An improved circuit model of MUTs

An electrical circuit model is introduced to describe the behavior of microfabricated ultrasonic transducers. A systematic analysis of the loss mechanisms of an air-coupled transducer is presented. At atmospheric pressure, it is found that loss due to viscous flow in the the transducer cavity is equivalent to 1779 rayls of mechanical loading, while loss due to heat generation from strain in the membrane and thermal loss from gas compression is equivalent to 126 rayls. Acoustic radiation into air is modeled by an effective impedance of 332 rayls. Experimental results are presented which require an additional 1450 rayls in the mechanical impedance of the transducer, and some possible explanations for the unexpected loss are discussed.