CN-122025284-A - Preparation system for forming liquid metal conductive pipeline through microfluidic injection

CN122025284ACN 122025284 ACN122025284 ACN 122025284ACN-122025284-A

Abstract

The invention discloses a preparation system for forming a liquid metal conductive pipeline through microfluidic injection, and belongs to the technical field of flexible electronic device manufacturing. The system employs a novel manufacturing process for directly injecting liquid metal into a biocompatible polymer microchip by an air diffusion mechanism to form a conductive channel having excellent conductivity and flexibility. The system reduces the surface tension of the polydimethylsiloxane chip by utilizing the surface modification technology, and adopts a constant low-pressure injection mode, thereby effectively solving the problems that the liquid metal is difficult to completely fill the micro-channel, air bubbles are easy to generate and the filling efficiency is low in the traditional method. The liquid metal conductive pipeline prepared by the system has high conductivity, high thermal conductivity, excellent ductility and repeatability, is suitable for manufacturing flexible circuit boards with complex three-dimensional irregular patterns, provides a brand-new preparation technology for the fields of wearable equipment, flexible sensors and the like, solves the problem that the traditional circuit boards are difficult to modify and repair, effectively protects circuits and achieves high fidelity.

Inventors

ZHANG HAORAN
CAO XINGWEN
ZHANG ZICHEN
ZHAO MUHUA
LIU WENZHAO
LIANG ZHIRONG
ZHANG QIONG

Assignees

北京大学深圳研究生院

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (10)

1. A manufacturing system for forming a liquid metal conductive pipe by microfluidic injection, comprising: a. the preparation unit of the biological bionic mould is used for preparing a polymer micro-fluidic chip with a complex three-dimensional topological structure; b. The surface wettability optimization unit is used for performing plasma treatment on the inner surface of the polymer micro-fluidic chip so as to improve the surface wettability of the polymer micro-fluidic chip; c. The constant low-pressure injection unit is used for injecting liquid metal into the polymer micro-fluidic chip subjected to surface treatment under constant pressure so as to fill the internal micro-channels of the polymer micro-fluidic chip; d. and the solidifying and packaging unit is used for solidifying and packaging the polymer micro-fluidic chip filled with the liquid metal to form a flexible conductive pipeline network.
2. The manufacturing system of claim 1, wherein the biomimetic mold manufacturing unit manufactures the polymeric microfluidic chip by directly replicating natural plant veins.
3. The manufacturing system according to claim 1, wherein the surface wettability optimization unit treats the inner surface of the polymer microfluidic chip with a plasma cleaner.
4. The manufacturing system of claim 1, wherein the constant low pressure injection unit employs a syringe pump and the constant pressure is less than 100 kPa.
5. The manufacturing system of claim 1, wherein the liquid metal is gallium or a gallium alloy.
6. The manufacturing system of claim 1, wherein the polymer is polydimethylsiloxane.
7. The manufacturing system of claim 1, wherein the curing and packaging unit packages the liquid metal filled polymeric microfluidic chip with another piece of polymeric substrate or glass substrate.
8. The preparation method for forming the liquid metal conductive pipeline through microfluidic injection is characterized by comprising the following steps of: a. preparing a polymer microfluidic chip, namely pouring a polymer prepolymer on a die with a complex three-dimensional topological structure, solidifying the polymer prepolymer, and stripping the die to obtain the polymer microfluidic chip; b. Carrying out surface treatment on the polymer micro-fluidic chip to improve the wettability of the inner surface of the polymer micro-fluidic chip; c. injecting liquid metal into the micro-channel of the polymer micro-fluidic chip subjected to surface treatment under constant pressure so as to be completely filled; d. And packaging the polymer micro-fluidic chip filled with the liquid metal to form a flexible conductive pipeline network.
9. The method according to claim 8, wherein in step a, the mold is obtained by direct replication of the natural plant veins.
10. The method according to claim 8, wherein in the step b, the surface treatment is a plasma treatment.

Description

Preparation system for forming liquid metal conductive pipeline through microfluidic injection Technical Field The invention belongs to the technical field of flexible electronics, and particularly relates to a preparation system for forming a liquid metal conductive pipeline through microfluidic injection. Background In recent years, flexible electronic devices have demonstrated great application potential in emerging fields such as human-machine interfaces, health monitoring, intelligent robots and the like due to their unique advantages of thinness, flexibility, stretchability and the like. As a foundation stone for flexible electronic devices, research and development of flexible conductive materials is of great importance. Conventional rigid conductors, such as copper, silver, etc., are prone to fatigue fracture during bending and stretching, resulting in degradation and even failure of device performance. Therefore, the development of flexible conductive materials having excellent conductivity and mechanical deformability is a hot spot of current research. Liquid metals, particularly gallium and its alloys, which are liquid at room temperature, are of great interest due to their high electrical conductivity, excellent flowability, low vapor pressure and good biocompatibility, and liquid metals are a desirable choice for flexible conductors. However, direct printing or patterning using bulk liquid metal still presents a number of challenges. First, liquid metals have extremely high surface tension, are difficult to wet on most substrates, often in the form of droplets or particles, resulting in poor interfacial compatibility with the substrate and distortion of the printed pattern. Second, exposure of the liquid metal to air spontaneously forms a weak oxide shell, typically 0.7-3 nm a thick. Although the oxide layer can stabilize the liquid metal particles and prevent agglomeration, the effective conductive connection among the particles is seriously hindered, so that the conductive performance of a printed circuit is greatly reduced. When the flexible device is subjected to strain or pressure, this fragile oxide shell is prone to rupture, resulting in leakage of liquid metal, thereby causing shorting or device failure. To solve the above problems, researchers have proposed various strategies. One mainstream approach is to multi-scale composite liquid metal nanoparticles with other materials through the preparation of composite materials to improve their rheological properties, reduce surface tension and enhance mechanical stability. However, existing preparation methods, such as ultrasonic treatment, shear mixing, etc., although capable of preparing liquid metal nanoparticles, are difficult to achieve precise control of particle size, morphology and surface properties, and the preparation process may introduce impurities, affecting the final properties. In addition, how to efficiently and precisely prepare the liquid metal nanocomposite into a flexible pipeline with stable conductive performance, and apply the flexible pipeline to actual electronic devices is still a technical problem to be solved. Flexible printed circuit boards have become an integral part of intelligent consumer electronics due to their high wiring density, light weight, thin profile and good bending properties, and are widely used in small, portable wearable devices such as smart watches, cell phones, unmanned aerial vehicles and automobile terminals. Conventional flexible circuit fabrication methods typically use electroplating on flexible insulating substrates or screen printing techniques with conductive ink as a conductor to form the desired circuit. However, these conventional methods have a number of limitations. The plating process is complicated and may cause work hardening of the metal plating layer in repeated bending use, thereby causing fatigue fracture. Modification and repair of the circuit is also very difficult. In addition, the heat dissipation capability of the electroplated metal is low, and the biocompatibility of the base material is poor. Screen printing, while relatively simple, has limited resolution and pattern definition by the aperture of the screen, making it difficult to produce complex, high-precision circuit patterns. Currently, the fabrication of circuits with complex irregular patterns remains a technical challenge. In recent years, researchers have come to pay attention to injecting conductive liquid materials directly into biocompatible protective material tubing. This approach can effectively protect the conductor from direct exposure to the external environment. Liquid metals, particularly gallium and its alloys, are favored because they are liquid at room temperature, have excellent electrical conductivity, thermal conductivity, ductility, stability, and low toxicity. Gallium has a thermal conductivity of about 60 times that of water and 1000 times that of air, which enables a liquid metal cir