Enhancement of Electret Charge Retention

Electrets are polymeric materials which can retain the electrostatic charge for long time. They have many applications such as microphones, filters and energy harvesters. High charge retention is required to enhance their use in the aforementioned areas. However, it is known that electret exposure in organic solvents or high relative humidity could detrimentally affect charge retention. A possible mechanism that can attribute to this behaviour is the increase of charge mobility due to the vapour condensation on the electret which leads to the swelling of the polymer.

We have setup a system to charge the polymeric materials and monitor their discharge online (Figure below). We study the charging mechanism which affects the charge retention properties due to the different natures of charge carriers. Electrets are charged with various mechanisms and a possible link among the charging mechanism, filter properties, and electret performance is investigated.