Lightweight Soft Conductive Composites Embedded with Liquid Metal Fiber Networks

Conductive liquid metal composites are an emerging class of super-stretchable soft conductors. Recently, liquid metal composites have been demonstrated to have promising applications in soft electronics, sensors, and soft robotics. Existing liquid metal composites usually have a relatively high filling ratio of the liquid metal phase, which not only increases the density but also the material cost. Future applications in soft electronics and robotics highly demand liquid metal composites with low density and high conductivity for large-scale, low-cost, lightweight, and more sustainable applications. This presentation will introduce our recent research progress targeting this need. Specifically, we synthesized lightweight and highly conductive composites embedded with liquid metal fiber networks. The liquid metal fiber network serves as an ultra-lightweight conductive pathway for electrons in a compliant rubber matrix. We have developed a novel manufacturing process to fabricate various liquid metal fiber networks, achieving fiber diameters as small as sub-3 microns. The microstructure, mechanical properties, and electro-mechanical behavior of the liquid metal fiber composites are thoroughly studied. Overall, our composites exhibit high electrical conductivity, low volume ratio of liquid metals, strain-insensitive resistance, excellent stretchability, and superior cyclic stability. To demonstrate the potential applications, we showcase the composites as interconnects in stretchable circuits and as electrodes in sensors and heaters. The liquid metal fiber composites we developed significantly reduce the material consumption and bulk density, which will promote the large-scale application of liquid metal composites in emerging technologies.