Biodegradable silk fibroin-based bio-piezoelectric/triboelectric nanogenerators as self-powered electronic devices

Bio-piezoelectric/triboelectric nanogenerators (PENGs/TENGs) are promising components for the next genera-tion of self-powered electronic devices due to their green energy harvesting characteristics, biodegradability, and biocompatibility, which are not fully present in regular PENGs/TENGs. As a natural and abundant biomaterial, silk fibroin (SF) shows great potential for fabricating bio-PENGs/TENGs. In this review, the working principles of typical SF-based bio-PENGs/TENGs are summarized. The latest advances in partially and fully biodegradable SF-based bio-PENGs/TENGs are highlighted, focusing on aspects including their molding structures, performance, working mechanisms, and application scenarios. Challenges including output performance, achieving full biodegradability, encapsulation structure, and biosafety are also described. These SF-based bio-PENGs/TENGs show great potential for emerging energy and electronic applications, as well as for in vitro/in vivo biomedicine.