Viscous Damping Effect on the CMUT Device in Air

摘要

Acoustic damping of a capacitive micromachined ultrasonic transducer (CMUT) having a perforated circular membrane in air causes mechanical impedance to the plate vibration. We observed the effect of acoustic damping on the operation of the perforated membrane plate of a CMUT under various geometrical conditions. The damping force of the perforated plate was computed for each area ratio of the acoustic holes (AR) condition; and the results were introduced into calculations of the frequency response function (FRF) using the finite element method (FEM) to take the squeeze-film damping effect into account. The Q factor and the damping ratio of the CMUT under various AR and air-gap height (h) conditions of the device were studied; the acoustic damping effect is discussed in terms of design optimization.