Low cost and highly sensitive flexible pressure sensor based on branched micro-structures

Highly sensitive and flexible sensor is an essential component for the development of wearable electronic device and medical equipment. For the property optimization of piezoresistive sensors, the key is to properly design conductive networks, which in principle should be both deformed readily and reversibly upon external load/unload. However, the preparation of such high-performance sensor generally involves complex physiochemical process, and more importantly, high sensitivity is generally realized at the cost of stability, thus limiting its practical applications. In this paper, conductive powders with branched micro-structures are prepared via facile dip-coating polyurethane sponge with graphene oxide, followed by reduction and pulverization. Thin film sensor consists of those conductive powders without any polymeric binder, which provides high structure stability and high sensitivity (125.5 kPa⁻¹), owing to the branched micro-structure as well as the significant increasing number of contract points resulted from pulverization process. After 3000 cycles of deformation, the sensor can still maintain stable signal detection with negligible drift. The combination of high sensitivity, cycling stability and low cost of our sensor could greatly expand its practical applications.