Finite element modeling analysis of photostrictively driven optical actuators for excitation of microdevices

Photostriction is a phenomenon in which strain is induced in the sample by incident light. In principle, this effect arises from a superposition of the photovoltaic effect, i.e.the generation of large voltage from the irradiation of light, and the converse piezoelectric effect, i.e.expansion or contraction under the voltage applied. Photostrictive materials are ferrodielectric ceramics that have a photostrictive effect. Some photostrictive materials are (Pb, La)(Zr, Ti) O₃ ceramics doped with WO₃, called PLZT, which exhibit large photostriction under uniform illumination with high-energy light. They have potential use in numerous micro-electro-mechanical system (MEMS) devices where actuation of microbeams is a common phenomenon. The objective of this research is to develop and analyze a finite element model to study the feasibility of photostrictively driven actuators for excitation of microdevices. Much work has been carried out toward developing microdevices which are capacitively driven or piezoelectrically driven. The effect of different parameters such as actuator thickness, incident light intensity and convective heat transfer coefficient on the actuation of a beam using thin film photostrictive actuators has been investigated. Also the derived finite element for static analysis of photostrictive thin films has been used to investigate the application of photostrictive actuators for different structures and various boundary conditions of microbeams with various actuator locations and lengths. A successful conclusion of these tasks will affirm the potential of the technology for use in actual microdevices.