Liquid Metal Reversible Contacts for Flexible Tactile Sensor with High Sensitivity and Wide Detection Range

Flexible tactile sensors inspired by human skin enable significant potential applications, including e-skin for intelligent robotics, wearable healthcare devices, and human–machine interfaces. Although the application of liquid metals (LM) and their composites has improved the stretchability of various tactile sensors, there remains a considerable gap between the performance of current flexible tactile sensors and human skin, attributed to their limited sensitivity and narrow working range. In this work, a liquid metal droplet (LMD)-based flexible tactile sensor that achieves both high-pressure sensitivity of 3 × 10⁻² kPa⁻¹ and a wide working range from 50 Pa to 1.2 MPa is proposed. The novel sensor consists of an LMD array in which each pair of droplets is connected by an electrolyte solution within the polydimethylsiloxane microchannel grid. It is demonstrated that the 2-LMD sensor is capable of detecting human motion and physiological signals, while the electrical impedance tomography-based 3.5 × 3.5 cm sensor can detect the shape and position of single-point, multipoint, and other complex contact using only eight evenly distributed electrodes along the sensor's edge. These findings highlight the promising potential of the sensors in future robotic and wearable electronic applications.