Optimization of a circular piezoelectric bimorph for a micropump driver

Piezoelectric bimorph actuation has been successfully used in numerous type s of microdevices, most notably micropumps. However, even for the simple ca se of circular geometry, analytical treatments are severely limited. This s tudy utilized the finite-element method to optimize the deflection of a cir cular bimorph consisting of a single piezoelectric actuator, bonding materi al and elastic plate of finite dimensions. Optimum actuator dimensions were determined for given plate dimensions, actuator-to-plate stiffness ratio a nd bonding layer thickness. Dimensional analysis was used to present the re sults for fixed- and pinned-edge conditions in a generalized form for use a s a design tool. For an optimally-thick actuator, the optimum actuator-to-p late radius ratio ranged from 0.81 to 1.0, and was independent of the Young 's modulus ratio. For thin plates, a bonding layer minimally affected the o ptimum dimensions. The optimized actuator dimensions based on a model of an actual device were within 13% of the fixed-edge condition.