SOI Mass-Sensitive Microresonators with Off-Chip Piezoelectric Excitation by PZT Thick Films

A hybrid system composed by a resonant piezo layer (RPL) and a SOI microelectromechanical system is conceived in this work as highly sensitive mass sensitive sensor for applications in various fields. The idea consists in using PZT screen-printed elements, behaving as thickness-mode resonators to induce oscillations to the micromechanical device and, if the resonance condition is matched for this latter system, a sensitivity of about 400 Hz/mug can be obtained when variation of the proof mass occurs. Prototypes of both the mentioned two constitutive parts have been separately realized by the authors showing potentials for batch production. Poly silicon strain gauges embedded into the beams, supporting a suspended silicon mass, allow exploitation of electrical signals for the realization of a closed loop configuration as conditioning circuits for the realized prototypes