Electrospun flexible PVDF/GO piezoelectric pressure sensor for human joint monitoring

In this paper, the piezoelectric pressure sensor (PPS) with a sandwich structure for human joint monitoring was prepared by electrospun poly (vinylidene fluoride) (PVDF) membranes. The electrospinning method can transform the α-phase to β-phase in PVDF matrix effectively. The effects of Graphene oxide (GO) on the crystal structure, morphology, and piezoelectric performance of PVDF nanofibers were investigated. Results investigate that the presence of GO not only further increases the content of β-phase in PVDF nanofibers but also forms new conductive network among PVDF nanofibers, which are conducive to electron transmission, and the increase in the peak current in PVDF material. The PPS prepared with 0.5 wt% GO doped PVDF membranes possesses optimal piezoelectric properties and sensitivity. Under the impact force of 120 N, the maximum output voltage of the pressure sensor increases from 1.05 V to 4.93 V, the peak current increases from 60.02 nA to 190.17 nA, and the sensitivity was improved from 14.4 mV/N to 38.8 mV/N. In addition, as a real-time human joint monitoring device mounted in shoes or elbow joints, PPS also displays excellent electrical signal sensitivity that corresponds to different bending states. All results show that the PPS based on PVDF/GO membranes possesses high sensitivity and durability, and can detect the pressure change at the human joint or skin surface in real-time, indicating its wide application prospect in wearable electronic products such as personal sports evaluation.