Charged polymer foams represent a new class of piezoelectric transducer materials. These so-called ferroelectrets often exhibit good piezoelectric properties. Thickness changes of electrically charged voids which also represent large macroscopic electric dipoles either lead to or are caused by electric signals. The softness and the internal charge yield strong piezoelectricity up to hundreds of pC/N or pm/V that can be employed in sensors or actuators, respectively. On readily available cellular polypropylene, various aspects such as the preparation of suitably voided thin films, their charging as well as their possible use in various transducers have been investigated in detail.
展开▼
