Nacre‐Inspired, Liquid Metal‐Based Ultrasensitive Electronic Skin by Spatially Regulated Cracking Strategy

Abstract The realization of liquid metal‐based wearable systems will be a milestone toward high‐performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal‐based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre‐inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain‐sensitive Ag film as “mortar” is developed, which breaks the long‐standing sensitivity bottleneck of liquid metal‐based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal‐based strain sensors rival the state‐of‐art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut‐through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid‐metal paths and create crack‐free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal‐based electronic skins, and reveals a pathway for sensor development via crack engineering.