Development of a piezoelectric resonator with in-plane displacement-amplification mechanism

A piezoelectric in-plane resonator with symmetrical oblique-beam amplification mechanism was analyzed and developed. The resonator is comprised of a piezoelectric-heterogeneous-bimorph beam in the middle and elastic oblique beams symmetrically distributed on both sides. Firstly, analytical model for its in-plan deformation was derived by combining elastic deformation of the oblique beams with electrostriction bending of the piezoelectric beam. Then geometric parameters of the whole structure were optimized mainly based on the analytical model to obtain the maximum output horizontal displacement. Besides, its finite element model was simulated and analyzed to verify the analytical model, and find the optimal operating mode, at which the significant amplified horizontal displacement is generated with suppressed vertical one. The resonator was fabricated on a SOI wafer with deposited PNZT piezoelectric film. The fabricated resonator was characterized and tested. Its optimal operating mode was verified and the operating frequency was measured as 16.57 kHz with in-plan displacement of 7.71 μm under 20V_p-p driving signal. The device obtained significant in-plane resonance with almost no out-of-plane displacement.