High electromechanical coupling piezoelectric micro-machined ultrasonic transducer (PMUT) elements for medical imaging

This paper presents a multi-cell lead zirconate titanate (PZT) pMUT element geometrically optimized for high effective electromechanical coupling (k
_eff
²
) and acoustic power and manufactured via a commercially viable, array compatible and wafer-scale process. A top-down fabrication approach facilitates achievement of a high fill factor (≈1250 transducers/mm
²
) multi-cell element array, and more substantially, results in a frequency based k
_eff
²
measurement of 9±1.4% per element, a nearly two fold improvement over the previous state-of-the-art.