<i>The Acoustic Bubble</i>

Leighton, T. G.; Apfel, Robert E.

doi:10.1121/1.410082

Cited by 633 publications

(633 citation statements)

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“…The decrease in cavitation activity under saturation and oversaturation conditions has previously been discussed [24,26,29], and is essentially due to the screening action of the cavitation field and inter-bubble impact. An increase in the intensity of bubble interactions and a simultaneous increase in bubble concentration will increase the probability of bubble deformation and nonspherical collapse; non-spherical collapse is less effective in generating shock waves and high temperatures inside bubbles [29].…”

Section: Methodsmentioning

confidence: 95%

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Sonoluminescence and acoustic emission spectra at different stages of cavitation zone development

Дежкунов

Francescutto

Serpe

et al. 2018

Ultrasonics Sonochemistry

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The way in which a cavitation zone develops in a focused pulsed ultrasound field is studied in this work. Sonoluminescence (SL), total hydrophone output and cavitation noise spectra have been recorded across a gradual, smooth increase in applied voltage. It is shown that the cavitation zone passes through a number of stages of evolution, according to increasing ultrasound intensity, decreasing pulse period and increasing ultrasound pulse duration. Sonoluminescence is absent in the first phase and the hydrophone output spectra consists of a main line with two or three harmonics whose intensity is much lower than that of the main (fundamental) line. The second stage sees the onset of SL whose intensity increases smoothly and is accompanied by the appearance of higher harmonics and subharmonics in the cavitation noise spectra. In some cases, the wide-band (WBN) component can be seen in noise spectra during the final part of the second stage. In the third stage, SL intensity increases significantly and often quite sharply, while WBN intensity increases in the same manner. This is accompanied by a synchronous increase in the absorption of ultrasound by the cavitation zone, which is manifested in a sharp decrease in the hydrophone output. In the fourth stage, both SL and WBN intensities tend to decrease despite the increased voltage applied to the transducer. Furthermore, the fundamental line tends to decrease in strength as well, despite the increasing ultrasound intensity. The obtained results clearly identify the different stages of cavitation zone development using cavitation noise spectra analyses. We then hypothesize that three of the above stages may be responsible for three known types of ultrasound action on biological cells: damping viability, reversible cell damage (sonoporation) and irreversible damage/cytotoxicity.3

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Section: Methodsmentioning

confidence: 95%

“…An increase in the intensity of bubble interactions and a simultaneous increase in bubble concentration will increase the probability of bubble deformation and nonspherical collapse; non-spherical collapse is less effective in generating shock waves and high temperatures inside bubbles [29].…”

Section: Methodsmentioning

confidence: 99%

Sonoluminescence and acoustic emission spectra at different stages of cavitation zone development

Дежкунов

Francescutto

Serpe

et al. 2018

Ultrasonics Sonochemistry

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“…The interaction between microbubbles and the ultrasound field is strongly affected by the ultrasound frequency (Leighton 1994). For example, the frequency has a large effect on the inertial cavitation threshold and on the growth of microbubbles within the ultrasound field during sonication.…”

Section: Introductionmentioning

confidence: 99%

Blood-Brain Barrier Disruption Induced by Focused Ultrasound and Circulating Preformed Microbubbles Appears to Be Characterized by the Mechanical Index

McDannold

Vykhodtseva

Hynynen

2008

Ultrasound in Medicine & Biology

235

199

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This work investigated the effect of ultrasonic frequency on the threshold for blood-brain barrier (BBB) disruption induced by ultrasound pulses combined with an ultrasound contrast agent. Experiments were performed in rabbits using ultrasound pulses at 2.04 MHz using sonications with peak pressure amplitudes ranging from 0.3 to 2.3 MPa. BBB disruption was evaluated using contrastenhanced magnetic resonance imaging. The threshold for BBB disruption was estimated using probit regression. Representative samples with similar amounts of contrast enhancement were examined in light microscopy. Results from these experiments were compared to data from previous studies that used ultrasound frequencies between 0.26 and 1.63 MHz. We found that the BBB disruption threshold (value where the probability for disruption was estimated to be 50%) expressed in terms of the peak negative pressure amplitude increased as a function of the frequency. It appeared to be constant, however, when the exposures were expressed as a function of the mechanical index (peak negative pressure amplitude estimated in situ divided by square root of frequency). Regression of data from all frequencies resulted in an estimated mechanical index threshold of 0.46 (95% confidence intervals: 0.42-0.50). Histological examination of representative samples with similar amounts of blood-brain barrier disruption found that the number of regions containing extravasated red blood cells per unit area was substantially lower on average for lower ultrasound frequencies. This data suggests that the mechanical index is a meaningful metric for ultrasound-induced blood-brain barrier disruption, at least for when other parameters that are not taken into account by the mechanical index are not varied. It also suggests that lower frequency sonication produces less red blood cell extravasation per unit area.

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“…The phenomenon is known as acoustic cavitation [1,2]. The strong collapse, following the explosive expansion of these bubbles, induces extreme conditions inside or near the bubbles, Email address: louisnar@enstimac.fr (O. Louisnard).…”

Section: Introductionmentioning

confidence: 99%

“…The strong collapse, following the explosive expansion of these bubbles, induces extreme conditions inside or near the bubbles, Email address: louisnar@enstimac.fr (O. Louisnard). 1 Corresponding author which are responsible for a specific chemistry, known as sonochemistry [3].…”

Section: Introductionmentioning

confidence: 99%

FEM simulation of a sono-reactor accounting for vibrations of the boundaries

Louisnard

González-Garcı́a

Tudela

et al. 2009

Ultrasonics Sonochemistry

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The chemical effects of acoustic cavitation are obtained in sono-reactors built-up from a vessel and an ultrasonic source. In this paper, simulations of an existing sono-reactor are carried out, using a linear acoustics model, accounting for the vibrations of the solid walls. The available frequency range of the generator (19 kHz-21 kHz) is systematically scanned. Global quantities are plotted as a function of frequency in order to obtain response curves, exhibiting several resonance peaks. The attenuation coefficient of the wave is taken as a variable parameter, in absence of the precise knowledge of the bubble size distribution, and its influence is studied. The concepts of acoustic energy, intensity and active power are recalled, along with the general balance equation for acoustic energy. The latter is used as a convergence check of the simulations. Finally, it is shown that the interface between the liquid and the solid walls cannot be correctly represented by the simple approximations of either infinitely soft, or infinitely hard boundaries. Moreover, the liquid-solid coupling allows the cooling jacket to receive a noticeable part of the input power, although it is not in direct contact with the sonotrode. It may therefore undergo cavitation and this feature opens the perspective to design sono-reactors which avoid direct contact between the working liquid and the sonotrode.

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The Acoustic Bubble

Cited by 633 publications

References 0 publications

Sonoluminescence and acoustic emission spectra at different stages of cavitation zone development

Sonoluminescence and acoustic emission spectra at different stages of cavitation zone development

Blood-Brain Barrier Disruption Induced by Focused Ultrasound and Circulating Preformed Microbubbles Appears to Be Characterized by the Mechanical Index

FEM simulation of a sono-reactor accounting for vibrations of the boundaries

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