A compact photoacoustic sensing probe using surface-micromachined optical ultrasound transducer (SMOUT)

In this paper, a new compact photoacoustic (PA) sensing probe based on a surface-micromachined optical ultrasound transducer (SMOUT) is reported. In addition to high acoustic sensitivity and good optical uniformity, the excellent optical transparency of the SMOUT allows the pulsed laser to propagate through to the target for PA excitation, thereby enabling the use of a single optical fiber for both PA excitation and ultrasound reception. The design, fabrication, and experimental characterization of a prototype SMOUT-based compact PA sensing probe are presented. PA sensing experiments are conducted on red-dye solutions with various concentrations and on black tape buried at different depths in biological tissue, and the results validate the performance of the probe. In summary, the compact SMOUT-based PA sensing probe is promising for a wide range of applications, and its compatibility with uniform mass production makes it low-cost and amenable to 1-D, 2-D, or even 3-D array configurations for imaging applications.