Triboelectric generators made of mechanically robust PVDF films as self-powered autonomous sensors for wireless transmission based remote security systems

Abstract

In this study, we report on the development of triboelectric energy generators (TEGs) made of porous polyvinylidene fluoride (PVDF) and bacterial cellulose (BC) layers and their demonstration as a self-powered sensor for remote security applications. PVDF films are fabricated by room temperature solution casting at different relative humidity (RH) with denser, stronger, and transparent PVDF films obtained at lower relative humidity. Among all the PVDF film based TEGs, the triboelectric generator (TEG) made of the film prepared at a low relative humidity of 10% (PVDF10) shows the highest voltage, current and power density of 410 V, 14.8 μA (current density: 0.57 μA cm⁻²) and 3.5 mW, respectively and a maximum power density of 0.136 mW cm⁻² at 33 MΩ. Enhancement in the value of power density is almost three-fold as compared to that of the PVDF film cast at a high relative humidity of 54% (PVDF54). The high output response of the PVDF10 based TEG is attributed to the rough surface, higher γ-phase fraction, and high dielectric constant of the PVDF10 film. Finally, the potential of a TEG device for practical application in biomechanical energy harvesting is demonstrated by lighting up more than 100 light-emitting diodes using a low-frequency foot strike as a mechanical stimulus along with lighting up of a 5-bit 7 segment LCD display. The device was also used as a self-powered motion sensor for application in wireless security, which could be practically realistic. Overall, the study demonstrates the possible applications of PVDF thin film based TEG devices, which can be fabricated using an easy, room temperature, and environment-friendly processing method.