Silicon micromachined ultrasonic transducers

This paper reviews capacitor micromachined ultrasonic transducers (cMUTs). Transducers for air-borne and immersion ap plications are made from paralle l-plate capacitors whose dimensions are controlled through traditional inte grated circuit manufacturing methods. Transducers for airborne ultrasound a pplications have been operated in the frequency range of 0.1-11 MHz, while immersion transducers have been operated in the frequency range of 1-20 MHz . The Mason model is used to represent the cMUT and highlight the important parameters in the design of both airborne and immersion transducers. Theor y is used to compare the dynamic range and the bandwidth of the cMUTs to pi ezoelectric transducers. It is seen that cMUTs perform at least as well if not better than piezoelectric transducers. Examples of single-element trans ducers, linear-all-ay transducers, and two-dimensional arrays of transducer s will be presented.