Spray coating of polymer electret with nano particles for stable surface charge

In this paper, we have proposed a spray coating method for electret material deposition. With this method, the thickness of electret can be well controlled and the surface potential of the charged electret can be improved comparing to the traditional spin coated polymer electrets. Furthermore, we have added some polystyrene nano particles into the electret, which can improve the surface charge stability of the electret at high temperature or in high humidity environment. We have also confirmed that our new electret could be used in the energy harvesting devices and may have promising applications on other MEMS devices.