A Compact Photoacoustic Sensing Probe using Surface-Micromachined Optical Ultrasound Transducer (SMOUT)

In this paper, we report an innovative compact photoacoustic (PA) sensing probe based on a surface-micromachined optical ultrasound transducer (SMOUT). Owing to its excellent optical transparency, the excitation light can propagate through the SMOUT to the target, enabling the use of a single optical fiber for both excitation and reception. In addition, the SMOUT provides high acoustic sensitivity and good optical uniformity. For demonstration, a prototype PA sensing probe using the SMOUT has been designed, fabricated, and experimentally characterized. Red-dye solutions with different concentrations and a piece of black tape embedded at various depths in biological tissue are used as sensing targets, and the probe performance is validated by the experimental results. Overall, the compact and sensitive SMOUT-based probe shows strong potential for a wide range of PA sensing applications, and its uniform mass production makes it amenable to be arranged into 1-D and 2-D planar or spherical arrays for imaging applications.