A ferroelectret, also known as a piezoelectret, is a thin film of polymer foams, exhibiting piezoelectric and pyroelectric properties after electric charging.
Ferroelectret foams usually consist of a cellular polymer structure filled with air.
Their elastically soft composite structure is one essential key for the working principle of ferroelectrets, besides the permanent trapping of electric charges inside the polymer voids.
In the new polymer systems, the required cavities are formed by means of e.g. stamps, templates, laser cutting, etc.
Thermo-forming of layer systems from electret films led to thermally more stable ferroelectrets.