Optimization of a circular piezoelectric micro-mechanical ultrasonic transducer on electromechanical coupling coefficient

Optimization for a piezoelectric micromachined ultrasonic transducer on electromechanical coupling coefficient is investigated theoretically. The transducer is composed of (Au/Cr)/PZT/(Au/Cr)/Ti(Adhesive)/Si/SiO₂/Si multimorph, while titanium is used as adhesive layer, (Au/Cr) as the electrodes,PZT as exciting element, Si as substrate material. A theoretical model of a circular thin-film piezoelectric actuator on a clamped elastic plate is cited to predict the performance of piezoelectric micromachined ultrasonic transducer. The model is used to explore the effect of design and process parameters, such as Si thickness, PZT thickness and adhesive thickness, on the electromechanical coupling coefficient. The results show that an optimum ratio of PZT to Si thickness can be found to achieve the maximum coupling coefficient. The results can be used to form a set of design guidelines for the performance optimization of piezoelectric micromachined ultrasonic transducer.