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Communication Dans Un Congrès Année : 2009

An overview of medical microbubble phenomena

Résumé

Ultrasound contrast agents consist of bubbles in the micrometer range encapsulated by nanoshells. These medical microbubbles oscillate linearly upon insonification at low acoustic amplitudes, but demonstrate highly nonlinear, destructive behaviour at relatively high acoustic amplitudes. This behaviour has been associated with sonoporation, the transient formation of pores in cells. Sonoporation is used for ultrasound-assisted drug delivery. An overview of the physical mechanisms associated with this behaviour is presented. Microbubbles have been observed to pulsate symmetrically and asymmetrically, translate, coalesce, fragment, crack, and jet during one single ultrasonic cycle. The temporary formation of an antibubble has also been observed. Assuming that fragmentation will occur only if the kinetic energy of a collapsing microbubble exceeds the instantaneous bubble surface energy, it is shown that the fragmentation threshold is not equal to the threshold at which cavitation occurs. Sonic cracking is the disruption of a bubble shell or a cell membrane and the subsequent release of encapsulated gas. We investigated the role of sonic cracking for the disruption of blue-green algae. At ultrasonic frequencies between 200 kHz and 2.5 MHz, physical damage to the algae was observed. We found that it is feasible to eradicate blue-green algae in the clinical diagnostic range (MI<0.3). Based on our observations, we conclude that safety indices should be revised for media in which bubbles are present.
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Dates et versions

hal-03576240 , version 1 (15-02-2022)

Identifiants

  • HAL Id : hal-03576240 , version 1

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Michiel Postema, Spiros Kotopoulis. An overview of medical microbubble phenomena. International Congess on Ultrasonics (2009ICU), Universidad de Santiago de Chile, Jan 2009, Santiago, Chile. ⟨hal-03576240⟩
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