Characterization of cMuts in rarefied gases.

The performance of capacitive micromachined ultrasonic transducers (cMUTs) was investigated at low pressures in various gases such as air, carbon dioxide, and helium. The aim was to replicate the pressure conditions likely to meet on the surface of other planets such as Mars, where ultrasonic wind velocity measurements might be possible. It is demonstrated that cMUTs are capable of operating at low pressures, and the response to pressures below terrestrial atmospheric values is observed experimentally and compared to theoretical predictions.

Radiated fields of capacitive micromachined ultrasonic transducers in air.

This paper presents a study of the radiated ultrasonic fields of capacitive micromachined ultrasonic transducers (often referred to as cMUTs) in air. These fields were modeled theoretically and then compared to the experimental near-field amplitude variations and directivity patterns of square cMUTs. The good agreement between theory and experiment indicates that the devices can be approximated to plane piston radiators.