Ring-shaped PZT film resonator for bio-sensing applications in liquid environment

This work reports a novel design of a ring-shaped PZT film resonator for bio-sensing applications in liquid environment. The ring-shaped resonator reacts with a mass perturbation to provide eigenstate (frequency) shifts which could transfer to electrical signals by piezoelectric effect of PZT. The aforementioned resonator is mainly comprised with a multilayer of Pt/Ti/PZT/Pt/Ti/SiO ₂ deposited on the silicon-on-insulator (SOI) wafer and expected to be used at a contour mode. In order to estimate the sensitivity of the ring-shaped resonator against the mass perturbation, the theoretical analysis was conducted by ANSYS from two aspects including: a) the view point of geometrical design and b) the mass application methodology. When a mass perturbation (i.e., a liquid droplet) of 10 ng is homogeneously contacting on the top insulation layer of the resonator, frequency shifts from 2.11 to 4.07 kHz could be obtained when excited in the contour mode.