Electret charging method based on X-ray photoionization for MEMS applications

A novel electret charging method using soft X-ray irradiation is proposed for MEMS applications. It is found that the charging principle is actually based on the photoionization of gas molecules, and the charging time is minimized with Xe as the process gas. In addition, the charged electret has good thermal stability, showing that the present charging method can be applicable to various MEMS electret transducers.