A method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper

Abstract

This invention discloses a method for constructing a programmable, modular, green, clean, biomimetic flexible gripper, belonging to the field of flexible gripper technology. It involves a bio-crosslinking reaction between a natural polymer, sodium alginate, and a novel microbial extracellular polysaccharide gellan gum, followed by the addition of lignocellulose to obtain a mixed solution of a biogel-like electro-actuated layer. A "wheel-like" outer shell mold is then prepared, into which the mixed electro-actuated layer solution is injected and dried. The shell is then dissolved using acetic acid solution to obtain the biogel-like electro-actuated layer. Using sodium alginate solution as a matrix, a two-dimensional ceramic material is hybridized with a metal-organic framework and injected into the solution to prepare a non-metallic electrode film solution. After drying, a non-metallic electrode film is obtained. The prepared non-metallic electrode film is then attached to a pre-reserved groove in the electro-actuated layer to form a flexible gripper with a "squid-like tentacle" structure. This invention features high structural strength, strong adaptability, simple manufacturing process, green and clean operation, and suitability for mass production.

Description

Technical Field

[0001] This invention relates to the field of flexible gripper technology, and in particular to a method for constructing a programmable, modular, green, clean, biomimetic flexible gripper. Background Technology

[0002] Artificial muscles are a new type of intelligent polymer material that can reversibly contract or deform in response to specific stimuli. Currently, there are a wide variety of common types, such as shape memory alloys and shape memory polymer actuators, piezoelectric actuators, and electroactive polymer actuators. They are highly favored by researchers due to their unique properties.

[0003] Flexible grippers, as a novel type of gripper, have been increasingly widely used in various applications since their inception due to their advantages such as flexibility, softness, lightness, adaptability, and simple structure. Compared to traditional metal grippers, existing flexible grippers overcome many limitations, such as the inability to achieve flexible gripping, susceptibility to corrosion, and high cost. However, existing flexible sensors also have many problems. By replacing metal materials with flexible materials, existing flexible grippers have achieved flexible gripping actions; however, their driving method still relies on traditional pneumatic methods. This method not only requires precise design and is expensive, but existing flexible grippers cannot be assembled according to actual conditions, which greatly limits their application range and prevents their widespread adoption in daily life. Therefore, developing a biomimetic flexible gripper that combines the advantages of existing flexible grippers and artificial muscles to improve its driving efficiency and broaden its application range is of great value in promoting the multi-field integration and application of flexible grippers. Summary of the Invention

[0004] The purpose of this invention is to provide a method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper, which has high structural strength, strong adaptability, simple manufacturing process, is green and clean, and is suitable for mass production.

[0005] To achieve the above objectives, this invention provides a method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper, mainly comprising the following steps: First, a bio-crosslinking reaction is carried out using the natural polymer sodium alginate and a novel microbial extracellular polysaccharide gellan gum, and lignocellulose is added to obtain a mixed solution of biogel electro-actuated layer. Then, a "wheel-like" outer shell mold is obtained by 3D printing using the novel biodegradable material chitin. The prepared mixed electro-actuated layer solution is injected into the mold and dried. Finally, the outer shell is dissolved using an appropriate amount of acetic acid solution to obtain the bio-gel. A biocompatible gel electro-actuating layer is formed. Secondly, using sodium alginate solution as a matrix, a two-dimensional ceramic material (MXene) is hybridized with metal-organic frameworks (MOFs) and injected into the solution. Then, a non-metallic electrode film solution is prepared by water bath heating and thorough stirring. After drying, a non-metallic electrode film is obtained, exhibiting high conductivity, rapid response, and safety / non-toxicity. Finally, the prepared non-metallic electrode film is adhered to a pre-reserved groove in the electro-actuating layer according to actual needs, forming a flexible gripper with a "squid-tentacle-like" structure.

[0006] The specific steps of the above main methods are as follows:

[0007] Step 1: Preparation of the biogel electro-actuated layer: A bio-crosslinking reaction is carried out using sodium alginate, a natural polymer, and gellan gum, a novel microbial extracellular polysaccharide. Lignocellulose is then added to obtain a mixed solution of the biogel electro-actuated layer. A "wheel-like" outer shell mold is obtained by 3D printing using chitin, a novel biodegradable material. The prepared mixed solution of biogel electro-actuated layer is injected into the mold and dried. Then, an appropriate amount of acetic acid solution is used to dissolve the outer shell to obtain a biocompatible biogel electro-actuated layer.

[0008] Step 2, Preparation of non-metallic electrode membrane: Dissolve sodium alginate powder in deionized water, heat in a water bath and stir thoroughly. Then, add secondary dispersed MXene aqueous dispersion and MOFs aqueous dispersion dropwise to the solution and continue stirring until fully mixed. Then, add glycerol solution dropwise to the mixed solution, stir thoroughly, and dry to obtain non-metallic electrode membrane.

[0009] Step 3, Construction and molding of the flexible gripper: The prepared non-metallic electrode film is attached to the grooves reserved inside and outside the biogel electro-actuation layer according to the actual situation to obtain a programmable modular green clean biomimetic flexible gripper with a "squid tentacles" structure. Different gripping actions can be achieved by independently energizing different energizing areas.

[0010] Preferably, the specific process for obtaining the biogel electro-actuated layer mixed solution in step one is as follows: Sodium alginate powder and gellan gum powder are dissolved in deionized water, heated in a water bath and stirred thoroughly, then the sodium alginate aqueous solution and gellan gum aqueous solution are mixed together, lignocellulose is added, the mixture is heated in a water bath and stirred for a certain time, and then an appropriate amount of glycerol solution is added dropwise and stirred until completely mixed to obtain the biogel electro-actuated mixed solution for later use.

[0011] Preferably, the specific preparation method of the outer shell mold in step one is as follows: After drawing the "wheel-like" structure using 3D modeling software and outputting it as an STL file, it is imported into a 3D printer, and chitin is used as the printing material to print layer by layer and bond them together to obtain the outer shell mold.

[0012] Preferably, the raw materials used in step one include 0.1g of lignocellulose powder, 0.625g each of sodium alginate and gellan gum powder, 50ml of deionized water, and 3ml of glycerol.

[0013] Preferably, the conditions for water bath heating in step one are as follows: heating temperature 50℃ and rotation speed 800r / min.

[0014] Preferably, the raw materials used in step two include 0.24g of sodium alginate powder, 10ml of MXene aqueous dispersion, 10ml of MOFs aqueous dispersion, 50ml of deionized water, and 3ml of glycerol.

[0015] Preferably, the heating temperature in step two is 50°C.

[0016] Therefore, the method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper using the above-described structure has the following advantages:

[0017] First, both sodium alginate and gellan gum are natural biomaterials. Sodium alginate is an excellent polymer, while gellan gum is a linear polysaccharide composed of four basic monosaccharide molecules: glucose residues, glucuronic acid residues, and rhamnose residues. Glucuronic acid can combine with sodium ions in sodium alginate, creating a synergistic effect on polymerization performance, thus leveraging the advantages of both natural polymers. Furthermore, the glyceryl and acetyl groups in gellan gum endow the gel with high elasticity and low hardness, significantly improving the toughness of the electro-actuated layer. Gellan gum also exhibits high adhesion, maintaining good bonding to various material surfaces, especially in the low-temperature environment of the deep sea, where it retains its viscosity essentially unchanged, facilitating the gripping of smooth, small objects. Secondly, gellan gum has excellent water retention, maintaining its internal ion concentration while improving its elasticity, effectively ensuring the stability of the gripping force. The addition of lignocellulose introduces a new macroscopic framework into the electro-actuated layer, significantly improving its mechanical strength, making it highly valuable for constructing flexible grippers.

[0018] Secondly, MOFs are organic-inorganic hybrid materials, possessing both the rigidity of inorganic materials and the flexibility of organic materials. MXene, a two-dimensional inorganic compound, provides more channels for ion movement through its unique internal structure, significantly increasing the speed of ion movement. The combination of the two, through synergistic effects, allows MXene, with its abundant surface functional groups, to easily combine with other two-dimensional materials to form heterostructures. Furthermore, its flat, layered structure is not only an excellent conductor for electron transport but also a potential MOF structural agent, ensuring uniform distribution of MOFs among MXenes. The presence of MOF inserts also eliminates redundant stacking within MXenes, thus improving its stability. Additionally, the hydrogen bonding between sodium alginate and the surface functional groups of MXene synergistically enhances the conductivity of the non-metallic electrode film. Compared to traditional metal electrode films, its manufacturing process is simple, bend-resistant, environmentally friendly, clean, and has a rapid reaction time and low cost, making it ideal for mass production.

[0019] Third, the bio-gel flexible gripper is constructed using a "squid-tentacle-like" structure. Squid are known for their agile movement, and this biomimetic design partially mimics the squid's swimming posture, which is then applied to the flexible gripper to enable grasping activities. Secondly, the length of the "tentacles" can be controlled by assembling and casting the 3D-printed mold to meet different working requirements, achieving a modular design goal. Through the grooves reserved in the electro-actuated layer, users can attach non-metallic electrode films according to actual conditions. When the electro-actuated layer and non-metallic electrode films form a "sandwich" structure and voltage is applied, significant bending occurs to achieve the grasping action. By applying current in different directions, the "tentacles" can achieve two-degree-of-freedom coupled movement in both directions, thus realizing the programmable design requirements of the flexible gripper. The designed flexible gripper has excellent adaptability and can meet the flexible grasping needs of most scenarios. Moreover, the modular design simplifies the production process, reduces production costs, and exhibits excellent electromechanical performance and economic applicability.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a flowchart of the green construction process for the programmable, modular, green, clean, biomimetic, flexible gripper of the present invention.

[0022] Figure 2 This is a schematic diagram of a 3D printed mold for the programmable, modular, green, clean, biomimetic, flexible gripper of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the programmable modular green clean biomimetic flexible gripper of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of the programmable modular green clean biomimetic flexible gripper of the present invention;

[0025] Figure 5 This is a schematic diagram of the programmable modular green clean biomimetic flexible gripper of the present invention gripping objects with porous structures.

[0026] Figure 6 This is a schematic diagram of the grasping state of the programmable modular green clean biomimetic flexible grasper of the present invention when grasping a general object.

[0027] Figure labels: 1. Non-metallic electrode membrane; 2. Biogel electro-actuated layer. Detailed Implementation

[0028] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0030] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0031] A method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper, such as... Figure 1 As shown, the process can be mainly divided into three stages: preparation of the biogel electro-actuated layer, preparation of the non-metallic electrode film, and construction of the flexible gripper. Furthermore, the entire construction process is simple and controllable, highly efficient, and environmentally friendly, enabling the mass production of modular biomimetic flexible grippers.

[0032] Example 1

[0033] The specific process for preparing the biogel electro-actuated layer 2 is as follows:

[0034] First, weigh out 0.1g of lignocellulose powder, 0.625g each of sodium alginate (90%) and gellan gum (≥99%) powder using an electronic analytical balance. Take two small beakers, add 50ml of deionized water, place a magnetic stir bar in each beaker, and then place the beakers in a magnetic stirrer. Set the stirring temperature to 50℃ and the speed to 800 rpm for water bath heating. Once the temperature is reached, slowly pour the weighed sodium alginate and gellan gum powders along the beaker wall and stir uniformly for 60 minutes. Then, mix the two solutions together until completely homogeneous, with a drug-to-powder mass ratio of 1:1.

[0035] Next, the lignocellulose powder (0.1g) to be used was evenly poured into the above crosslinking solution and stirred evenly. Then, 3ml of glycerol (one dropper) was gradually added dropwise to the solution until the solution was stirred evenly. Thus, a biogel electro-actuated layer solution was obtained, in which the concentration of sodium alginate-gellan gum was 6.25mg / ml. Subsequently, the electro-actuated membrane solution was placed in an ultrasonic oscillator, the temperature was set at 50℃ and the oscillation frequency at 20KHz, and the oscillation degassing treatment was performed twice (15min / time), for a total of 30min. With the continuous oscillation of ultrasound, the small bubbles dispersed in the electro-actuated layer solution will continuously rise and gather on the solution surface and burst to form foam. Then, the surface solution containing residual bubbles and foam can be removed.

[0036] Finally, the biomimetic flexible gripper was modeled using SolidWorks modeling software to create a "wheel-like" structure, which was then output as an STL file. A 3D printer was then used to read the model information from the file and print the "wheel-like" structure mold layer by layer using chitin, a natural biodegradable material. Figure 2 As shown; further, the prepared 6.25 mg / ml sodium alginate-gellan gum solution was injected into the printed "rotor-like" structure mold and placed in a hot drying oven for vacuum constant temperature drying. The oven temperature was set to 60℃, the vacuum degree to -0.085 MPa, and the drying time to 48 h. During this period, the vacuum drying oven door was opened for 10 min every 3 h to remove the saturated water vapor inside the oven; then the vacuum was evacuated again for constant temperature drying. After the biogel electro-actuated layer was completely dried and formed, the vacuum drying oven was slowly cooled down. This increases the flexibility of the electro-actuated layer and improves the force output performance. The mold was removed and placed in a beaker. A certain amount of acetic acid (GC, 5%, pH = 2.4) was poured in to dissolve the chitin mold. This dissolution process is convenient, safe, and non-toxic. After the mold vaporizes and dissolves, the biogel electro-actuated layer 2 is obtained.

[0037] Example 2

[0038] The specific process for preparing the non-metallic electrode film 1 is as follows:

[0039] First, measure 50 ml of deionized water into a beaker and place the beaker in a magnetic stirrer, setting the heating temperature to 50°C. Once the temperature is reached, weigh 0.24 g of sodium alginate powder using an electronic analytical balance and slowly pour it into the deionized water along the center of the beaker; place the magnetic stir bar in the beaker and stir at a constant speed of 800 rpm for 30 minutes until the sodium alginate powder is completely dissolved.

[0040] The second step involves thoroughly mixing 10 ml of MXene aqueous dispersion and 10 ml of MOFs aqueous dispersion, and placing the mixture in the center of the lifting platform of the ultrasonic cell disruptor's soundproof chamber. A Φ12 amplitude transformer is selected, with its end immersed approximately 10 mm to 20 mm into the liquid surface. Simultaneously, the dispersion time is set to 5 min, the ultrasonic time to 3 s, the interval to 2 s, and the protection temperature to 60℃. This solution is ultrasonically dispersed 5 times (5 min / time), with a 10 min interval between each treatment, for a total time of 65 min. Subsequently, the twice-dispersed MXene-MOFs aqueous dispersion is poured into a sodium alginate solution and stirred for another 30 min. Then, 3 ml of glycerol (one dropperful) is added dropwise until the solution is fully mixed, thus obtaining a non-metallic electrode membrane solution with a sodium alginate concentration of 6 mg / ml. The electro-actuated membrane solution was then placed in an ultrasonic oscillator at a temperature of 50℃ and an oscillation frequency of 20kHz for two cycles of degassing (15min / cycle), totaling 30min. The degassed non-metallic electrode membrane solution was then placed in a vacuum drying oven for constant temperature and vacuum drying. The oven temperature was set at 80℃, the vacuum degree at -0.085MPa, and the drying time at 48h. During this period, the oven door was opened for 10min every 3h to remove saturated water vapor. After drying, non-metallic electrode membrane 1 was obtained.

[0041] Example 3

[0042] The specific construction process for the flexible gripper is as follows:

[0043] Cut the electro-actuated layer axially with a knife to obtain the "gripper" structure; measure 50 ml of deionized water into a beaker, place the beaker in a magnetic stirrer, and set the heating temperature to 50℃. After the temperature is reached, weigh 0.24 g of sodium alginate powder using an electronic analytical balance, and slowly pour it into the deionized water along the center of the beaker; place a magnetic stir bar and stir at a constant temperature of 800 r / min for 30 min until the sodium alginate powder is completely dissolved, resulting in a viscous paste-like electrode film solution. Use a brush to apply the electrode film solution evenly to the grooves reserved inside and outside the "gripper" part of the prepared electro-actuated layer 2 and the non-metallic electrode film 1, so that the non-metallic electrode film 1 is placed in the groove, as shown. Figure 3As shown; it is fixed with clamps and placed in a vacuum constant temperature drying oven for drying. The temperature is set at 50℃, the vacuum degree at -0.085MPa, and the drying time is 2 hours. A pneumatic hot press is used to level and correct it, with a pressure of 1 kPa, a temperature of 50℃, and a hot pressing time of 15 minutes. This yields a biomimetic flexible gripper, where the "gripper" part forms a three-layer structure resembling a "sandwich"—a non-metallic electrode film, a bio-gel electro-actuated layer, and another non-metallic electrode film. Depending on the working conditions, the biomimetic flexible gripper mold can be stacked to meet different gripping requirements, such as... Figure 4 As shown.

[0044] Specific working principle:

[0045] Sodium alginate and gellan gum are both natural biomaterials. Sodium alginate is a polyanionic copolymer, and the addition of gellan gum introduces more active groups into the sodium alginate solution. A dual-network structure is constructed through ionic cross-linking and hydrogen bonding between gellan gum and sodium alginate. Under the excitation of a DC electric field, a large number of free positively charged ions within the electro-actuated layer of the biogel move directionally as hydrated ions and accumulate at the negative end. The continuous accumulation of charged ions causes the negative end to expand in volume; the electrostatic repulsion between the positively charged ions (van der Waals force) causes the positive end to contract. This allows the "tentacles" to be directionally deflected for grasping objects, such as… Figure 5 As shown; by changing the direction of the current, the "tentacle" deflects in the opposite direction, as... Figure 6 As shown, this enables the "tentacle" to achieve two-degree-of-freedom coupled motion in both directions.

[0046] Programmable modular implementation principle:

[0047] Based on actual usage requirements, standardized molds are stacked and interlocked for objects of different sizes, and an integrated electro-actuated layer is formed. On the one hand, this enables the assembly of the flexible gripper to meet modular requirements; on the other hand, the integrated molding also improves the assembly accuracy and structural strength of the electro-actuated layer. The electro-actuated layer with pre-reserved grooves can be regarded as a standardized template in a certain sense. Users can measure and estimate the object to be gripped, formulate a gripping strategy, and then attach the manufactured electrode film to different grooves. This achieves the programmable design requirements, enabling the gripper to deflect at different positions, thereby realizing the gripping action of different objects.

[0048] Therefore, this invention employs a method for constructing a programmable, modular, green, clean, biomimetic flexible gripper with the aforementioned structure. The biogel-based flexible gripper is constructed using a "squid-tentacle-like" structure. Squid are known for their agile movement, and this method partially mimics the squid's swimming posture, which is then applied to the flexible gripper to enable gripping activities. Secondly, the length of the "tentacles" can be controlled by assembling and casting the 3D-printed mold, allowing it to meet different working requirements and achieving a modular design. Furthermore, by using grooves pre-reserved in the electro-actuated layer... The device can be fitted with a non-metallic electrode film according to the actual situation. When the electro-actuation layer and the non-metallic electrode film form a "sandwich" structure and a voltage is applied, it can bend significantly to achieve the grasping action. By applying current in different directions, the "tentacle" can achieve two-degree-of-freedom coupled motion in both directions. This achieves the programmable design requirements of the flexible gripper. The designed flexible gripper has excellent adaptability and can meet the flexible grasping needs of most scenarios. Moreover, the modular design simplifies the production process, reduces production costs, and exhibits excellent electromechanical performance and economic applicability.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper, characterized in that: Includes the following steps: Step 1: Preparation of the biogel electro-actuated layer: A bio-crosslinking reaction is carried out using sodium alginate, a natural polymer, and gellan gum, a novel microbial extracellular polysaccharide. Lignocellulose is then added to obtain a mixed solution of the biogel electro-actuated layer. A "wheel-like" shell mold is obtained by 3D printing using chitin, a novel biodegradable material. The prepared mixed solution of biogel electro-actuated layer is injected into the mold and dried. Then, an appropriate amount of acetic acid solution is used to dissolve the shell to obtain a biocompatible biogel electro-actuated layer. Step 2, Preparation of non-metallic electrode membrane: Dissolve sodium alginate powder in deionized water, heat in a water bath and stir thoroughly. Then, add secondary dispersed MXene aqueous dispersion and MOFs aqueous dispersion dropwise to the solution and continue stirring until fully mixed. Then, add glycerol solution dropwise to the mixed solution, stir thoroughly, and dry to obtain non-metallic electrode membrane. Step 3, Construction and molding of the flexible gripper: The prepared non-metallic electrode film is attached to the grooves reserved inside and outside the biogel electro-actuation layer according to the actual situation to obtain a programmable modular green clean biomimetic flexible gripper with a "squid tentacles" structure. Different gripping actions can be achieved by independently applying electricity to different electrified areas.

2. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 1, characterized in that: The specific process for obtaining the biogel electro-actuated layer mixed solution in step one is as follows: Sodium alginate powder and gellan gum powder are dissolved in deionized water, heated in a water bath and stirred thoroughly. Then, the sodium alginate aqueous solution and the gellan gum aqueous solution are mixed together. Lignocellulose is added to the mixture, heated in a water bath and stirred for a certain period of time. Then, an appropriate amount of glycerol solution is added dropwise and stirred until completely mixed to obtain the biogel electro-actuated mixed solution for later use.

3. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 2, characterized in that: The specific preparation method of the outer shell mold in step one is as follows: After drawing the "wheel-like" structure using 3D modeling software and outputting it as an STL file, it is imported into a 3D printer. Chitin is used as the printing material to print layer by layer and then bonded together to obtain the outer shell mold.

4. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 3, characterized in that: The raw materials used in step one include 0.1g of lignocellulose powder, 0.625g each of sodium alginate and gellan gum powder, 50ml of deionized water, and 3ml of glycerol.

5. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 4, characterized in that: The conditions for water bath heating in step one are as follows: heating temperature is 50℃ and rotation speed is 800r / min.

6. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 5, characterized in that: The raw materials used in step two include 0.24g of sodium alginate powder, 10ml of MXene aqueous dispersion, 10ml of MOFs aqueous dispersion, 50ml of deionized water, and 3ml of glycerol.

7. The method for constructing a programmable, modular, green, clean, biomimetic, flexible gripper according to claim 6, characterized in that: The heating temperature in step two is 50°C.

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