Recent Progress of Wearable Piezoelectric Nanogenerators

Considering the limited supply of fossil fuel, pollution, problems with chemical batteries, and the many potential applications of wearable electronics, the development of more effective lightweight energy sources is important. Piezoelectric nanogenerators (PENGs) can convert a mechanical energy into an electric energy and sometimes may even have the potential to replace conventional chemical batteries. The combination of conventional textiles with PENGs leads to so-called "smart textiles", in other words, textile-based PENGs. More generally, textile-based PENGs can endow conventional textiles with special functionalities such as energy conversion and online health testing (using sensors), while the used conventional textiles can provide platforms for their deployment. This paper reviews the research progress of textile-based PENGs, discusses the classification of piezoelectric materials and electrode materials, and summarizes ways to improve their piezoelectric performance. In addition, several preparation methods of different device structures of textile-based PENGs are compared. Finally, the most important obstacles for the application of textile-based PENGs are addressed at the end of this paper. This compact but relatively comprehensive review will not only aid researchers to better understand textile-based PENGs but also attract the attention of related fields and perhaps inspire more exciting research and progress of wearable textile-based PENGs.