High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone
| Autor: | William M. Behnke-Parks, Kazuki Maeda, Tim Colonius, Yuri A. Pishchalnikov, Thomas W. Kenny, Daniel J. Laser, Kevin Schmidmayer |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Acoustics and Ultrasonics Bubble Contrast Media Video microscopy 01 natural sciences Models Biological 010305 fluids & plasmas Physics::Fluid Dynamics symbols.namesake Arts and Humanities (miscellaneous) 0103 physical sciences Computer Simulation 010306 general physics Toroid Microbubbles Microscopy Video Adaptive mesh refinement Biomedical Acoustics Mechanics Acoustics Elasticity Euler equations Orders of magnitude (time) symbols Urinary Calculi Tomography |
| Zdroj: | J Acoust Soc Am |
| ISSN: | 1520-8524 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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