A pure bamboo thin film actuator and a preparation method thereof

Abstract

This invention provides a pure bamboo film actuator and its preparation method. It involves selecting 1-2 year old bamboo (Phyllostachys edulis) with a smooth, unpolluted surface and free from insect damage. The main culm is taken from a height of 1-10m above the ground, branches are removed, and the bamboo is sawn 1cm above and below each node to remove the nodes and obtain a round bamboo tube at the internode. The round bamboo tube is then scraped to remove the surface wax layer and chlorophyll. The round bamboo is radially split into strips, each strip having an average width of 1-2cm. The strips are then tangentially split into thin bamboo strips, each strip having an average thickness of 0.8-1.2mm. The first 1-3 layers of bamboo strips closest to the green part are taken and radially scraped to a fixed thickness, forming a bamboo film with a thickness of 0.01-0.15mm, which is the actuator. This invention uses inexpensive and readily available raw materials, has a simple and efficient production process, is energy-saving and environmentally friendly, produces a product with sensitive reaction, excellent wet deformation performance, and good stability.

Description

Technical Field

[0001] This invention provides a pure bamboo film actuator and its preparation method, belonging to the field of actuator technology. Background Technology

[0002] Actuators can convert other forms of energy in the environment (humidity, temperature, light, pH value, magnetic / electric fields, etc.) into their own mechanical energy and produce mechanical deformation, showing promising application prospects in fields such as soft robots, artificial muscles, sensors, and smart generators. To achieve mechanical response and generate deformation to complete actions such as movement and grasping, the choice of actuator materials is crucial.

[0003] Most actuators are made from graphene-based or polymer materials. Here, we take the graphene oxide / polydopamine (RGO-PDA) composite film (Highly Efficient Actuator of Graphene / Polydopamine Uniform Composite Thin Film Driven by Moisture Gradients) reported in the literature as an example to introduce its technical solution: Graphene oxide (200 mg) was dispersed in 250 mL of deionized water and stirred vigorously for 2 h, then 250 mL of Tris buffer (pH = 8.5) was added. Next, dopamine hydrochloride (80 mg) was slowly added to the ice bath mixture and stirred for a few minutes. The reaction mixture was then stirred at 40 °C for 24 h. The RGO-PDA precipitate was repeatedly washed with distilled water for 3 days using a centrifugal washing method to remove free PDA particles, obtaining a clean RGO-PDA dispersion. Finally, the RGO-PDA dispersion was vacuum filtered through a 0.45 μm pore size filter membrane and air-dried at room temperature to prepare the RGO-PDA composite film. These graphene-based or polymer materials are all based on petroleum-based materials, which are non-renewable and non-biodegradable, and have relatively high costs and complex reaction processes. Therefore, the trend of looking for actuator materials from natural materials is becoming more and more obvious.

[0004] To address the significant environmental hazards caused by petroleum-based materials, the selection of actuator materials is increasingly leaning towards natural materials such as cellulose, agarose, and proteins. This paper uses the reported technique of nanocellulose film (Dynamics of Hydration of Nanocellulose Films) as an example to illustrate its technical solution: 1g of cellulose slurry (undried soft bleached paper) is added to 100mL of water and stirred for 1 hour. Then, 0.1g NaBr, 3.1g NaClO, and 0.16mg 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) are added, followed by vigorous stirring. The pH of the solution is maintained constant between 10.5 and 11.0 by adding 1M NaOH. The solution is then washed at least 20 times with 400mL of high-purity water to lower the pH to approximately 6.8. 45mL of the solution is then sonicated for 4 minutes using a 13mm diameter ultrasonic tip at 20kHz and 100W output power. This step is repeated twice to obtain a transparent nanocellulose suspension. Then, 50 mL of distilled water was added, and the suspension was filtered through a 1.2 μm cellulose ester Millipore filter to remove residual coarse fibers. Finally, the transparent suspension was cast onto a 10 cm diameter petri dish and completely dried on copper foil in a 60 °C oven to maintain a uniform temperature across the entire film surface, thus obtaining a nanofiber cellulose film. While this method addresses the issues of renewability and biodegradability, the manufacturing process of these natural materials is bottom-up (i.e., first crushing the natural materials into small units and then reassembling them). This method is energy-intensive, environmentally unfriendly, and extremely time-consuming. Therefore, exploring simpler, more efficient, environmentally friendly, and low-cost actuator fabrication methods based on natural materials remains a key technological challenge. Summary of the Invention

[0005] This invention provides a pure bamboo thin film actuator and its preparation method, which overcomes the disadvantages of petroleum-based actuator materials being non-renewable and non-biodegradable; it also overcomes the disadvantages of natural material actuators being costly, having complex reaction processes, high energy consumption, and long processing times.

[0006] The specific technical solution is as follows:

[0007] A method for preparing a pure bamboo thin film actuator includes the following steps:

[0008] (1) Select 1-2 year old bamboo, requiring smooth surface without pollution and free from insects. Take the main bamboo stem 1m-10m above the ground, remove branches and saw along the bamboo node 1cm above and below to remove the bamboo node and obtain the round bamboo tube at the internode.

[0009] Step (1) The cut bamboo tubes should be stored in water or refrigerated in a refrigerator to ensure that the moisture content of the bamboo tubes is greater than 100%. If stored in water, the storage time should not exceed 3 days in summer and 5 days in winter. If stored in a refrigerator, the temperature should be below -10℃.

[0010] (2) After the surface moisture of the round bamboo tube prepared in step (1) is dried, scraping is performed to remove the wax layer and chlorophyll on the surface of the round bamboo tube.

[0011] In step (2), the bamboo tube moisture content should be greater than 100% during the scraping process. After scraping, the bamboo should be stored naturally for no more than 2 hours. If long-term storage is required, it should be stored in water or refrigerated.

[0012] (3) The round bamboo tube after step (2) is split into bamboo strips along the radial direction. The average width of each bamboo strip is equal, and each strip is 1-2 cm.

[0013] The bamboo splitting process in step (3) requires that the bamboo tube moisture content be greater than 100%. After splitting, the bamboo strips should be stored naturally for no more than 2 hours. If long-term storage is required, they should be stored in water or refrigerated.

[0014] (4) The bamboo strips processed in step (3) are divided into thin bamboo strips along the tangential direction, with an average thickness of 0.8-1.2 mm for each thin bamboo strip;

[0015] The bamboo strips in step (4) need to have a moisture content greater than 100%. After splitting, the bamboo strips should be stored in a ventilated place to prevent mold and rot; or they can be completely soaked in water for storage. In summer, the storage time should not exceed 3 days and in winter, it should not exceed 5 days.

[0016] (5) Take the 1-3 layers of bamboo strips closest to the green part of the bamboo after step (4), and scrape the bamboo strips along the radial direction to fix the thickness. The bamboo strips are scraped into a bamboo film with a thickness of 0.01-0.15mm, which is the actuator.

[0017] Before scraping and fixing the thickness in step (5), if the bamboo strips are stored in the air, soak them in water for more than 24 hours to achieve a 100% moisture content. During the scraping process, ensure that the moisture content of the bamboo strips is always 100% by continuously dripping water onto the surface of the bamboo strips or soaking the bamboo strips in water every 1-2 minutes.

[0018] The technical effects of this invention are as follows:

[0019] 1. Raw materials are inexpensive and readily available. The only raw material used in this invention is bamboo. my country has a large bamboo forest area and abundant bamboo resources. Moreover, bamboo grows quickly (up to 100cm / day), making it an inexpensive and readily available biomass raw material.

[0020] 2. Simple and efficient production process. The production process of this invention requires only four mechanical processing steps from round bamboo to bamboo film: cutting bamboo tubes, splitting bamboo sections, splitting bamboo strips, and scraping bamboo strips. The production process is simple. In addition, since the production process only involves mechanical processing, it can be carried out in a fast assembly line, thus achieving high production efficiency.

[0021] 3. Energy-saving and environmentally friendly production process. Since the production process involves only mechanical processing and requires no heating or stirring, it is energy-efficient. Furthermore, because it consumes no chemicals and generates no wastewater or waste, the production process is environmentally friendly. The only byproduct is bamboo powder, which can be effectively reused as a raw material for bamboo-plastic composites or bamboo charcoal products.

[0022] 4. The product obtained by this invention (pure bamboo film actuator) is highly responsive, exhibits excellent wet deformation performance, and demonstrates good stability. The pure bamboo film actuator obtained by this technology reaches a maximum bending angle of 300° within 9 seconds under 100% humidity stimulation. Figure 4 This technology significantly outperforms most petroleum-based and nanocellulose-based actuators. Furthermore, the pure bamboo film actuator obtained through this technology exhibits rapid bending under the influence of finger moisture. Figure 5 It can lift objects up to 60 times its own weight. Figure 6 ), to perform a grabbing action ( Figure 7 ), complete the forward movement ( Figure 8 The bamboo film actuator, with a step diameter of 0.5 cm, exhibits excellent wet-induced deformation performance. Finally, the pure bamboo film actuator obtained using this technology still maintains a sensitive reaction rate and wet-induced deformation capability after 50 dry and wet deformation cycles, or after treatment in extreme environments (boiling in water at 90℃, 10% HCl, 10% NaOH) for 10 minutes, demonstrating excellent stability.

[0023] 5. The product obtained by this invention (pure bamboo film actuator) is 100% biodegradable. The pure bamboo film obtained by this technology can degrade naturally by burying it in soil. A 1.5cm × 1.5cm × 0.01mm (length × width × thickness) pure bamboo film completely degrades in approximately 21 weeks, resulting in significant environmental and ecological benefits. Figure 9 ). Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the use of a scraper to flatten and fix the thickness of bamboo strips along the radial direction in this invention.

[0025] Figure 2 Photograph of the pure bamboo film actuator of this invention;

[0026] Figure 3 This is a SEM image of the cross-section of the pure bamboo film actuator of the present invention;

[0027] Figure 4The pure bamboo film actuator of this invention reaches a maximum bending angle of 300° within 9 seconds under stimulation of 100% relative humidity.

[0028] Figure 5 This is a photograph of the pure bamboo film actuator of the present invention bending when a finger approaches;

[0029] Figure 6 The pure bamboo film actuator of this invention can lift an object (plastic) 60 times its own weight when driven by the moisture of a finger;

[0030] Figure 7 This is a schematic diagram of the pure bamboo film actuator of the present invention completing a grasping action under the drive of finger humidity;

[0031] Figure 8 This is a schematic diagram of the pure bamboo film actuator of the present invention completing a forward movement (step diameter 0.5cm) driven by the moisture of a finger;

[0032] Figure 9 The soil degradation rate and photographs of the pure bamboo film actuator of this invention. Detailed Implementation

[0033] The specific technical solutions of the present invention will be described with reference to the embodiments.

[0034] A method for preparing a pure bamboo thin film actuator includes:

[0035] (1) Select 1-2 year old bamboo, ensuring the surface is smooth, unpolluted, and free from insect infestation. Take the main culm at a height of 1m-10m above the ground, remove branches and twigs, and use a saw (or band saw, circular saw, hand saw, etc.) to cut along the bamboo nodes 1cm above and below, in order to remove the nodes and retain only the internodes as round bamboo tubes. To ensure that the moisture content of the round bamboo tubes is greater than 100% in the next step of preparation, the cut round bamboo tubes should be stored in water or refrigerated: if stored in water, the storage time should not exceed 3 days in summer and 5 days in winter; if stored in a refrigerator, the temperature should be below -10℃, and the storage time is unlimited.

[0036] (2) After removing the round bamboo tubes made in step (1) from the water (or refrigerator) and allowing the surface moisture to air dry (or thaw the bamboo tubes), manually scrape off the waxy coating and chlorophyll on the surface of the round bamboo tubes using a wood-chopping knife (scraper, machete, planer, blade, steel bar, or other tools, or sandpaper, sanding belt, etc.) (or mechanically scrape off the waxy coating using an outer round polishing machine, bamboo tube sander, or other mechanical equipment). The scraping process requires ensuring that the moisture content of the bamboo tubes is greater than 100%. The scraped bamboo cannot be stored naturally for a long time (less than or equal to 2 hours) and should be processed as soon as possible. If long-term storage is required, refer to the storage method for round bamboo tubes in (1).

[0037] (3) After processing the round bamboo tube in step (2), use a bamboo splitter (or bamboo opener, or hand-splitting with a cleaver) to split the round bamboo tube radially into 6-10 bamboo strips (depending on the diameter of the round bamboo). The average width of each bamboo strip should be equal, and each strip should be 1-2 cm. During the splitting process, the moisture content of the bamboo tube should be greater than 100%. The split bamboo strips should not be stored naturally for a long time (less than or equal to 2 hours) and should be processed in the next step as soon as possible. If long-term storage is required, refer to the storage method of the round bamboo tube in (1).

[0038] (4) After processing the bamboo strips in step (3), use a bamboo splitting machine (or a manual bamboo splitting machine, or a bamboo strip layering machine) to split the bamboo strips into 5-8 thin bamboo strips along the tangential direction (depending on the thickness of the bamboo strips). The average thickness of each thin bamboo strip is about 0.8-1.2 mm. The bamboo strips need to have a moisture content greater than 100% during the splitting process. The split bamboo strips can be stored in a ventilated place, but care should be taken to prevent mold and rot; they can also be completely soaked in water for storage, but the storage time should not exceed 3 days in summer and 5 days in winter.

[0039] (5) Take the first 1-3 layers of bamboo strips closest to the green part after step (4), and use a scraper (or a cleaver, planer, blade, utility knife, or other tools, or sandpaper, sanding belt, or other mechanical processing methods such as cutting, planing, or peeling) to smooth and fix the thickness of the bamboo strips along the radial direction. Figure 1 As shown. If the bamboo strips are stored in the air, they need to be soaked in water for more than 24 hours to reach 100% moisture content. The scraping process also requires maintaining 100% moisture content on the bamboo strips. This can be achieved by continuously dripping water onto the surface of the bamboo strips or by immersing the bamboo strips in water every 1-2 minutes. The preparation process is complete when the bamboo strips are scraped to a thickness of 0.01-0.15mm, and the resulting bamboo film is the target actuator.

[0040] A humidity-responsive pure bamboo thin-film actuator was prepared using the method described above. Figure 2 and Figure 3 As shown, this actuator exhibits different wet-induced response rates and maximum bending curvatures under varying sample thicknesses, ambient humidity, and fiber angles. For example, a 0.01 mm thick actuator reaches its maximum bending angle of 300° within 9 seconds under 100% humidity stimulation. Figure 4 Furthermore, this actuator bends rapidly under the influence of finger moisture. Figure 5 It can even lift objects 60 times its own weight. Figure 6 ), to perform a grabbing action ( Figure 7 ), complete the forward movement ( Figure 8(Step diameter 0.5cm). Furthermore, this actuator retains a sensitive reaction rate and wet deformability even after 50 dry and wet deformation cycles, or after treatment in extreme environments (boiling in water at 90℃, 10% HCl, 10% NaOH) for 10 minutes. Additionally, this actuator can be degraded naturally by burying in soil; a 1.5cm × 1.5cm × 0.01mm (length × width × thickness) pure bamboo film is 100% degraded in approximately 21 weeks. Figure 9 .

Claims

1. A method for preparing a pure bamboo thin-film actuator, characterized in that, Includes the following steps: (1) Select 1-2 year old bamboo, requiring smooth surface without pollution and free from insects. Take the main bamboo stem 1m-10m above the ground, remove branches and saw along the bamboo node 1cm above and below to remove the bamboo node and obtain the round bamboo tube at the internode. (2) After the surface moisture of the round bamboo tube prepared in step (1) is dried, scraping is performed to remove the wax layer and chlorophyll on the surface of the round bamboo tube. (3) The round bamboo tube after step (2) is split into bamboo strips along the radial direction of the round bamboo tube. The average width of each bamboo strip is equal, and each strip is 1-2cm. (4) The bamboo strips processed in step (3) are divided into thin bamboo strips along the tangential direction, with an average thickness of 0.8-1.2 mm for each thin bamboo strip; (5) Take the 1-3 layers of bamboo strips closest to the green part of the bamboo after step (4), and scrape the bamboo strips along the radial direction to fix the thickness. The bamboo strips are scraped into a bamboo film with a thickness of 0.01-0.15mm, which is the actuator.

2. The method for preparing a pure bamboo thin-film actuator according to claim 1, characterized in that, Step (1) The cut bamboo tubes should be stored in water or refrigerated in a refrigerator to ensure that the moisture content of the bamboo tubes is greater than 100%. If stored in water, the storage time should not exceed 3 days in summer and 5 days in winter. If stored in a refrigerator, the temperature should be below -10℃.

3. The method for preparing a pure bamboo thin-film actuator according to claim 1, characterized in that, In step (2), the bamboo tube moisture content should be greater than 100% during the scraping process. After scraping, the bamboo should be stored naturally for no more than 2 hours. If long-term storage is required, it should be stored in water or refrigerated.

4. The method for preparing a pure bamboo thin-film actuator according to claim 1, characterized in that, The bamboo splitting process in step (3) requires that the bamboo tube moisture content be greater than 100%. After splitting, the bamboo strips should be stored naturally for no more than 2 hours. If long-term storage is required, they should be stored in water or refrigerated.

5. The method for preparing a pure bamboo thin-film actuator according to claim 1, characterized in that, The bamboo strips in step (4) need to have a moisture content greater than 100%; after splitting, the bamboo strips should be stored in a ventilated place to prevent mold and decay; or they can be completely soaked in water for storage, with a storage time of no more than 3 days in summer and no more than 5 days in winter.

6. The method for preparing a pure bamboo thin-film actuator according to claim 1, characterized in that, Before scraping and fixing the thickness in step (5), if the bamboo strips are stored in the air, soak them in water for more than 24 hours to achieve a 100% moisture content. During the scraping process, ensure that the moisture content of the bamboo strips is always 100% by continuously dripping water onto the surface of the bamboo strips or soaking the bamboo strips in water every 1-2 minutes.

7. A pure bamboo thin film actuator characterized by, Obtained by the preparation method according to any one of claims 1 to 6.

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