SURFACE MICROMACHINED CAPACITIVE ULTRASONIC TRANSDUCERS

The current state of a novel technology, surface microfabricated ultra sonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave trans mission through aluminum is demonstrated, implying a 110 dB dynamic ra nge for transducers at 2.3 MHz in air. Water transmission experiments from 1 to 20 MHz are performed, with a measured 60 dB SNR at 3 MHz. A theoretical model is proposed that agrees well with observed transduce r behavior. Most significantly, the model is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive altern ative to piezoelectric transducers in many applications.