A Novel Conductive Core–Shell Particle Based on Liquid Metal for Fabricating Real‐Time Self‐Repairing Flexible Circuits

Abstract

As a critical part of flexible electronics, flexible circuits inevitably work in a dynamic state, which causes electrical deterioration of brittle conductive materials (i.e., Cu, Ag, ITO). Recently, gallium-based liquid metal particles (LMPs) with electrical stability and self-repairing have been studied to replace brittle materials owing to their low modulus and excellent conductivity. However, LMP-coated Ga 2 O 3 needs to activate by external sintering, which makes it more complicated to fabricate and gives it a larger short-circuit risk. Coreshell structural particles (Ag@LMPs) that exhibit excellent initial conductivity (8.0 Ω sq −1 ) without extra sintering are successfully prepared by coating nanosilver on the surface of LMPs through in situ chemical reduction. The critical stress at which rigid Ag shells rupture can be controlled by adjusting the Ag shell thickness so that LM cores with low moduli can release, achieving real-time self-repairing (within 200 ms) under external destruction. Furthermore, a flexible circuit utilizing Ag@LMPs is fabricated by screen printing, and exhibits outstanding stability and durability (R/R 0 < 1.65 after 10 000 bending cycles in a radius of 0.5 mm) because of the functional core-shell structure. The self-repairable Ag@LMPs prepared in this study are a candidate filler for flexible circuit design through multiple processing methods.

Galvanic replacement reaction for in situ fabrication of litchi-shaped heterogeneous liquid metal-Au nano-composite for radio-photothermal cancer therapy

“…Therefore, rather than a novel kind of functional materials with fundamental interest, the unprecedented chemistry offered by LM may also provide facile manner that has significant implications for many applications as well. Most recently, the growth of MnO 2 and Ag nanosheets on the LM NPs had been achieved by the reduction of the permanganate ions and AgNO 3 solution [ 34 , 35 ]. The as-prepared nano-heterogeneous structures could be successfully applied as efficient photocatalysis or real-time self-repairing flexible circuit materials.…”

Pervasive liquid metal printed electronics: From concept incubation to industry

“…Further, based on more generalized liquid metal composite strategy ( Chen et al., 2020 ), the liquid metal dispersed into micro-nano droplets can form liquid metal-polymer composites with the polymer ( Chechetka et al., 2017 ; Fassler and Majidi, 2015 ; Krisnadi et al., 2020 ; Li et al., 2018 , 2020 ; Peng et al., 2019 ; Tang et al., 2018 ; Wang et al., 2018b ), and the resulting ink can be flexibly applied to different substrates ( Figure 2 B). But because of the dispersed liquid metal droplets, special treatments to make them conductive are usually necessary, such as laser ( Deng and Cheng, 2019 ; Liu et al., 2018a ), low temperature ( Chen et al., 2019 ; Wang et al., 2019 ), mechanical pressure ( Boley et al., 2015 ; Zhang et al., 2019a ), evaporation ( Li et al., 2019b ), in situ reduction of silver shell ( Zheng et al., 2020 ), and stretch ( Thrasher et al., 2019 ; Xin et al, 2019 ). Along with more inks and printing, liquid metal can be printed into 2D semiconductor ( Lin et al., 2019 ) or applied to directly compose transistor and functional device ( Li et al., 2019a ).…”

Surface Modification of Gallium‐Based Liquid Metals: Mechanisms and Applications in Biomedical Sensors and Soft Actuators

“…[54,73,74,80,81] Mechanical deformation of the oxide layer can help facilitate metal-metal contact between LM particles and diverse metals (Au, Mg, Ag, Cu, and Fe). [54,[82][83][84][85][86] Figure 3b shows an example of LM particles contacting silver nanoparticles (AgNPs). Stirring LM and AgNPs provides shear forces on the oxide layer that allows metal-metal contact.…”