Liquid metal fiber and its preparation method and application

Abstract

The present invention provides a liquid metal fiber and a preparation method and application thereof. The liquid metal fiber comprises a hollow fiber, liquid metal and a chemical adhesive. The use of the chemical adhesive can strengthen the adhesion between the liquid metal and the hollow fiber, reduce the injection of air or holes on the surface of the hollow fiber, and can effectively enhance the conductive properties of the liquid metal fiber. The injection technology is used to achieve the infusion of liquid metal in the hollow fiber, and also provides a new technology for the functionalization of the fiber.

Description

Technical Field

[0001] The invention relates to the technical field of conductive materials, and in particular to a liquid metal fiber and a preparation method and application thereof. Background Art

[0002] Wearable electronic devices are an emerging electromechanical technology that combines electronic devices with flexible substrates. Compared with traditional integrated electronic circuit devices, wearable electronic devices have greater flexibility and toughness and can perform their functions in different deformation states. However, the weavable nature of the substrate of wearable electronic devices places higher requirements on the material's soft deformation and good conductivity, which poses a challenge to the selection of substrate materials.

[0003] Room temperature liquid metal is a non-toxic or low-toxic metal that is liquid at room temperature, amorphous and flowable, and has a melting point of no more than 200°C and its alloys. Room temperature liquid metal combines the high electrical conductivity and thermal conductivity of traditional metals with the low viscosity and rheological properties of fluids, and is therefore widely used in the fields of heat conduction, heat convection, and flexible wearable electronic devices.

[0004] Due to the high volatility and toxicity of mercury, its use has been restricted and banned. Compared with highly toxic mercury, metallic gallium and its alloys show lower toxicity, so they are often used to replace mercury to prepare conductive and deformable wires, recoverable antennas, flexible electrodes and sensors, and other new flexible electronic devices. However, gallium-based liquid metals have extremely high surface tension and are easily oxidized in air environments. They are also selective in adhesion to substrate materials. Therefore, reliable and rapid adhesion control of liquid metals on substrate surfaces is a key issue that needs to be solved in its application.

[0005] The liquid metal used in flexible wearable devices is usually fibrous liquid metal. The existing preparation process of liquid metal fiber, for example, uses surface modified conductive coating to prepare conductive fiber, but this method has requirements for the selection of coating, and there is metal waste and coating shedding during use. Another example is the use of microfluidic technology to prepare fiber materials wrapped in liquid metal. This method can continuously and controllably prepare conductive fibers, but the preparation process is complicated and the manufacturing is troublesome, which is not conducive to rapid and efficient large-area preparation. Summary of the invention

[0006] In order to solve the demand of flexible wearable devices for the deformability of conductive materials and the problem of liquid metal adhesion, the present invention provides a liquid metal fiber and a preparation method thereof and application in flexible wearable devices and the like.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] A liquid metal fiber comprises a hollow fiber, liquid metal and a chemical adhesive; wherein the hollow fiber is filled with liquid metal, and a chemical adhesive layer is provided between the hollow fiber and the liquid metal.

[0009] According to an embodiment of the present invention, the thickness of the chemical adhesive layer is 10 to 100 micrometers, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 micrometers.

[0010] According to an embodiment of the present invention, both ends of the liquid metal fiber are sealed by metal slurry or tape to encapsulate the liquid metal inside the hollow fiber and lead out the electrode, which is made of silver, copper, etc.

[0011] According to an embodiment of the present invention, the hollow fiber can be a thermoplastic fiber and / or a thermosetting fiber to ensure hollow injection. Exemplarily, the hollow fiber is selected from at least one of PET / PBT hollow fiber, PU / TPU hollow fiber, latex tube and rubber tube.

[0012] According to an embodiment of the present invention, the outer diameter of the hollow fiber is 100-1000 μm, the inner diameter of the hollow fiber is 60-200 μm, and the length of the hollow fiber is not particularly defined, for example, it can be in the range of millimeters to meters.

[0013] According to an embodiment of the present invention, the liquid metal is selected from gallium and its alloys, bismuth and its alloys, for example, selected from Ga 74.5 In 25.5 , Ga 90 In 10 , EGaInSn (eutectic GaInSn alloy), GaZn alloy, etc.

[0014] According to an embodiment of the present invention, the chemical adhesive is selected from a water-soluble printing adhesive, for example, at least one selected from propylene glycol methyl ether acetate (PMA), polyurethane, etc.; the chemical adhesive can form hydrogen bonds and van der Waals forces with liquid metal, strengthen the adhesion between liquid metal and fiber, thereby solving the adhesion problem of liquid metal.

[0015] The present invention also provides a method for preparing the liquid metal fiber, the method comprising the following steps:

[0016] (1) Encapsulating one end of the hollow fiber in an injection device using silicone rubber;

[0017] (2) injecting a chemical adhesive into the interior of the hollow fiber through an injection device, and then flowing out to completely wet the flow channel inside the hollow fiber;

[0018] (3) injecting liquid metal into the interior of the hollow fiber through an injection device, and then separating the hollow fiber from the injection device;

[0019] (4) Encapsulating both ends of the hollow fiber containing liquid metal obtained in step (3) with metal slurry or tape to prepare the liquid metal fiber.

[0020] According to an embodiment of the present invention, the method further comprises the following steps:

[0021] (5) Lead out the electrodes at the same time at the end of the metal paste or tape.

[0022] According to an embodiment of the present invention, the encapsulation is performed by curing the silicone rubber.

[0023] According to an embodiment of the present invention, the silicone rubber is selected from silicone rubber that can be cured below 50°C, for example, at least one selected from polydimethylsiloxane (PDMS), Ecoflex00-30 / 00-50 silicone, and Dragon skin 00-30 silicone. The curing conditions are, for example, drying at room temperature for 12 hours, or drying in a 40°C oven for 1 hour. After curing, the silicone rubber can seal the gap between the hollow fiber and the injection device to achieve the perfusion process and prevent leakage during the perfusion process.

[0024] According to an embodiment of the present invention, the injection device is selected from at least one of an automated injection pump body, a microfluid pump, and a syringe to ensure that the liquid metal can be injected into the hollow fiber.

[0025] According to an embodiment of the present invention, the liquid metal is injected into the interior of the hollow fiber of step (2) by an injection device and filled to form a passage.

[0026] The present invention also provides the application of the liquid metal fiber in wearable electronic devices based on conductive fiber weaving.

[0027] The present invention also provides the application of the liquid metal fiber in eliminating static electricity, absorbing electromagnetic waves, and detecting and transmitting electrical signals.

[0028] The present invention also provides the application of the liquid metal fiber in novel flexible display devices, information storage devices and sensors.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a liquid metal fiber and a preparation method and application thereof. The liquid metal fiber comprises a hollow fiber, liquid metal and a chemical adhesive. The use of the chemical adhesive can strengthen the adhesion between the liquid metal and the hollow fiber, reduce the injection of air or holes on the surface of the hollow fiber, and can effectively enhance the conductive properties of the liquid metal fiber. The injection technology is used to achieve the infusion of liquid metal in the hollow fiber, and also provides a new technology for the functionalization of the fiber.

[0031] The present invention can prepare liquid metal fibers of different sizes by adjusting the injection device and the diameter of the fiber. The preparation method of the present invention is simple to operate, has low experimental condition requirements, low cost, strong experimental repeatability, and can quickly achieve large-scale production. The fiber structure prepared by the present invention is uniform, the size is controllable, and it has good electrical and thermal conductivity properties, and can be widely used in flexible wearable devices. Not only that, the liquid metal in the liquid metal fiber of the present invention can be recycled, reducing damage to the environment, and is an environmentally friendly conductive working fluid. The use of a simple injection system can ensure the maximum utilization of materials, avoid waste of raw materials, and reduce pollution. At the same time, it can achieve millimeter-level to meter-level fiber preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the preparation process of the liquid metal fiber.

[0033] Figure numerals: 1 - injection pump body; 2 - hollow fiber; 3 - fiber yarn; 4 - hollow fiber cross section; 5 - chemical adhesive; 6 - liquid metal. DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0035] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0036] Example 1

[0037] (1) inserting one end of the PBT / PET hollow fiber into the needle hole of a 20G syringe, and encapsulating the PBT / PET hollow fiber inserted into the needle hole of the syringe with silicone rubber, wherein the encapsulation is cured by drying at room temperature for 12 hours. After the silicone rubber is cured, the gap between the hollow fiber and the needle hole of the syringe can be sealed to realize the perfusion process and prevent leakage during the perfusion process;

[0038] (2) injecting the chemical adhesive PMA into the interior of the hollow fiber through a syringe, and then flowing out to achieve complete wetting of the flow channel inside the hollow fiber;

[0039] (3) Filling the entire hollow fiber with liquid metal EGaInSn using a syringe;

[0040] (4) The hollow fiber filled with liquid metal is removed from the needle hole of the syringe, and both ends of the hollow fiber are sealed with silver paste, and the electrodes are led out at the same time to prepare the liquid metal fiber.

[0041] When the prepared liquid metal fiber is bent, the liquid metal inside is squeezed, causing the resistance of the liquid metal fiber to change. The resistance change can reflect the stress of the liquid metal fiber. The prepared liquid metal fiber is woven together with the braid to form a wearable device. When an electric field is applied, under the action of Joule heat, the liquid metal fiber can output heat and realize the heat preservation and heating function.

[0042] Example 2

[0043] (1) inserting one end of the PBT / PET hollow fiber into the needle hole of a 20G syringe, and encapsulating the PBT / PET hollow fiber inserted into the needle hole of the syringe with silicone rubber, wherein the encapsulation is cured by drying at room temperature for 12 hours. After the silicone rubber is cured, the gap between the hollow fiber and the needle hole of the syringe can be sealed to realize the perfusion process and prevent leakage during the perfusion process;

[0044] (2) injecting the chemical adhesive PMA into the interior of the hollow fiber through a syringe, and then flowing out to achieve complete wetting of the flow channel inside the hollow fiber;

[0045] (3) Filling the entire hollow fiber with liquid metal EGaIn through a syringe;

[0046] (4) The hollow fiber filled with liquid metal is removed from the needle hole of the syringe, and both ends of the hollow fiber are sealed with silver paste, and the electrodes are led out at the same time to prepare the liquid metal fiber.

[0047] The prepared liquid metal fiber is woven together with a braid to form a wearable device. When an external force is applied, the resistance of the liquid metal fiber changes.

[0048] Comparative Example 1

[0049] The other operations are the same as those in Example 1, except that step (2) is omitted.

[0050] In Comparative Example 1, since no adhesive is added, a conductive path inside the hollow fiber cannot be formed, and liquid metal-based conductive fiber cannot be obtained; in Example 1 and Example 2, since an adhesive is added, the wettability between the liquid metal and the hollow fiber is improved, and a conductive path can be achieved.

[0051] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A liquid metal fiber, comprising a hollow fiber, liquid metal and a chemical binder; wherein: The hollow fiber is filled with liquid metal, and a chemical adhesive layer is provided between the hollow fiber and the liquid metal; The thickness of the chemical adhesive layer is 10 to 100 microns; The chemical adhesive is selected from at least one of propylene glycol methyl ether acetate and polyurethane; The chemical adhesive layer is prepared by the following method: using an injection device to inject the chemical adhesive into the interior of the hollow fiber, and then the chemical adhesive flows out to completely wet the flow channel inside the hollow fiber.

2. The liquid metal fiber according to claim 1, wherein: Both ends of the liquid metal fiber are sealed by metal slurry or adhesive tape.

3. The liquid metal fiber according to claim 2, wherein: Lead out the electrode at the end of the metal paste or tape.

4. The liquid metal fiber according to claim 1, wherein: The liquid metal is selected from gallium and its alloys, bismuth and its alloys.

5. The liquid metal fiber according to claim 4, wherein: The liquid metal is selected from Ga 74.5 In 25.5 , Ga 90 In 10 , EGaInSn, GaZn alloy.

6. The method for preparing the liquid metal fiber according to any one of claims 1 to 5, comprising the following steps: (1) Encapsulating one end of the hollow fiber in an injection device using silicone rubber; (2) injecting a chemical adhesive into the interior of the hollow fiber through an injection device, and then flowing out to completely wet the flow channel inside the hollow fiber; (3) injecting liquid metal into the interior of the hollow fiber through an injection device, and then separating the hollow fiber from the injection device; (4) Encapsulating both ends of the hollow fiber containing liquid metal obtained in step (3) with metal slurry or tape to prepare the liquid metal fiber.

7. The preparation method according to claim 6, wherein: The method further comprises the steps of: (5) Lead out the electrodes at the same time at the end of the metal paste or tape.

8. The preparation method according to claim 6, wherein: The encapsulation is performed by curing the silicone rubber.

9. The preparation method according to claim 6, wherein: The injection device is selected from at least one of an automated injection pump body, a microfluid pump, and a syringe.

10. Use of the liquid metal fiber according to any one of claims 1 to 5 in wearable electronic devices based on conductive fiber weaving.

11. Use of the liquid metal fiber according to any one of claims 1 to 5 in eliminating static electricity, absorbing electromagnetic waves, and detecting and transmitting electrical signals.

12. Application of the liquid metal fiber according to any one of claims 1 to 5 in new flexible display devices, information storage devices and sensors.

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