Piezoelectric 0.72 Pb(Zr0.47Ti0.53)O-3-0.28 Pb[(Zn0.45Ni0.55)(1/3)Nb-2/3]O-3 + 0.5 mol% CuO (PNNC) particles were made for use in a composite of flexible energy harvester (FEH) that can convert sustainable mechanical deformation into electrical energy. The PNNC particles with a high transduction coefficient (d33 x g33) were mixed with polydimethylsiloxane (PDMS) matrix to produce the FEH. The FEH generated maximum output voltage of 55.24 V and current density of 2.76 mu A/cm(2) (power density: 554 mu W/cm(3), 3.2 mW) at the resonance frequency of 11?Hz. The energy conversion efficiency of about 20.7% has been achieved. The developed energy harvester is demonstrated in the self-powered wireless sensor node application in which the FEH spontaneously generated stable power under continuous mechanical stress. (C) 2018 Elsevier Ltd. All rights reserved.