Ring-shaped Transparent and Broadband Ultrasonic Transducer for Photoacoustic Systems

Photoacoustic systems provide high-resolution, non-invasive imaging, but conventional designs often require bulky components to align optical and acoustic paths, limiting miniaturization and practical use. In this paper, we present a ring-shaped, transparent, broadband ultrasonic transducer fabricated using Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) deposited on an indium-tin-oxide (ITO) glass substrate. The transducer combines optical transparency with effective piezoelectric properties, featuring a ring-shaped electrode design that allows light to pass through the center. Finite element simulations were used to optimize the structure for broadband acoustic performance. The transducer achieves a center frequency of 3.125 MHz with bandwidth of 115%. When integrated into an photoacoustic system using a 532 nm laser, it delivers accurate distance measurements in phantom tests. This compact design enhances the integration of optical and acoustic paths, facilitating the development of efficient, miniaturized, and wearable photoacoustic systems for biomedical imaging applications.