Boosting piezoelectric and triboelectric effects of PVDF nanofiber through carbon-coated piezoelectric nanoparticles for highly sensitive wearable sensors

Piezoelectric and triboelectric effects are vital mechanisms in motion sensing. Improving both the piezoelectric performance and triboelectric effect for a single material is an important approach to further improve the sensitivity of the sensor. Herein, we achieve the enhancement of both effects in electrospun polyvinylidene fluoride (PVDF) nanofiber by simply adding carbon-coated zinc oxide (ZnO@C) nanoparticles as additive. We found that ZnO@C can not only increase the β-phase in PVDF, resulting in an enhanced piezoelectric coefficient. It also negatively shifted the surface potential of PVDF to a high value of −740 mV, thereby modifying the triboelectric effect. The fabricated ZnO@C/PVDF nanogenerator exhibits 4 times enhancement in the voltage output, thus resulting in high sensitivity of 0.98 V kPa−1 when used as wearable sensors. Due to the good mechanical properties of nanofibers, we also demonstrated the application of ZnO@C/PVDF nanogenerator as body motion sensor with excellent deformation stability. Therefore, adding carbon-coated piezoelectric nanoparticles provides an effective approach to simultaneously enhance the piezoelectric and triboelectric effects of ferroelectric polymer for highly sensitive wearable sensors.