Recoverable Liquid Metal Paste with Reversible Rheological Characteristic for Electronics Printing.

Gallium-based liquid metals are applied in the fabrication of soft electronics because of their conductivity and flexibility. However, the large surface tension and weak adhesion of liquid metals limit the available printing substrates. Recent researches indicate that amalgamating metal particles can turn liquid metal from fluid into a paste which has superb electrical conductivity, plasticity, and strong adhesion to substrates. In this work, a recoverable liquid metal paste was made by mixing eutectic Ga-In alloy and nonmetallic SiO2 (quartz) particles (Ga-In-SiO2 paste, called GIS). GIS has excellent conductivity and printable properties similar to those of previously reported liquid metal pastes. Furthermore, the bonding between Ga-In alloy and quartz particles is reversible. In acidic or alkaline solution, Ga-In alloy can be separated from quartz particles and agglomerated to bulk by stirring. Moreover, the study of the mechanism of adhesion behavior suggests that extruding fresh liquid metal droplets to form more oxide and shearing friction are the critical factors for adhesion. This work proposed a new liquid metal paste with a reversible rheological property and promoted the understanding of the working principle of liquid metal paste.