Breakup of finite thickness viscous shell microbubbles by ultrasound: A simplified zero-thickness shell model

Hsiao, Chao-Tsung; Chahine, Georges L.

doi:10.1121/1.4792492

Cited by 9 publications

(5 citation statements)

References 27 publications

(35 reference statements)

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“…The modeling showed nonspherical deformations due to the presence of a nearby rigid boundary and, depending on the standoff distance, one of the following dynamics of the collapse: (1) a single reentrant jet, (2) a ring-type reentrant jet, and (3) a pinching of the bubble. 26 Here, we report experimental observations of a circumferential pinching and the numerical modeling showing that the pinching propels two microjets directed away and toward the rigid boundary. When hitting the boundary, the jet was either a single reentrant jet or a ring-type jet, depending on the amount of gas modeled in the bubble.…”

Section: Introductionmentioning

confidence: 91%

“…8,9 The use of a 2 D code instead of a one-dimensional (1D) spherical model [10][11][12][13][14][15][16] was motivated by the present and previous observations showing that oscillations of microbubbles can be highly nonspherical. 2,[17][18][19][20][21][22][23][24][25] Hsiao and Chahine 26 modeled a shelled microbubble subjected to one cycle of 2.5-MHz ultrasound at 1 MPa. The modeling showed nonspherical deformations due to the presence of a nearby rigid boundary and, depending on the standoff distance, one of the following dynamics of the collapse: (1) a single reentrant jet, (2) a ring-type reentrant jet, and (3) a pinching of the bubble.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Pishchalnikov¹,

Behnke-Parks²,

Schmidmayer

et al. 2019

The Journal of the Acoustical Society of America

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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.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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

Pishchalnikov¹,

Behnke-Parks²,

Schmidmayer

et al. 2019

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

show abstract

“…It involves a large computational domain for describing the propagation of the acoustic wave, and a very long time interval. Hsiao & Chahine [43] recently modelled the bubble coating using a layer of a Newtonian viscous fluid, to study the mechanism of bubble break-up during non-spherical deformations resulting from the presence of a nearby rigid boundary. The effects of the shell thickness and the bubble standoff distance from the solid wall on the bubble break-up were studied parametrically.…”

Section: Computational Bubble Dynamicsmentioning

confidence: 99%

Cell mechanics in biomedical cavitation

2015

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Studies on the deformation behaviours of cellular entities, such as coated microbubbles and liposomes subject to a cavitation flow, become increasingly important for the advancement of ultrasonic imaging and drug delivery. Numerical simulations for bubble dynamics of ultrasound contrast agents based on the boundary integral method are presented in this work. The effects of the encapsulating shell are estimated by adapting Hoff's model used for thin-shell contrast agents. The viscosity effects are estimated by including the normal viscous stress in the boundary condition. In parallel, mechanical models of cell membranes and liposomes as well as state-of-the-art techniques for quantitative measurement of viscoelasticity for a single cell or coated microbubbles are reviewed. The future developments regarding modelling and measurement of the material properties of the cellular entities for cutting-edge biomedical applications are also discussed.

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“…The mechanical stresses at the endothelial interface were assessed using coupled solid and fluid models (Hosseinkhah et al 2013;Wiedemair et al 2012). The breakup of MBs near rigid walls (Hsiao and Chahine 2013) and inside MVs (Hosseinkhah et al 2015) was also studied numerically.…”

Section: Introductionmentioning

confidence: 99%

The breakup of intravascular microbubbles and its impact on the endothelium

Wiedemair

Tuković

Jasak

et al. 2016

Biomech Model Mechanobiol

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Encapsulated microbubbles (MBs) serve as endovascular agents in a wide range of medical ultrasound applications. The oscillatory response of these agents to ultrasonic excitation is determined by MB size, gas content, viscoelastic shell properties and geometrical constraints. The viscoelastic parameters of the MB capsule vary during an oscillation cycle and change irreversibly upon shell rupture. The latter results in marked stress changes on the endothelium of capillary blood vessels due to altered MB dynamics. Mechanical effects on microvessels are crucial for safety and efficacy in applications such as focused ultrasound-mediated blood-brain barrier (BBB) opening. Since direct in vivo quantification of vascular stresses is currently not achievable, computational modelling has established itself as an alternative. We have developed a novel computational framework combining fluid-structure coupling and interface tracking to model the nonlinear dynamics of an encapsulated MB in constrained environments. This framework is used to investigate the mechanical stresses at the endothelium resulting from MB shell rupture in three microvessel setups of increasing levels of geometric detail. All configurations predict substantial elevation of up to 150 % for peak wall shear stress upon Zurich Center for Integrative Human Physiology, and Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland MB breakup, whereas global peak transmural pressure levels remain unaltered. The presence of red blood cells causes confinement of pressure and shear gradients to the proximity of the MB, and the introduction of endothelial texture creates local modulations of shear stress levels. With regard to safety assessments, the mechanical impact of MB breakup is shown to be more important than taking into account individual red blood cells and endothelial texture. The latter two may prove to be relevant to the actual, complex process of BBB opening induced by MB oscillations.

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Breakup of finite thickness viscous shell microbubbles by ultrasound: A simplified zero-thickness shell model

Cited by 9 publications

References 27 publications

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

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

Cell mechanics in biomedical cavitation

The breakup of intravascular microbubbles and its impact on the endothelium

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