Liquid-tolerant electret using super-lyophobic pillar surface

For the first time, we have realized electret that can be used in the liquid environment toward better performance of electret-based generators and actuators. By using super-lyophobic overhanging pillar surface, stable Cassie-Baxter (C-B) state is sustained even with low-surface-tension hexadecane liquid and with high surface potential. Pillar surface with a SiO₂ electret layer has been successfully charged with soft X-ray photoionization we previously developed. The pillar surface significantly suppressed the charge decay, and surface potential as high as 160 V has been maintained after 5-day contact with hexadecane droplet.