Bubble-Driven Detachment of Bacteria from Confined Microgeometries. Author Sepideh Khodaparast, Minyoung Kim, Justin Silpe, Howard Stone Publication Year 2017 Type Journal Article Abstract Moving air-liquid interfaces, for example, bubbles, play a significant role in the detachment and transport of colloids and microorganisms in confined systems as well as unsaturated porous media. Moreover, they can effectively prevent and/or postpone the development of mature biofilms on surfaces that are colonized by bacteria. Here we demonstrate the dynamics and quantify the effectiveness of this bubble-driven detachment process for the bacterial strain Staphylococcus aureus. We investigate the effects of interface velocity and geometrical factors through microfluidic experiments that mimic some of the confinement features of pore-scale geometries. Depending on the bubble velocity U, at least three different flow regimes are found. These operating flow regimes not only affect the efficiency of the detachment process but also modify the final distribution of the bacteria on the surface. We organize our results according to the capillary number, [Formula: see text], where μ and γ are the viscosity and the surface tension, respectively. Bubbles at very low velocities, corresponding to capillary numbers Ca < 5 × 10, exhibit detachment efficiencies of up to 80% at the early stage of bacterial adhesion. In contrast, faster bubbles at capillary numbers Ca > 10, have lower detachment efficiencies and cause significant nonuniformities in the final distribution of the cells on the substrate. This effect is associated with the formation of a thin liquid film around the bubble at higher Ca. In general, at higher bubble velocities bacterial cells in the corners of the geometry are less influenced by the bubble passage compared to the central region. Keywords Bacterial Adhesion, Bacteria, Staphylococcus aureus, Surface Properties, Colloids Journal Environ Sci Technol Volume 51 Issue 3 Pages 1340-1347 Date Published 2017 Feb 07 ISSN Number 1520-5851 DOI 10.1021/acs.est.6b04369 Alternate Journal Environ Sci Technol PMID 28075119 PubMedGoogle ScholarBibTeXEndNote X3 XML