The word “piezo” is derived from the Greek word piezein, meaning “to press tightly”. Piezoelectricity is the ability of a material to convert mechanical energy (pressing) into electric energy (polarization) and vice versa. The direct piezoelectric effect is the generation of electric polarization in response to an applied stress. The directionality and the magnitude of polarization is proportional to the stress applied, and the polarization can have components in the parallel and perpendicular directions. The opposite phenomenon, the inverse piezoelectric effect, is the generation of a mechanical deformation in response to an applied electrical field.
