Piezoelectric in-plane microplate resonators based on contour and flexure-actuated modes

In this paper we present piezoelectric in-plane microresonators designed by two different approaches: contour mode-based plates, in which nearly the whole structure suffers considerable deformation; and flexure-actuated plates, in which a central plate with almost no deformation is moved by low-stiffness flexures that also support it. Two separated issues are considered in the analysis: the quality factor, especially critical when dealing with resonators immersed in liquid, and the piezoelectric and elastic characteristics, inherent to the geometry of the structure. Devices fabricated following both approaches are compared in these terms, concluding that contour mode-based resonators are more advantageous regarding both the quality factor in liquid and the piezo-elastic performance. Nevertheless, the flexure-actuated approach results more adequate when dealing with the design of actuators, i.e. when trying to maximize the ratio of the displacement achieved to the voltage applied.