MRI: Development and Fabrication of a Novel Defocusing Ultrasonic Imaging Camera

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Proposal No. CTS-0421568Principal Investigator: M. Gharib, California Inst. Of TechnologyThis grant is to develop an ultrasound 3-D velocimetry system based on the image-defocusing concept, which will provide a unique tool for engineering applications and lead to deeper scientific understanding of many important industrial and biological systems that are currently inaccessible. Many environmental, industrial and biological flows occur in three-dimensional, multi-phase, unsteady complex geometries with significant boundary deformation. In general these flows are not optically accessible. To study these flows, ultrasound imaging techniques as non-invasive modalities that can image opaque objects or flows have become methods of choice, over optical or potentially dangerous x-ray techniques. Despite the very important advantages that ultrasound imaging offers, it is limited as a two-dimensional imaging technique. Attempts to resolve this deficiency involve scanning of the desired volume by mechanically stepping or rotating the ultrasound beam generated by one or two-dimensional transducers, and have met with limited success. Currently, there is no research-quality instrumentation on the market that can facilitate dynamic volume mapping in opaque media. The basic imaging principles of the proposed ultrasound version are very similar to its optical counterpart, which has been developed and successfully implemented at Caltech. Such instrumentation development will yield a substantial step ahead of present state-of-the-art in ultrasound dynamic volumetric imaging. The broader impact of the research effort will be the availability of new research and development tools in the area of experimental fluid mechanics, providing the opportunity for a deeper scientific understanding. These new discoveries will enable development and evaluation novel industrial, environmental and medical devices. In particular, this project will have clinical impact, as it will provide improved paradigms for cardiovascular hemodynamic studies, as well as for multi-phase flow investigation. Another important impact will be at computational fluid mechanics forefront where time resolved 3-D flow information at all ranges of Reynolds number is badly needed for code validation and testing of new sub-grid scale models. The Principal Investigators will involve undergraduate students in their research activities through SURF (summer undergraduate research fellowship), MURF (minority undergraduate research fellowship) and work-study programs Caltech.