The film electret has two times high piezoelectricity (d33=31pC/N) than PVDF (d33=1 5pC/N).

• 使用介电谐振谱测量的双层膜的压电d33系数(31pC/N)是传统的铁电聚合物材料PVDF相应值(15 pC/N)的2倍左右。