Optoacoustic µ-Machined Ultrasound Transducers (OMUTs)

Shai Ashkenazi
Department of Biomedical Engineering
University of Minnesota

Intravascular ultrasound (IVUS) imaging utilizes high frequency transducers for diagnoses of vascular disease and therapy guidance. IVUS probe design presents a very tough challenge for the current piezoelectric transducer technology. It requires arrays of hundreds of individual elements packed in a very small case (less than 1 mm) for high resolution imaging and compatibility with catheter delivery into blood vessels. The two major difficulties are low sensitivity and complex array connectivity.

We present an alternative approach to high resolution ultrasound imaging by using optoacoustic techniques. Laser generated ultrasound and optical detection of ultrasound are applied to the design of miniaturized imaging probes incorporating 1-d or 2-d arrays. Short laser pulses are used to illuminate highly absorbing thin films and generate ultrasound by the thermo-elastic effect. Optical resonators such as Fabry-Perot etalons, micro-ring waveguides, and Bragg grating waveguides are used for ultrasound detection. In this colloquium I will present our explorations in optoacoustics for high resolution ultrasound imaging, the major challenges, and prospective applications.