A method for manufacturing an electrically driven artificial muscle

Abstract

This invention discloses a method for preparing an electrically driven artificial muscle, relating to the field of novel smart materials technology. The method includes the following steps: 1. Pretreatment process; 2. Metal electrode preparation process; 3. Nylon fiber twisting process. The method for preparing the electrically driven artificial muscle provided by this invention utilizes chemical plating to prepare a uniform and dense platinum electrode on the surface of nylon fibers. Then, a motor is used to twist the platinum-plated nylon fibers. After high-temperature annealing heat treatment, a high-performance artificial muscle is obtained. Under a 14V square wave voltage drive, it produces a maximum contraction of 10.8mm, a maximum strain of 15.6%, and a mechanical work output of 6.37kJ / kg during contraction.

Description

Technical Field

[0001] This invention relates to the field of novel smart materials technology, and in particular to a method for preparing an electrically driven artificial muscle. Background Technology

[0002] As robotics research deepens, traditional motors and rigid transmission structures are increasingly unable to meet the driving requirements of machines due to their large space requirements and limited driving modes. Over the past 30 years, rapid progress in the fabrication and characterization of nanomaterials (such as carbon nanotubes and graphene) has enabled the rapid development and expansion of flexible actuators—artificial muscles.

[0003] Artificial muscles are intelligent materials that integrate sensing and actuation; under the influence of external stimuli (light, electricity, magnetism, temperature, pH value, pressure, etc.), they produce reversible movements such as contraction, expansion, and rotation. Currently, the more mature artificial muscle products are pneumatic artificial muscles and hydraulic artificial muscles. Their principle is to inject fluid into an elastic cavity through air pressure or hydraulic pressure devices, causing the cavity to expand (or contract). However, due to the large size of the muscle body (air pump, liquid pump), it is difficult to transport, and there is a risk of leakage of toxic and harmful gases (liquids).

[0004] Currently, fibrous artificial muscles have made good progress, characterized by providing rapid, stretchable, and long-lasting stretching and torsion. From the initial raw material of carbon nanotubes to nylon, polyethylene fibers, and natural fibers such as silk and cotton, nylon fibers, as an inexpensive and high-strength polymer, are used to prepare coiled nylon actuators through twisting. Because highly oriented semi-crystalline polymers exhibit anisotropic thermal expansion behavior (expanding along the diameter and contracting along the axis) when highly oriented along their length, nylon fibers are typically stimulated to produce reversible movements such as contraction, expansion, and rotation using electrothermal, hydrothermal, or electrochemical heating methods. Electricity, being readily available, easily adjustable, and requiring low experimental conditions, is chosen here for electrothermal heating, specifically Joule heating. Traditional methods involve twisting conductive metal wires together with nylon fibers or spirally wrapping the coiled muscle with carbon nanotube sheets, using the conductivity of the metal wires (carbon nanotubes) to heat the muscle fibers via Joule heating. This can impair the performance of the muscle fibers or require high operating voltages. This invention uses a chemical plating method to prepare a dense metal electrode layer on the surface of nylon fiber, and then twists and turns the platinum-plated nylon fiber to prepare an electrically driven artificial muscle. Summary of the Invention

[0005] The purpose of this invention is to ensure the performance of artificial muscles while driving nylon fibers to contract with a relatively low operating voltage.

[0006] A layer of platinum was deposited on the surface of nylon fibers using chemical plating, serving as an electrode for Joule heating of the fibrous muscle. A high-performance electrically driven artificial muscle was fabricated by low-voltage actuation without significantly affecting muscle performance.

[0007] This invention provides a method for preparing an electrically driven artificial muscle, comprising the following steps:

[0008] I. Pre-processing

[0009] 1) Fiber surface cleaning: At room temperature, immerse the nylon fiber in an alcohol solution with a concentration of 400 mL / L for 30 minutes, then remove it and rinse it with deionized water, and let it air dry naturally;

[0010] 2) Polydopamine modification: Prepare a 0.1 mol / L tris(hydroxymethyl)aminomethane solution, then add 0.1 mol / L HCl solution to the 0.1 mol / L tris(hydroxymethyl)aminomethane solution to adjust the pH to 8.5. Take 200 mL of the mixture and add 0.4 g of dopamine hydrochloride to obtain a 2 g / L dopamine modification solution. Immerse the cleaned nylon fibers in the dopamine modification solution and stir with a magnetic stirrer for 24 h. Then remove them, wash them with deionized water, and let them air dry.

[0011] II. Process of preparing metal electrodes

[0012] A uniform and dense platinum electrode was prepared on the nylon surface by chemical plating through multiple chemical plating processes.

[0013] 1) The pretreated nylon fibers were immersed in a 0.5wt% tetraammineplatinum chloride aqueous solution for 24 hours to allow the nylon surface to adsorb a large number of platinum ammonia ions;

[0014] 2) Take out the soaked nylon and put it into 50g of water. Heat the water to 40℃ and stir with a magnetic stirrer. Add 5mL of 5wt% sodium borohydride aqueous solution as a reducing agent every 30min for a total of 10 times. After adding the reducing agent, the platinum ammonia ions on the surface of the nylon will be reduced into platinum nanoparticles. The small-scale and multiple reduction method can make the metallic platinum on the surface of the nylon more uniform and dense.

[0015] 3) Repeat steps 1) and 2) twice to form a uniform and dense platinum electrode on the nylon surface;

[0016] III. Nylon Fiber Twisting Process

[0017] 1) Connect the top of a certain length of the above-mentioned platinum-plated nylon fiber to a motor, and connect the bottom to a suspended mass and loop it onto a paperclip; take a steel wire and pass it through the paperclip so that the bottom of the nylon fiber cannot rotate around the vertical axis, so that the fiber increases its twist by one turn for every revolution of the motor; start the motor to rotate forward to twist the nylon, and within the specified tension range, the fiber twist gradually increases, and stop twisting immediately when a twisted structure appears;

[0018] 2) Fold the platinum-plated nylon fiber in the middle to form two fibers, connect one end to the motor and the other end to double the suspension mass, start the motor to reverse and continue to twist the nylon until all the fibers spontaneously form a twisted structure.

[0019] 3) Remove the hanging weight, fix both ends to prevent untwisting, place in a vacuum drying oven, heat anneal at 150℃ in a vacuum for one hour, then let the sample cool naturally at room temperature and remove the fixation to complete the preparation process of artificial muscle fibers.

[0020] The prepared artificial muscle connection is powered by a square wave voltage to drive Joule heating. As the temperature rises, the artificial muscle connection load gradually contracts along the axial direction, thus achieving work under load.

[0021] By using dopamine solution to form a polydopamine composite layer on the surface of nylon fibers, the fiber surface is modified, thereby improving the adhesion ability of nylon surface to metal.

[0022] Artificial muscles with strong load-bearing capacity and reversibility are obtained by twisting and coiling fibers into coils and then heat annealing them.

[0023] By using Joule heating, muscle fibers are driven to produce large strain with a relatively low voltage.

[0024] The advantages and beneficial effects of the present invention are as follows:

[0025] 1. The artificial muscle fiber prepared by this invention is made by twisting chemically plated platinum nylon fiber. It has low resistivity, can be driven by low voltage, and the platinum metal on the surface is not easily oxidized, so no additional protective layer is required.

[0026] 2. This invention obtains reversible, high-strength, long-stretch-length, and high-load-bearing artificial muscles by twisting and heat-annealing polymer fibers. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the twisting of the platinum-plated nylon fiber artificial muscle of the present invention.

[0028] Figure 2 This is the curve showing the change in contraction length of the platinum-plated nylon fiber artificial muscle as a function of voltage.

[0029] Figure 3 This is a physical image of the electrothermal drive for the platinum-plated nylon fiber artificial muscle of this invention. Detailed Implementation

[0030] Example 1:

[0031] I. Pre-processing

[0032] 1) Fiber surface cleaning: At room temperature, immerse the nylon fiber in an alcohol solution with a concentration of 400 mL / L for 30 minutes, then remove it and rinse it with deionized water, and let it air dry naturally;

[0033] 2) Polydopamine modification: Prepare a 0.1 mol / L tris(hydroxymethyl)aminomethane solution, then add 0.1 mol / L HCl solution to the 0.1 mol / L tris(hydroxymethyl)aminomethane solution to adjust the pH to 8.5. Take 200 mL of the mixture and add 0.4 g of dopamine hydrochloride to obtain a 2 g / L dopamine modification solution. Immerse the cleaned nylon fibers in the dopamine modification solution and stir with a magnetic stirrer for 24 h. Then remove them, wash them with deionized water, and let them air dry.

[0034] II. Process of preparing metal electrodes

[0035] A uniform and dense platinum electrode was prepared on the nylon surface by chemical plating through multiple chemical plating processes.

[0036] 1) The pretreated nylon fibers were immersed in a 0.5wt% tetraammineplatinum chloride aqueous solution for 24 hours to allow the nylon surface to adsorb a large number of platinum ammonia ions;

[0037] 2) Take out the soaked nylon and put it into 50g of water. Heat the water to 40℃ and stir with a magnetic stirrer. Add 5mL of 5wt% sodium borohydride aqueous solution as a reducing agent every 30min for a total of 10 times. After adding the reducing agent, the platinum ammonia ions on the surface of the nylon will be reduced into platinum nanoparticles. The small-scale and multiple reduction method can make the metallic platinum on the surface of the nylon more uniform and dense.

[0038] 3) Repeat steps 1) and 2) twice to form a uniform and dense platinum electrode on the nylon surface;

[0039] III. Nylon Fiber Twisting Process

[0040] 1) Connect the top of a certain length of the above-mentioned platinum-plated nylon fiber to a motor, and connect the bottom to a suspended mass and loop it onto a paperclip; take a steel wire and pass it through the paperclip so that the bottom of the nylon fiber cannot rotate around the vertical axis, so that the fiber increases its twist by one turn for every revolution of the motor; start the motor to rotate forward to twist the nylon, and within the specified tension range, the fiber twist gradually increases, and stop twisting immediately when a twisted structure appears;

[0041] 2) Fold the platinum-plated nylon fiber in the middle to form two fibers, connect one end to the motor and the other end to double the suspension mass, start the motor to reverse and continue to twist the nylon until all the fibers spontaneously form a twisted structure.

[0042] 3) Remove the hanging weight, fix both ends to prevent untwisting, place in a vacuum drying oven, heat anneal at 150℃ in a vacuum for one hour, then let the sample cool naturally at room temperature and remove the fixation to complete the preparation process of artificial muscle fibers.

[0043] The prepared artificial muscle connection is powered by a square wave voltage to drive Joule heating. As the temperature rises, the artificial muscle connection load gradually contracts along the axial direction, thus achieving work under load.

[0044] By using dopamine solution to form a polydopamine composite layer on the surface of nylon fibers, the fiber surface is modified, thereby improving the adhesion ability of nylon surface to metal.

[0045] Artificial muscles with strong load-bearing capacity and reversibility are obtained by twisting and coiling fibers into coils and then heat annealing them.

[0046] By using Joule heating, muscle fibers are driven to produce large strain with a relatively low voltage.

[0047] Example 2:

[0048] The present invention provides an electrically controlled artificial muscle that can provide high driving force at a relatively low driving voltage. A square wave signal with a specific frequency and voltage is applied to both ends of a platinum-plated nylon fiber artificial muscle using a signal generator and power amplifier, and the contraction length of the muscle is recorded by a camera. When the rated load is fixed, the contraction length of the platinum-plated nylon fiber increases with increasing voltage. Figure 2 As shown in the figure, the relationship between the maximum contraction length of a muscle and the magnitude of the applied voltage is displayed for a platinum-plated nylon fiber with a nominal length of 69.2 mm under different applied voltages with a load of 75 g. As can be seen from the figure, the greater the applied voltage, the greater the stroke of the platinum-plated nylon fiber. When the voltage is 14 V, the maximum contraction length of the platinum-plated nylon fiber can reach 10.8 mm, the maximum strain is 15.6%, and the mechanical work output during contraction is 6.37 kJ / kg.

Claims

1. A method for producing an electrically driven artificial muscle, characterized by: Includes the following steps: I. Pre-processing 1) Fiber surface cleaning: At room temperature, immerse the nylon fiber in an alcohol solution with a concentration of 400 mL / L for 30 minutes, then remove it and rinse it with deionized water, and let it air dry naturally; 2) Polydopamine modification: Prepare a 0.1 mol / L tris(hydroxymethyl)aminomethane solution, then add 0.1 mol / L HCl solution to the 0.1 mol / L tris(hydroxymethyl)aminomethane solution to adjust the pH to 8.

5. Take 200 mL of the mixture and add 0.4 g of dopamine hydrochloride to obtain a 2 g / L dopamine modification solution. Immerse the cleaned nylon fibers in the dopamine modification solution and stir with a magnetic stirrer for 24 h. Then remove them, wash them with deionized water, and air dry them naturally. II. Process of preparing metal electrodes A uniform and dense platinum electrode was prepared on the nylon surface by chemical plating through multiple chemical plating processes. 1) The pretreated nylon fibers were immersed in a 0.5wt% tetraammineplatinum chloride aqueous solution for 24 hours to allow the nylon surface to adsorb a large number of platinum ammonia ions; 2) Take out the soaked nylon and put it into 50g of water. Heat the water to 40℃ and stir with a magnetic stirrer. Add 5mL of 5wt% sodium borohydride aqueous solution as a reducing agent every 30min for a total of 10 times. After adding the reducing agent, the platinum ammonia ions on the surface of the nylon will be reduced into platinum nanoparticles. The small-scale and multiple reduction method can make the metallic platinum on the surface of the nylon more uniform and dense. 3) Repeat steps 1) and 2) above twice to form a uniform and dense platinum electrode on the nylon surface; III. Nylon Fiber Twisting Process 1) Connect the top of a certain length of platinum-plated nylon fiber to a motor, and connect the bottom to a suspended mass and loop it onto a paperclip; take a steel wire and pass it through the paperclip so that the bottom of the nylon fiber cannot rotate around the vertical axis. Therefore, the fiber will increase its twist by one turn for every revolution of the motor. Start the motor to rotate forward to twist the nylon. Within the specified tension range, the fiber twist gradually increases. Stop twisting immediately when a twisted structure appears. 2) Fold the platinum-plated nylon fiber in the middle to form two fibers, connect one end to the motor and the other end to double the suspension mass, start the motor to reverse and continue to twist the nylon until all the fibers spontaneously form a twisted structure. 3) Remove the hanging weight, fix both ends to prevent untwisting, place in a vacuum drying oven, heat anneal at 150°C under vacuum for one hour, then let the sample cool naturally at room temperature and remove the fixation to complete the preparation process of artificial muscle fibers. The prepared artificial muscle connection is powered by a square wave voltage to drive Joule heating. As the temperature rises, the artificial muscle connection load gradually contracts along the axial direction, thus achieving work under load.

2. The method for preparing an electrically driven artificial muscle according to claim 1, characterized in that: By using dopamine solution to form a polydopamine composite layer on the surface of nylon fibers, the fiber surface is modified, thereby improving the adhesion ability of nylon surface to metal.

3. The method for preparing an electrically driven artificial muscle according to claim 1, characterized in that: Artificial muscles with strong load-bearing capacity and reversibility are obtained by twisting and coiling fibers into coils and then heat annealing them.

4. The method for preparing an electrically driven artificial muscle according to claim 1, characterized in that: By using Joule heating, muscle fibers are driven to produce large strain with a relatively low voltage.

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