Soft and stretchable sensors are essential to the development of electronic skin, especially their potential applications in health care and intelligent robots, which have increasingly attracted attentions. Herein, inspired by the epidermal tissue hierarchy, we propose a high-sensitivity fully soft capacitive pressure sensor with bionic spine-pillar microstructure. Benefiting from the combination of the random microscale spines and the millimeter-sized pillar array prepared based on polydimethylsiloxane, the proposed sensor exhibits a well deformability, a high sensitivity up to 2.87 k/Pa at low-pressure range, and a broad linear pressure dynamic range from 5 Pa to 100 kPa. A simple equivalent circuit model was established to demonstrate the sensing mechanism and geometric effect. For practical application demonstrations, the sensor was utilized to monitor local subtle and large movements of the skin, such as finger bending, wrist bending, swallowing, and facial muscle movements. The sensor shows a conformality with human skin to follow the skin extension closely. Furthermore, the proposed sensing strategy can provide a distinguishable tactile feedback for controlling robot arm and soft claw in various tasks, illustrating its potential applications in robotics.
Keywords: capacitive sensors; microspines; motion monitoring; pressure sensors; soft robots.