We report observation of the giant direct flexoelectric effect in α-phase polyvinylidene fluoride (PVDF) films. This unexpected phenomenon was detected in the α-phase PVDF film undergoing elastic tensile stretching. Our results have shown that the physical mechanism behind the flexoelectricity in polymers might be more complicated than the one proposed for solid crystalline dielectrics.

The relationship between the applied elastic strain gradient and the induced electric polarization in the α-phase polyvinylidene fluoride (PVDF) films under bending conditions has been investigated. Our experimental studies have shown that the flexoelectric polarization is linearly proportional to the strain gradient and the corresponding direct flexoelectric response is strong. It is reasonable to believe that the physical mechanisms behind the flexoelectric effects in polymers and solid dielectrics are different.

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Harvesting waste energy through electromechanical coupling in practical devices requires combining device design with the development of synthetic strategies for large-area controlled fabrication of active piezoelectric materials. Here, we show a facile route to the large-area fabrication of ZnO nanostructured arrays using commodity galvanized steel as the Zn precursor as well as the substrate. The ZnO nanowires are further integrated within a device construct and the effective piezoelectric response is deduced based on a novel experimental approach involving induction of stress in the nanowires through pressure wave propagation along with phase-selective lock-in detection of the induced current. The robust methodology for measurement of the effective piezoelectric coefficient developed here allows for interrogation of piezoelectric functionality for the entire substrate under bending-type deformation of the ZnO nanowires.

The empirical Coffin-Manson law has been used to characterize the low-cycle mechanical fatigue failure of metallic materials for decades. Our experimental studies reported in this letter have shown that the electrical fatigue failure in dielectrics can be well described by a fitting function having the same mathematical expression as that of the Coffin-Manson law. This observation indicates that the physical mechanism beneath the formation and evolution of atomic disordered structures, the key factor influencing both mechanical and electrical fatigue, might be the same.