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Journal of Biomedical Optics

Photodistruptive laser nucleation of ultrasonic cavitation for biomedical applications
Author(s): Doug L. Miller; Greg J. R. Spooner; Alun R. Williams
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Paper Abstract

Pulses of high intensity laser light, when focused into transparent materials, may produce localized electron–ion plasmas through optical breakdown. By simultaneously incorporating the resulting volume of vaporized material within the focal volume of a high intensity ultrasound source, the photodisruption (1.05 µm wavelength) void served as a nucleation site for ultrasonic cavitation. Dilute suspensions of canine erythrocytes in phosphate buffered saline were exposed in a flow-through exposure chamber and the percentage of lysed cells was used as a measure of the biologically effective cavitation activity produced in the chamber. Brief (about 30 µs) acoustic emissions were detected from the photodisruption alone (indicating laser nucleation of bubbles), but the cell lysis produced was undetectable against the background. However, combined exposure greatly increased both the duration of the acoustic emissions (up to 1.5 ms) and the amount of cell lysis above an ultrasonic pressure amplitude threshold of about 4.3 MPa at 2.5 MHz. The amount of cell lysis (sometimes approaching 100%) increased with increasing ultrasonic intensity, laser pulse energy and laser PRF. Addition of 5% serum albumin enhanced the effect, apparently by stabilizing bubbles and nuclei. Photodisruptive laser nucleation of ultrasonic cavitation can provide controlled and synergistic enhancement of bioeffects.

Paper Details

Date Published: 1 July 2001
PDF: 8 pages
J. Biomed. Opt. 6(3) doi: 10.1117/1.1380669
Published in: Journal of Biomedical Optics Volume 6, Issue 3
Show Author Affiliations
Doug L. Miller, Univ. of Michigan (United States)
Greg J. R. Spooner, Univ. of Michigan (United States)
Alun R. Williams, Haemacoustics, Ltd. (United Kingdom)

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