Acoustic Streaming

Nyborg, Wesley L.

doi:10.1016/b978-0-12-395662-0.50015-1

Cited by 474 publications

(407 citation statements)

References 44 publications

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“…The spatial distribution of the radiation force field (i.e., the region of excitation, or ROE) is determined by both the acoustic excitation parameters and the tissue properties. In soft tissues, where the majority of attenuation results from absorption (Parker, 1983;Christensen, 1988), the following equation can be used to determine radiation force magnitude (Torr, 1984;Nyborg, 1965):…”

Section: Shear Wave Generationmentioning

confidence: 99%

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Palmeri

Wang

Dahl

et al. 2008

Ultrasound in Medicine & Biology

623

510

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The speed at which shear waves propagate in tissue can be used to quantify the shear modulus of the tissue. As many groups have shown, shear waves can be generated within tissues using focused, impulsive, acoustic radiation force excitations, and the resulting displacement response can be ultrasonically tracked through time. The goals of the work herein are two-fold: first, to develop and validate an algorithm to quantify shear wave speed from radiation force-induced, ultrasonicallydetected displacement data that is robust in the presence of poor displacement signal-to-noise ratio (SNR), and second, to apply this algorithm to in vivo datasets acquired in human volunteers in order to demonstrate the clinical feasibility of using this method to quantify the shear modulus of liver tissue in longitudinal studies. The ultimate clinical application of this work is non-invasive quantification of liver stiffness in the setting of fibrosis and steatosis.In the proposed algorithm, time to peak (TTP) displacement data in response to impulsive acoustic radiation force outside the region of excitation (ROE) are used to characterize the shear wave speed of a material, which is used to reconstruct the material's shear modulus. The algorithm is developed and validated using finite element method (FEM) simulations. Using this algorithm on simulated displacement fields, reconstructions for materials with shear moduli (μ) ranging from 1.3-5 kPa are accurate to within 0.3 kPa, while stiffer shear moduli ranging from 10-16 kPa are accurate to within 1.0 kPa. Ultrasonically tracking the displacement data, which introduces jitter in the displacement estimates, does not impede the use of this algorithm to reconstruct accurate shear moduli.Using in vivo data acquired intercostally in 20 volunteers with body mass indices (BMI) ranging from normal to obese, liver shear moduli have been reconstructed between 0.9 and 3.0 kPa, with an average precision of ±0.4 kPa. These reconstructed liver moduli are consistent with those reported in the literature (μ = 0.75-2.5 kPa) with a similar precision (±0.3 kPa). Repeated intercostal liver shear modulus reconstructions were performed on 9 different days in 2 volunteers over a 105 day period, yielding an average shear modulus of 1.9 ± 0.50 kPa (1.3-2.5 kPa) in the first volunteer, and 1.8 ± 0.4 kPa (1.1-3.0 kPa) in the second volunteer. The simulation and in vivo data to date demonstrate that this method is capable of generating accurate and repeatable liver stiffness measurements and appears promising as a clinical tool for quantifying liver stiffness.

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Section: Shear Wave Generationmentioning

confidence: 99%

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Palmeri

Wang

Dahl

et al. 2008

Ultrasound in Medicine & Biology

623

510

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“…However, time-averaging leaves only the steady part since sampling rate is at rates much slower than oscillation frequency. The steady flow, known as "cavitation microstreaming," 162,163 has streaming Reynolds number defined as Re s 2p 2 a 2 f = , where ; a; a, and f are the kinematic viscosity of the liquid, bubble radius, oscillation amplitude, and frequency, respectively. Depending on f, bubble oscillates in different oscillation modes; however, oscillation amplitude and the corresponding cavitation microstreaming are more pronounced when the bubble is excited at its resonance frequency.…”

Section: A Cavitation Microstreamingmentioning

confidence: 99%

Hydrodynamic mechanisms of cell and particle trapping in microfluidics

2013

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Focusing and sorting cells and particles utilizing microfluidic phenomena have been flourishing areas of development in recent years. These processes are largely beneficial in biomedical applications and fundamental studies of cell biology as they provide cost-effective and point-of-care miniaturized diagnostic devices and rare cell enrichment techniques. Due to inherent problems of isolation methods based on the biomarkers and antigens, separation approaches exploiting physical characteristics of cells of interest, such as size, deformability, and electric and magnetic properties, have gained currency in many medical assays. Here, we present an overview of the cell/particle sorting techniques by harnessing intrinsic hydrodynamic effects in microchannels. Our emphasis is on the underlying fluid dynamical mechanisms causing cross stream migration of objects in shear and vortical flows. We also highlight the advantages and drawbacks of each method in terms of throughput, separation efficiency, and cell viability. Finally, we discuss the future research areas for extending the scope of hydrodynamic mechanisms and exploring new physical directions for microfluidic applications.

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“…One of the main advantages of this approach is that it does not require any valves or other moving components. There are two types of acoustic streaming: one where the traveling surface waves or oscillating interfaces generate a boundary layer flow [116]; and the so-called "quartz wind type", where the absorption of acoustic beams in the open fluid induces the flow. In both instances, the generated flow has parabolic profile similar to pressure-driven flow.…”

Section: Flow Generation and Pumping Mechanismmentioning

confidence: 99%

New advances in microchip fabrication for electrochromatography

Szekeres

Guttman

2005

Electrophoresis

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There is a great demand in separation technologies for faster and more effective analysis processes. Miniaturization is a suitable technique for satisfying this demand as reduction in size gives increased separation speed with higher efficiency. CEC is an electric-field-mediated separation technique where the liquid flow is generated by the electric field itself. The main advantage of using electric field over pressure for flow generation is the flat flow profile of the EOF; thus, CEC is one of the best candidates to construct a novel and high-efficiency microanalytical device. The aim of the present paper is to review the basic fabrication and bonding principles, as well as connection and system integration options for microfluidics-based electrochromatography. The physical structure and fluidic channel formation are critically evaluated, including glass microstructuring and fusion bonding. Recent developments in nanoflow measurements and the application of various flow control units are also extensively discussed.

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Acoustic Streaming

Cited by 474 publications

References 44 publications

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Quantifying Hepatic Shear Modulus In Vivo Using Acoustic Radiation Force

Hydrodynamic mechanisms of cell and particle trapping in microfluidics

New advances in microchip fabrication for electrochromatography

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