High-Performance Dual-Mode Triboelectric Nanogenerator Based on Hierarchical Auxetic Structure

High-performance stretchable triboelectric nanogenerators (STENGs) based on hierarchical auxetic films consisting of polyurethane (PU) foam and Ag electrode layers were fabricated. The high conformability and stretchability of the STENGs enable the dual-mode operation in both contact–separation and stretching–releasing modes. Compared with STENG devices with a single operation mode, our dual-mode STENG exhibits a high output voltage of 320 V and a current of 45 μA with an instantaneous output power density of 3 mW. The working principles of dual-mode STENG and the relationships between its output performance and the various types of mechanical motions were systematically studied, providing a working mode of STENGs for various practical applications. The high output power generation from dual-mode STENG can be used to operate light-emitting diodes and charge a wearable electronic device. The proposed energy harvester offers a promising way to provide power sources for micropower systems, stretchable electronics, and self-powered biomechanical sensors.