Physics of electromechanically active, cellular materials

Cellular space-charge electrets have recently emerged as a new class of materials for electromechanical devices, offering chances for a wide range of applications and challenges for materials optimisation. However, many fundamental and applied aspects of the physics of these space-charge electrets are not yet fully explored. Here we summarise briefly our present understanding of the charging process and of the piezo- and pyroelectric response. In addition, wide-ranging similarities between cellular space-charge electrets and ferroelectric materials are outlined, especially switching of polarization and piezoelectricity.