"The Good, the Bad, and the Bubbly!"

Abstract

My group have been studying acoustically driven bubbles, ostensibly for their potential medical 
applications, since 2004. During this period we have developed a protocol that integrates optical 
tweezing for spatial control, with high speed imaging to resolve bubble behaviour at MHz framing 
rates. Here, single bubbles exhibit some unusual features, especially when driven at high amplitudes,
where their non-linear response can lead to the development of extremely high core energy densities 
during the collapse phase: a process underpinning phenomena such as sonoluminescence and even plasma 
formation. When rigid surfaces (such as endothelial cells in a tissue plane) are nearby during 
cavitation, bubbles are then predisposed to asymmetric collapse, often forming fast moving liquid jets
that potentiate localised surface damage and facilitate drug or gene delivery in a controlled manner.
Moreover, when scenarios involving multiple bubbles are developed and observed, a new level of
richness in the prevalent physical phenomena emerges.

In this talk, I will give a review of the technology that we developed, and the salient features of 
single and multiple bubble behaviour in acoustic fields, especially in the context of their therapeutic
potential. Notably also, we gathered all of our data using a high speed camera borrowed from the EPSRC
instrument loan pool, and which has a variety of interesting quirks that will be discussed and
explained at length, lest some other wretched souls trip headfirst into the pitfalls that we have 
previously encountered.