Masked Deposition of Gallium‐Indium Alloys for Liquid‐Embedded Elastomer Conductors

Abstract A fabrication method is introduced that utilizes masked deposition and selective wetting to produce hyperelastic electronic circuits that are composed of a thin elastomer film embedded with microchannels of liquid‐phase gallium‐indium (Ga‐In) alloy. This method exploits the low melting‐point and controllable wetting dynamics of Ga‐In alloys, as well as the ability for Ga‐In alloys to form irregularly‐shaped, free‐standing, micrometer‐scale structures via gallium surface oxidation. Masked deposition eliminates the need for manual injection filling, which enables certain geometries that cannot be produced by injection and allows for the automated, high‐volume production of Ga‐In based “liquid‐embedded elastomer electronics” (LE3). With this approach, LE3 circuits can be produced with isolated features that have planar dimensions of less than 200 μm and edge‐to‐edge feature separations as small as 25 μm.