Revisiting δ-PVDF based piezoelectric nanogenerator for self-powered pressure mapping sensor

δ-phase comprising polyvinylidene fluoride (PVDF) nanoparticles are fabricated through an electrospray technique by applying a 0.1 MV/m electric field, which is 103 times lower than the typical value, required for δ-phase transformation. X-ray diffraction and selected area electron diffraction patterns clearly indicate the δ-phase formation that limits the infrared vibrational spectroscopic technique due to identical molecular chain conformations to that of non-polar α-phase. The piezo- and ferro-electric response of δ-PVDF nanoparticles have been demonstrated through a scanning probe microscopic technique based on piezoresponse force microscopy. The localized piezoelectric response, indicated by d33 coefficient, is found to be ∼−11 pm/V. To utilize the distinct electromechanical response of δ-PVDF nanoparticles, the piezoelectric nanogenerator (PNG) has been fabricated. Due to the stress confinement effect in the spherical shape of δ-PVDF nanoparticles, the PNG exhibits synergistic effect than that of the film-based counterpart. The maximum power, i.e., 930 μW/m2 determined by the PNG under ∼4.5 N of periodic force impact, indicates the potential to use it as a self-powered sensor. As a proof of concept, a self-powered pressure sensor mapping has been demonstrated for representing its realistic technological applicability.