Discharge patterns in three-layer ferroelectret systems with perforated polymer films

Ferroelectrets have attracted fundamental and applied research due to their large piezoelectric coefficients combined with mechanical flexibility and high compliance. Recently, it was demonstrated that dielectric barrier discharges (DBDs) inside the voids are necessary to generate large dipoles by means of bipolar charging of the internal void surfaces. In industry, polymer foams for ferroelectrets are often produced by stretching filler-loaded polymers under suitable conditions, which results in a broad distribution of void sizes.