Figure 1.

Inertial Cavitation of Lipid-Coated Microbubbles: Ultrasound causes lipid-coated microbubbles to expand and contract. If the pressure is below a critical value, called the inertial cavitation threshold, then the bubble undergoes sustained oscillations (A). If the pressure is above the inertial cavitation threshold, then inertial forces govern the collapse; this is typically associated with the bubble imploding and breaking into small fragments (B). The inertial cavitation threshold pressure depends on the material properties of the lipid coating (e.g., area expansion modulus and surface tension), which are set by the monolayer composition (lipid chain length and PEG mol. wt. & regime - brush vs. mushroom), and on the presence of a PLA microcapsule and distance to the PLA wall (C).