Design, Modelling, and Simulation of PMUT Device for Ultrasound Imaging Applications.

In this work, a circular piezoelectric micromachined ultrasonic transducer (PMUT) suitable for ultrasound imaging applications has been designed, modelled, and simulated using COMSOL™. The PMUT device uses Aluminum Nitride (AlN) as the piezoelectric material for achieving optimal performance. The resonant frequency, membrane displacement, and pressure-induced voltages have been studied. Moreover, a comparative study of circular, square and hexagonal geometries was also carried out to evaluate their impact on the eigenfrequency. Further, parametric sweeps are performed to study the influence of the radius and thickness of the piezoelectric layer on device performance. In addition, device performance was compared with Lead Zirconate Titanate (PZT) as the piezoelectric material. The simulation results show a resonant frequency of 7.7511 MHz and a maximum membrane displacement of 0.228 µm at the resonant frequency, while pressure-induced voltage reaches 0.292 V/mN. The parametric studies show that resonant frequency decreases when increasing the radius of the diaphragm while it increases when the piezoelectric layer’s thickness increases. Moreover, the resonant frequency of AlN-PMUT was higher than PZT-PMUT for various geometries. The results have been verified using an analytical model developed on MATLAB™.