Design and experimental study of microcantilever ultrasonic detection transducers

This paper presents the analysis, design, and experimental study of a microcantilever optically-activated ultrasonic detection transducer. An analytical model was derived using 1-D cantilever structural dynamics, leading to the optimization of the transducer design. Finite element modeling enabled dynamic simulation to be performed, with results in good agreement with the analytical model. Transducers were fabricated using MEMS (microelectromechanical systems) techniques. Experimental results are presented on remote noncontact detection of ultrasound using the fabricated transducers; high SNR is achieved for the detected signals, even for relatively low ultrasonic amplitudes. Both analysis and experimental study show that the transducer has a sensitivity ∼1 to 2 orders of magnitude higher than that of conventional optical detection techniques. Furthermore, we show that the dominant factor in the increased sensitivity of the transducer is the resonant nature of the finger structure.