An optically-transparent PVDF transducer array for photoacoustic tomography

Photoacoustic tomography (PAT) is a hybrid imaging technique, which is capable of providing abundant optical contrast and high spatial resolution at deep penetration depth. One fundamental challenge in current PAT system design is caused by the opaque structure of the ultrasound transducer arrays, which prevents effective light energy delivery onto the imaging target. To address this issue, we report a new optically-transparent PVDF (polyvinylidene fluoride) transducer array for PAT. It consists of a 1D array of 16 elements, each of which has a transparent window to allow the excitation laser pulses to directly pass through. As a result, the optical excitation and ultrasound detection zones are automatically aligned to improve the illumination condition and PA excitation efficiency. Its imaging performance, such as contrast, lateral resolution, and penetration depth has been characterized with optical phantoms. Preliminary ex-vivo PAT experiments on chicken breast tissues have been conducted to demonstrate its imaging capability on real biological samples. The experimental results show that the optically-transparent PVDF transducer array could provide a new solution for the miniaturization and clinical translation of handheld PAT systems.