Polarization-free high-crystallization ß-PVDF piezoelectric nanogenerator toward self-powered 3D acceleration sensor

The strong piezoelectric lead zirconate titanate (PZT) ceramic with inherent brittleness and highly tough Poly (vinylidene fluoride) (PVDF) polymer with intrinsic weak piezoelectricity cannot simultaneously fulfill the requirements of high sensitivity and excellent stability as a piezoelectric acceleration sensor in extreme service environments, such as intense impact. Here, we developed a polarization-free high-crystallization ss-PVDF (h ss-PVDF) based piezoelectric nanogenerator (PENG) as acceleration sensor with high sensitivity (2.405 nA s(2) m(-1)) and excellent stability (97% remaining after 10000 cycles). Fundamentally, the excellent performance benefits from the PVDF by high-pressure melt crystallization with a high ss-phase crystallinity of 86.48%, indicative of the enhanced piezoelectricity (high short-circuit current density of 145 nA cm(-2)). With integration of PENGs in three axes, the self-powered 3D acceleration sensor is developed for vector acceleration measurement in any directions. Moreover, a dynamic 3D frequency and acceleration sensor system is targetedly applied to cooperate the acceleration sensor for real-time collision monitoring and alert signal transmission, which presents a significant step toward vehicle safety monitoring. Therefore, we believe this easy process of h ss-PVDF and device has potential for commercial production in the field of transportation, self-powered devices, and energy harvesting.