Computational models and irradiation imaging in multi-phase microfluidic flow configurations

by Prof. Manolis Gavaises (City University of London)

Tuesday 10 Dec 2024, 13:00 → 14:00 Europe/Berlin

XHQ / E1.173 (European XFEL )

Multiphase flows in confined microchannel configurations are realised in many engineering applications and biomedical settings. Widely known examples include boiling, electrolysing bubbles, cavitation in hydraulic systems, bubbles formed in the human body including traumatic brain injury, ultrasound-induced lithotripsy, histotripsy, drug delivery, cleaning and even microbial deactivation and ultrasound contrast agents. The presentation gives an overview of such cases and the relevant computational models that have been developed to address them. An example from previous studies from high-flux synchrotron radiation and X-ray Phase-Contrast Imaging (XPCI) is presented; this experiment offered sharp-refractive index gradients in the liquid/vapour interface region and was capable of capturing fine morphological fluctuations of transient cavitation structures. Recently obtained results from a separate campaign performed in the spallation source of the Paul Scherrer Institut have also been obtained and briefly discussed. Finally, results form the experiment contacted in XFEL (proposal number 4556) are presented. These refer to the visualisation of the interaction between microbubbles and high intensity focused ultrasound (HIFU) in an microchannel channel using ultrafast X-ray microscopy at a frame rate of 1.1 MHz. An aqueous solution of the US contrast agent (SonoVue, Bracco) was pumped through the channels. The bubble mixture was treated with HIFU at 5 MHz in the artificial channel. The SonoVue bubbles had a mean diameter of 2.5 µm and are initially not visible in the X-rays. Only due to ultrasonication bubbles become visible in the channel, as they start oscillating and hence, increasing in size.

 

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