Modeling non-spherical oscillations and stability of acoustically driven shelled microbubbles.
The oscillation and destruction of microbubbles under ultrasound excitation form the basis of contrast enhanced ultrasound imaging and microbubble assisted drug and gene delivery. A typical microbubble has a size of a few micrometers and consists of a gas core encapsulated by a shell. These bubbles can be driven into surface mode oscillations, which not only contribute to the measured acoustic signal but can lead to bubble destruction. Existing models of surface model oscillations have not considered the effects of a bubble shell. In this study a model was developed to study the surface mode oscillations in shelled bubbles. The effects of shell viscosity and elasticity on the surface mode oscillations were modeled using a Boussinesq-Scriven approach. Simulation was conducted using the model with various bubble sizes and driving acoustic pressures. The occurrence of surface modes and the number of ultrasound cycles needed for the occurrence were calculated. The simulation results show a significant difference between shelled bubbles and shell free bubbles. The shelled bubbles have reduced surface mode amplitudes and a narrower bubble size range within which these modes develop compared to shell free bubbles. The clinical implications were also discussed.
Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.
Jonathan
J
Loughran
Robert J
RJ
Eckersley
Meng-Xing
MX
Tang
D003287:Contrast Media; D004548:Elasticity; D045423:Microbubbles; D008962:Models, Theoretical; D010743:Phospholipids; D013459:Sulfur Hexafluoride; D014465:Ultrasonics; D014783:Viscosity
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride