Photo-patternable, large-area solid-state liquid metal film coated via solution shearing for soft electronics

Abstract Liquid metal (LM) is considered one of the most promising conducting materials for soft electronics due to its unique combination of metal-level high conductivity with exceptional deformability and stretchability. However, their practical applicability has thus far been limited due to the challenges of generating chemically and mechanically stable film over a large-area and the need for non-standard fabrication approaches. Here, we report materials and manufacturing methods that enable multiscale patterning (from microns to centimeters) and multilayer integration of ‘solid-state liquid metal (SSLM)’ with the conventional cleanroom process. In this work, solution shearing of a polyelectrolyte-attached LM particle ink is used to generate SSLM films. The stabilized LM particles were observed to form a close-packed thin-film without particle rupture when coated under evaporative regime. This is essential in enabling a subsequent photolithographic lift-off process at wafer-scale to produce high-resolution features (~ 10 µm) of varying thicknesses irrespective of the substrate. Demonstrations of wearable multilayer tactile sensing systems and stretchable skin-interfaced electronics validate the simplicity, versatility, and reliability of this manufacturing strategy, suggesting broad utility in the development of advanced soft electronics.