it controls the gentle adhesion of the suction cup 104 to the object, thereby achieving the gentle grasping of the ultra-soft object. When the second injection pump 203 is started forward, it controls the relaxation of the suction cup 104 to gently leave the object. When the first injection pump 202 is started in reverse, it controls the bending of the gripping body 101 to leave the object, thereby achieving the non-destructive release of the ultra-soft object.

[0066] In the present invention, the number of the suction cups 104 is preferably not less than 1, and more preferably a plurality of suction cups of different sizes are arranged in an array inside the gripping body 101.

[0067] In the present invention, the number of the bionic hydrogel gripper units 201 is preferably not less than 1.

[0068] The present invention also provides a method for preparing the bionic flexible gripper described in the above technical solution. First, obtain the hydrogel ink according to the above technical solution, and then use a photocuring 3D printer to print and form the hydrogel ink according to the model program to obtain the bionic hydrogel gripper unit 201 with a complex pipeline design, and then assemble it to obtain the bionic flexible gripper.

[0069] The objects grasped by the bionic flexible gripper of the present invention preferably include ultra-soft objects, and the ultra-soft objects refer to a class of materials or objects with extremely low elastic modulus (extremely soft), fragile and prone to significant deformation.

[0070] In the present invention, the ultra-soft object is preferably egg yolk or tofu.

[0071] The objects grasped by the bionic flexible gripper of the present invention preferably include various flat surfaces, curved surfaces, and irregular non-ultra-soft objects.

[0072] In the present invention, the non-ultra-soft object is preferably a box.

[0073] The bionic flexible grippers of the present invention are preferably used alone or in combination.

[0074] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0075] Example 1

[0076] Preparation of photocuring hydrogel material

[0077] Dissolve NASC (8.33 g), acrylamide (3.13 g), and acrylic acid (1.04 g) in a mixed solution of dimethyl sulfoxide (26.25 g) and deionized water (11.25 g) by magnetic stirring to obtain a precursor solution. Stir the precursor solution, LAP (0.0625 g), and lemon yellow (0.015 g) to mix them to obtain a hydrogel ink that can be used for photocuring. Put the hydrogel ink into the material box of a photocuring 3D printer, and use the photocuring 3D printer to print and form according to the model program (the light source intensity of the 3D printer is 300 mW, the slice layer thickness is 0.1 mm, the exposure time of the bottom layer is 15 s, and the exposure time of the remaining layers is 10 s) to obtain a base gel. Subsequently, soak the base gel in deionized water for 3 days to obtain a photocuring hydrogel material with flexible mechanical properties.

[0078] Using a universal material testing machine, the mechanical properties of the photocurable hydrogel material were tested, and the test results are as follows: the elongation at break was 893.88 ± 55.55%, the tensile strength reached 1.30 ± 0.07 MPa, the elastic modulus was 0.24 ± 0.02 MPa, and the tear toughness was 2.32 ± 0.012 kJ·m -2 , and the fracture toughness was 6.87 ± 0.66 MJ·m 3 , and the tear strength was 2.50 ± 0.06 N / mm.

[0079] Example 2

[0080] Design and manufacture of the bionic hydrogel gripper unit 201

[0081] A. The preparation of the hydrogel ink is the same as that in Example 1.

[0082] B. Using the 3D modeling software Solidworks to design the structure of the bionic hydrogel gripper unit and construct the device model, and then importing the constructed hydrogel gripper unit model into commercial DLP 3D printing for printing parameter optimization and printing manufacturing, a basic hydrogel gripper unit can be obtained. Subsequently, the basic hydrogel gripper unit is soaked in deionized water for 3 days to obtain a hydrogel gripper unit with excellent adhesion performance.

[0083] The bionic hydrogel gripper unit 201 includes a gripping body 101, a first pipe 102, a second pipe 103, a suction cup 104, a suction cup air cavity 1041, and a suction cup membrane 1042. The first pipe 102 and the second pipe 103 are inside the gripping body 101 and do not communicate with each other. The first pipe 102 is connected to the suction cup air cavity 1041, the suction cup membrane 1042 is connected to the suction cup air cavity 1041, and the suction cup 104 is divided into multiple arrays of different sizes and fixed on the inner side of the gripping body 101.

[0084] Example 3

[0085] Design and manufacture of the bionic flexible gripper

[0086] A. The material preparation is the same as that in Example 2.

[0087] B. The manufacturing method is the same as that in Example 2.

[0088] The bionic flexible gripper includes: a bionic hydrogel gripper unit 201, a first syringe pump 202, a second syringe pump 203, a robotic arm 206, a silicone tube 205, a syringe pump controller 204, and a robotic arm controller 207. The bionic hydrogel gripper unit 201 is connected to the first syringe pump 202 and the second syringe pump 203 through the silicone tube 205. The syringe pump controller 204 is connected to the first syringe pump 202 and the second syringe pump 203. The bionic hydrogel gripper unit 201 is fixed on the robotic arm 206. The robotic arm controller 207 is connected to the robotic arm 206. The bionic hydrogel gripper unit is made of the photocurable hydrogel material described in Example 2. The robotic arm 206 controls the bionic hydrogel gripper unit 201 to move near the object to be grasped. The syringe pump controller 204 controls the first syringe pump 202 to move forward, so as to control the bionic hydrogel gripper unit 201 to bend close to the object to be grasped through the silicone tube 205. The syringe pump controller 204 controls the second syringe pump 203 to move backward, so as to control the suction cup of the bionic hydrogel gripper unit 201 to contract through the silicone tube 205, thereby adhering to the object to be grasped. The robotic arm controller 207 controls the robotic arm 206 to move so that the object to be grasped is moved to a specified position. Then, the syringe pump controller 204 controls the second syringe pump 203 to move forward and the first syringe pump 202 to move backward, so that the bionic hydrogel gripper unit 201 bends back and the suction cup expands, thereby releasing the object to be grasped.

[0089] Figure 5 The process diagram for using a combination of the one or more bionic hydrogel gripper units to achieve grasping and releasing of various objects, especially the non-destructive grasping process of ultra-soft objects such as tofu and egg yolks.

[0090] Comparative Example 1

[0091] Same as Example 1, except that acrylamide is not added, and the prepared hydrogel is P(NASC-co-AAc).

[0092] Using a universal material testing machine, the mechanical properties of the obtained hydrogel were tested, and the test results are as follows: the elongation at break is 1287.98 ± 112.26%, the tensile strength is 3.15 ± 0.36 MPa, the elastic modulus is 1.09 ± 0.12 MPa, the fracture toughness is 28.42 ± 4.52 MJ·m -3 , the tear toughness is 150 ± 5.44 kJ·m -2 , the tear strength is 15.61 ± 0.52 N / mm. It can be seen that the elastic modulus and tensile strength of the hydrogel material are too high and are not suitable for preparing a soft-body driven gripper.

[0093] Using the hydrogel of this comparative example to prepare a driving gripper, the physical picture is as Figure 6 shown. It can be seen that the driving deformation degree of the driving gripper is very low.

[0094] Comparative Example 2

[0095] The same as Example 1, the difference is only that acrylic acid is not added, and the obtained hydrogel is P(NASC-co-AAm).

[0096] Using a universal material testing machine, the mechanical properties of the obtained hydrogel were tested, and the test results are as follows: the elongation at break is 302.48±35.19%, the tensile strength is 0.20±0.002 MPa, the elastic modulus is 0.06±0.003 MPa, and the fracture toughness is 0.29±0.032 MJ·m -3 , the tearing toughness is 0.12±0.022 kJ·m -2 , the tearing strength is 0.02±0.004 N / mm. It can be seen that the elastic modulus and tensile strength of the hydrogel material are too low to be suitable for preparing a soft driving gripper and are easily damaged.

[0097] Comparative Example 3

[0098] The same as Example 1, the difference is only that the amounts of raw materials are: 8.93 g of NASC, 0.89 g of acrylamide, 2.68 g of acrylic acid, 26.25 g of dimethyl sulfoxide, 11.25 g of deionized water, 0.0625 g of LAP, and 0.015 g of lemon yellow.

[0099] Using a universal material testing machine, the mechanical properties of the obtained hydrogel were tested, and the test results are as follows: the elongation at break is 1357.29±248.12%, the tensile strength is 3.87±0.190 MPa, the elastic modulus is 0.94±0.146 MPa, and the fracture toughness is 23.94±3.911 MJ·m -3 , the tearing toughness is 40.52±4.12 kJ·m -2 , the tearing strength is 8.11±0.12 N / mm. It can be seen that the elastic modulus of the hydrogel material is relatively high and is not suitable for preparing a soft driving gripper, and the driving deformation degree is very low.

[0100] Comparative Example 4

[0101] Acrylamide (18.4 g) and acrylic acid (4.32 g) were dissolved in a mixed solution of dimethyl sulfoxide (15 mL) and deionized water (35 mL) by magnetic stirring to obtain a precursor solution. The precursor solution, polyethylene glycol diacrylate (PEGDA750, 0.35 g), LAP (0.0436 g), and tartrazine (0.03 g) were stirred to mix them, obtaining a hydrogel ink. The hydrogel ink was placed in the cartridge of a photocuring 3D printer, and the photocuring 3D printer was used to print and form according to the model program (the light source intensity of the 3D printer was 300 mW, the slice layer thickness was 0.1 mm, the exposure time of the bottom layer was 15 s, and the exposure time of the remaining layers was 10 s), obtaining a basic gel. Subsequently, the basic gel was immersed in a 0.1 M zirconium hydroxide aqueous solution for 48 h, and then dialyzed with deionized water for 48 h to obtain a hydrogel material.

[0102] Using a universal material testing machine, the mechanical properties of the obtained hydrogel were tested, and the test results were as follows: the elongation at break was 355.83 ± 53.52%, the tensile strength was 1.56 ± 0.003 MPa, the elastic modulus was 0.50 ± 0.05 MPa, and the fracture toughness was 3.59 ± 0.61 MJ·m -3 , the tear toughness was 2.52 ± 0.02 kJ·m -2 , and the tear strength was 1.01 ± 0.03 N / mm. It can be seen that the hydrogel material has a relatively high elastic modulus and a too low elongation at break, is not suitable for preparing a soft-driven gripper, has a very low driving deformation degree and is very easy to break.

[0103] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a photocurable hydrogel material, characterized in that, Comprising the following steps: Mix acrylic acid, acrylamide, N - acryloyl semicarbazide and a solvent to obtain a precursor solution; the mass ratio of acrylic acid to acrylamide is 3:1 to 1:3, and the mass ratio of the sum of the masses of acrylic acid and acrylamide to N - acryloyl semicarbazide is 0.3 to 0.6:1; Mix the precursor solution, a photoinitiator and a photopolymerization inhibitor to obtain a hydrogel ink; Perform photocuring on the hydrogel ink to obtain the photocured hydrogel material.

2. The preparation method according to claim 1, characterized in that, The solvent includes an organic solvent and water, and the volume ratio of the organic solvent to water in the solvent is 1:9 to 9:

1.

3. The preparation method according to claim 2, characterized in that, The organic solvent includes one or more of dimethyl sulfoxide, glycerol and ethanol.

4. The preparation method according to claim 1 or 2, characterized in that The mass ratio of acrylamide, organic solvent and water is 3.13:26.25:11.

25.

5. The preparation method according to claim 1, characterized in that, The mass of the photoinitiator is 0.1 to 1% of the mass of the monomers, and the monomers include acrylic acid, acrylamide and N - acryloyl semicarbazide.

6. The preparation method according to claim 1 or 5, characterized in that, The mass ratio of the photoinitiator to the photopolymerization inhibitor is 0.0625:0.

015.

7. The photocurable hydrogel material prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The tensile strength of the photocurable hydrogel material is 1 to 10 MPa, the elastic modulus is 0.05 to 1 MPa, the elongation at break is 800 to 1500%, and the tear toughness is 1 to 50 kJ·m -2 .

8. Use of the photocured hydrogel material according to claim 7 in the field of flexible grippers.

9. A bionic flexible gripper, characterized in that, Including: A bionic hydrogel gripper unit, a first syringe pump, a second syringe pump, a robotic arm, a silicone tube, a syringe pump controller and a robotic arm controller; The bionic hydrogel gripper unit is connected to the first syringe pump and the second syringe pump through the silicone tube, the syringe pump controller is connected to the first syringe pump and the second syringe pump, the bionic hydrogel gripper unit is fixed on the robotic arm, the robotic arm controller is connected to the robotic arm, and the bionic hydrogel gripper unit is made of the photocured hydrogel material according to claim 7.

10. The bionic flexible gripper according to claim 9, characterized in that, The bionic hydrogel gripper unit includes a gripping body, a first pipe, a second pipe and a suction cup. The suction cup includes a suction cup air chamber and a suction cup membrane. The first pipe and the second pipe are not connected to each other. The first pipe is connected to the suction cup air chamber, the suction cup membrane is connected to the suction cup air chamber, and the suction cup is arranged inside the gripping body.

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