Non-contact gravitational energy harvesting from solid spheres using a two-stage triboelectric nanogenerator

Abstract

Off-grid connected objects are widely used for environmental monitoring applications such as air and water quality, soil salinity, weather forecasting and more. In recent studies, mechanical energy harvesting using triboelectric nanogenerators (TENGs) have gained in efficiency, even though the design of these TENGs was kept simple. In this context, the durability of the mechanical contact between triboelectric materials is challenged. This is why, free-standing balls have been proposed to reduce the friction in TENGs instead of foils, which are commonly used. Thus, a non-contact gravitational TENG at state-of-the-art performances is proposed in this work. This two-stage design is based on free-standing balls in a rotor and a contactless capacitive coupler. The power generation has been investigated for these two stages according to analytical models. A new methodology to extract the Norton model parameters from a moving TENG is suggested. Through an optimized interdigitated design of the capacitive coupler, a 27-fold increase of the primary stage power is demonstrated and a state-of-the-art peak output power density of 24.45 W m−2 is reached. This study is a leading-edge example of how TENGs could be adopted to power small remote apparatus, in addition of battery.