New Methods for Creating Soft Electronics Using Liquid Metals

Soft electronics are an exciting new class of materials that can be utilized to create electronic functionality in devices that are deformable, stretchable, and soft.  These devices may be utilized for wearable electronics, microfluidic systems, or in soft substrates.  Liquid metals are the softest conductors possible and are therefore well-suited for soft electronics.  Eutectic gallium indium (EGaIn) is a liquid metal with low toxicity composed of 75% gallium and 25% indium. This alloy is a liquid at room temperature and forms an oxide skin composed of oxides of gallium when exposed to air. EGaIn has metallic properties while also being able to flow as a liquid. The oxide that forms on the metal allows it to maintain shapes that do not minimize surface energy.   For example, the metal can be injected into microfluidic channels readily and the oxide helps hold the metal within the channels after injection.  At present, there are many ways to inject liquid metals into microfluidic channels, and this project focuses on innovative ways to fill microfluidic channels with liquid metals, thus paving the way for development of soft electronics.