Enhanced piezoelectric performance of multi-layered flexible polyvinylidene fluoride–BaTiO3–rGO films for monitoring human body motions

Poly(vinylidene fluoride) (PVDF)/Barium titanate (BaTiO3, BTO)/reduced graphene oxide (rGO) (BTO/PVDF/rGO) ternary flexible piezoelectric composite films were successfully prepared, and multi-layered PVDF/BTO/rGO composite piezoelectric nanogenerator (PNG) was also designed via layer-by-layer method. The maximum output value of the PVDF/BTO/rGO PNG achieves at 4-layered design when the rGO content is 0.5 wt%. The output voltage and current are 16.91 V, 3.53 µA, which is 18.9% and 45.9% higher than 4-layered PNGs without rGO, respectively. In addition, the relative dielectric constant was increased by 72.67% and the Pr was increased by 27.47% compared with the composite film without rGO. Finally, the feasibility of the practical application was verified by using composite PNG to charge the capacitor, and over 4000 cycles pressing-releasing test demonstrated its mechanical reliability and stability. Simple-structured and self-charged PNGs were performed onto a finger, wrist, elbow joints, and sole of foot, which suggested PNGs were successfully applied as potential platforms for distinctively monitoring a wide range of human body motions in real time. These promising features of PVDF/BTO/rGO flexible PNGs will promote potential applications in the fields of human movement monitoring, intelligent skin, and soft robotics.