Liquid Metal‐Based Strain Sensor with Ultralow Detection Limit for Human–Machine Interface Applications

Flexible strain sensors play vital role in human–machine interaction. Despite their vast development, a strain sensor having broad strain sensing range, ultralow detection limit, and negligible hysteresis still remains a challenge. Herein, a liquid metal (LM)‐based stretchable resistive strain sensor, prepared by selective wetting and transferring process to attain improved compatibility between LM and polydimethylsiloxane substrate, is reported. This sensor exhibits broad strain sensing range (105%), with ultralow detection limit (0.05%), minimal hysteresis, fast response time (58 ms), and excellent repeatability. When practically demonstrated, this sensor successfully monitored various human activities, such as blink motion monitoring, voice intensity differentiation, heartbeat and wrist pulse monitoring. Moreover, when the current sensor is used in the form of smart kneecap and smart glove, it efficiently detected various human gestures, which confirms its great application potential in the fields of human health and motion monitoring, human–machine interface, and virtual reality applications.