Defect-free, high resolution patterning of liquid metals using reversibly sealed, reusable polydimethylsiloxane microchannels for flexible electronic applications

This paper describes a simple and reliable approach for high-resolution patterning of liquid metals onto elastomeric substrates and their applications in flexible and wearable electronics. In this method, the liquid metal eutectic gallium indium (EGaIn) alloy was first dispensed into an air plasma-treated polydimethylsiloxane (PDMS) substrate through a reversibly sealed PDMS microchannel. The liquid metal-filled substrate was then placed on a cold plate, where the liquid metal was solidified. Finally, defect-free patterns were obtained by directly peeling off the PDMS microchannel on a hot plate while the liquid metal started to melt. The as-made liquid metal patterns exhibited excellent electrical and mechanical performance. As a proof of concept, the as-made flexible patterns of liquid metals were applied as flexible electrical conductors, capacitive sensors, and touch keyboards.