Ultrasound Imaging with Pre-charged Collapse-Mode CMUTs

Abstract

Capacitive micromachined ultrasonic transducers (CMUTs) with a built-in charge layer are known as a pre-charged CMUT. In our prior work, we have shown how to model and characterize the charges inside the precharged collapse-mode CMUT and conducted life-time test that showed that the charges trapped inside the dielectric were stable in the order of years [1]. However, our prior work focused on the use of pre-charged collapse-mode CMUTs as a way to achieve ultrasound power reception, which does not require the CMUT to be actively driven. In this work, for the first time we use pre-charged collapse-mode CMUTs with an Al2O3 charge-trapping layer to create a B-mode ultrasound image. Thus, this work shows the first example that precharged collapse-mode CMUTs can fully operate with only an AC voltage.