Engineering Bacterial Cellulose Films by Nanocomposite Approach and Surface Modification for Biocompatible Triboelectric Nanogenerator

Bio-triboelectric nanogenerators (bio-TENGs) have received a lot of attention for the applications in self-powered implantable or wearable electronics. Several types of cellulose-based bio-TENGs exhibited outstanding output performance, in particular, bacterial cellulose (BC) based bio-TENGs. However, the cellulose needs to go through several processes involving solubilization and regeneration to form the film. These processes destroy the nanostructure and crystallinity, and thus, the maximum output voltage and current may not be utilized. In this work, the bio-TENGs based on BC nanocomposites were simply fabricated by a gradually drying BC hydrogel on a conductive substrate. The BC film was adhesively bonded on the indium tin oxide (ITO) substrate directly without the use of any conductive paste. Furthermore, ZnO nanoparticles were impregnated into the BC nanostructure, particularly at the film surface, to increase the surface roughness and polarizability. The BC/ZnO (ZBC) nanocomposite could not directly bond to the substrate so that it was modified by amino-silane treatment before drying on the substrate. The triboelectric measurements showed that the bio-TENGs based on the BC and ZBC films generated relatively high open-circuit voltage (Voc) and short-circuit current (Isc), compared to the BC-TENGs fabricated via other routes. The results emphasize the significance of our preparation method that preserves the nanostructure of the BC and the direct attachment of the films on the substrate without using adhesive tapes. Our bio-TENGs exhibit the maximum Voc and Isc of 57.6 V and 5.78 μA, and the maximum power density of 42 mW/m2 when matched with an external load. The results from the triboelectric measurements were supported by several characterization techniques to confirm the phase formation, morphology, functional group, thermal stability, and hydrophobicity/hydrophilicity.