Optimal materials selection for bimaterial piezoelectric microactuators

Piezoelectric actuation is one of the commonly employed actuation schemes in microsystems. This paper focuses on identifying and ranking promising active material/substrate combinations for bimaterial piezoelectric (BPE) microactuators based on their performance. The mechanics of BPE structures following simple beam theory assumptions available in the literature are applied to evolve critical performance metrics which govern the materials selection process. Contours of equal performance are plotted in the domain of the governing piezoelectric material properties (d coefficients, elastic modulus, coupling factors and dielectric constants) for commonly employed substrates to identify optimal material combinations for various functional requirements. The influence of materials selection on the actuation efficiency, quality factor and the electromechanical impedance is also discussed. Selection of a suitable actuation mechanism for a boundary layer flow control application is illustrated by comparing the performance limits of BPE and bimaterial electrothermal actuators considering the constraints on the functional requirements imposed by the associated microfabrication routes.