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Laser Generated Ultrasound Sources Using Polymer Nanocomposites for High Frequency Metrology

Rajagopal, S; Sainsbury, T; Treeby, BE; Cox, BT; (2017) Laser Generated Ultrasound Sources Using Polymer Nanocomposites for High Frequency Metrology. In: Proceedings of the 2017 IEEE International Ultrasonics Symposium (IUS). IEEE: Washington, DC, USA. Green open access

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Abstract

Accurate characterization of ultrasound fields generated by diagnostic and therapeutic transducers is critical for patient safety. This requires hydrophones calibrated to a traceable standard and currently the upper calibration frequency range available to the user community is limited to a frequency of 40 MHz. However, the increasing use of high frequencies for both imaging and therapy necessitates calibrations to frequencies well beyond this range. For this to be possible, a source of high amplitude, broadband, quasi-planar and stable ultrasound fields is required. This is difficult to achieve using conventional piezoelectric sources, but laser generated ultrasound is a promising technique in this regard. In this study, various polymer-carbon nanotube nanocomposites (PNC) were fabricated and tested for their suitability for such an application by varying the polymer type, carbon nanotubes weight content in the polymer, and PNC thickness. A broadband hydrophone was used to measure the peak pressure and bandwidth of the laser generated ultrasound pulse. Peak-positive pressures of up to 8 MPa and -6dB bandwidths of up to 40 MHz were recorded. There is a nonlinear dependence of the peak pressure on the laser fluence and the bandwidth scales inversely proportionally to the peak pressure. The high-pressure plane waves generated from this preliminary investigation has demonstrated that laser generated ultrasound sources are a promising technique for high frequency calibration of hydrophones.

Type: Proceedings paper
Title: Laser Generated Ultrasound Sources Using Polymer Nanocomposites for High Frequency Metrology
Event: IEEE International Ultrasonics Symposium (IUS)
Location: Washington, DC
Dates: 06 September 2017 - 09 September 2017
ISBN-13: 978-1-5386-3384-7
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/ULTSYM.2017.8092019
Publisher version: http://dx.doi.org/10.1109/ULTSYM.2017.8092019
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Technology, Physical Sciences, Engineering, Electrical & Electronic, Physics, Applied, Engineering, Physics, FUNCTIONALIZATION, Polymers, Ultrasonic imaging, Measurement by laser beam, Sonar equipment, Lasers, Optical pulses, Nanocomposites
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10052613
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