Epidermis Microstructure Inspired Graphene Pressure Sensor with Random Distributed Spinosum for High Sensitivity and Large Linearity.

Recently, wearable pressure sensors have attracted tremendous attentions because of their potential applications in monitoring physiological signals for human healthcare. The sensitivity and linearity are the two most essential parameters to pressure sensors. Although various designed micro/nano-structure morphologies introduced, the trade-off between sensitivity and linearity can not be well balanced. The human skin that contains force receptors in reticular layer owns high sensitivity even for large external stimulus. Herein, inspired by the skin epidermis with high-performance force sensing we have proposed a special surface morphology with spinosum microstructure of random distribution via the combination of abrasive paper template and reduced graphene oxide (rGO). The sensitivity of graphene pressure sensor with random distribution spinosum (RDS) microstructure is as high as 25.1 kPa-1 in a wide linearity range of 0-2.6 kPa. Our pressure sensor exhibits the superior comprehensive properties compared with previous surface modified pressure sensors. According to simulation and mechanism analysis, the spinosum microstructure and random distribution contribute to the high sensitivity and large linearity range respectively. In addition, the pressure sensor shows promising potential in detecting human physiological signals, such as heart beat, respiration, phonation, human motions of pushup, arm bending, and walking. The wearable pressure sensor array was further used to detect gait states of supination, neutral and pronation. The RDS microstructure provides alternative strategy to improve performance of pressure sensors and extend its potential applications in monitoring human activities.