Stretchable nanogenerator with micro-nano hierarchical interfaces for self-powered biometric authentication

Multifunctional integration and heterogeneous surface integration are two crucial challenges in the in-depth use and development of triboelectric nanogenerators (TENGs) in the wearable electronic field. A promising solution is to develop stretchable TENGs (STENG), which have the potential for microenergy supply and self-powered sensing. The key challenge is to endow its functional components with good deformability and realize heterogeneous surface integration. Herein, we proposed a fully stretchable, surface adaptable TENG using stretchable micro-nano hierarchical friction interfaces. It integrated microenenrgy supply and multifunctional self-powered sensing (i.e., bend, force, and frequency sensing) abilities successfully. The highly-linear sensing abilities endows the STENG with a good biometric ability. As an application, a STENG array based-stretchable wearable keyboard was proposed. It identified dynamic keystroke motions of all users with a Support Vector Machine, with a high accuracy of 93.21%. Besides, the intruders who were not sampled were distinguished from users, with an accuracy of 81.50%.