An Electret Energy Harvester for Kinetic Energy at Ultra-Low Frequency

This paper proposes an electret energy harvester based on an inertial rotating structure to collect ultra-low frequency kinetic energy. The harvester can convert the low-frequency linear motion into the high-speed rotational motion to improve the power output. The main affecting factors on output performance have also been investigated, such as excitation frequency, pressing velocity, and number of fan-shaped blades. At 1 Hz excitation frequency and 250 mm/s pressing velocity, the harvester with 10 blades can generate an average output power of $146.8\ \mu \mathrm{W}$ and a normalized power density of $8.3\ \mu \mathrm{W}/\text{cm}^{2}$ . Finally, a self-powered wireless sensing system based on the energy harvester has been successfully demonstrated.