A pendulum hybrid generator for water wave energy harvesting and hydrophone-based wireless sensing

The environmental monitoring system is of great significance in marine scientific research and exploration. However, battery-operated sensors in such a system limit its working time and make maintenance difficult. Harvesting water wave energy to power these sensors becomes a promising way to overcome challenges. Herein, a pendulum type hybrid generator to scavenge wave energy and power the hydrophone is presented. The proposed pendulum structure can harvest random water wave energy from arbitrary directions sensitively. The combination of a freely rolling mode triboelectric nanogenerator (TENG) and a magnetic sphere based electromagnetic generator (EMG) provides complementary advantages and harvests wave energy in a wide frequency range. The hybrid generator is demonstrated to drive 177 LEDs and power an electronic device. At a wave driving frequency of 1.4 Hz, the output power of the EMG and TENG is 6.7 mW and 8.01 µW, respectively. A capacitor can be charged to 26 V by the hybridized generator within 200 seconds at the frequency of 1.8 Hz. The new type of hydrophone-based system realizes sustainable wireless sensing of acoustic signals and positioning information and has important application value for long-term synchronous ocean monitoring.