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AshkenaziS

Research Abstracts Online
January - December 2011

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University of Minnesota Twin Cities
College of Science and Engineering
Department of Biomedical Engineering

PI: Shai Ashkenazi

Optoacoustic Devices

Optoacoustic technology utilizes optical methods to generate and detect ultrasound. During the last decade several research groups have demonstrated its potential in forming dense arrays of ultrasound receivers for high-resolution 3D imaging. These researchers have focused on developing high-frequency and wide-bandwidth (up to 100 MHz) optoacoustic transducers and integration techniques optimized for minimally-invasive catheter based imaging probes. Sensitive ultrasound detectors based on polymer thin film optical resonator (etalon) were developed. The active area for detection is defined by the spot size and location of a laser beam probing the etalon surface. Etalon detectors show better sensitivity than conventional piezoelectric transducers of similar size. The researchers have also developed highly efficient ultrasound transmitters, based on thermoelastic expansion of thin light absorbing films illuminated by a pulsed laser. To integrate a receiver and a transmitter in a single thin film device, they have designed a gold nano-structure optimized for high reflectivity at 1550 nm wavelength and high absorption at 800 nm. This layer was utilized for both etalon mirror and thermoelastic generation in an integrated optoacoustic transducer. To facilitate the development of catheter-based devices, optic fiber bundles are investigated for light delivery between a console system and a remote optoacoustic imaging probe.

Group Member

Clay Sheaff, Graduate Student