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Johansen K.♦, Kimmel E.♦, Postema M., Theory of Red Blood Cell Oscillations in an Ultrasound Field,
ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2017-0013, Vol.42, No.1, pp.121-126, 2017Streszczenie: Manipulating particles in the blood pool with noninvasive methods has been of great interest in therapeutic delivery. Recently, it was demonstrated experimentally that red blood cells can be forced to translate and accumulate in an ultrasound field. This acoustic response of the red blood cells has been attributed to sonophores, gas pockets that are formed under the influence of a sound field in the inner-membrane leaflets of biological cells. In this paper, we propose a simpler model: that of the compressible membrane. We derive the spatio-temporal cel dynamics for a spherically symmetric single cell, whilst regarding the cell bilayer membrane as two monolayer Newtonian viscous liquids, separated by a thin gas void. When applying the newly-derived equations to a red blood cell, it is observed that the void inside the bilayer expands to multiples of its original thickness, even at clinically safe acoustic pressure amplitudes. For causing permanent cell rupture during expansion, however, the acoustic pressure amplitudes needed would have to surpass the inertial cavitation threshold by a factor 10. Given the incompressibility of the inner monolayer, the radial oscillations of a cell are governed by the same set of equations as those of a forced antibubble. Evidently, these equations must hold for liposomes under sonication, as well. Słowa kluczowe: spatio-temporal cell dynamics, Rayleigh-Plesset equation, spherical cell, red blood cell, erythrocyte Afiliacje autorów:
Johansen K. | - | University of Bergen (NO) | Kimmel E. | - | Technion - Israel Institute of Technology (IL) | Postema M. | - | IPPT PAN |
| | 20p. |
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Johansen K.♦, Postema M., Lagrangian formalism for computing oscillations of spherically symmetric encapsulated acoustic antibubbles,
HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.197-208, 2016Streszczenie: Antibubbles are gas bubbles containing a liquid droplet core and, typically, a stabilising outer shell. It has been hypothesised that acoustically driven antibubbles can be used for active leakage detection from subsea production facilities. This paper treats the dynamics of spherically symmetric microscopic antibubbles, building on existing models of bubble dynamics. A more complete understanding of microbubble dynamics demands that the effects of the translational dynamics is included into the Rayleigh-Plesset equation, which has been the primary aim of this paper. Moreover, it is a goal of this paper to derive a theory that is not based on ad-hoc parameters due to the presence of a shell, but rather on material properties. To achieve a coupled set of differential equations describing the radial and translational dynamics of an antibubble, in this paper Lagrangian formalism is used, where a Rayleigh-Plesset-like equation allows for the shell to be modelled from first principles. Two shell models are adopted; one for a Newtonian fluid shell, and the other for a Maxwell fluid shell. In addition, a zero-thickness approximation of the encapsulation is presented for both models. The Newtonian fluid shell can be considered as a special case of the Maxwell fluid shell. The equations have been linearised and the natural and damped resonance frequencies have been presented for both shell models. Słowa kluczowe: microbubbles, spatio–temporal bubble dynamics, Rayleigh-Plesset equation Afiliacje autorów:
Johansen K. | - | University of Bergen (NO) | Postema M. | - | IPPT PAN |
| | 6p. |
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Kotopoulis S.♦, Johansen K.♦, Gilja O.H.♦, Poortinga A.T.♦, Postema M.♦, Acoustically Active Antibubbles,
ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.127.99, Vol.127, No.1, pp.99-102, 2015Streszczenie: In this study, we analyse the behaviour of antibubbles when subjected to an ultrasonic pulse. Speci cally, we derive oscillating behaviour of acoustic antibubbles with a negligible outer shell, resulting in a Rayleigh Plesset equation of antibubble dynamics. Furthermore, we compare theoretical behaviour of antibubbles to behaviour of regular gas bubbles. We conclude that antibubbles and regular bubbles respond to an acoustic wave in a very similar manner if the antibubble's liquid core radius is less than half the antibubble radius. For larger cores, antibubbles demonstrate highly harmonic behaviour, which would make them suitable vehicles in ultrasonic imaging and ultrasound-guided drug delivery. Afiliacje autorów:
Kotopoulis S. | - | Haukeland University Hospital (NO) | Johansen K. | - | University of Bergen (NO) | Gilja O.H. | - | Haukeland University Hospital (NO) | Poortinga A.T. | - | Eindhoven University of Technology (NL) | Postema M. | - | inna afiliacja |
| | 15p. |
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Johansen K.♦, Kotopoulis S.♦, Postema M.♦, Ultrasonically driven antibubbles encapsulated by Newtonian fluids for active leakage detection,
LECTURE NOTES IN ENGINEERING AND COMPUTER SCIENCE, ISSN: 2078-0958, Vol.2216, pp.750-754, 2015Streszczenie: An antibubble consists of a liquid droplet, surrounded by a gas, often with an encapsulating shell. Antibubbles of microscopic sizes suspended in fluids are acoustically active in the ultrasonic range. In this study, a Rayleigh-Plesset-like model is derived for micron-sized antibubbles encapsulated by Newtonian fluids. The theoretical behaviour of an encapsulated antibubble is compared to that of an antibubble without an encapsulating shell, a free gas bubble, and an encapsulated gas bubble. Antibubbles, with droplet core sizes in the range of 60– 90% of the equilibrium antibubble inner radius were studied. Acoustic pressures of 100kPa and 300kPa were studied. The antibubble resonance frequency, the phase difference of the radial oscillations with respect to the incident acoustic pulse, and the presence of higher harmonics are strongly dependent of the core droplet size. The contribution to the radial dynamics from a zero-thickness shell is negligible for the bubble size studied, at high acoustic amplitudes, antibubbles oscillate highly nonlinearly independent of core droplet size. This may allow for active leakage detection using harmonic imaging methods. Słowa kluczowe: Active leakage detection, Antibubble, Bubble resonance, Microbubble, Nonlinear dynamics Afiliacje autorów:
Johansen K. | - | University of Bergen (NO) | Kotopoulis S. | - | Haukeland University Hospital (NO) | Postema M. | - | inna afiliacja |
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