Flexible piezoelectric generator based on PLLA/ZnO oriented fibers for wearable self-powered sensing

Herein, PLLA/ZnO oriented fibers were prepared via orientation electrospinning towards a piezoelectric generator, omitting polarization and stretching postprocesses. The composite fibers achieved macroscopic orientation and molecular alignment, as well as higher crystallinity and more polar phase for PLLA. Collectively, the resulting generator exhibited dramatic and stable piezoelectric signals over 1000 s, boosting the open-circuit voltage to 7.9 V, nearly 4.6 times larger than that of the random neat device. With the same changing tendency, the simulated results confirmed oriented fibers and ZnO induced stress concentration, imparting better piezoelectricity. Furthermore, the generated electricity from the generator with a short-circuit current of 286nA and an output power density of 1.25 mW cm−3 charged a 10 μF capacitor up to 2 V at 210 s then illuminated a LED. Encouragingly, high flexibility and sensitivity allowed this device to function as a wearable self-powered sensor for differentiating human movement and monitoring human health.