Accurate evaluation of the electro-mechanical and parasitic parameters of CMUTs through electrical impedance characterization

Electrical impedance characterization is often used to evaluate the electro-mechanical parameters of Capacitive Micromachined Ultrasonic Transducers (CMUTs). Evaluation is achieved by fitting the measured data with simple equivalent circuit models, which do not account for many parasitic phenomena. Such parasitic phenomena may include resistive and inductive behavior of electrical interconnections, stray capacitance, and dielectric loss of the insulating materials used in CMUT microfabrication. In this paper, we propose an accurate CMUT characterization method, based on an improved equivalent circuit model, able to evaluate the electro-mechanical and parasitic parameters starting from electrical impedance measurements at several bias voltages.