Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 2019 | Published
Journal Article Open

High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone

Abstract

Ultra-high-speed video microscopy and numerical modeling were used to assess the dynamics of microbubbles at the surface of urinary stones. Lipid-shell microbubbles designed to accumulate on stone surfaces were driven by bursts of ultrasound in the sub-MHz range with pressure amplitudes on the order of 1 MPa. Microbubbles were observed to undergo repeated cycles of expansion and violent collapse. At maximum expansion, the microbubbles' cross-section resembled an ellipse truncated by the stone. Approximating the bubble shape as an oblate spheroid, this study modeled the collapse by solving the multicomponent Euler equations with a two-dimensional-axisymmetric code with adaptive mesh refinement for fine resolution of the gas-liquid interface. Modeled bubble collapse and high-speed video microscopy showed a distinctive circumferential pinching during the collapse. In the numerical model, this pinching was associated with bidirectional microjetting normal to the rigid surface and toroidal collapse of the bubble. Modeled pressure spikes had amplitudes two-to-three orders of magnitude greater than that of the driving wave. Micro-computed tomography was used to study surface erosion and formation of microcracks from the action of microbubbles. This study suggests that engineered microbubbles enable stone-treatment modalities with driving pressures significantly lower than those required without the microbubbles.

Additional Information

© 2019 Acoustical Society of America. Received 4 March 2019; revised 21 June 2019; accepted 26 June 2019; published online 26 July 2019. We thank Dr. Marshall Stoller for valuable discussion, suggesting and arranging micro-CT, and for providing urinary stones, Dr. Sunita Ho for micro-CT of urinary stones, Dr. Ryoji Shiraki for chemical analysis of stone composition, Dr. Kyle Morrison (Sonic Concepts) for piezoelectric transducers, Dr. Matt Hopcroft for the development of the driving acoustic system and software for scanning of acoustic beams, David Bell for help with programming of the signal generator, and Todd Rumbaugh (Hadland Imaging) for advice on high-speed imaging. T.K. is a founding member of Applaud. Y.P., W.B.P., and D.L. are employees/investigators for Applaud. Experiments where performed at Applaud, the numerical modeling in Caltech. T.C. and K.S. acknowledge support from the Office of Naval Research (ONR, N0014-18-1-2625). T.C. and K.M. also acknowledge support from the ONR (N00014-17-1-2676) and the NIH (P01-DK043881).

Attached Files

Published - 1.5116693.pdf

Files

1.5116693.pdf
Files (4.3 MB)
Name Size Download all
md5:13f9e9713cf696414baf3e440257c6f6
4.3 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 18, 2023