Biodegradable silk fibroin-based triboelectric nanogenerator with enhanced output regulated by interfacial and ionic polarization

Bio-based triboelectric nanogenerators (TENGs) are expected to power medical device and detect real-time human motion behavior due to eco-friendliness and biocompatibility. However, the output performance of the TENGs needs to be boosted. In this study, a biodegradable silk fibroin-based TENG with enhanced output performance regulated by interfacial and ionic polarization is proposed. The friction layers, regenerated silk fibroin (RSF) film and silk nanoribbon (SNR) film, are functionalized through the induction of histidine with imidazolyl and lithium chloride, respectively, thus increasing the dielectric constant and triboelectric properties of friction layers. The enhancement is attributed to the enlarged difference of electron-absorbing ability and electrondonating ability of the two friction layers. The total silk fibroin-based TENG shows a maximum voltage of 63.0 V, and a current of 2.4 mu A. Moreover, the obtained maximum power density of 828.8 mW m- 2 is 9.5 times higher than that of the counterpart without functionalization. And the output power density is much higher than that of existing fully degradable bio-based TENGs reported previously. The components of the silk fibroin-based TENG can gradually degrade in vitro. As a wearable device, the silk fibroin-based TENG can precisely monitor real-time human motion due to its high sensitivity, which can realize self-powered supply and simultaneous sensing. Moreover, the unencapsulated TENG is successfully used as a self-powered humidity sensor. The biobased TENGs with enhanced performance highlight their application potential in wearable and implantable fields.