Ultrathin and High-Stress-Resolution Liquid-Metal-Based Pressure Sensors with Simple Device Structures

Soft pressure sensors based on liquid metals (LMs) may find broad applications, but it is challenging to fabricate such sensors that can achieve high stress resolution without additional parts. Herein, a method named laser-induced selective adhesion transfer (LISAT) is proposed. LISAT can pattern LM by selectively changing high adhesion of the poly(dimethylsiloxane) (PDMS) surface to LM into low adhesion with the aid of rough micro/nanostructures induced by a femtosecond laser. Based on this principle, LM microchannels with controllable shapes can be obtained by LM transfer and subsequent encapsulation. Since the smallest microchannel thickness is only ∼25 μm, sensor stress resolution can reach 0.0168 kPa without any additional parts to amplify the effect of pressure. As proof-of-concept demonstrations, the sensor is used for sensing the dynamic movement of a small sphere (∼0.16 g) and even an ant (∼0.025 g). LISAT provides a versatile platform for fabricating high-stress-resolution LM pressure sensors with controllable patterns and device structures to adapt to different application scenarios.