Chaotic behavior in acoustic cavitation

Lauterborn, Werner; Holzfuss, Joachim; Billo, Andreas

doi:10.1109/ultsym.1994.401765

“…Subharmonics and ultraharmonics are developed in a strongly nonlinear system, when bubbles oscillate nonlinearly (Bohn 1957, Walton 1984and Leighton et al 1991. As the subharmonic pressure threshold is exceeded, there is a potential for the volumetric pulsations to bifurcate as the oscillations become more chaotic (Lauterborn et al 1994). The bubble radius displacement reaches two different maxima, one at the transmit frequency and the other one at half of the transmit frequency or the subharmonic.…”

Section: Subharmonic Generation From Resonating Bubblesmentioning

confidence: 99%

Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

Iradji¹

2021

Preprint

0

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The microcirculation can be differentiated from the surrounding tissue using high frequency ultrasound subharmonic imaging. This imaging technique relies on the detection of energy scattered from ultrasound contrast agents at half the transmit frequency due to their resonant oscillations. The current contrast agents and the subharmonic imaging parameters have not been optimized for high frequencies. Moreover, the origin of subharmonic generation from submicron bubbles is not well-understood. The size distribution of Definity™ phospholipid-shelled microbubbles was altered to find the optimal bubble size to be resonant over a wide range of high frequencies. The resonant behaviour of bubbles was investigated through in vitro attenuation measurements. The transmit frequency and pressure were varied to optimize the backscattered subharmonic signal. Alteration of Definity™ population significanatly improved the scattering for subharmonic imaging at 20 MHz. A peak negative pressure between 400 to 600 kPa is suggested for this frequency range.

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“…In this study, subharmonic emission was chosen to measure the occurrence of cavitation because subharmonic emission is reported to be generated at lower acoustic pressures than those required for the generation of broadband noise. 21) To measure only the cavitation induced by the sustained bubbles, the pressure and duration for cavitation induction were set low and short enough so as not to induce new bubbles from PCNDs, which may further generate cavitation. As representative subharmonic components of fundamental component f 0, halfharmonic (1/2 f 0) and a half-ultra harmonic component 22) (3/2 f 0) were chosen.…”

Section: Introductionmentioning

confidence: 99%

Sustaining Microbubbles Derived from Phase Change Nanodroplet by Low-Amplitude Ultrasound Exposure

Kawabata

¹

,

Asami

²

,

Yoshikawa

³

et al. 2010

Jpn. J. Appl. Phys.

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To improve the short lifetime of microbubbles induced upon application of triggering ultrasound pulse to a phase change nanodroplet (PCND), the effect of low-pressure continuous ultrasound for sustaining microbubbles was studied in a gel phantom. A pulse with 100 cycles of 1.1 MHz ultrasound with a peak negative pressure of 2.4 MPa was used for the generation of microbubbles while superimposing a bubble-sustaining ultrasound at a frequency of 1.1 MHz with a relatively low-pressure amplitude. It was found that a peak negative pressure in the range from 0.01 to 0.1 MPa was suitable for sustaining the microbubbles without inducing cavitation. The presence of sustained bubbles could be echographycally observed as a beam-shaped brightness change. Moreover, the sustained microbubbles induced cavitation upon additional application of ultrasound pulse at a peak negative pressure of 0.2 MPa. The results obtained suggested that not only the lifetime but also the activity of the microbubbles can be controlled.

show abstract

Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

Iradji¹

2021

Preprint

View full text Add to dashboard Cite

The microcirculation can be differentiated from the surrounding tissue using high frequency ultrasound subharmonic imaging. This imaging technique relies on the detection of energy scattered from ultrasound contrast agents at half the transmit frequency due to their resonant oscillations. The current contrast agents and the subharmonic imaging parameters have not been optimized for high frequencies. Moreover, the origin of subharmonic generation from submicron bubbles is not well-understood. The size distribution of Definity™ phospholipid-shelled microbubbles was altered to find the optimal bubble size to be resonant over a wide range of high frequencies. The resonant behaviour of bubbles was investigated through in vitro attenuation measurements. The transmit frequency and pressure were varied to optimize the backscattered subharmonic signal. Alteration of Definity™ population significanatly improved the scattering for subharmonic imaging at 20 MHz. A peak negative pressure between 400 to 600 kPa is suggested for this frequency range.

show abstract

Chaotic behavior in acoustic cavitation

Cited by 3 publications

References 18 publications

Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

Sustaining Microbubbles Derived from Phase Change Nanodroplet by Low-Amplitude Ultrasound Exposure

Optimization of subharmonic generation from ultrasound contrast agents at high frequency ultrasound

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