Photostrictive actuators using piezoelectric materials

Photostrictive materials, exhibiting light-induced strains, are of interest for future generation wireless remote control photo-actuators, micro-actuators, and micro-sensor applications. The photostrictive effect arises from a superposition of the 'bulk' photovoltaic effect, i.e. generation of large voltage from the irradiation of light, and the converse piezoelectric effect, i.e. expansion or contraction under the voltage applied. (Pb,La)(Zr,Ti) O₃ (PLZT) ceramics doped with WO₃ exhibit large photostriction under uniform illumination of near-ultraviolet light. Using a bimorph configuration, a photo-driven relay and a micro walking device have been demonstrated. However, for the fabrication of these devices, higher response speed must be achieved. This chapter first reviews the theoretical background of the photostrictive effect, then discusses enhanced performance through composition modification and sample preparation techniques (thickness and surface characteristics of the sample). Future applications of photostrictive actuators are briefly described.