Transparent Flexible Piezoelectric Ultrasound Transducer for Photoacoustic Imaging System

Photoacoustic imaging (PAI) has become a popular technique for biomedical diagnosis. However, current systems are overly complex or use bulky piezoelectric materials, necessitating options other than these methods for future PAI systems. In this study, a wearable transparent ultrasonic transducer was developed and applied in a PAI system with excellent performance. The acoustic sensor was fabricated with a sandwich structure consisting of 150 nm thick amorphous indium tin oxide on both sides of a $110~\mu \text{m}$ commercial polyvinylidene fluoride film. This single-element sensor exhibited the performance of a 6.7 MHz center frequency, an 86.3% −3 dB fractional bandwidth, and a $20\times20\,\,\times $ 36 mm ³ volumetric imaging field. Modified imaging phantoms were made to evaluate the lateral resolution, imaging depth, ability to make a convex photoacoustic image, quality of 3D imaging, and capability to perform PAI directly in the ambient environment with a customized phantom. In summary, the study has demonstrated the sensor’s potential for large-field PAI application in wearable health devices at a low cost.