Triboelectric nanogenerator based wearable energy harvesting devices

With the miniaturization and functionalization of electronic devices, wearable electronics has drawn generally attention, but the energy supply for wearable electronics becomes one of the most burning questions. The triboelectric nanogenerator based on the coupling effects of electrostatic induction and triboelectrification, which has low cost and wide material selection attributes, proves to be a powerful technology for converting low-frequency mechanical energy into electricity. In this review, the four fundamental modes of triboelectric nanogenerator and the physical mechanism of contact-electrification are presented first. Then, we introduce the research progress of wearable from the direct and indirect aspects. Directly wearable triboelectric nanogenerator can be integrated into a skin while indirectly wearable device is only allowed to assemble into user's clothing or its appendages. In addition, the power management circuits for driving electronic devices and energy storage are summarized. Finally, we discuss the current bottlenecks and present our perspectives on future directions in this field.