Parylene-based electret power generators

Abstract

An electret power generator is developed using a new electret made of a charged parylene HTR � thin-film polymer. Here, parylene HTR � is a room-temperature chemical-vapor-deposited thin-film polymer that is MEMS and CMOS compatible. With corona charge implantation, the surface charge density of parylene HTR � is measured as high as 3.69 mC m−2. Moreover, it is found that, with annealing at 400 ◦C for 1 h before charge implantation, both the long-term stability and the high-temperature reliability of the electret are improved. For the generator, a new design of the stator/rotor is also developed. The new micro electret generator does not require any sophisticated gap-controlling structure such as tethers. With the conformal coating capability of parylene HTR � , it is also feasible to have the electret on the rotors, which is made of either a piece of metal or an insulator. The maximum power output, 17.98 μW, is obtained at 50 Hz with an external load of 80 M� . For low frequencies, the generator can harvest 7.7 μW at 10 Hz and 8.23 μ Wa t 20 Hz. (Some figures in this article are in colour only in the electronic version)