Transparent and stretchable triboelectric nanogenerator for self-powered tactile sensing

Wearable electronic devices have attracted numerous attention in tactile sensing, motion detecting, and biomedical signal monitoring. In particular, a wearable and self-powered sensor combining all the merits of sensitivity, transparency, stretchability, and flexibility is highly demanded to adapt human skins. Herein, we report a fully transparent, highly stretchable, and self-powered contact-separation triboelectric nanogenerator (TENG) as a tactile sensor. The TENG consists of a double-network ionogel with the transparency, stretchability, and conductivity as the electrode and one friction layer, and patterned polydimethylsiloxane (PDMS) as another friction layer. The fabricated sensor reaches a maximum sensitivity of 1.76 V N-1 when detecting impacting forces in the range of 0.1-1 N. Meanwhile, with good stretchability of the sensor, the triboelectric signals maintain a good linearity with impacting forces at different tensile ratios (0%, 10%, 50%, and 80% strain). These properties enable the sensor to be capable of monitoring a variety of human activities, including finger touching and bending, breathing, and pulse beating. We believe such a transparent, stretchable and self-powered tactile TENG sensor has tremendous application potential in wearable and soft electronics.