Bacterial accumulation mediated by flow compression-expansion

GASTÓN L. MIÑO; ERNESTO ALTSHULER; ANKE LINDNER; ROMAN STOCKER; CARLOS A. CONDAT ; ADOLFO J. BANCHI; VERONICA I. MARCONI; ERIC CLÉMENT

San Francisco

Congreso; 67th Annual Meeting of the APS Division of Fluid Dynamics; 2014

American Physical Society

Swimming bacteria can be concentrated using a suitable microfluidic device. The combination of flow rate and surface shape can have significant impact on the microorganisms´ behavior. In those processes rheotaxis, accumulation caused by ratchets and even attachment to surfaces leading biofilm formation can be observed. Under these conditions, the transport of the active suspension is deeply modified, and differs significantly from passive suspensions. In this work, we present experimental evidence of Escherichia coli suspension flowing in a straight channel with a funnel-like constriction in the middle. This constriction is characterized by the aperture (wf) and its angle (Θf). We explore how the modification of wf and Θf affects the accumulation of bacteria in the channel. Concentrations of bacteria passing the constriction were observed for all the cases. However, the range of the flow rate that produced such accumulation varied with the geometry. In order to obtain a better understanding of this phenomenon, experiments are compared with a simple phenomenological model.