CN-122025215-A - Liquid metal flexible conductor with strain insensitivity characteristic and preparation method and application thereof

CN122025215ACN 122025215 ACN122025215 ACN 122025215ACN-122025215-A

Abstract

The invention discloses a liquid metal flexible conductor with strain insensitivity, a preparation method and application thereof, relating to the technical field of flexible electronic and liquid metal composite materials, alloying the liquid metal and the metal wetting layer at a solid-liquid interface to generate an intermetallic compound interface layer in situ, so that the liquid metal is spontaneously infiltrated and densely filled to the depth of a pore under normal pressure; meanwhile, the conductive composite layer is subjected to penetration packaging by adopting a curable elastic polymer material, an elastomer-skeleton mechanical interlocking structure is formed in the pores after curing, so that the geometric limiting region and shearing-resistant anchoring of liquid metal are realized, and in the stretching deformation process, the liquid metal is subjected to fluid redistribution and path bridging under the constraint of the pore limiting region and the elastomer, so that the conductive path is reconstructed, and the strain insensitive conductive characteristic of low resistance drift is obtained.

Inventors

WANG ZHENYANG
LI NIAN
LI ZHAO
SONG YANPING
YANG CHANGDE
ZHANG SHUDONG
LIU CUI

Assignees

安徽格兰科新材料技术有限公司
中国科学院合肥物质科学研究院

Dates

Publication Date: 20260512
Application Date: 20260327

Claims (10)

1. The liquid metal flexible conductor with the strain insensitive characteristic comprises a conductive composite layer and a flexible packaging layer arranged on at least one side of the conductive composite layer, and is characterized in that the conductive composite layer comprises a three-dimensional porous conductive framework, a metal wetting layer covering at least part of the surface of the three-dimensional porous conductive framework and liquid metal infiltrated into pores of the three-dimensional porous conductive framework, the liquid metal and the metal wetting layer are subjected to alloying reaction at an interface to form an intermetallic compound interface layer, and the flexible packaging layer is at least partially infiltrated into the pores of the three-dimensional porous conductive framework and is solidified.
2. The liquid metal flexible conductor with the strain-insensitive characteristic of claim 1 wherein the three-dimensional porous conductive framework is at least one of a porous carbon framework, a porous graphene/carbon nanotube sponge, a carbon cloth/carbon paper, a porous metal, a foam metal, a porous conductive polymer material, and a conductive fabric; Preferably, the porous carbon skeleton is preferably a laser-induced graphene skeleton, a foam graphene skeleton or a porous carbonized polymer skeleton; preferably, the three-dimensional porous conductive framework has a communicated pore structure, the average pore diameter is 0.1-500 mu m, and the thickness of the framework is 20-2000 mu m.
3. The liquid metal flexible conductor with strain-insensitive properties of claim 1 wherein the metal wetting layer is made of at least one of copper, nickel, silver, gold, tin, zinc, indium, aluminum, iron, titanium, chromium, stainless steel; Preferably, the metal wetting layer is a copper layer and/or a nickel layer; preferably, the metal wetting layer is distributed on the pore wall surface of the three-dimensional porous conductive framework in the form of a continuous thin layer, an island-shaped thin layer, a particle layer or a gradient layer.
4. The flexible liquid metal conductor with strain insensitivity according to claim 1, wherein said liquid metal is a gallium-based metal alloy selected from at least one of eutectic gallium-indium alloy, gallium-indium-tin alloy, gallium-indium-zinc alloy, gallium-tin alloy; Preferably, the mass fraction of gallium in the eutectic gallium-indium alloy is 70-80 wt%, and the mass fraction of indium is 20-30 wt%; Preferably, the intermetallic interface layer is selected from at least one of CuGa 2 、Cu 9 Ga 4 、NiGa 4 、Ni 2 Ga 3 、Ag 2 Ga、AuGa 2 .
5. The flexible conductor of claim 1, wherein the flexible encapsulation layer is made of an elastic polymer material selected from at least one of silicone rubber, polyurethane elastomer, thermoplastic elastomer, SEBS, TPU, nitrile rubber, natural rubber, gel, and hydrogel; Preferably, the depth of the flexible packaging layer penetrating into the three-dimensional porous conductive framework is 5-100% of the thickness of the conductive composite layer, and continuous sealing edges are formed at the edges of the conductive composite layer so as to limit liquid metal from penetrating outwards.
6. The flexible liquid metal conductor with strain insensitivity according to claim 1, wherein a resistance strain coefficient GF of said flexible liquid metal conductor is not more than 0.2 in a uniaxial tensile strain range of 0-600%, wherein GF is defined as (DeltaR/R 0 )/ε,R 0 is an initial resistance, deltaR is a resistance change amount, and epsilon is a strain; Preferably, in the uniaxial tensile strain range of 0-300%, the ΔR/R 0 of the liquid metal flexible conductor is not more than 0.12; Preferably, the apparent conductivity of the liquid metal flexible conductor at 0% strain is not less than 1 x 10 5 S/m, more preferably not less than 5 x 10 5 S/m; Preferably, the electromagnetic shielding effectiveness SE of the liquid metal flexible conductor in the frequency range of 1-40 GHz is not less than 30 dB, more preferably in the frequency range of 26.5-40 GHz and in the tensile strain range of 0-500% is not less than 40 dB; preferably, the in-plane heat conductivity coefficient of the liquid metal flexible conductor is 2-30 W.m -1 ·K -1 .
7. The method for manufacturing a liquid metal flexible conductor with strain-insensitive characteristics according to any one of claims 1 to 6, characterized by comprising the following steps: s1, providing a three-dimensional porous conductive framework with a surface at least partially covered with a metal wetting layer; S2, activating the three-dimensional porous conductive framework; s3, soaking and filling liquid metal into the pores of the three-dimensional porous conductive framework to form a conductive composite layer; s4, applying an elastic polymer material on at least one side of the conductive composite layer to enable the elastic polymer material to permeate into pores of the three-dimensional porous conductive framework, and solidifying the porous conductive framework to form a flexible packaging layer to obtain the liquid metal flexible conductor.
8. The method of claim 7, wherein the three-dimensional porous conductive skeleton has a metal wetting layer distribution area and a non-metal wetting layer distribution area with preset patterns, and the liquid metal is selectively infiltrated under the reactive wetting action to form conductive lines with corresponding patterns; Preferably, the activation treatment is at least one selected from acid washing, alkali washing, chelating treatment, electrochemical reduction, plasma treatment and mechanical shearing, more preferably, the acid washing adopts inorganic acid or organic acid, the acid concentration is 0.001-6 mol/L, and the treatment time is 1-600 s; Preferably, the liquid metal is infiltrated/filled in at least one mode selected from dripping, knife coating, rolling coating, spraying, dipping, vacuum dipping, calendaring and injection; Preferably, the area density load of the liquid metal is 1-80 mg/cm 2 , preferably 10-50 mg/cm 2 .
9. The application of the liquid metal flexible conductor with the strain-insensitive characteristic as claimed in any one of claims 1 to 6 or the liquid metal flexible conductor with the strain-insensitive characteristic prepared by the preparation method as claimed in claim 7 in wearable bioelectronics, electromagnetic shielding materials and flexible thermal diffusion/thermal management components.
10. A flexible electronic device comprising a flexible substrate and the liquid metal flexible conductor with strain-insensitive characteristics according to any one of claims 1 to 6 or prepared by the preparation method according to claim 7 disposed on the flexible substrate.

Description

Liquid metal flexible conductor with strain insensitivity characteristic and preparation method and application thereof Technical Field The invention relates to the technical field of flexible electronic and liquid metal composite materials, in particular to a liquid metal flexible conductor with strain insensitivity and a preparation method and application thereof. Background With the development of wearable health monitoring, soft robots, man-machine interaction, and other fields, stretchable conductors are required to maintain low resistance and long-term stability under conditions of large deformation (stretching, bending, torsion) as key interconnection components in flexible electronic systems. The traditional metal film and metal wire net are easy to crack and lead to rapid increase of resistance when being stretched, and the carbon-based composite conductor (such as carbon nano tube/graphene-elastomer composite) has certain stretchability, but the resistance of the carbon-based composite conductor changes obviously along with the strain, and often shows high-sensitivity strain sensing behavior, and is difficult to serve as a stable interconnection wire. Gallium-based liquid metal is considered as an ideal flexible conductor material due to the high conductivity and fluid deformability of the gallium-based liquid metal, but the high surface tension and the oxide film of the gallium-based liquid metal lead to poor wettability on a non-metal or carbon-based surface, so that agglomeration, displacement or leakage in the deformation process are easy to occur, and the conductive path is discontinuous and the device is invalid. In addition, under the requirements of complex electromagnetic environment or thermal management, the flexible conductor is also required to have the functions of electromagnetic shielding, joule heating or thermal diffusion, etc., however, the conductive network of the traditional stretchable shielding/heating material is easily damaged under large strain, so that the shielding efficiency or thermal performance is attenuated. Therefore, there is a need for a liquid metal flexible conductor and a method for manufacturing the same that can achieve stable conduction, firm interface and scalable multi-functional applications while ensuring a large strain deformation capability. Disclosure of Invention In order to solve the problems that the existing liquid metal flexible conductor is difficult to spontaneously infiltrate in a porous framework, has insufficient interface binding force, large resistance drift under stretching, easy agglomeration leakage, poor multifunctional stability and the like, the invention provides the liquid metal flexible conductor with strain insensitivity and a preparation method thereof, and the liquid metal flexible conductor is prepared by introducing a metal wetting layer on the surface of a three-dimensional porous conductive framework, so that the liquid metal and the metal wetting layer are subjected to alloying reaction at a solid-liquid interface and an intermetallic compound interface layer is generated in situ, the interface energy is reduced in terms of thermodynamics, a reactive wetting driving force is formed, and the liquid metal is spontaneously infiltrated under normal pressure and densely filled into the deep part of a pore; meanwhile, the conductive composite layer is subjected to penetration packaging by adopting a curable elastic polymer material, an elastomer-skeleton mechanical interlocking structure is formed in the pores after curing, so that the geometric limiting region and shearing-resistant anchoring of liquid metal are realized, and in the stretching deformation process, the liquid metal is subjected to fluid redistribution and path bridging under the constraint of the pore limiting region and the elastomer, so that the conductive path is reconstructed, and the strain insensitive conductive characteristic of low resistance drift is obtained. The technical problems to be solved by the invention are realized by adopting the following technical scheme: The invention aims to provide a liquid metal flexible conductor with strain insensitivity, which comprises a conductive composite layer and a flexible packaging layer arranged on at least one side of the conductive composite layer, wherein the conductive composite layer comprises a three-dimensional porous conductive framework, a metal wetting layer covering at least part of the surface of the three-dimensional porous conductive framework and liquid metal infiltrated into and filled in pores of the three-dimensional porous conductive framework, the liquid metal and the metal wetting layer are subjected to alloying reaction at an interface to form an intermetallic compound interface layer, and the flexible packaging layer at least partially infiltrates into the pores of the three-dimensional porous conductive framework and is solidified. In the present invention, the liquid metal and the