We report work on a new type of ultrasonic transducers, Micromachined
Ultrasonic Air-Transducers, which offer a very promising alternative t
o piezo-electric transducers thanks to micromachining technology. Expe
riments show that very high frequency signals (11 MHz) can be emitted
and detected in air using MUTs. Theoretical explanation for the behavi
or of MUTs is proposed. It agrees well with experimental results. Opti
mization will eventually lead to exciting applications of MUTs in medi
cal imaging and non destructive evaluation.