Natural bioproducts’ hybridization creates transient dynamic electret nanogenerators

Abstract

Breakthroughs in transient electronic materials are key to advancing the state of the art in transient electronics. Here, we use a remarkable combination of two natural bioproducts, microbial polyhydroxybutyrate (PHB) and sulfonated cellulose nanocrystals (S-CNCs), to develop a novel class of transient dynamic electrets via electrospinning. They are in the form of free-standing thin films consisting of highly aligned S-CNCs/PHB-based electret fibers. In the electret fibers, the charged S-CNCs fill the voids of PHB and serve as a new type of artificial macro-dipole. Meanwhile, the charged S-CNCs allow a large-scale preferential orientation of piezoelectric phase PHB crystals. The synergistic action of dynamically active S-CNC macro-dipoles and inherent highly oriented PHB micro-dipoles further enables a significant piezoelectric output of the S-CNCs/PHB-based poling-free electret fibers. The measured piezoelectric output of a self-poled S-CNCs/PHB electret fiber-based nanogenerator is about 5 times higher than that of a state-of-the-art PHB fiber-based nanogenerator. Moreover, the S-CNCs/PHB electret fiber-based nanogenerator as a flexible piezoelectric sensor demonstrates ultrahigh sensitivity in real-time monitoring of subtle human physiology and small changes in an external environment. It possesses the ability for acoustics pattern identification. In particular, it shows considerable potential for application in smart sports training. We believe that the S-CNCs/PHB-based dynamic electrets can be promising constituent materials for developing a new generation of eco-friendly transient power sources.