Evaluation of High Frequency Piezoelectric Micromachined Ultrasound Transducers for Photoacoustic Imaging.

In this work, the design, fabrication, and characterization of piezoelectric micromachined ultrasound transducer (PMUT) arrays for photoacoustic imaging applications are reported. An 80-element linear PMUT array with each element having 53 PMUT cells of 125 μm cell diameter were fabricated using 650 nm thick lead zirconate titanate (PZT) as the active piezoelectric layer. The PMUTs are designed to operate at ~10 MHz resonant frequency. The PMUT elements are validated for photoacoustic imaging using an agar gel phantom with embedded pencil leads as the imaging target. Photoacoustic A-line response of the targets captured by single PMUT element shows ~7 MHz center frequency with ~4.8 MHz bandwidth. B-mode images reconstructed from A-lines recorded during the linear scanning of a single element clearly imaged all the targets, thus validating the potential of the fabricated PMUTs for photoacoustic imaging.