Acoustically-driven cloud cavitation of coated microbubbles

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Acoustic cavitation, i.e. the pressure-driven behaviour of bubbles in a liquid environment, is utilised in a large variety of engineering applications, ranging from ultrasonic cleaning to coated microbubbles as ultrasonic contrast agents (UCA) in medical imaging. Especially the acoustic cavitation of UCA microbubbles, which are coated with a phospholipid monolayer or protein layer, has seen a steadily increasing number of diagnostic and therapeutic biomedical applications, including targeted drug delivery and novel cancer treatments. However, despite a substantial body of literature on the acoustic cavitation of microbubble clouds, a comprehensive understanding of the behaviour of clouds of coated microbubbles in an acoustic field still remains elusive. In particular, a detailed understanding of the pressure, velocity and temperature distribution as a result of the collapse of the bubble cloud is critical for treatment safety and success in biomedical applications, but has not been studied systematically yet. With this in mind, the primary objectives of the proposed project are (i) a detailed analysis of the pressure and temperature in the vicinity of collapsing clouds of microbubbles, and (ii) a comprehensive comparison of the acoustic cloud cavitation of clean and coated microbubbles, which will together lay the foundation for a safer and more efficient use of acoustic cavitation in biomedical applications. To facilitate this research, we will develop new numerical methods in the context of an Euler-Lagrange framework, extending the state-of-the-art by eliminating current limitations regarding the bubble size and improving the temperature prediction in liquids significantly. Especially for biomedical applications, we expect such numerical schemes to provide a valuable research tool that can complement experiments.