Modeling and theoretical characterization of circular pMUT for immersion applications

This paper reported modeling and theoretical characterization of circular piezoelectric micromachined ultrasonic transducer (pMUT) for immersion applications. Zinc oxide (ZnO) was employed as piezo active material and nickel aluminum bronze alloy UNS C63000 (CuAl₁₀Ni₅Fe₄) also known as “sea bronze”, was introduced as electrodes. First, virtual fabrication process was carried out within software environment to form a pMUT model. Then, resonance frequency of the model was finalized and fine tuned by manipulating its structural parameters which are diaphragm diameter and piezo active layer thickness. Next, receiving and transmitting responses were estimated using finite element approach through the combination of piezoelectric analysis and modal analysis. From these analyses, the pMUT model having a resonance frequency of 40.82 kHz was successfully modeled. Transmitting response was estimated at 137 dB (re 1 μPa/V) at 41 kHz on the surface of the transducer while the receiving response was estimated at - 93 dB (re 1 V/μPa) at 38 kHz of frequency. Virtual fabrication process and finite element analysis for model performances estimation have proved to reduce the development time. From the comparison made, the usage of sea bronze and ZnO film replacing conventional gold, platinum and lead zirconate titanate (PZT) were proven to deliver exceptional performances with better durability. However, device fabrication is essential in order to validate the findings and this will be included in our future works. Furthermore, the model needs to be extended so that the value of acoustic impedance within the device can be estimated.