Stretchable microfiber electrode with core-shell structure using liquid metal nanoparticles

Abstract

Stretchable electrodes have been studied to be applied to various stretchable electronics such as biosensors and stretchable displays. There are structural-based strategies as a general method for fabricating stretchable electrodes, such as island-bridge, kirigami, and pre-wrinkled structures. However, these methods have limitations in stretchability because hard and brittle metals are used. The liquid metal is often used to solve these problems. However, liquid metals have high surface tension, making it difficult to make fine patterns, and free-standing electrodes cannot be manufactured by liquid metal alone. Here, we report stretchable microfiber electrodes using liquid metals and elastomers together. A system called charge reversal electro-writing process (CREW), one of the electrospinning, was used to fabricate the microfiber electrode. As a conductive material, liquid metal nanoparticles, not bulk liquid metal, were used. In the electrospinning process where a high voltage is applied, overcurrent could be prevented through the oxide film of liquid metal particles. In addition, by adopting a core-shell structure, the conductivity and stretchability of the microfiber electrode are improved by dividing it into a core part with a lot of liquid metal nanoparticles and a shell part mainly made of polymer.