A flexible piezoelectric generator based on KNN/PVDF composite films: Role of KNN concentration on the piezoelectric performance of generator

In the present work, a high output piezoelectric generator (PEG) based on Potassium Sodium Niobate/Poly (vinylidene fluoride) (KNN/PVDF) flexible composite films with various percentages of KNN ceramic particles (0%, 5%, 10%, 15% and 20% on the weight of the polymer) were constructed. The phase analysis of the prepared pure PVDF and composite films was done by X-Ray diffraction and Fourier Transform Infrared spectroscopy. The microstructure of the prepared composite films was investigated by Scanning Electron Microscope (SEM). Significant influence of the KNN ceramic particles concentration in the PVDF matrix was observed on various properties. When force was applied on the surface of the fabricated PEG device, maximum open-circuit voltage of 11.2 V and short-circuit current of 0.3 μA were obtained for the device prepared with 15 wt.% KNN in the PVDF. Finally, the practical applicability of the fabricated PEG device was demonstrated by placing it on elbow and on the finger joint for monitoring human body motion, which shows a maximum voltage of 0.7 V (for elbow) and 0.64 V (for finger) by bending and stretching. Overall, the obtained results for developed flexible PEG suggest their considerable potential to be used in self-powered and wearable devices.