Direct-Current Rotary-Tubular Triboelectric Nanogenerators Based on Liquid-Dielectrics Contact for Sustainable Energy Harvesting and Chemical Composition Analysis

Ambient mechanical energy harvesting technology introduces a promising solution to alleviate expanding energy demands on a sustainable basis, of which the drawbacks should attract attention for further advances. In this work, a liquid-dielectrics interface based triboelectric nanogenerator (TENG) with direct-current output is reported as an energy harvester and a chemical sensor, with advantages of feasible fabrication, anti-wearing durability, and low energy consumption. The TENG consisting of an fluorinated ethylene propylene (FEP) tube and Cu electrodes is designed into a ring structure, with two electric brushes bilaterally anchored that converts an alternating-current output into direct-current output. The liquids and copper pellets as the fluid-state dielectrics are prefilled to generate triboelectric charges with an FEP tube. The relevant parameters of TENG are initially optimized, enabling a satisfactory output under rotating excitations. Furthermore, the inherent impacts of various liquids on the output performance of TENG are comprehensively studied, based on which chemical analysis system is developed. Meanwhile, the design for TENG with pellets is also modified for output-current enhancement. Finally, an assembled TENG has been demonstrated not only for energy harvesting without rectification but also for chemical detecting in liquid composition and moisture content analysis. The proposed TENG renders a more-efficient method for energy harvesting and greatly expands its application in direct-current self-powered systems.