The ultrasound-driven bubble

Abstract: Microbubbles (i.e. bubbles below 5 microns in radius) are the unrivaled agent for contrast and therapy in biomedical ultrasound. These bubbles are riddled with physical challenges from their production to their oscillations within an ultrasound field. Produced using hydrodynamic instability in microfluidic chips, these bubbles are highly nonlinear both in frequency and pressure. These nonlinearities are both a tremendous advantage for imaging a patients’ vasculature with high, and a formidable difficulty to design advanced imaging strategies that are robust to nonlinear responses. While the addition of a shell, which typically consists of phospholipids, is paramount for producing and stabilizing the bubbles, this soft, monolayer shell renders bubbles significantly more nonlinear. This fact can be exploited, for example, for remote pressure sensing, molecular imaging, and super-resolution. Finally, confinement within a vessel or near a boundary (almost inevitable in practice) drastically changes bubble dynamics by making the bubble oscillations nonspherical. These features are essential for local drug delivery and locally sensing tissue elasticity. During this presentation, we will walk through what makes a bubble so interesting form a physical standpoint and how we can exploit these features to bring about new ultrasound imaging methods.

Le mardi 25 mars 2025 à 11h00 / Amphithéâtre François Canac, LMA

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