Printed Bilayer Liquid Metal Soft Sensors for Strain and Tactile Perception in Soft Robotics

Abstract A liquid metal (LM) soft sensors for strain monitoring and self‐powered tactile detection in soft robotics are developed. The sensor is fabricated by printing a bilayer of oxidized LM paste and bare LM on a soft substrate. This bilayer design overcomes the challenges in scalable printing of liquid metal and demonstrates soft sensors with exceptional electromechanical performance. Specifically, the sensor exhibits a strain sensing range of over 400% with a gauge factor of over 2, while displaying low hysteresis and high mechanical stability. Furthermore, the sensor utilizes a single electrode triboelectric effect to achieve self‐powered tactile sensing. To demonstrate the potential of these sensors in soft robotics, it is integrated into a soft pneumatic actuator and successfully demonstrate their ability to perceive gestures, motion, and grasping. This work highlights the potential of LM‐based soft sensors in advancing the field of soft sensing and soft robotics.