Ultrasensitive and Stretchable Strain Sensors Based on Mazelike Vertical Graphene Network

• Published in: ACS applied materials & interfaces 2018-10, Vol.10 (42), p.36312-36322
• Main Authors: Wu, Shuying, Peng, Shuhua, Han, Zhao Jun, Zhu, Hongwei, Wang, Chun H
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.8b15848

Here, we report a new type of strain sensors consisting of vertical graphene nanosheets (VGNs) with mazelike network, sandwiched between poly­(dimethylsiloxane) (PDMS) substrates. The new sensors outperform most graphene thin-film-based sensors reported previously and show an outstanding combination of high stretchability of ∼120%, excellent linearity over the entire detection range, and high sensitivity with a gauge factor of ∼32.6. The sensitivity can be tuned by controlling the thickness of VGNs, with sensors consisting of thicker VGNs showing higher sensitivity but slightly lower stretchability (the maximum gauge factor is ∼88.4 with a maximum detection strain of ∼55%). Detailed microscopic examinations reveal that the ultrahigh sensitivity stems from the formation of microcracks initiated in the buffer layer. These microcracks are bridged by strings of graphene/PDMS, enabling the conductive network to continue to function up to a strain level significantly higher than that of previously reported graphene thin-film-based sensors. Furthermore, the present sensors have been found to be insensitive to temperatures and various liquids, including water and 0.1 mol L–1 sodium chloride solution (similar to the sweat on human skin). Demonstrations are presented to highlight the new sensors’ potential as wearable devices for human motion detection and pressure distribution measurement.