A method for preparing liquid metal fibers

Abstract

This invention discloses a method for preparing liquid metal fibers. The method includes: S1, obtaining a flexible and stretchable substrate material; S2, preparing multiple sheet-like coated preforms, taking one coated preform as a bottom coated preform, and injecting liquid metal into a predetermined area; then taking another coated preform as a top coated preform, covering the bottom coated preform, with the top coated preform completely covering the liquid metal; sealing the edges to form an initial coated structure; S3, axially stretching the initial coated structure to a target diameter and attaching it to the surface of a target carrier, and solidifying it to form liquid metal fibers with a coating layer; wherein, the target diameter is a predetermined diameter of the liquid metal fiber, and the predetermined diameter is less than 100 μm. The preparation method provided by this invention is simple to operate, environmentally friendly, and produces small-diameter liquid metal fibers, facilitating device integration and miniaturization.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronic materials technology, specifically relating to a method for preparing liquid metal fibers. Background Technology

[0002] Highly sensitive, hysteresis-free, and highly conductive stretchable fiber sensors hold significant application potential in stretchable electronics, soft robotics, and smart clothing. Compared to traditional solid metal fibers, which are rigid but lack flexibility and are prone to failure under strain, liquid metal fibers offer feasible solutions for wearable devices and smart textiles due to their intrinsic stretchability, electrical stability, and excellent conductivity. However, mainstream liquid metal fiber preparation methods have significant limitations. For example, fiber diameters are difficult to exceed 100μm; sintering and post-processing rely on large-scale equipment, resulting in complex processes and insufficient stability; pre-matching to specific scenarios is required, preventing on-site dynamic stretching and adaptation; the cost is high, liquid metals are difficult to recycle, and some processes use hazardous materials, posing environmental risks.

[0003] Currently, the preparation of liquid metal fibers mainly involves the following technical approaches.

[0004] 1. Fiber Internal Filling Method: This method involves injecting liquid metal into the interior of prefabricated hollow fibers to form a conductive path. It mainly includes two methods: hollow filling method and injection method.

[0005] Hollow fiber filling method: First, superelastic hollow fibers are prepared by die extrusion curing or coaxial wet spinning process. For example, polydimethylsiloxane (PDMS) is used as raw material and is extruded and cured by die composed of circular slits with different inner diameters, or styrene-butadiene-styrene (SBS) hollow fibers are manufactured by coaxial wet spinning process. Then, liquid metal is slowly injected into the hollow fiber using a syringe or a combination of "propulsion pump-vacuum pump" to complete the preparation.

[0006] Injection molding: There are two main approaches. The first is the preparation of double-helix carbon nanotube yarn. Liquid metal is injected into silicone tubes, which are then twisted on a spinning machine to form a double-helix structure. This structure is then combined with drawn and combed skin-friendly fibers through negative pressure suction and friction rollers, ensuring the skin-friendly material evenly coats the core fiber surface. The second approach is a "melt spinning + injection filling" composite process. Stretchable materials such as SEBS are first heated and melted using a melt spinning machine, extruded through a hollow die, cooled and drawn to form a hollow substrate, into which liquid metal is then injected. Finally, it is encapsulated and fixed with a UV-curable adhesive.

[0007] II. Fiber substrate surface coating method: Functionalization is achieved by constructing a liquid metal conductive layer on the surface of fibers or fabrics. The two main solutions are as follows.

[0008] Spraying-chemical silver plating-fluorination method: First, the fabric surface is cleaned with alcohol to remove impurities for pretreatment. Then, liquid metal is evenly sprayed onto both sides of the fabric using an air compressor. Next, a silver ammonia solution is prepared and glucose solution is added in proportion. The sprayed fabric is then immersed in the solution to form a "liquid metal-silver" composite conductive layer. Finally, the fabric is dried in a vacuum oven, and FAS-17 (heptadecyltrimethoxysilane) is deposited on the surface through vapor deposition to obtain a superhydrophobic liquid metal electronic fabric.

[0009] Improved dip-coating-intermediate adhesive layer method: Applicable to the preparation of ultra-stretchable conductive fibers. First, deionized water is added to propylene glycol methyl ether acetate (PMA) adhesive and stirred evenly. Commercial PU (polyurethane) fibers are then immersed in the adhesive and dried in a vacuum drying oven. Next, the PU fibers are immersed in a liquid metal bath, allowing the liquid metal to adhere firmly to the fiber surface through the PMA adhesive layer. After draining, a three-layer fiber structure of "PU core layer + PMA adhesive layer + liquid metal" is formed.

[0010] III. Fiber Molding Method: Based on wet spinning or 3D printing, functional fibers containing liquid metal are directly molded.

[0011] Wet spinning: Both methods utilize coaxial wet spinning as the core technology, including two schemes. Scheme 1 is a one-step coaxial wet spinning process, in which a sheath solution and a core dispersion are prepared, loaded into an injection pump and connected to a coaxial spinning needle, and the flow rate is adjusted to form a stable coaxial flow bundle between the core and sheath fluids. After entering a deionized water coagulation bath, the sheath solidifies, and a winding machine collects the fiber roll. Scheme 2 is "coaxial wet spinning + negative pressure injection", in which hollow fiber rolls are first prepared by coaxial spinning, cut to the required length, and then liquid metal is injected into the hollow channels using a negative pressure device until they are completely filled. Finally, electrodes are installed and the mixture is solidified.

[0012] 3D printing method: The process of “3D printing water-soluble mold + elastomer embedding + liquid metal filling + 3D dome forming” is adopted. First, water-soluble PVA microchannel mold is prepared by 3D printing technology. After embedding in the elastomer, the mold is removed to form microchannels. After injecting liquid metal, a 3D dome structure is formed by vacuum induction. Finally, an array of liquid metal microchannels distributed along the dome is obtained.

[0013] The main drawbacks of the aforementioned existing technologies are as follows: 1. Difficulty in achieving fiber fineness breakthroughs: Existing technologies struggle to produce ultrafine fibers with diameters less than 100 μm. Hollow-filled fibers typically have an inner diameter of no less than 500 μm, while coated fibers have a diameter close to 100 μm and are difficult to further reduce. 2. Significant dependence on large-scale equipment: Technologies such as 3D printing, coaxial wet spinning, and hollow-filling all require large-scale precision equipment such as 3D printers, vacuum chambers, and friction spinning machines. The operation process is complex, and parameter control is difficult. 3. Insufficient flexibility in adapting to different scenarios: All technologies operate on a "pre-forming - post-functionalization" model. Once the fiber diameter and structure are solidified, they cannot be adjusted. Application scenario design parameters must be pre-matched, and if size adjustments are needed, equipment parameters must be readjusted. 4. Poor cost and environmental friendliness: Liquid metals are expensive, and fibers produced by existing technologies are difficult to recycle and reuse. The use of fillers such as silver particles and carbon nanotubes further increases costs. Simultaneously, the use of organic solvents such as DMF and chloroform easily causes environmental pollution. 5. Limited to large-scale production: Most technologies require additional post-processing steps such as sealing, cleaning, and drying, which significantly increases the complexity of the process and production costs, and also results in poor repeatability.

[0014] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0015] To address the aforementioned problems in the prior art, this invention provides a method for preparing liquid metal fibers. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing liquid metal fibers, comprising the following steps: S1. Obtain a flexible and stretchable substrate material; S2. Using the flexible and stretchable substrate material, prepare multiple sheet-like coated blanks. Take one coated blank as the bottom coated blank and inject liquid metal into a predetermined area on the upper surface of the bottom coated blank. Then take another coated blank as the top coated blank and cover the bottom coated blank with the top coated blank, so that the top coated blank completely covers the liquid metal. After sealing the edges, an initial coated structure is formed. S3. The initial coating structure is axially stretched to the target diameter and attached to the surface of the target carrier. After curing, it forms a liquid metal fiber with a coating layer. The target diameter is a preset diameter of the liquid metal fiber, and the preset diameter is less than 100 μm.

[0016] In one embodiment of the present invention, step S4 is also included; Step S4 includes: dissolving the coating layer with a dissolving solution to obtain liquid metal fibers attached to the target carrier; forming a 0.5-3 nm metal oxide layer on the surface of the liquid metal fibers, the metal oxide layer being used to overcome the surface tension of the liquid metal and maintain the filamentous structure of the liquid metal fibers.

[0017] In one embodiment of the present invention, the thickness of the covered blank is 1 mm to 5 mm; in the same initial covered structure, the thickness of the bottom covered blank is the same as the thickness of the top covered blank.

[0018] In one embodiment of the present invention, in step S1, the flexible and stretchable substrate material is a water-soluble hydrogel; The water-soluble hydrogel comprises 5 wt% to 10 wt% polyvinyl alcohol, 1 wt% to 5 wt% glycerol, 1 wt% to 3 wt% borax, and the balance being deionized water.

[0019] In one embodiment of the present invention, the water-soluble hydrogel further includes 0.1 wt% to 0.3 wt% of preservative and 1 wt% to 10 wt% of humectant.

[0020] In one embodiment of the present invention, in step S3, during the process of stretching the initial covering structure to the target diameter, the tensile strength is 0.1MPa to 2.0MPa, and the tensile range is 0 to 300% strain.

[0021] In one embodiment of the present invention, in step S3, the curing is to let the stretched initial covered structure stand at 15°C to 30°C to allow the moisture to evaporate and cure, or to heat at 50°C to 60°C to allow the moisture to evaporate and cure. In step S4, the dissolving solution is deionized water.

[0022] In one embodiment of the present invention, in step S1, the flexible and stretchable substrate material is sodium alginate hydrogel; The sodium alginate hydrogel comprises 1.0 wt% to 3.0 wt% sodium alginate, 1.0 wt% to 5.0 wt% calcium ion crosslinking agent, and the balance being deionized water.

[0023] In one embodiment of the present invention, in step S3, during the process of stretching the initial covering structure to the target diameter, the tensile strength is 0.1MPa to 1.5MPa, and the tensile range is 0 to 300% strain.

[0024] In one embodiment of the present invention, in step S3, the curing includes: allowing the stretched initial coating structure to stand at 15°C to 30°C for preliminary curing, and then immersing it in a 0.5 wt% to 1 wt% calcium chloride solution for complete curing; In step S4, the dissolving solution is an EDTA solution.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The liquid metal fiber preparation method provided by the present invention can prepare ultrafine liquid metal fibers with a diameter as low as 30 μm. Using this liquid metal fiber is beneficial to realizing the integration and miniaturization of devices, while improving the response rate of liquid metal in the phase transition process.

[0026] 2. The method provided by this invention has a simple and easy-to-operate preparation process, requires no large-scale equipment, and allows for rapid molding, facilitating large-scale production. The coating material is inexpensive, and no harmful substances are involved in the entire preparation process, meeting green and environmentally friendly requirements. Furthermore, this method can directly stretch and mold on the target carrier without a pre-forming step, adapting to the surfaces of various target carriers. The prepared liquid metal fibers with the coating can be transferred from the target carrier to the surface of other carriers, while maintaining stable structure and performance.

[0027] 3. The coating layer of the liquid metal fiber prepared by this invention is soluble (e.g., using water or EDTA as a corresponding solvent), which can realize the efficient recovery and recycling of liquid metal.

[0028] 4. The extremely fine liquid metal fibers prepared by this invention can still maintain their filamentous shape after the coating layer is removed, which facilitates stable transfer of the substrate, improves the application flexibility of liquid metal fibers, and expands the application scenarios of liquid metal fibers.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of a method for preparing liquid metal fibers according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of another method for preparing liquid metal fibers provided in an embodiment of the present invention; Figure 3 This is a microscopic characterization image of the liquid metal fiber with a coating layer prepared in Example 4 of the present invention; Figure 4 yes Figure 3 The image shows magnified microscopic characterizations of any three local locations of a liquid metal fiber with a coating layer. Figure 5This is a schematic diagram of the process of preparing liquid metal fibers with a coating layer in Example 5 of the present invention; Figure 6 These are magnified microscopic images of any three local locations of the liquid metal fiber with a coating layer prepared in Example 5 of this invention.

[0031] The attached figures are labeled as follows: 1-Target carrier; 2-Liquid metal fiber with coating layer; 21-Liquid metal fiber; 22-Coating layer. Detailed Implementation

[0032] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of a method for preparing liquid metal fiber according to the present invention is provided in conjunction with the accompanying drawings and specific embodiments.

[0033] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0034] It should be noted that, in this document, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed.

[0035] The terms “thickness,” “upper,” “lower,” “top,” “bottom,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0036] The term "axial tension" refers to the axial extension direction of the initial liquid metal column formed within the initial cladding structure. The term "gravitational effect" refers to the normal gravitational acceleration at the Earth's surface (approximately 9.8 m / s²). 2 Natural behavior in an environment.

[0037] Example 1 This invention provides a method for preparing liquid metal fibers, see [link to relevant documentation]. Figure 1 This includes the following steps S1-S3.

[0038] S1. Obtain a flexible and stretchable substrate material.

[0039] In this embodiment, the flexible and stretchable substrate material used is a water-soluble hydrogel, and the liquid metal used is a gallium indium tin liquid metal that is liquid at room temperature.

[0040] Specifically, the water-soluble hydrogel may include 5 wt%–10 wt% polyvinyl alcohol, 1 wt%–5 wt% glycerin, 1 wt%–3 wt% borax, 0.1 wt%–0.3 wt% preservative, 1 wt%–10 wt% humectant, and the balance being deionized water. The water-soluble hydrogel is obtained by mixing and stirring the above components until homogeneous. The humectant can be glycerin, propylene glycol, or polyethylene glycol; the preservative can be sodium benzoate. Glycerin acts as a plasticizer and also as a humectant.

[0041] S2. Prepare multiple sheet-like coated preforms using the above-mentioned water-soluble hydrogel; take one coated preform as the bottom coated preform, and inject liquid metal into a predetermined area on the upper surface of the bottom coated preform. Generally, the predetermined area is located near the middle of the bottom coated preform.

[0042] Take another cladding blank as the top cladding blank and place it over the bottom cladding blank, ensuring the top cladding blank completely covers the liquid metal. Tweezers can be used to press along the sealing edges of the bottom and top cladding blanks to ensure their edges adhere, guaranteeing complete and leak-free liquid metal coverage. Trim the edge material so that the predetermined area containing the liquid metal is in the center, forming the initial cladding structure.

[0043] Furthermore, the thickness of the coated preform is 1mm to 5mm; this avoids the coating preform being too thin, which would cause it to crack during the stretching process; it also avoids the coating preform being too thick, which would cause the intrinsic axial tensile resistance of the coating preform to be too large, resulting in the stretchability of the liquid metal fiber 21 not reaching the preset diameter requirement.

[0044] Furthermore, within the same initial coating structure, the thickness of the bottom coating blank is the same as the thickness of the top coating blank. Having bottom and top coating blanks of the same thickness improves the uniformity during the stretching process, thereby increasing the stretching ratio of the liquid metal fiber. This ensures that the diameter of the liquid metal fiber meets the preset diameter requirement, avoiding fractures caused by uneven coating blank thickness leading to localized thinning during stretching.

[0045] S3. The initial coating structure is axially stretched to the target diameter and attached to the surface of the target carrier 1. After curing, a liquid metal fiber 2 with a coating layer is formed. The target diameter is the preset diameter of the liquid metal fiber 21, which is less than 100 μm.

[0046] In this embodiment, during the process of stretching the initial cladding structure to the target diameter, the tensile strength is 0.1MPa to 2.0MPa, and the tensile range is 0 to 300% strain.

[0047] Specifically, the stretching method can be carried out using a special stretching instrument to precisely control the stretching strength, or it can be carried out using a clamping tool to stretch the initial covered structure by gravity.

[0048] During the stretching process, the diameter of the liquid metal fibers 21 can be precisely monitored using an electron microscope. The diameter can also be predicted by calculation. For example, if the initial axial length of the liquid metal in the initial coating structure is 1 cm, and the injected liquid metal is 0.2 ml, stretching it to 250 times its original length will yield liquid metal fibers 21 with a diameter of approximately 30 μm. It is important to note that the stretching does not involve the hydrogel itself being stretched 250 times in its intrinsic axis; rather, it is the liquid metal encapsulated within it that is stretched 250 times in its axial length, forming filamentous liquid metal fibers 21. The water-soluble hydrogel coating the outside of the liquid metal fibers 21 is simply spread out, thinned, and adheres tightly to the liquid metal fibers 21.

[0049] Furthermore, in this step, curing can be achieved by allowing the water to evaporate and cure at a temperature of 15℃ to 30℃, or by heating at a temperature of 50℃ to 60℃ to allow the water to evaporate and cure.

[0050] In this embodiment, a water-soluble hydrogel prepared from PVA-borate is used as the coating preform. After coating with liquid metal, it is uniformly stretched, causing the liquid metal and the substrate (coated preform) to deform synchronously. During the stretching process, the liquid metal forms fibers with a diameter of less than 100 μm, and can even reach 30 μm. During the stretching process, it can directly act on the target carrier 1, causing the initial coated structure to deform synchronously under tensile force, realizing a dynamic forming process of "stretching and adapting simultaneously". The final result is a double-layer structure with a core layer of liquid metal fiber 21 and a coating layer 22 of flexible and stretchable substrate material. After forming, it is placed at room temperature or in a heating instrument to evaporate the moisture in the flexible and stretchable substrate material to achieve solidification, obtaining a structurally stable and electrically continuous liquid metal fiber 2 with a coating layer. In some examples, this liquid metal fiber 2 with a coating layer can be externally connected to a voltage as an electrode sensor.

[0051] Thus, the liquid metal fibers prepared using the method provided by this invention have the following advantages: First, they possess ultra-fine fiber diameters, as low as 30 μm, offering a significant size advantage over existing technologies. Second, the preparation process is simple and easy to operate, requiring no large-scale equipment, and is rapid in molding, facilitating large-scale production; furthermore, the water-soluble hydrogel, used as the coating preform, is inexpensive, and the entire preparation process involves no harmful substances, meeting green and environmentally friendly requirements. Finally, the water-soluble hydrogel is water-degradable, facilitating the efficient recovery and recycling of liquid metals.

[0052] Example 2 Based on Example 1, step S4 is also included. Step S4 involves dissolving the coating layer 22 with a dissolving solution to obtain liquid metal fibers 21 attached to the target carrier 1.

[0053] For example, deionized water is used as the dissolving solution to dissolve the coating layer 22 covering the outside of the liquid metal fiber 21, exposing the liquid metal fiber 21. That is, all components in the coating layer 22 are dissolved in water. For example, in this embodiment, glycerin is water-soluble and dissolves completely in water; borax, preservatives, and humectants also dissolve in water; polyvinyl alcohol slowly swells and softens in cold water, its structure is destroyed, but it also dissolves completely in hot water (65°C to 75°C).

[0054] For example, in this embodiment, after dissolving the coating layer 22 with deionized water, the surface of the prepared liquid metal fiber 21 has a metal oxide layer of 0.5 to 3 nm. It is precisely because of the presence of the metal oxide layer that the surface tension of the liquid metal can be overcome and the filamentous structure of the liquid metal fiber 21 can be maintained.

[0055] In Example 2, the outer coating layer 22 of the liquid metal fiber 21 is dissolved and peeled off to obtain a liquid metal fiber 21 that still retains its filamentous shape. This allows for cross-substrate transfer after encapsulation with substrates of other materials, expanding the application scenarios of the extremely fine liquid metal fiber 21. For example, the liquid metal fiber can be encapsulated in silicone to prepare a liquid metal fiber with a silicone substrate as the coating layer 22.

[0056] Example 3 This invention provides a method for preparing liquid metal fibers, see [link to relevant documentation]. Figure 2 This includes the following steps S1-S4.

[0057] S1. Obtain a flexible and stretchable substrate material.

[0058] In this embodiment, the flexible and stretchable substrate material used is sodium alginate hydrogel, and the liquid metal used is gallium indium tin liquid metal, which is liquid at room temperature (15℃~30℃).

[0059] Specifically, the sodium alginate hydrogel may comprise 1.0 wt% to 3.0 wt% sodium alginate, 1.0 wt% to 5.0 wt% calcium ion crosslinking agent, and the balance being deionized water. The sodium alginate hydrogel is obtained by mixing and stirring the above components until homogeneous.

[0060] S2. Prepare multiple sheet-like coated preforms using the sodium alginate hydrogel described above; take one coated preform as the bottom coated preform, and inject liquid metal into a predetermined area on the upper surface of the bottom coated preform. Generally, the predetermined area is located near the middle of the bottom coated preform.

[0061] Take another cladding blank as the top cladding blank and place it over the bottom cladding blank, ensuring the top cladding blank completely covers the liquid metal. Tweezers can be used to press along the sealing edges of the bottom and top cladding blanks to ensure their edges adhere, guaranteeing complete and leak-free liquid metal coverage. Trim the edge material so that the predetermined area containing the liquid metal is in the center, forming the initial cladding structure.

[0062] Furthermore, the thickness of the coated preform is 1mm to 5mm; this avoids the coated preform being too thin, which would cause it to break easily during stretching; it also avoids the coated preform being too thick, which would cause the intrinsic axial tensile resistance of the coated preform to be too large, resulting in the stretchability of the liquid metal fiber 21 not reaching the preset diameter requirement.

[0063] Furthermore, within the same initial coating structure, the thickness of the bottom coating blank is the same as the thickness of the top coating blank. Having bottom and top coating blanks of the same thickness improves the uniformity during the stretching process, thereby increasing the stretching ratio of the liquid metal fiber 21 and ensuring that the diameter of the liquid metal fiber 21 meets the preset diameter requirement.

[0064] S3. The initial coating structure is axially stretched to the target diameter and attached to the surface of the target carrier 1. After curing, a liquid metal fiber 2 with a coating layer 22 is formed. The target diameter is the preset diameter of the liquid metal fiber 21, which is less than 100 μm.

[0065] In this embodiment, during the process of stretching the initial cladding structure to the target diameter, the tensile strength is 0.1MPa to 1.5MPa, and the tensile range is 0 to 300% strain.

[0066] Specifically, the stretching process can be performed using specialized stretching instruments to precisely control the tensile strength, or by using clamping tools to stretch the initial coated structure using gravity. During the stretching process, the diameter of the liquid metal fiber 21 can be precisely monitored using an electron microscope. The diameter of the liquid metal fiber can also be predicted through calculation.

[0067] Furthermore, in this step, the curing process includes: allowing the stretched initial coating structure to stand at 15°C to 30°C for preliminary curing, and then immersing it in a 0.5 wt% to 1 wt% calcium chloride solution for complete curing.

[0068] The liquid metal fiber prepared in this step, with sodium alginate hydrogel as the coating layer 22, can be connected to an external voltage as a highly stable electrode sensor.

[0069] S4. Dissolve the coating layer 22 with a dissolving solution to obtain liquid metal fiber 21 attached to the target carrier 1.

[0070] For example, an EDTA solution is used as a dissolving agent to dissolve the coating layer 22 covering the outside of the liquid metal fiber 21, exposing the liquid metal fiber 21. EDTA, as a chelating agent, can disrupt the ionic cross-linking network, causing the sodium alginate hydrogel to dissolve and release the liquid metal for recycling or substrate transfer.

[0071] For example, a metal oxide layer of 0.5 to 3 nm is formed on the surface of the liquid metal fiber 21. The metal oxide layer can overcome the surface tension of the liquid metal, thereby maintaining the filamentous structure of the liquid metal fiber 21.

[0072] Similarly, the outer coating layer 22 of the liquid metal fiber 21 can be dissolved and peeled off using an EDTA solution to obtain the liquid metal fiber 21 that retains its filamentous shape. Alternatively, it can be encapsulated with a substrate of other materials to achieve cross-substrate transfer.

[0073] Example 4 The preparation of water-soluble hydrogels using PVA-borate specifically includes the following steps: Step 1: Preparation of PVA-borate hydrogel: Mix 10wt% polyvinyl alcohol, 8wt% glycerol, 0.2wt% preservative (sodium benzoate), 2wt% borax, and the balance is deionized water to prepare a flexible and stretchable substrate material. This material has good flexibility, sealing properties and biodegradability.

[0074] Step 2: Take a flexible, stretchable substrate material and knead it into a uniform, thin sheet-like coating preform; the thickness of the coating preform is 3mm. Take one coating preform as the bottom coating preform and lay it flat on a clean platform; use a medical syringe to draw up liquid gallium indium tin (CITi) metal, which is liquid at room temperature, and precisely inject it into the predetermined area of ​​the bottom coating preform. Take another coating preform as the top coating preform and place it over the bottom coating preform, ensuring that the top coating preform completely covers the liquid metal. Use tweezers to press and adhere it along the edge of the coating area, ensuring that the liquid metal is completely covered without leakage. Trim and remove excess material from the edges so that the predetermined area containing the liquid metal is in the center, thus obtaining the initial coating structure.

[0075] Step 3: Fix the two ends of the initial coating structure to the target carrier 1, and apply axial tension to stretch it uniformly until the diameter of the liquid metal is reduced to 30μm and it is in a uniform fibrous shape, and it is tightly attached to the surface of the target carrier 1 during the stretching process.

[0076] Step 4: After stretching and forming, place it in a room temperature environment to allow the moisture in the flexible stretchable substrate material to evaporate naturally, thereby obtaining liquid metal fiber 2 with a coating layer.

[0077] The liquid metal fiber 2 with a coating layer prepared in Example 4 was observed under a microscope. The results are shown in [reference needed]. Figure 3 and Figure 4 .like Figure 3 The image shows the macroscopic structure of the liquid metal fiber 2 with a coating layer on the target carrier 1. To further verify the uniformity of the formed liquid metal fiber, further... Figure 3 Magnify and observe any three different positions in the image, such as Figure 4 As shown, the diameters of the liquid metal fibers 21 were measured to be 31 μm, 31 μm, and 30 μm, respectively. A thin film-like material, called the coating layer 22, is attached to the outer side of the liquid metal fibers 21. This indicates that the liquid metal fibers 21 prepared by the method of this embodiment have small and uniform diameters, providing a good structural basis for practical applications.

[0078] Example 5 The difference between this embodiment and embodiment four is that in step 3, as follows: Figure 5 As shown in Figure A, one end of the obtained initial covering structure is firmly clamped in a clamping device arranged perpendicular to the ground, ensuring that the initial covering structure is stable and without tilting during suspension. Utilizing the inherent flexibility of the initial covering structure and the effect of gravity, it naturally falls, gradually extending downwards under the influence of gravity during suspension, as... Figure 5 As shown in Figure B, the central region synchronously and uniformly thins and elongates to form a continuous fiber structure with a consistent diameter. This structure is then carefully transferred and smoothly spread onto the surface of the pre-designed target carrier 1. Magnified observations are then performed at any three different locations on the fiber segment, as shown... Figure 6 As shown, the diameters of the liquid metal fibers 21 were measured to be 76 μm, 79 μm, and 81 μm, respectively. A thin film-like material, called the coating layer 22, was attached to the outer side of the liquid metal fibers 21. Subsequently, they were placed in a room temperature ventilated environment to dry, allowing the water in the water-soluble hydrogel to slowly evaporate naturally and gradually solidify into a dense and morphologically stable liquid metal fiber with a coating layer. The core liquid metal fiber was firmly encapsulated in the coating layer 22 formed by a flexible and stretchable substrate material, ensuring conductive continuity and structural integrity.

[0079] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0080] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method of producing liquid metal fibers, characterized by, Includes the following steps: S1. Obtain a flexible and stretchable substrate material; S2. Using the flexible and stretchable substrate material, prepare multiple sheet-shaped coated blanks. Take one coated blank as the bottom coated blank and inject liquid metal into a preset area on the upper surface of the bottom coated blank. Then take another coated blank as the top coated blank and cover the bottom coated blank with the top coated blank, so that the top coated blank completely covers the liquid metal. After sealing the edges, an initial encapsulated structure is formed; S3. The initial coating structure is axially stretched to the target diameter and attached to the surface of the target carrier. After curing, it forms a liquid metal fiber with a coating layer. The target diameter is a preset diameter of the liquid metal fiber, and the preset diameter is less than 100 μm.

2. The method of claim 1, wherein the liquid metal fiber is formed by the steps of: It also includes step S4; Step S4 includes: dissolving the coating layer with a dissolving solution to obtain liquid metal fibers attached to the target carrier; A metal oxide layer of 0.5–3 nm is formed on the surface of the liquid metal fiber. The metal oxide layer is used to overcome the surface tension of the liquid metal and maintain the filamentous structure of the liquid metal fiber.

3. The method of claim 2, wherein the liquid metal fiber is formed by The thickness of the coated blank is 1mm to 5mm; in the same initial coated structure, the thickness of the bottom coated blank is the same as the thickness of the top coated blank.

4. The method of claim 1-3, wherein In step S1, the flexible and stretchable substrate material is a water-soluble hydrogel; The water-soluble hydrogel comprises 5 wt% to 10 wt% polyvinyl alcohol, 1 wt% to 5 wt% glycerol, 1 wt% to 3 wt% borax, and the balance being deionized water.

5. The method of claim 4, wherein the liquid metal fiber is formed by The water-soluble hydrogel also includes 0.1 wt% to 0.3 wt% of preservative and 1 wt% to 10 wt% of humectant.

6. The method of claim 5, wherein the liquid metal fiber is formed by the process of: In step S3, during the process of axially stretching the initial covered structure to the target diameter, the tensile strength is 0.1MPa to 2.0MPa, and the tensile range is 0 to 300% strain.

7. The method of claim 6, wherein the liquid metal fiber is formed by a process comprising: In step S3, the curing process involves allowing the stretched initial covered structure to stand at 15°C to 30°C to allow the moisture to evaporate and cure, or heating it at 50°C to 60°C to allow the moisture to evaporate and cure. In step S4, the dissolving solution is deionized water.

8. The method for preparing liquid metal fibers according to any one of claims 1-3, characterized in that, In step S1, the flexible and stretchable substrate material is sodium alginate hydrogel; The sodium alginate hydrogel comprises 1.0 wt% to 3.0 wt% sodium alginate, 1.0 wt% to 5.0 wt% calcium ion crosslinking agent, and the balance being deionized water.

9. The method for preparing liquid metal fibers according to claim 8, characterized in that, In step S3, during the process of axially stretching the initial covered structure to the target diameter, the tensile strength is 0.1MPa to 1.5MPa, and the tensile range is 0 to 300% strain.

10. The method for preparing liquid metal fibers according to claim 9, characterized in that, In step S3, the curing includes: allowing the stretched initial coating structure to stand at 15℃~30℃ for preliminary curing, and then immersing it in a 0.5 wt%~1 wt% calcium chloride solution for complete curing; In step S4, the dissolving solution is an EDTA solution.

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