Polymer-assisted dispersion of reduced graphene oxide in electrospun polyvinylidene fluoride nanofibers for enhanced piezoelectric monitoring of human body movement

Electrospun graphene oxide (GO)/polyvinylidene difluoride (PVDF) and reduced graphene oxide (rGO)/PVDF piezoelectric hybrid nanofibers were prepared via electrospinning to enhance the beta-phase content of the PVDF crystal structure. The addition of rGO increased the number of nucleation sites in the PVDF matrix, leading to an improved beta-phase content in the nanofibers. Although the inclusion of GO also increased the beta-phase content, rGO addition resulted in higher output voltages due to its greater conductivity compared to GO. rGO/PVDF produced higher output voltages than GO/PVDF because rGO has few oxygen-containing groups on its carbon atoms. The 1 wt% GO/PVDF nanofibers exhibited an 86.24 % beta-phase content and an average output voltage of 3.2 V under a 15 N load. The 0.5 wt% rGO/PVDF nanofibers demonstrated an 84.09 % beta-phase content and an average output voltage of 3.66 V under the same load. The nonionic surfactant Triton X-100 improved rGO dispersal, enhancing its effectiveness in inducing beta-phase formation, and increasing the number of stress concentration points in the nanofibers. A piezoelectric device composed of TX-100/rGO/PVDF nanofibers exhibited stable performance even after 1,500 load cycles, generating an average output voltage of 7.13 V under a 15 N load. This device serves as both an energy harvester and a footwear sensor, offering potential applications in new sports monitoring technologies and self-powered wearables.