Biocompatible CaTiO₃-PVDF composite-based piezoelectric nanogenerator for exercise evaluation and energy harvesting

Biocompatible energy-harvesting platforms can significantly promote the development of self-powered devices to improve the human lifestyle. However, the low power of these devices is a bottleneck and requires an alternative power source. Herein, we have developed calcium titanate (CTO) perovskite-based polymeric composite (polyvinylidene fluoride (PVDF)) as a piezoelectric nanogenerator (PENG) to be used as a power source. X-ray tomography images confirm that CTO particles are well dispersed inside the PVDF matrix. It is realized that the electrical output of the device increases with the addition of CTO in PVDF. The maximum device performance was observed for 8 wt. % CTO-PVDF composite film with an output voltage of 20 V, current of 250 nA, and power density of 0.19 μW/cm² at 10⁸ Ω. The PENG delivered a consistent output and could charge commercial capacitors demonstrating its potential as a sustainable power source. Moreover, the biocompatibility of CTO-PVDF film was validated by NIH3T3 cells. The CTO-PVDF composite-based PENG device was installed in the heel area to collect the signal generated from the skipping practice of individuals. The digital signal processing techniques and the artificial neural network (ANN) were utilized to detect the skipping patterns. Such a self-powered activity tracker unit will correctly monitor human health, preventing severe chronic conditions such as knee pain, calf strain, and plantar fasciitis.