Wrinkled, cracked and bridged carbon networks for highly sensitive and stretchable strain sensors

Abstract

With rapid advance of wearable electronics technologies, flexible strain sensors having both high sensitivity and high stretchability are highly desired. In this work, inspired by lotus roots whose fibers remain joined even after fracture, highly sensitive and stretchable strain sensors are designed using single-walled carbon nanotube (SWNT)/graphene oxide (GO) hybrid thin films with unique wrinkled, cracked and bridged morphologies. The distinctive wrinkled and cracked structure is created by tuning the pre-stretching releasing of the hybrid film on a silicone rubber substrate. Under tension, the myriad SWNTs bridged the wrinkled film by sliding within the hybrid film giving rise to high stretchability, while the nano/microscale cracks provide the strain sensor with a high sensitivity through tunneling. Thanks to the synergy arising from the wrinkles, cracks and bundles bridged the cracks, the hybrid sensor exhibits a wide sensing range of 100 %, an ultrahigh gauge factor of 2000 with excellent stability for over 1000 cycles. These exceptional properties enable the sensor to monitor full range human motions from tiny eye blinks to large joint movements. A wearable gaming controller is prototyped using the developed sensor to demonstrate voice-empowered maneuver of car racing games.