Stretchable muscle fiber based on shape memory alloy and method for manufacturing the same

Abstract

The application discloses a kind of stretchable muscle fiber based on shape memory alloy and preparation method thereof, belong to muscle fiber technical field, preparation method is as follows: preparation hollow hot-drawing preform;Shape memory metal wire is passed through hot-drawing preform hollow passage, then hot-drawing preform and shape memory metal wire are vertically sent into heating device, and hot-drawing preform wrapped outside shape memory metal wire is formed fiber silk, fiber silk is collected;Thermoplastic elastomer solution is injected into the hollow passage of fiber silk, then fiber silk is stretched and relaxed, shape memory metal wire is curled using thermoplastic elastomer solution, and stretchable muscle fiber is prepared after plastic elastomer solution solidification.The muscle fiber has the advantages of simple preparation method, suitable for mass production, and the prepared fiber has the advantages of small fineness, large length, fast response speed and high energy density, which can effectively solve the existing problems of muscle fiber.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy muscle fibers, and in particular relates to a stretchable muscle fiber based on shape memory alloy and a preparation method thereof. Background Art

[0002] Artificial muscle is an intelligent shape-memory material that reversibly undergoes a range of basic movements, including contraction, expansion, and rotation, in response to external stimuli (such as voltage, current, pressure, temperature, and light). Its miniaturization, lightweightness, flexibility, and intelligence make it a crucial development not only for medicine but also for robotics. With the advancement of artificial intelligence technologies like robotics, artificial muscle, as a key driver of these devices, has garnered widespread attention.

[0003] Currently, fiber-based artificial muscles have made significant progress, characterized by their ability to provide rapid, retractable, and long-lasting stretching and torsion. Fiber-based artificial muscles, with their excellent actuation performance and broad application prospects, have attracted increasing research interest. From the initial raw material of carbon nanotubes to nylon, polyethylene fibers, and natural fibers such as silk and cotton, researchers have conducted extensive research on artificial muscle fibers. Current artificial muscles include electrochemical fibers and thermally driven carbon nanotube helical fibers. Electrochemical fibers offer high thermal conductivity, large actuation strains, and high actuation frequencies, but they are relatively expensive to produce and require the addition of additional electrolytes, making the fabrication process relatively cumbersome. Thermally driven helical polymer fibers offer relatively long life, high actuation forces, and high power and energy densities. However, due to inherent material and structural limitations, these fibers also suffer from slow heat dissipation, slow response speed, and limited actuation frequencies. Dielectric elastomer artificial muscles, driven by high-voltage electricity, offer advantages such as high actuation frequencies and fast response speeds, but are susceptible to material breakdown under high-voltage conditions, presenting significant safety risks and significant performance limitations in key areas.

[0004] Scientists have long been striving to rapidly mass-produce artificial muscle fibers with large actuation deformation, fast response rate, high energy density, and long service life. A variety of methods exist for preparing muscle fibers, including melt drawing, twisting, mold forming, electrospinning, microfluidic spinning, and 3D printing. Melt drawing is simple and easy to use, but the diameter of the muscle fibers produced is uneven, and it does not allow for continuous and rapid production, lacking the prospect of large-scale production. This is also a disadvantage of twisting and mold forming methods for producing muscle fibers. Electrospinning can produce micron- or even nanometer-sized LCE fibers when preparing liquid crystal elastomer fibers, but it cannot continuously produce fibers of longer lengths. Microfluidics can continuously produce LCE fibers with smaller diameters, but the preparation speed is very slow, affecting preparation efficiency. 3D printing technology offers sufficient flexibility to produce a variety of muscle fibers well-suited for complex working conditions, but it also has the disadvantages of material limitations, low printing efficiency, and low quality accuracy. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides a stretchable muscle fiber based on shape memory alloy and a preparation method thereof. The muscle fiber has the advantage of a simple preparation method and is suitable for large-scale production. The prepared fiber has the advantages of small fineness, large length, fast response speed and high energy density, which can effectively solve the problems existing in existing muscle fibers.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention to solve the technical problem is:

[0007] A method for preparing stretchable muscle fibers based on shape memory alloys comprises the following steps:

[0008] (1) preparing a hollow hot-stretched preform;

[0009] (2) passing the shape memory metal wire through the hollow channel of the heat-stretched preform, and then vertically feeding the heat-stretched preform and the shape memory metal wire into a heating device for heating, and the heat-stretched preform flowing out is wrapped around the outside of the shape memory metal wire to form fiber filaments, and the fiber filaments are collected;

[0010] (3) A thermoplastic elastomer solution is injected into the hollow channel of the fiber filament, and then the outer fiber sheath of the fiber filament is stretched and then relaxed. The thermoplastic elastomer solution is used to drive the shape memory metal wire to curl. After the thermoplastic elastomer solution solidifies, a stretchable muscle fiber is obtained.

[0011] Furthermore, the material of the hot-stretched preform is COCE, PSu, SEBS or Geniomer, and the thermoplastic elastomer solution is ecoflex solution, SEBS solution or TPU solution.

[0012] Furthermore, the shape memory metal wire is made of nickel-titanium alloy, copper-based alloy or iron-based alloy.

[0013] Furthermore, the diameter of the shape memory metal wire is 0.04-0.06 mm.

[0014] Furthermore, the hot-stretched preform described in step (1) is prepared by the following method: spreading the hot-stretched preform material particles between flat metal molds, pressurizing the mold with the particles and heating it at 170-200°C, and obtaining a hot-stretched preform material sheet after cooling; placing multiple hot-stretched preform material sheets in a metal mold with a rectangular cross-section, arranging them into a hollow rectangular shape in the mold, and then filling the cavity of the rectangular shape with polytetrafluoroethylene material, heating the mold at 170-200°C, cooling, and removing the polytetrafluoroethylene filler in the middle to obtain a hollow hot-stretched preform.

[0015] Furthermore, the inner diameter of the hot-stretched preform in step (1) is 18-22 mm*10-14 mm.

[0016] Furthermore, in step (2), the hot-stretched preform is fed into a heating device at a speed of 1-3 mm / min, and the heating temperature of the heating device is 190-210°C.

[0017] Furthermore, before stretching in step (3), the length excess of the shape memory metal wire relative to the heat-stretched preform is 20-50%.

[0018] Furthermore, the width of the stretchable muscle fibers is 0.5-0.9 mm.

[0019] A stretchable muscle fiber based on shape memory alloy is prepared by the above method.

[0020] The beneficial effects produced by the present invention are:

[0021] 1. The present invention combines shape memory metal wire and heat-stretched preform (thermoplastic elastomer) by designing the cross section. A macroscopic preform is first produced. The shape memory metal wire is then placed inside the thermoplastic elastomer. The thermoplastic elastomer is caused to shrink by heating to obtain long and thin fiber filaments. The cavity of the thermoplastic elastomer is then filled with ecoflex material. The thermoplastic elastomer is then stretched and then relaxed to curl the shape memory metal wire. The curled structure of the shape memory metal wire is fixed by the ecoflex material. Muscle fibers are prepared through the heat-stretching process. The restorative properties of the thermoplastic elastomer and the shortening properties of the shape memory metal wire when heated are utilized to cause the muscle fibers to produce stretching and contracting movements. The prepared muscle fibers have the advantages of fast response speed and high energy density.

[0022] 2、The preparation method in the application has simple preparation process, can continuously prepare long and thin and external uniform fiber filaments, and can be produced on a large scale; meanwhile, the diameter of the fiber can be controlled by controlling the speed of feeding into the heating device, and the fiber with appropriate size can be prepared according to different requirements.

[0023] 3、The muscle fiber prepared in the application has large driving power, good stretchability and cycle stability, and has the advantages of fast response speed, high capacity density and the like. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the preparation method in the application;

[0025] Figure 2 is a schematic diagram of the coiling process of the shape memory metal wire in Example 1 of the application;

[0026] Figure 3 is a physical diagram of the muscle fiber in Example 1 of the application;

[0027] Figure 4 is a physical diagram of the muscle fiber in Example 1 of the application before and after stretching;

[0028] Figure 5 is a driving force test result diagram of the muscle fiber in Example 1 of the application before and after heating under a load of 8g weight;

[0029] Figure 6 is a driving force test result diagram of the muscle fiber in Example 1 of the application before and after heating under a load of 20g weight;

[0030] Figure 7 is a driving force test result diagram of the muscle fiber in Example 1 of the application before and after heating under a load of 50g weight. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the application more clear and understandable, the application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the application and are not used to limit the application, that is, the described examples are only a part of the examples of the application, but not all the examples.

[0032] Therefore, the detailed description of the provided examples of the application below is not intended to limit the scope of the claimed application, but only represents selected examples of the application. Based on the examples of the application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0033] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0034] The features and performance of the present invention are further described in detail below with reference to the embodiments and drawings.

[0035] Example 1

[0036] A stretchable muscle fiber based on shape memory alloy, the preparation method of which comprises the following steps:

[0037] (1) preparing a hollow hot-stretched preform, specifically:

[0038] ① Evenly spread the COCE particles in a customized rectangular stainless steel mold, and place a layer of PTFE film on the upper and lower surfaces that contact the mold;

[0039] ② Place the mold with the particles in a flat vulcanizer and pressurize it at 180°C for 15 minutes. After cooling, peel off the film to obtain a COCE sheet.

[0040] ③ Arrange the multiple COCE sheets produced in step ② into rectangular hollow structures in a custom mold, fill the middle with PTFE cuboids, and also place a layer of PTFE film on the upper and lower surfaces in contact with the mold;

[0041] ④ Place the mold with the COCE sheet and PTFE in a flat vulcanizer and pressurize it at 180°C for 15 minutes. After cooling, remove the PTFE filler in the middle to obtain a hollow hot-stretched preform; the inner diameter of the hot-stretched preform is 20mm*12mm;

[0042] (2) a shape memory metal wire with a diameter of 0.05 mm is passed through the hollow channel of the hot-stretched preform, and then the hot-stretched preform and the nickel-titanium alloy shape memory metal wire are vertically fed into a vertical tube furnace heated to 200° C. at a speed of 1.5 mm / min for heating. The hot-stretched preform that flows out is wrapped around the outside of the shape memory metal wire to form a fiber filament with a width of 0.7 mm, which is wound on a roller collector to collect the fiber filament. The winding speed of the roller collector is 300 mm / min.

[0043] (3) Injecting ecoflex solution into the hollow channel of the fiber filament, at this time, the length of the shape memory metal wire exceeds the length of the hot-stretched preform by 50%, then stretching the fiber filament sheath to make it equal to the length of the shape memory metal wire, and then relaxing it to make the shape memory metal wire curled. After the ecoflex solution solidifies, a stretchable muscle fiber is obtained.

[0044] Example 2

[0045] A stretchable muscle fiber based on shape memory alloy, the preparation method of which comprises the following steps:

[0046] (1) preparing a hollow hot-stretched preform, specifically:

[0047] ① Evenly spread the COCE particles in a customized rectangular stainless steel mold, and place a layer of PTFE film on the upper and lower surfaces that contact the mold;

[0048] ② Place the mold with the particles in a flat vulcanizer and pressurize it at 170°C for 15 minutes. After cooling, peel off the film to obtain a COCE sheet.

[0049] ③ Arrange the multiple COCE sheets produced in step ② into rectangular hollow structures in a custom mold, fill the middle with PTFE cuboids, and also place a layer of PTFE film on the upper and lower surfaces in contact with the mold;

[0050] ④ Place the mold with the COCE sheet and PTFE in a flat-plate vulcanizer and pressurize it at 170°C for 15 minutes. After cooling, remove the PTFE filler in the middle to obtain a hollow hot-stretched preform; the inner diameter of the hot-stretched preform is 20mm*12mm;

[0051] (2) passing a shape memory metal wire with a diameter of 0.05 mm through the hollow channel of the hot-stretched preform, and then vertically feeding the hot-stretched preform and the nickel-titanium alloy shape memory metal wire into a vertical tube furnace heated to 190° C. at a speed of 2 mm / min for heating. The hot-stretched preform that flows out is wrapped around the outside of the shape memory metal wire to form a fiber filament with a width of 0.5 mm, which is wound on a roller collector to collect the fiber filament. The winding speed of the roller collector is 300 mm / min.

[0052] (3) Injecting ecoflex solution into the hollow channel of the fiber filament, at this time, the length of the shape memory metal wire exceeds the length of the hot-stretched preform by 50%, then stretching the fiber filament sheath to make it equal to the length of the shape memory metal wire, and then relaxing it to make the shape memory metal wire curled. After the ecoflex solution solidifies, a stretchable muscle fiber is obtained.

[0053] Example 3

[0054] A stretchable muscle fiber based on shape memory alloy, the preparation method of which comprises the following steps:

[0055] (2) preparing a hollow hot-stretched preform, specifically:

[0056] ① Evenly spread the COCE particles in a customized rectangular stainless steel mold, and place a layer of PTFE film on the upper and lower surfaces that contact the mold;

[0057] ② Place the mold with the particles in a flat-plate vulcanizer and pressurize it at 200°C for 15 minutes. After cooling, peel off the film to obtain a COCE sheet;

[0058] ③ Arrange the multiple COCE sheets produced in step ② into rectangular hollow structures in a custom mold, fill the middle with PTFE cuboids, and also place a layer of PTFE film on the upper and lower surfaces in contact with the mold;

[0059] ④ Place the mold with the COCE sheet and PTFE in a flat vulcanizer and pressurize it at 200°C for 15 minutes. After cooling, remove the PTFE filler in the middle to obtain a hollow hot-stretched preform; the inner diameter of the hot-stretched preform is 22mm*14mm;

[0060] (2) a shape memory metal wire with a diameter of 0.06 mm is passed through the hollow channel of the hot-stretched preform, and then the hot-stretched preform and the nickel-titanium alloy shape memory metal wire are vertically fed into a vertical tube furnace heated to 210° C. at a speed of 3 mm / min for heating. The hot-stretched preform that flows out is wrapped around the outside of the shape memory metal wire to form a fiber filament with a width of 0.9 mm, which is wound on a roller collector to collect the fiber filament. The winding speed of the roller collector is 300 mm / min.

[0061] (3) Injecting ecoflex solution into the hollow channel of the fiber filament, at this time, the length of the shape memory metal wire exceeds the length of the hot-stretched preform by 50%, then stretching the fiber filament sheath to make it equal to the length of the shape memory metal wire, and then relaxing it to make the shape memory metal wire curled. After the ecoflex solution solidifies, a stretchable muscle fiber is obtained.

[0062] Example 4

[0063] On the basis of Example 1, the excess length of the shape memory metal wire relative to the heat-stretched preform in step (3) is set to 20%.

[0064] Example 5

[0065] On the basis of Example 1, the excess length of the shape memory metal wire relative to the heat-stretched preform in step (3) is set to 30%.

[0066] Example 6

[0067] On the basis of Example 1, the excess length of the shape memory metal wire relative to the heat-stretched preform in step (3) is set to 40%.

[0068] Example 7

[0069] On the basis of Example 1, the COCE particles in step (1) were replaced with Psu particles, and the rest remained unchanged.

[0070] Example 8

[0071] On the basis of Example 1, the COCE particles in step (1) were replaced with SEBS particles, and the rest remained unchanged.

[0072] Example 9

[0073] On the basis of Example 1, the COCE particles in step (1) were replaced with Geniomer particles, and the rest remained unchanged.

[0074] Example 10

[0075] On the basis of Example 1, the nickel-titanium alloy in step (2) was replaced with a copper-based alloy, and the rest remained unchanged.

[0076] Example 11

[0077] On the basis of Example 1, the nickel-titanium alloy in step (2) was replaced by an iron-based alloy, and the rest remained unchanged.

[0078] Example 12

[0079] On the basis of Example 1, the ecoflex solution injected in step (3) was replaced by SEBS solution, and the rest remained unchanged.

[0080] Example 13

[0081] On the basis of Example 1, the ecoflex solution injected in step (3) was replaced by TPU solution, and the rest remained unchanged.

[0082] In the above embodiment, the calculation method of the excess ratio of the length of the shape memory metal wire relative to the heat-stretched preform is: (shape memory metal wire length-fiber cladding length) / fiber cladding length*100%.

[0083] Experimental example

[0084] Taking the muscle fiber prepared in Example 1 as an example, 100 mm was taken to test its performance. The specific testing process is as follows: ① The memory metal wires at both ends of the fiber were peeled off from the fiber and connected to a power source;

[0085] ② One end of the fiber is fixed and the other end is tied to the contact of the push-pull force gauge;

[0086] ③ Turn on the power supply and use a constant current source with a current of about 0.08 amperes to heat the fiber through Joule heat;

[0087] ④ Read the output force of the muscle fibers on the dynamometer.

[0088] The specific test results are shown in Table 1.

[0089] Table 1:

[0090] Tensile force (100mm / N) Example 1 0.35 Example 2 0.33 Example 3 0.34 Example 4 0.15 Example 5 0.22 Example 6 0.28 Example 7 0.34 Example 8 0.33 Example 9 0.34 Example 10 0.31 Example 11 0.32 Example 12 0.33

[0091] It can be seen from the data in the above table that the muscle fibers prepared by the method of this application have good tensile performance. Through calculation, it is known that they can lift objects more than 800 times their own weight and have a high output energy density, while existing muscle fibers can generally only lift objects about 600 times their own weight.

[0092] By attaching Figure 4 It can be seen that the stretching rate of the prepared muscle fibers can reach 45%.

[0093] By attaching Figure 5-6 It can be seen that the prepared muscle fibers can lift objects weighing 8g and 20g to a certain height, respectively, proving that they have strong tensile force.

[0094] By attaching Figure 7 It can be seen that the prepared muscle fibers can lift heavier objects by integrating multiple fibers, demonstrating the integrated application of fibers.

Claims

1. A method for preparing stretchable muscle fibers based on shape memory alloys, characterized in that: The following steps are involved: (1) Preparation of a hollow hot-stretched preform; (2) The shape memory metal wire is passed through the hollow channel of the hot-stretched preform, and then the hot-stretched preform and the shape memory metal wire are vertically fed into a heating device for heating. The hot-stretched preform that flows out after heating is wrapped around the outside of the shape memory metal wire to form fiber filaments, and the fiber filaments are collected; (3) A thermoplastic elastomer solution is injected into the hollow channel of the fiber filament, and then the outer fiber sheath of the fiber filament is stretched and then relaxed. The thermoplastic elastomer solution is used to drive the shape memory metal wire to curl. After the thermoplastic elastomer solution solidifies, a stretchable muscle fiber is obtained; The material of the hot-stretching preform is COCE, PSu, SEBS or Geniomer, and the thermoplastic elastomer solution is ecoflex solution, SEBS solution or TPU solution.

2. The method for preparing a stretchable muscle fiber based on a shape memory alloy according to claim 1, wherein: The shape memory metal wire is made of nickel-titanium alloy, copper-based alloy or iron-based alloy.

3. The method for preparing a stretchable muscle fiber based on a shape memory alloy according to claim 1, wherein: The diameter of the shape memory metal wire is 0.04-0.06 mm.

4. The method for preparing a stretchable muscle fiber based on a shape memory alloy according to claim 1, wherein: The hot-stretched preform described in step (1) is prepared by the following method: spreading the hot-stretched preform material particles between flat metal molds, pressurizing the mold with the particles and heating it at 170-200°C, and obtaining a hot-stretched preform material sheet after cooling; placing multiple hot-stretched preform material sheets in a metal mold with a rectangular cross-section, arranging them into a hollow rectangular shape in the mold, and then filling the cavity of the rectangular shape with polytetrafluoroethylene material, heating the mold at 170-200°C, cooling, and removing the polytetrafluoroethylene filler in the middle to obtain a hollow hot-stretched preform.

5. The method for preparing a stretchable muscle fiber based on a shape memory alloy according to claim 1 or 4, wherein: The inner diameter of the hot-stretched preform in step (1) is 18-22 mm*10-14 mm.

6. The method for preparing stretchable muscle fibers based on shape memory alloys according to claim 1, wherein: In step (2), the hot-stretched preform is fed into a heating device at a speed of 1-3 mm / min, and the heating temperature of the heating device is 190-210°C.

7. The method for preparing stretchable muscle fibers based on shape memory alloys according to claim 1, wherein: Before stretching in step (3), the length of the shape memory metal wire exceeds the length of the hot-stretched preform by 20-50%.

8. The method for preparing stretchable muscle fibers based on shape memory alloys according to claim 1, wherein: The width of the stretchable muscle fiber is 0.5-0.9 mm.

9. A stretchable muscle fiber based on shape memory alloy, characterized in that: Prepared by the method according to any one of claims 1 to 8.

Images