Focused Optical Ultrasound Detector and Transducer for Medical Imaging Applications

Medical optoacoustic imaging is a hybrid deep tissue imaging technique that combines optics and ultrasound via the optoacoustic effect – ultrasound generation resulting from pulsed light illumination of tissue and rapid thermal expansion of optically absorbing molecules. The optically generated ultrasound signals are acquired with ultrasound detectors and are used to reconstruct an ultrasound-resolution image of optical absorbers, such as hemoglobin or lipids. The image has optical contrast and is essentially a map of wavelength-dependent optical absorption coefficient in tissue. The primary applications of optoacoustic imaging are microvasculature imaging, early cancer detection, and cardiovascular disease diagnostics.

In this talk, I will present a miniature optical ultrasound detector designed for intravascular optoacoustic imaging. The detector is based on a sub-millimeter acoustic lens bonded to silicon photonics π-shifted waveguide Bragg grating. It has an order of magnitude higher sensitivity than conventional miniature piezoelectric transducers, has a lateral resolution of 50 μm, a bandwidth of at least 84 MHz, and is capable of high-fidelity optoacoustic imaging. In addition, I will demonstrate how the developed detector can be transformed into an all-optical focused ultrasound transducer, i.e., a single optical element that both generates and detects ultrasound. The transducer has an unprecedented lateral and axial resolution, surpassing the current state-of-the-art piezoelectric intravascular ultrasound transducers.

Ph.D. Under the supervision of Prof. Amir Rosenthal.