Optimization of Membrane Structure in Capacitive ultrasonic transducer

Capacitive micromachined ultrasonic transducers (cMUTs) have been attracting attentions as an alternative to traditional piezoelectric transducers for medical diagnostic imaging. A cMUT is composed of a suspended membrane with top electrode and a substrate which acts as a bottom electrode. In operation, the membrane deflects toward the substrate due to electrostatic force by a bias voltage applied between these electrodes. In order to achieve higher sensitivity and low driving voltage, a novel membrane structure partly reinforced by beams to realize uniform deflection at the center part was proposed. It was confirmed that cMUT with the proposed membrane structure has 3 times higher sensitivity than a conventional cMUT. The validity of the proposed cMUT will be verified through the prototyping and evaluation.

[International Conference]

M. Sato, Y. Hirai, K. Sugano, T. Tsuchiya, O. Tabata, “Capacitive micromachined ultrasonic transducers with novel membrane design,” The 23rd Conference EUROSENSORS 2009, Lausanne, Switzerland, Sept. 6-9, 2009, pp. 389-392.