A fiber optic optoacoustic ultrasound sensor for photoacoustic endoscopy

Photoacoustic Endoscopy (PE) is a new imaging modality that can provide high-resolution vascular imaging in vivo. Optoacoustic sensing (optical detection of ultrasound) is a good candidate for PE due to its enhanced sensitivity, wide bandwidth, and miniaturizability in comparison to piezoelectric, PVDF, and capacitive transducers. In this work we present the fabrication and testing of a fiber optic optoacoustic ultrasound sensor (fiber etalon), and we propose the development of a rectilinear ultrasound array for PE based on this device. The design entails the bundling of several fiber etalons which, when combined with photoacoustic excitation, would yield a flexible and compact, forward-viewing photoacoustic endoscope. To simulate the performance of a bundled device, we have mechanically scanned a single fiber etalon to image simple photoacoustic targets. The results demonstrate the viability of using a fiber optic-based photoacoustic endoscope to image optically absorptive structures such as blood in vasculature. A potentially significant application of our device could be the monitoring of angiogenesis - an early marker of tumor formation.