Electromechanical Properties of Smart Materials

A smart material is one that can perform both sensor and actuator functions. This definition allows for some flexibility in deciding how to qualify a material as "smart", since the fun damental mechanisms of operation may differ greatly between types of smart materials. From the point of view of an electroceramist, piezoelectric materials, which show reversible electromechan ical coupling, may be thought of as "naturally" smart materials since the same piezoelectric material may act as a sensor and/or an actuator. Piezoelectric single crystals, polymers, and poled poly crystalline ceramics all show good electromechanical coupling. In addition, they may be combined in a composite material that exaggerates their beneficial properties by eliminating their detrimental properties. Some common piezoelectric materials are reviewed, along with some examples of smart materials that incorporate piezoelectric ceramics.