Highly stretchable multilayer electronic circuits using biphasic gallium-indium

Abstract

Stretchable electronic circuits are critical for soft robots, wearable technologies and biomedical applications. Development of sophisticated stretchable circuits requires new materials with stable conductivity over large strains, and low-resistance interfaces between soft and conventional (rigid) electronic components. To address this need, we introduce biphasic Ga–In, a printable conductor with high conductivity (2.06\u2009×\u2009106\u2009S\u2009m−1), extreme stretchability (>1,000%), negligible resistance change when strained, cyclic stability (consistent performance over 1,500 cycles) and a reliable interface with rigid electronics. We employ a scalable transfer-printing process to create various stretchable circuit board assemblies that maintain their performance when stretched, including a multilayer light-emitting diode display, an amplifier circuit and a signal conditioning board for wearable sensing applications. The compatibility of biphasic Ga–In with scalable manufacturing methods, robust interfaces with off-the-shelf electronic components and electrical/mechanical cyclic stability enable direct conversion of established circuit board assemblies to soft and stretchable forms. Conductors made of a mixture of liquid and solid domains of Ga–In alloy can be stretched over 1,000%, keeping almost constant conductivity, and used to connect commercial electronic components and realize stretchable multilayer printed circuit boards.