Collapse and Jet Formation of Ultrasound Contrast Microbubbles near a Membrane for Sonoporation

Contrast agents, in the presence of ultrasound, can help facilitate the uptake of drugs and genes into desired cells through the process called sonoporation. Sonoporation is the temporarily rupture of cell membranes in the presence of ultrasound. In this work, we studied the behaviour of a contrast agent near a rigid wall in the presence of ultrasound using boundary integral equation method. A contrast microbubble forms a high-velocity microjet at the last stage of the collapse phase. The microjet and the adjacent surrounding fluid impinges on the membrane and spreads radially, generating high shear stress resulting in the rupture and perforation of the cell membrane. The encapsulation of the microbubble can be assumed as an interface with an infinitesimal thickness. There are several models to simulate the interface. In this study, the encapsulation is modelled using strain-softening interfacial elastic model called the exponential elasticity model (EEM).