Ph.D Thesis


Ph.D StudentHazan Yoav
SubjectSilicon-Photonics Arrays for Ultrasound Detection
DepartmentDepartment of Electrical and Computer Engineering
Supervisor ASSOCIATE PROF. Amir Rosenthal


Abstract

Medical ultrasound and optoacoustic (photoacoustic) imaging commonly rely on the concepts of beam-forming and tomography for image formation, enabled by piezoelectric array transducers whose element size is comparable to the desired resolution. However, the tomographic measurement of acoustic signals becomes increasingly impractical for resolutions beyond 100 µm due to the reduced efficiency of piezoelectric elements upon miniaturization. For higher resolutions, a microscopy approach is preferred, in which a single focused ultrasound transducer images the object point-by-point, but the bulky apparatus and long acquisition time of this approach limit clinical applications.

In this thesis, I have developed interferometric techniques and sensing elements that could enable the next generation of high-resolution ultrasound and optoacoustic systems. My sensor technology is based on an optical resonator fabricated in a silicon-photonics platform, which is coated by a sensitivity-enhancing polymer, which also eliminates the parasitic effect of surface acoustic waves. The sensor technology preforms with high bandwidth and sensitivity while reducing detector size to micron scale. The different optical interrogation technologies, used to read-out the silicon-photonic sensor, advance in bandwidth, sensitivity, signal fidelity, and array detection capabilities beyond the prior state of the art technologies. All these advancements enabled high yield three-dimensional optoacoustic images, including in vivo optoacoustic tomography performed on a mouse ear, revealing its vasculature at detail that has been previously reserved to optoacoustic microscopy.