Construction method of programmable modularized green clean bionic flexible grabber

Abstract

The invention discloses a construction method of a programmable modular green clean bionic flexible gripper, and belongs to the technical field of flexible grippers. Natural high-molecular polymer sodium alginate and novel microbial exopolysaccharide gellan gum are subjected to biological crosslinking reaction; the preparation method comprises the following steps: preparing a bio-gel material, adding lignocellulose to obtain a bio-gel material electric actuating layer mixed solution, preparing a runner-like shell mold, injecting the mixed electric actuating layer solution into the runner-like shell mold, drying, and dissolving the shell by using an acetic acid solution to obtain a bio-gel material electric actuating layer; a sodium alginate solution is used as a matrix, a two-dimensional ceramic material and a metal organic framework are subjected to hybridization treatment and injected into the solution, a non-metal electrode membrane solution is prepared, and a non-metal electrode membrane is obtained after drying treatment; the prepared non-metal electrode film is attached to a groove reserved in an electric actuating layer, and a flexible grabber with a squid tentacle imitating structure is formed; the invention has the advantages of high structural strength, strong adaptability, simple production process, greenness, cleanness and suitability for batch production.

Description

Technical Field

[0001] The invention relates to the technical field of flexible grippers, and in particular to a method for constructing a programmable modular green cleaning bionic flexible gripper. Background Art

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

[0003] As a new type of gripper, the flexible gripper has been more and more widely used in different occasions since its introduction due to its advantages such as flexibility, softness, lightness, adaptability and simple structure. Compared with the traditional metal gripper, the existing flexible gripper overcomes many of its limitations, such as the inability to achieve flexible grasping, easy corrosion and high cost. However, the existing flexible sensors also have many problems. By replacing the metal material with a flexible material, the existing flexible gripper can achieve flexible grasping action, but its driving method still adopts the traditional pneumatic method, which not only requires precise design and is relatively expensive, but also the existing flexible gripper cannot be assembled according to the actual situation, which greatly limits its application scope. Therefore, it has not been widely popularized in life. Therefore, it is of great value to develop a bionic flexible gripper that combines the advantages of existing flexible grippers and artificial muscles to improve its driving efficiency and broaden its application scope, which is of great value to promote the combination and application of flexible grippers in multiple fields. Summary of the invention

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

[0005] To achieve the above-mentioned purpose, the present invention provides a method for constructing a programmable modular green clean bionic flexible gripper, which mainly includes the following processes: first, a natural high molecular polymer sodium alginate and a new microbial extracellular polysaccharide gellan gum are subjected to a bio-crosslinking reaction, and wood cellulose is added thereto to obtain a bio-gel electro-actuated layer mixed solution, and then a new biodegradable material chitin is used for 3D printing to obtain a "wheel-like" shell mold, the prepared mixed electro-actuated layer solution is injected into it and dried, and then an appropriate amount of acetic acid solution is used to dissolve the shell to obtain a bio-gel electro-actuated layer. A biogel electro-actuated layer with excellent compatibility; secondly, using sodium alginate solution as the matrix, a two-dimensional ceramic material (MXene) and a metal organic framework (MOFs) are hybridized and injected into the solution, and then heated in a water bath and fully stirred to prepare a non-metallic electrode film solution, and the prepared electrode film solution is dried to obtain a non-metallic electrode film, which has the characteristics of high conductivity, rapid response, safety and non-toxicity after film formation; finally, according to actual needs, the prepared non-metallic electrode film is attached to the groove reserved in the electro-actuated layer to form a flexible gripper with a "squid tentacle-like" structure;

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

[0007] Step 1, preparing a biogel electro-actuated layer: a natural high molecular weight polymer sodium alginate and a novel microbial extracellular polysaccharide gellan gum are subjected to a bio-crosslinking reaction, and wood cellulose is added thereto to obtain a mixed solution of a biogel electro-actuated layer; a "wheel-like" shell mold is obtained by 3D printing using a novel biodegradable material chitin, the prepared biogel electro-actuated mixed solution is injected into the mold and dried, and then an appropriate amount of acetic acid solution is used to dissolve the shell to obtain a biogel electro-actuated layer with excellent biocompatibility;

[0008] Step 2, preparing a non-metallic electrode film: dissolving sodium alginate powder in deionized water, heating in a water bath and stirring thoroughly, then dropping secondary dispersed MXene aqueous dispersion and MOFs aqueous dispersion into the solution, continuing to stir until fully mixed, then dropping propylene glycol solution into the mixed solution, stirring thoroughly and drying to obtain a non-metallic electrode film;

[0009] Step three, construction and molding of the flexible gripper: fit the prepared non-metallic electrode film into the grooves reserved inside and outside the biogel electro-actuated layer according to actual conditions, and obtain a programmable, modular, green, clean bionic flexible gripper with a "squid tentacle-like" structure. Different grasping actions can be achieved by independently powering different power-on areas.

[0010] Preferably, the specific process of obtaining the biogel electro-actuated layer mixed solution in step 1 is as follows: sodium alginate powder and gellan gum powder are respectively dissolved in deionized water, heated in a water bath and stirred sufficiently, then the sodium alginate aqueous solution and the gellan gum aqueous solution are mixed together, and then wood cellulose is added thereto, heated in a water bath and stirred for a certain period of time, and then an appropriate amount of propylene glycol solution is dropped into it, and stirred until completely mixed to obtain the biogel electro-actuated mixed solution for use.

[0011] Preferably, the specific preparation method of the shell mold in step 1 is as follows: use three-dimensional modeling software to draw a "wheel-like" structure, output it as an STL file, and then import it into a 3D printer, use chitosan as the printing material to print layer by layer and bond them together to obtain the shell mold.

[0012] Preferably, the raw materials used in step 1 include 0.1 g of lignocellulose powder, 0.625 g of sodium alginate and gellan gum powder, 50 ml of deionized water, and 3 ml of glycerol.

[0013] Preferably, the conditions for water bath heating in step 1 are as follows: the heating temperature is 50° C. and the rotation speed is 800 r / min.

[0014] Preferably, the raw materials used in step 2 include 0.24 g of sodium alginate powder, 10 ml of MXene aqueous dispersion, 10 ml of MOFs aqueous dispersion, 50 ml of deionized water, and 3 ml of glycerol.

[0015] Preferably, the heating temperature in step 2 is 50°C.

[0016] Therefore, the present invention adopts a method for constructing a programmable modular green cleaning bionic flexible gripper with the above structure, which has the following advantages:

[0017] First, sodium alginate and gellan gum are both natural biomaterials, and sodium alginate is an excellent high molecular polymer; gellan gum is a high molecular linear polysaccharide, which is composed of four monosaccharide molecules composed of glucose residues, glucuronic acid residues, and rhamnose residues. The glucuronic acid can combine with the sodium ions in sodium alginate to produce a synergistic effect in polymerization performance, thereby bringing out the inherent advantages of the two natural high molecular materials; and the glycerol acyl and acetyl groups in gellan gum give the gel the characteristics of high elasticity and low hardness, which significantly improves the toughness of the electro-actuated layer; gellan gum has high adhesion and has good adhesion on the surface of various materials, especially in the low temperature environment of deep sea, it can keep the viscosity basically unchanged, which is conducive to grasping tiny objects with smooth surfaces; secondly, gellan gum has good water retention, and maintains its internal ion concentration on the basis of improving its elasticity, effectively maintaining the stability of the grasping force; the addition of wood cellulose introduces a new macroscopic skeleton in the electro-actuated layer, which significantly improves the mechanical strength of the electro-actuated layer, and has high application value for constructing flexible grippers.

[0018] Second, MOFs is an organic-inorganic hybrid material that has both the rigidity of inorganic materials and the flexibility of organic materials; MXene is a two-dimensional inorganic compound whose unique internal structure provides more channels for the movement of ions, greatly increasing the speed of ion movement. After the two are combined, through synergy, MXene is easy to combine with other two-dimensional materials to form heterogeneous structures due to its rich surface functional groups, and its flat layered structure is not only an excellent conductor for electron transmission, but also a potential MOFs structural agent, thus ensuring that MOFs can be evenly distributed between MXenes. The presence of MOFs inserts also eliminates the repeated stacking inside MXene, thereby improving its stability, and utilizing the hydrogen bonding between sodium alginate and the surface functional groups of MXene to synergistically enhance the conductivity of non-metallic electrode films with MOFs materials; compared with traditional metal electrode films, its manufacturing process is simple, resistant to bending, green and clean, quick to react and low in cost, which is very suitable for mass production needs.

[0019] Thirdly, the biogel flexible gripper is constructed in the form of a "squid-like tentacle" structure. Squids are known for their flexible movements. The swimming posture of squids is partially imitated by bionics and then applied to the flexible gripper, which can enable the gripper to meet the requirements of grasping activities. Secondly, the length of its "tentacles" can be controlled by assembling and casting the 3D printed mold to meet different working requirements, so as to achieve the modular design goal. Through the grooves reserved in the electro-actuated layer, the user can fit the non-metallic electrode film to it according to the actual situation. When the electro-actuated layer and the non-metallic electrode film form a "sandwich" structure and voltage is applied, obvious bending can occur to achieve the grasping action. By applying currents in different directions to it, the "tentacles" can achieve forward and reverse dual-degree-of-freedom coupled movement, which realizes the programmable design requirements of the flexible gripper. The designed flexible gripper has excellent adaptability and can meet the flexible grasping of most scenarios. The modular design simplifies the production process, reduces the production cost, and exhibits excellent electro-mechanical properties and economic applicability.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a green construction process flow chart of the programmable modular green cleaning bionic flexible gripper of the present invention;

[0022] Figure 2 It is a schematic diagram of a 3D printing mold of a programmable modular green cleaning bionic flexible gripper of the present invention;

[0023] Figure 3 It is a schematic diagram of the structure of the programmable modular green cleaning bionic flexible gripper of the present invention;

[0024] Figure 4 It is a schematic diagram of the structure of the programmable modular green cleaning bionic flexible gripper of the present invention;

[0025] Figure 5 It is a schematic diagram of the grasping state of the programmable modular green cleaning bionic flexible grasper of the present invention for an object with a hole structure;

[0026] Figure 6 It is a schematic diagram of the grasping state of a general object by the programmable modular green cleaning bionic flexible grasper of the present invention.

[0027] Reference numerals: 1. non-metallic electrode film; 2. biogel electro-actuating layer. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0030] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0031] A method for constructing a programmable modular green cleaning bionic soft gripper, such as Figure 1 As shown in the figure, the process can be divided into three stages: preparation of the biogel electro-actuation layer, preparation of the non-metallic electrode film, and construction of the flexible gripper. At the same time, the entire construction process is simple and controllable, with high production efficiency and environmental friendliness, so that modular bionic flexible grippers can be realized in batches.

[0032] Example 1

[0033] The biogel electro-actuating layer 2 is prepared, and the specific process is as follows:

[0034] First, use an electronic analytical balance to weigh 0.1g of lignocellulose powder, 0.625g of sodium alginate (90%) and gellan gum (≥99%) powder respectively; take two small beakers, inject 50ml of deionized water, place the stirring magnet in the beaker, place the beaker in a magnetic stirrer, set the heating temperature of the magnetic stirrer to 50℃, the speed to 800r / min, and heat in a water bath. After the temperature is reached, slowly pour the weighed sodium alginate and gellan gum powders into the beaker along the wall of the cup, and stir at a constant speed for 60min. Then blend and cross-link the above two solutions until they are completely stirred, and the dissolved mass ratio of the drug is 1:1.

[0035] Secondly, pour the to-be-used wood cellulose powder (0.1 g) evenly into the above cross-linking solution, stir evenly, and then gradually add 3 ml of glycerol (one dropper) to the solution until the solution is stirred evenly. Thus, a biogel electro-actuated layer solution is obtained, in which the concentration of sodium alginate-gellan gum is 6.25 mg / ml. Then, the electro-actuated membrane solution is placed in an ultrasonic oscillator, set the temperature to 50°C, the oscillation frequency to 20 KHz, and perform oscillation degassing treatment twice (15 min / time), for a total of 30 min; with the continuous oscillation of the ultrasonic wave, the small bubbles dispersed in various places in the electro-actuated layer solution will continue to float up and gather on the surface of the solution to break and form foam; then, the surface solution containing residual bubbles and foam can be removed.

[0036] Finally, the SolidWorks modeling software was used to model the "wheel-like" structure of the bionic flexible gripper and output it as an STL file. The model information in the file was read by a 3D printer, and the "wheel-like" structure mold was printed layer by layer using the natural biodegradable material chitin. Figure 2 As shown; further, the prepared 6.25mg / ml sodium alginate-gellan gum solution is injected into the printed "wheel-like" structure mold, and placed in a hot drying oven for vacuum constant temperature drying, and the drying oven temperature is set to 60°C, the vacuum degree is -0.085MPa, and the drying time is 48h. During this period, the vacuum drying oven door is opened for 10min every 3h to discharge the saturated water vapor in the box; then vacuum is drawn again for constant temperature drying. After the biogel electro-actuated layer is completely dried and formed, the vacuum drying oven is slowly cooled down, which can increase the flexibility of the electro-actuated layer and improve the force output performance. Take out the mold, place it in a beaker, and pour a certain amount of acetic acid (GC, 5%, pH = 2.4) to dissolve the chitin mold. The dissolution process is convenient to operate and safe and non-toxic. After the mold is gasified and dissolved, the biogel electro-actuated layer 2 is obtained.

[0037] Example 2

[0038] The non-metallic electrode film 1 is prepared, and the specific process is as follows:

[0039] The first step is to measure 50 ml of deionized water and place it in a beaker, and then place the beaker in a magnetic stirrer and set the heating temperature to 50°C. When the temperature reaches 50°C, 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; add a magnetic stirrer and stir at a constant temperature of 800 r / min for 30 minutes until the sodium alginate powder is completely dissolved.

[0040] In the second step, 10 ml of MXene aqueous dispersion and 10 ml of MOFs aqueous dispersion were fully mixed and placed in the middle of the lifting platform of the ultrasonic cell crusher soundproof box; a Φ12-type amplitude rod was selected, and its end was immersed in the liquid surface by about 10 mm to 20 mm. At the same time, the dispersion time was set to 5 min, the ultrasonic time was 3 s, the interval time was 2 s, and the protection temperature was 60 ° C; the solution was subjected to ultrasonic dispersion treatment 5 times (5 min / time), and the heat dissipation interval was 10 min each time, and the total time was 65 min. Subsequently, the MXene-MOFs mixed aqueous dispersion that had been dispersed twice was poured into the sodium alginate solution and continued to stir for 30 min. Then 3 ml of propylene glycol (a dropper) was added to it until the solution was fully mixed; and a non-metallic electrode membrane solution was obtained, in which the concentration of sodium alginate was 6 mg / ml. Then, the electro-actuated membrane solution was placed in an ultrasonic oscillator, set at 50°C, oscillation frequency 20KHz, and oscillation degassing treatment was performed twice (15min / time), for a total of 30min; the non-metallic electrode membrane solution after oscillation degassing treatment was placed in a hot drying oven for vacuum constant temperature drying, and the drying oven temperature was set to 80°C, the vacuum degree was -0.085MPa, and the drying time was 48h. During this period, the vacuum drying oven door was opened for 10min every 3h to discharge the saturated water vapor in the oven; after drying, the non-metallic electrode membrane 1 was obtained.

[0041] Example 3

[0042] Construct a flexible gripper. The specific construction and molding process is as follows:

[0043] Use a knife to cut the electro-actuated layer axially to obtain the "gripper" structure; measure 50 ml of deionized water and place it in a beaker, and place the beaker in a magnetic stirrer, setting the heating temperature to 50°C. When the temperature is reached, use an electronic analytical balance to weigh 0.24 g of sodium alginate powder, and slowly pour it into the deionized water along the center of the beaker; add a stirring magnet and stir at a constant temperature of 800r / min for 30 minutes until the sodium alginate powder is completely dissolved to obtain a viscous paste-like electrode film solution. Use a brush to dip the electrode film solution and evenly apply it to the grooves reserved inside and outside the "gripper" part of the prepared electro-actuated layer 2 and on the non-metallic electrode film 1, so that the non-metallic electrode film 1 is placed in the groove, such as Figure 3As shown; fix it with a clip and place it in a vacuum constant temperature drying oven for drying, set the temperature to 50°C, the vacuum degree to -0.085MPa, and the drying time to 2h; use a pneumatic hot press to make it flat, set the pressure value to 1KPa, the temperature to 50°C, and the hot pressing time to 15min. A bionic flexible gripper is obtained, and at this time, a "sandwich-like" structure of a three-layer structure of a non-metallic electrode film-biogel electro-actuated layer-non-metallic electrode film is formed at the "gripper". According to different working conditions, the bionic flexible gripper mold can be stacked to meet different grasping conditions, such as Figure 4 shown.

[0044] Specific working principle:

[0045] Sodium alginate and gellan gum are both natural biological materials, among which sodium alginate is a polyanionic copolymer. The addition of gellan gum will introduce more active groups into the sodium alginate solution, and construct a double network structure through the cross-linking and hydrogen bonding of gellan gum and sodium alginate ions. Under the stimulation of the DC electric field, a large number of free positive counter ions inside the electro-actuated layer of the biogel will move in a directional manner in the form of hydrated ions and accumulate at the negative end. The continuous aggregation of charged ions inside causes the volume of the negative end to expand, and the electrostatic repulsion (van der Waals force) between the positive counter ions causes the positive end to shrink, so that the "tentacles" can be deflected in a directional manner to grab objects, such as Figure 5 As shown; by changing the direction of the current, the "tentacles" are deflected in the opposite direction, as shown Figure 6 As shown; thereby realizing the forward and reverse dual-degree-of-freedom coupled motion of the "tentacle".

[0046] Programmable modular implementation principle:

[0047] According to actual usage requirements, for objects of different sizes, standardized molds are nested and stacked, and the electro-actuated layer is formed through integrated molding; on the one hand, the assembly of the flexible gripper meets the 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 reserved grooves can be regarded as a standardized template in certain aspects. The user measures and estimates the object to be grasped, formulates a grasping strategy, and then attaches the manufactured electrode film to different grooves. This realizes the programmable design requirements, allowing the gripper to deflect at different positions, thereby realizing the grasping action of different objects.

[0048] Therefore, the present invention adopts a method for constructing a programmable modular green clean bionic flexible gripper of the above structure. The biogel flexible gripper is constructed in the form of a "squid-like tentacle-like" structure. Squids are known for their flexible movements. The bionics partially imitates the swimming posture of squids and then applies it to the flexible gripper, so that the gripper can meet the requirements of grasping activities. Secondly, by assembling and casting the 3D printed mold, the length of its "tentacles" can be controlled to meet different working requirements to achieve the modular design goal. By using the grooves reserved in the electro-actuated layer, The non-metallic electrode film can be bonded to it according to the actual situation. When the electro-actuated layer and the non-metallic electrode film form a "sandwich" structure and voltage is applied, they can bend significantly to achieve grasping action. By applying current in different directions, the "tentacle" can achieve forward and reverse dual-degree-of-freedom coupled motion. This realizes 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. The modular design simplifies the production process, reduces production costs, and exhibits excellent electro-mechanical properties and economic applicability.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for constructing a programmable modular green cleaning bionic flexible gripper, characterized in that: The steps include: Step 1, preparing a biogel electro-actuated layer: a natural high molecular weight polymer sodium alginate and a novel microbial extracellular polysaccharide gellan gum are subjected to a bio-crosslinking reaction, and wood cellulose is added thereto to obtain a mixed solution of a biogel electro-actuated layer; a "wheel-like" shell mold is obtained by 3D printing using a novel biodegradable material chitin, the prepared biogel electro-actuated mixed solution is injected into the mold and dried, and then an appropriate amount of acetic acid solution is used to dissolve the shell to obtain a biogel electro-actuated layer with excellent biocompatibility; Step 2, preparing a non-metallic electrode film: dissolving sodium alginate powder in deionized water, heating in a water bath and stirring thoroughly, then dropping secondary dispersed MXene aqueous dispersion and MOFs aqueous dispersion into the solution, continuing to stir until fully mixed, then dropping propylene glycol solution into the mixed solution, stirring thoroughly and drying to obtain a non-metallic electrode film; Step three, construction and molding of the flexible gripper: fit the prepared non-metallic electrode film into the grooves reserved inside and outside the biogel electro-actuated layer according to actual conditions, and obtain a programmable, modular, green, clean bionic flexible gripper with a "squid tentacle-like" structure. Different grasping actions can be achieved by independently powering different power-on areas.

2. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 1, characterized in that: The specific process of obtaining the biogel electro-actuated layer mixed solution in step 1 is as follows: sodium alginate powder and gellan gum powder are respectively dissolved in deionized water, heated in a water bath and stirred sufficiently, then the sodium alginate aqueous solution and the gellan gum aqueous solution are mixed together, and then wood cellulose is added thereto, heated in a water bath and stirred for a certain period of time, and then a proper amount of propylene glycol solution is dropped into it, and stirred until completely mixed to obtain the biogel electro-actuated mixed solution for use.

3. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 2, characterized in that: The specific preparation method of the shell mold in the step 1 is as follows: use 3D modeling software to draw a "wheel-like" structure, output it as an STL file, and then import it into a 3D printer, use chitin as the printing material to print layer by layer and bond them together to obtain the shell mold.

4. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 3, characterized in that: The raw materials used in step 1 include 0.1 g of lignocellulose powder, 0.625 g of sodium alginate and gellan gum powder, 50 ml of deionized water, and 3 ml of glycerol.

5. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 4, characterized in that: The conditions for water bath heating in step 1 are as follows: the heating temperature is 50° C. and the rotation speed is 800 r / min.

6. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 5, characterized in that: The raw materials used in step 2 include 0.24 g of sodium alginate powder, 10 ml of MXene aqueous dispersion, 10 ml of MOFs aqueous dispersion, 50 ml of deionized water, and 3 ml of glycerol.

7. The method for constructing a programmable modular green cleaning bionic flexible gripper according to claim 6, characterized in that: The heating temperature in the step 2 is 50°C.

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