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Aqueous microbubble flows in confined geometries: from hydrodynamics to multiscale antibacterial efficiency

Academic lead
Dr Sepideh Khodaparast, School of Mechanical Engineering, s.khodaparast@leeds.ac.uk
Co-supervisor(s)
Dr Mark Wilson, School of Mechanical Engineering, M.Wilson@leeds.ac.uk, Prof Stephen Evans, School of Physics and Astronomy, S.D.Evans@leeds.ac.uk
Project themes
Computational & Analytical Tools, Data-driven methods, Environmental Flows, Experimental Techniques, Fundamental, Health, Multiphysics & Complex Fluids

Synthetic objects in natural environments are often irreversibly inhabited by micro-organisms, especially bacterial cells, connected by a web of extracellular polymeric substances to form surface-colonising biofilms. Mature biofilms actively feed the formation of new colonies and promote the attachment of secondary micro- and macroscopic fouling, therefore, effective removal of bacterial fouling at early stages is of critical interest to engineering and biomedical applications. Challenging demands for biofilm removal are usually encountered on the solid walls of confined geometries with dimensions of hundreds of micrometres to a few millimetres, providing no or limited physical access. Using chemical antibacterial solutions in such cases often yields severe environmental and health hazards, as well as a long downtime for facilities.   

As an alternative strategy, air-water interfaces introduced in the form of small microbubbles (1-10’s micrometre in diameter) can be effectively used for the removal of bacterial cells and their extracellular matrix from the internal boundaries of confined geometries. This chemical-free mechanism is driven by a capillary force introduced at the bubble interface. Provided that this force is larger than the cell adhesion force, increasing the probability of microbubble-bacteria encounters and their contact time will improve the removal efficiency of the approach.  

This research focuses on identifying the critical interfacial and flow parameters impacting the outcome of the flow-bacteria interaction, through in-situ quantitative microscopy analysis in tandem with numerical simulations. Benefiting from the ongoing and previous successful proof-of-concept developments, the PhD project aims to construct a data-driven model to predict the bacteria removal efficiency of aqueous flows of microbubbles based on operational flow parameters.