High-Order Piezoelectric Micromachined Ultrasonic Transducer With Piezoelectric Layer Trench for Ultrasound Imaging

This letter presents a high-order PZT PMUT (HO-PMUT) array with trenched piezoelectric layer operating at 1.78 MHz. This high-order and trench design boosts the resonant frequency to MHz without reducing the radius, while increasing vibration amplitude and Q factor compared to fundamental PMUTs. Through optimized dual electrodes, the array achieved a normalized transmitting sensitivity (TS) of 19 kPa*mm*V<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>*mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup>. We demonstrated its pioneering application in ultrasound imaging by mechanically scanning a steel sample and generating a B-mode image with 7.34 dB SNR, showcasing its superior acoustic performance and potential for portable ultrasonic imaging devices. [2025-0027]