High-performance flexible yarn for wearable piezoelectric nanogenerators

The development and popularity of wearable electronics increase demand for wearable energy harvesters that can scavenge energy from environment or human body movements. In this paper, we present a novel yarn as a wearable piezoelectric nanogenerator (PNG) consisting of a layer of electrospun poly(vinylidene fluoride) (PVDF) nanofibers integrated with PVDF film around a silver deposited nylon filament acting as an inner electrode. Electrospun PVDF nanofiber was wrapped around core yarn using a customized electrospinning device followed by coating of PVDF solution. The mesh of PVDF electrospun layer ensured uniform coating of PVDF solution, and the after coated PVDF film improved interfacial properties with inner electrode as well as strengthened the abrasion resistance of the piezoelectric polymer layer. The resultant unique yarn produced an average peak voltage of 0.52 V, peak current of 18.76 nA, and power density of 5.54 mu W cm(-3) under a cyclic compression of 0.02 MPa at 1.85 Hz, which is significantly higher than the energy output of a yarn with only a PVDF electrospun nanofibrous layer. More importantly, the high-performance was retained after 50 000 cycles of compression. The flexible yarn-based PNG device with good energy output and durability demonstrated its great promise to be used as a wearable energy harvester.