Long-Lasting and Steady Triboelectric Energy Harvesting from Low-Frequency Irregular Motions Using Escapement Mechanism

Most mechanical energy harvesters produce only small amounts of electrical power from extremely low-frequency input motions and immediately stop generating electricity when mechanical kinetic energy is exhausted. Here, a steady, long-lasting and power-boosted triboelectric nanogenerator is reported that can efficiently harvest from extremely low-frequency irregular motions of less than 0.1 Hz by utilizing an escapement mechanism and frequency up-conversion device. The escapement mechanism-based triboelectric nanogenerator (EM-TENG) consists of a mechanical energy storage spring, escapement mechanism and a torsional resonator for regular operation and frequency up-conversion. In addition, the micro-patterned alternating dielectric surfaces of Nylon and polytetrafluoroethylene (PTFE) and the comb-type rotator significantly improve the output performance of the rotational EM-TENG, increasing the current density level approximately 4.2 times compared to flat surfaces. Under an input frequency of 0.067 Hz, the EM-TENG produces an open circuit voltage of 320 V and a short-circuit current density of 0.59 mA m^-2. Most importantly, the EM-TENG can produce long-lasting and steady output power for 110 s (22 times) under only 5 s of input motion. Therefore, the EM-TENG might pave the way to effectively harvest energy from extremely low-frequency motions in nature, such as human motion, structural vibration and ocean waves.