A wearable strain sensor based on the ZnO/graphene nanoplatelets nanocomposite with large linear working range

Flexible strain sensors are attracting more and more attentions in wearable devices and electronic skins. Currently, the fabrication of flexible strain sensor with features of high sensitivity and wide linear working range is still a great challenge. Herein, a stretchable and wearable strain sensor is fabricated with the ZnO nanoparticles (NPs)/graphene nanoplatelets nanocomposite (ZnO/GNP NC) as both the sensing element and reinforcement phase. The ZnO/GNP NC strain sensor exhibits fascinating performance, including high mechanical properties (fracture strength of 0.6 MPa and elongation of similar to 90%), large working range of 0-44%, high sensitivity (gauge factor of 8.8-12.8), and good reproducibility over 1700 cycles. Importantly, the ZnO/GNP NC strain sensor holds perfect linearity (R-2 = 0.999) in the whole working range, which can be attributed to the coupling effect between the ZnO NPs and the GNP. The ZnO/GNP NC strain sensor can not only detect large human motions such as elbow rotation, wrist rotation, clenching fist, and waving badminton racket, but also monitor subtle human motions in real time, such as pulse, phonation, coughing, and swallowing. The wide linear working range of the ZnO/GNP NC strain sensor makes it a potential choice for the application of wearable devices.