Biocompatible, breathable and degradable microbial cellulose based triboelectric nanogenerator for wearable transient electronics

Advances in the processing of natural biomaterials have brought to the fore new approaches for the development of biofriendly and sustainable triboelectric nanogenerators (TENGs). In particular, bacterial cellulose (BC)-based TENGs have attracted considerable attention even though they still lack the key combination for transient wearable electronics. Herein, we report on a novel and facile method for in situ chemical modification of BC for the fabrication of degradable, breathable and biocompatible triboelectric nanogenerators (TENG). To achieve that, nanocoatings of polydopamine, polypyrrole or SiO2 have been used to decorate BC nanofibrils and thus tune the surface potential of the BC layer. Such a modification enables the repositioning of BC in the triboelectric series, allowing for the fabrication of various BC-based TENG devices. Polydopamine based BC TENG is found to exhibit superior performance (when coupled with a PVDF as negative triboelectric) with a maximum output voltage of -1010 V and a power density of -8.7 W/m2, a 7-fold enhancement in the power density as compared to pristine BC (VOC = 530 V and Pout = 1.1 W/m2). It is worthmentioning that all the nanocoated-BC films are found to be breathable, bio-/hemo-compatible and degradable, fulfilling the main criteria for transient electronics. As a proof of concept, we also demonstrate an on-body biomechanical energy harvester based on a single electrode All-BC TENG with the capability to generate an output voltage of 40 V upon physical motion. This TENG technology provides a unique combination of properties and has the potential to be implemented in wearables electronics and in vivo applications.