A flexible conductive connector of a liquid metal-based flexible wire and a method for manufacturing the same

Abstract

This invention provides a flexible conductive connector based on a liquid metal-based flexible wire and its preparation method. The flexible conductive connector comprises a flexible polymer material and several filamentary conductive materials, with the flexible polymer material covering the periphery of the filamentary conductive materials. A liquid metal layer is disposed at one end of each filamentary conductive material along its length. When the flexible conductive connector is connected to a flexible wire, the end of the flexible conductive connector with the liquid metal layer extends into the flexible wire, and the liquid metal layer contacts the liquid metal in the flexible wire, forming a conductive connection. This connector enables a good conductive connection with the flexible wire and possesses excellent flexibility and stability, forming a fully flexible structure with the flexible wire, showing broad application prospects in flexible electronics technology.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics technology, and in particular to a flexible conductive connector based on liquid metal flexible wires and its preparation method. Background Technology

[0002] With the development of flexible electronics and wearable devices, flexible wires have attracted increasing attention due to their stretchability and comfort, and have broad application prospects in fields such as human-computer interaction, human health / motion monitoring, and smart clothing.

[0003] Currently, there are three main types of flexible wires: (1) Flexible wires made by directly braiding conductive yarns, conductive fibers, etc., have relatively low conductivity and are not resistant to washing; (2) Flexible wires made by winding traditional copper wires into spring wires, etc., have an insufficiently compact structure and poor tactile feel; (3) Flexible wires formed by filling flexible tubes with liquid metals, ionic liquids, etc., have good conductivity and flexibility, but when cutting such flexible wires, liquid substances are prone to leakage, so such flexible wires cannot be cut arbitrarily; (4) Flexible wires made by using conductive silver paste, conductive gel, conductive fillers, etc., combined with polymers as conductive polymers, are not resistant to bending, have poor tensile stability, or have poor conductivity.

[0004] In comparison, the third type of flexible wire has better conductivity and flexibility, and has good application prospects. Currently, there are two main connection methods for this type of flexible wire when connecting it to an external conductive unit:

[0005] (1) Directly connect the liquid metal with rod-shaped or columnar metal electrodes, and fix the outer layer with potting compound, etc. This method introduces rigid electrodes, thereby destroying the flexibility of the liquid metal wires and causing discomfort in use.

[0006] (2) Use conductive adhesive for filling, sealing and connecting; however, conductive adhesive has poor conductivity and cannot meet the requirements of high conductivity in the application environment.

[0007] Therefore, how to make a conductive connection between the flexible conductor and the outside, so that the connection part can take into account good conductivity, flexibility and stability, is of great significance to realizing a fully flexible conductor. Summary of the Invention

[0008] This invention provides a connector for flexible wires based on liquid metal. The connector enables a good conductive connection with the flexible wire and has good flexibility and stability, forming a fully flexible structure with the flexible wire.

[0009] The technical solution provided by this invention is: a flexible conductive connector for a liquid metal-based flexible wire, wherein the liquid metal-based flexible wire comprises a first liquid metal and an elastomer, and is conductive under tensile conditions; characterized in that: the flexible conductive connector comprises a flexible polymer material and a plurality of filamentous conductive materials, the flexible polymer material covering the periphery of the filamentous conductive materials; along the length direction of the filamentous conductive materials, a second liquid metal layer is disposed at one end of the filamentous conductive materials, and the second liquid metal layer is conductively connected to the end of the filamentous conductive materials; the other end of the filamentous conductive materials forms a conductive connection with an external conductive element;

[0010] When the flexible conductive connector is connected to the flexible wire, one end of the flexible conductive connector in which the second liquid metal layer is disposed extends into the flexible wire, and the second liquid metal layer comes into contact with the first liquid metal in the flexible wire to form a conductive connection.

[0011] In one implementation, the elastomer has a tubular structure, and the first liquid metal is located within the tubular structure. The method by which the first liquid metal and the elastomer form this structure is not limited, and includes one or more of the following methods: injection molding, filling, blending, co-extrusion, simultaneous injection molding, 3D printing, etc.

[0012] The elastomer includes, but is not limited to, one or more of the following: silicone, polyurethane (PU), polypropylene (PP), polyimide (PI), polyesters (PET, PBT, etc.), polylactic acid (PLA), polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), SEBS, POE, Ecoflex, etc.

[0013] The connection method between the flexible conductive connector and the liquid metal-based flexible wire is not limited, including bonding, stitching, riveting, plugging, snapping, etc. at the contact points, or fixing the two together through a flexible fixing layer.

[0014] The flexible fixing layer is made of a material with adhesive properties, including but not limited to one or more of the following materials: glue, silicone, polyurethane, polypropylene, polyethylene, epoxy resin, polylactic acid, etc.

[0015] The arrangement of several filamentous conductive materials is not limited, including one or more of the following: parallel, interlaced, parallel, spiral braided, and winding.

[0016] The filamentary conductive material is not limited, and includes one or more of the following: metal wire, conductive yarn, fibrous graphene, carbon nanotubes, fibrous graphite, etc., as well as composite materials formed by them and elastic materials. The metal wire is not limited, and includes copper wire, gold wire, silver wire, indium wire, tin wire, etc.

[0017] The method of coating the flexible polymer material onto the filamentous conductive material is not limited, including one or more of the following methods: immersion, dipping, coating, chemical growth, extrusion, injection molding, turning, and milling. Preferably, the coating thickness of the flexible polymer material is from 100 nanometers to 500 micrometers.

[0018] The flexible polymer material is a flexible polymer insulating material, including but not limited to insulating materials such as silicone, polyurethane (PU), polypropylene (PP), polyimide (PI), polyesters (PET, PBT, etc.), polylactic acid (PLA), polydimethylsiloxane (PDMS), and polyvinyl alcohol (PVA); conductive composite materials formed by combining one or more of conductive nanoparticles such as gold, silver, copper, graphene, and carbon nanotubes with silicone, polyurethane (PU), polypropylene (PP), polyimide (PI), polyesters (PET, PBT, etc.), polylactic acid (PLA), polydimethylsiloxane (PDMS), polyvinyl alcohol (PVA), SEBS, POE, and Ecoflex; and commercially available conductive materials such as conductive adhesives, conductive gels, and conductive silver paste.

[0019] The first liquid metal and the second liquid metal are conductive materials that are liquid at room temperature, including but not limited to mercury, gallium indium alloy, gallium indium tin alloy, as well as one or more transition metals, solid non-metallic elements doped with gallium indium alloy, gallium indium tin alloy, etc., ion-conducting liquids or conductive gels.

[0020] The present invention also provides a method for preparing the flexible conductive connector, comprising the following steps:

[0021] (1) Arrange several filamentous conductive materials;

[0022] (2) A flexible polymer material is wrapped around the arranged filamentous conductive material, and one end of the filamentous conductive material is exposed.

[0023] (3) A second liquid metal layer is provided at the exposed end of the filamentous conductive material.

[0024] In step (2), the method of exposing one end of the filamentous conductive material is not limited, including one or more of the following methods: cutting, grinding, plasma treatment, laser treatment, etc.

[0025] In step (3), the method of forming the second liquid metal layer is not limited. It can be that the filamentous conductive material is immersed in the second liquid metal so that the exposed end is adhered to the second liquid metal, or the second liquid metal is dripped onto the exposed end of the filamentous conductive material, etc.

[0026] This invention uses a flexible polymer material to coat the periphery of a filamentous conductive material, and sets a second liquid metal layer at one end to form a flexible conductive connector, which has the following beneficial effects:

[0027] (1) The flexible conductive connector has a simple structure. On the one hand, it can ensure the conductive connection with the flexible wire. On the other hand, it is flexible and has stable performance. Therefore, it forms a fully flexible structure with the flexible wire, which is comfortable to use. It has broad application prospects in flexible electronic technology, such as human-computer interaction, human health / movement monitoring, smart clothing and other fields.

[0028] (2) Liquid metal-based elastic conductors have a certain risk of leakage at both ends. When the flexible connector is connected to the liquid metal-based elastic conductor, the leakage of liquid metal can be effectively avoided because the flexible polymer material is wrapped around the filamentous conductive material, thus improving the stability of the elastic conductor.

[0029] (3) Liquid metal-based elastic wires cannot be cut arbitrarily. When the flexible connector is connected to the liquid metal-based elastic wire, the wire can be cut on the flexible connector, thus solving the problem that the elastic wire cannot be cut.

[0030] (4) Liquid metal-based elastic conductors do not have solderable properties. When the two ends of the liquid metal-based elastic conductor are connected to flexible connectors to form a fully flexible structure, they can be directly soldered to other components or circuit boards through the flexible connectors, making them more versatile. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the connection structure between the flexible wire and the flexible conductive connector in Embodiment 1 of the present invention.

[0032] Figure 2 yes Figure 1 Cross-sectional view of a flexible conductive connector.

[0033] Figure 3 This is a schematic diagram of the preparation process of the flexible conductive connector in Embodiment 1 of the present invention.

[0034] Figure 1-3 The reference numerals in the figures are as follows: flexible wire 10, first liquid metal 11, elastic silicone tube 12, flexible conductive connector 20, flexible polymer material 21, filamentous conductive material 22, second liquid metal layer 23, flexible fixing layer 30, liquid silicone 41, liquid silicone 42, tin-plated copper wire bundle coated with silicone 43, and a mixed solution of ferric chloride and hydrochloric acid 44. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and are not intended to limit it in any way.

[0036] Example 1:

[0037] In this embodiment, as Figure 1 As shown, the flexible conductor 10 includes a first liquid metal 11, which is formed by filling the elastic silicone tube 12 with the first liquid metal 11. The first liquid metal is GaInSn.

[0038] like Figure 1 , 2 As shown, the flexible conductive connector 20 includes a flexible polymer material 21 and a plurality of parallel arranged filamentous conductive materials 22. The flexible polymer material 21 covers the periphery of the filamentous conductive materials 22. Along the length direction of the filamentous conductive materials, a second liquid metal layer 23 is disposed at one end of the filamentous conductive materials 22, and the second liquid metal layer 23 is conductively connected to the end of the filamentous conductive materials 22 at that end. The other end of the filamentous conductive materials 22 forms a conductive connection with an external conductive element.

[0039] When the flexible conductive connector 20 is connected to the flexible wire 10, one end of the flexible conductive connector 20 in which the second liquid metal layer 23 is disposed extends into the flexible wire 10, and the second liquid metal layer 23 contacts the first liquid metal in the flexible wire 10 to form a conductive connection.

[0040] In this embodiment, the flexible polymer material 21 is made of silicone, the filamentous conductive material 22 is made of 8-micron tin-plated copper wire, and the second liquid metal is made of GaInSn.

[0041] In this embodiment, the preparation method of the flexible conductive connector 20 is as follows: Figure 3 As shown:

[0042] (1) As shown in Figure (a), prepare 13 8-micron tin-plated copper wires 41 and arrange them in parallel to form a tin-plated copper wire bundle.

[0043] (2) As shown in Figure (b), the above-mentioned tin-plated copper wire bundle is immersed in liquid silicone 42 with a hardness of 50A. After 30 minutes, it is taken out, hung for 5 minutes, and then sent to an oven to be heated to 100 degrees Celsius and kept for 15 minutes to obtain the tin-plated copper wire bundle 43 with silicone coating on the outside as shown in Figure (c).

[0044] (3) As shown in Figure (d), the end of the tin-plated copper wire bundle 43 covered with silicone (denoted as end A) is cut off vertically to expose the tin-plated copper wire.

[0045] (4) As shown in Figure (e), the A end of the tin-plated copper wire bundle is immersed in a mixed solution 44 of ferric chloride and hydrochloric acid. After 15 seconds, it is taken out, rinsed with water, and dried with a hair dryer. Then, as shown in Figure (f), the end is immersed in the second liquid metal 45. The whole bundle is placed in a sealed environment and vacuumed to -0.1 MPa. After the vacuum is broken, it is taken out. As shown in Figure (g), the A end of the tin-plated copper wire bundle forms a second liquid metal layer 23. The other end of the tin-plated copper wire bundle (referred to as the B end) is burned off with fire to expose the tin-plated copper wire, which is used to make a conductive connection with the conductive element.

[0046] The connection method between the flexible conductive connector 20 and the flexible wire 10 is as follows:

[0047] The A end of the tinned copper wire bundle is inserted into the flexible conductor 10, so that the second liquid metal layer is in direct contact with the first liquid metal; instant adhesive is applied around the contact area between the flexible conductive connector 20 and the flexible conductor 10 to form a flexible fixing layer 30 to fix the two together.

[0048] Example 2:

[0049] In this embodiment, the structure of the flexible wire 10 is exactly the same as that of Embodiment 1; the structure of the flexible conductive connector 20 is basically the same as that of Embodiment 1, except that the filamentous conductive materials 22 are arranged in parallel and twisted together in a spiral.

[0050] The preparation method of the flexible conductive connector 20 is basically the same as that of Example 1. The difference is that in step (1), 13 8-micron tin-plated copper wires are arranged in parallel and gently twisted together to form a tin-plated copper wire bundle.

[0051] The embodiments described above provide a detailed explanation of the technical solution of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for connecting a liquid metal-based flexible conductor to a flexible conductive connector, wherein the liquid metal-based flexible conductor comprises a first liquid metal and an elastomer, and is conductive under tensile conditions; characterized in that: The elastomer has a tubular structure, and the first liquid metal is located in the tubular structure; The flexible conductive connector includes a flexible polymer material and several filamentous conductive materials, with the flexible polymer material covering the periphery of the filamentous conductive materials; along the length direction of the filamentous conductive materials, a second liquid metal layer is disposed at one end of the filamentous conductive materials, and the second liquid metal layer is conductively connected to the end of the filamentous conductive materials; the other end of the filamentous conductive materials forms a conductive connection with an external conductive element. The method for preparing the flexible conductive connector includes the following steps: (1) Arrange several filamentous conductive materials; (2) A flexible polymer material is wrapped around the arranged filamentous conductive material, and one end of the filamentous conductive material wrapped with the flexible polymer material is cut off vertically to expose the end of the filamentous conductive material. (3) A second liquid metal layer is provided at the exposed end of the filamentous conductive material. The method for forming the second liquid metal layer is to immerse the end of the filamentous conductive material coated with flexible polymer material after step (2) into the liquid metal so that the exposed end is adhered to the second liquid metal. When the flexible conductive connector is connected to the flexible wire, one end of the flexible conductive connector in which the second liquid metal layer is disposed extends into the flexible wire, and the second liquid metal layer comes into contact with the first liquid metal in the flexible wire to form a conductive connection.

2. The connection method as described in claim 1, characterized in that: The first liquid metal is placed in the tubular structure by one or more methods, including injection, filling, blending, co-extrusion, simultaneous injection molding, and 3D printing.

3. The connection method as described in claim 1, characterized in that: The elastomer includes one or more of silicone, polyurethane, polypropylene, polyimide, polyester, polylactic acid, polydimethylsiloxane, polyvinyl alcohol, SEBS, POE, and Ecoflex.

4. The connection method as described in claim 1, characterized in that: The connection methods between flexible conductive connectors and liquid metal-based flexible wires include bonding, stitching, riveting, plugging, snapping, or fixing the two together through a flexible fixing layer at the contact points.

5. The connection method as described in claim 4, characterized in that: The fixing layer material includes one or more of the following: adhesive, silicone, polyurethane, polypropylene, polyethylene, epoxy resin, and polylactic acid.

6. The connection method as described in claim 1, characterized in that: The arrangement of several filamentous conductive materials includes one or more of the following: parallel, interlaced, parallel, spiral braided, and wound.

7. The connection method as described in claim 1, characterized in that: The filamentous conductive material includes one or more of metal wires, conductive yarns, fibrous graphene, carbon nanotubes, and fibrous graphite, as well as composite materials formed therefrom with elastic materials.

8. The connection method as described in claim 7, characterized in that: The metal wire includes one or more of the following: copper wire, gold wire, silver wire, indium wire, and tin wire.

9. The connection method as described in claim 1, characterized in that: The methods for coating flexible polymer materials onto the periphery of filamentous conductive materials include one or more of the following: soaking, dipping, scraping, chemical growth, extrusion, injection molding, turning, and milling.

10. The connection method as described in claim 1, characterized in that: The coating thickness of the flexible polymer material ranges from 100 nanometers to 500 micrometers.

11. The connection method as described in claim 1, characterized in that: The flexible polymer material includes one or more of the following materials: silicone, polyurethane, polypropylene, polyimide, polyester, polylactic acid, polydimethylsiloxane, and polyvinyl alcohol.

12. The connection method as described in claim 1, characterized in that: The liquid metal includes mercury, gallium-indium alloy, gallium-indium-tin alloy, ion-conducting liquid, or conductive gel.

13. The connection method as described in claim 1, characterized in that: The liquid metal includes gallium-indium alloys doped with transition metals and / or solid non-metallic elements.

14. The connection method as described in claim 1, characterized in that: The liquid metal includes a gallium indium tin alloy doped with transition metals and / or solid non-metallic elements.

15. The connection method as described in claim 1, characterized in that: In step (2), the method of exposing one end of the filamentous conductive material includes one or more of the following: shearing, cutting, grinding, plasma treatment, and laser treatment.

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