Many microorganisms have evolved chemotactic strategies to exploit the microscale heterogeneity that frequently characterizes microbial habitats. Chemotaxis has been primarily studied as an average characteristic of a population, with little regard for variability among individuals. Here, we adopt classic tool from animal ecology - T-maze and implement it at by using microfluidics expose bacteria sequence decisions, each consisting migration up or down chemical gradient. Single-cell...

PhenoChip enables the rapid characterization of unicellular photosynthetic phenotypes under user-defined physicochemical conditions.

Abstract Microfluidic models are proving to be powerful systems study fundamental processes in porous media, due their ability replicate topologically complex environments while allowing detailed, quantitative observations at the pore scale. Yet, media such as living tissues, geological substrates, or industrial typically display a porosity that spans multiple scales, most microfluidic date limited single small range of sizes. Here, novel system with multiscale is presented. By embedding...

Bacterial infections in the blood system are usually associated with flow oscillation generated by some cardiovascular pathologies and insertion of indwelling devices. The influence hydrodynamically induced shear stress fluctuations on Staphylococcus aureus biofilm morphology tolerance to antibiotics was investigated. Fluctuating stresses physiologically relevant levels were wells a six-well microdish agitated an orbital shaker. Numerical simulations performed determine spatial distribution...

The effects of non-uniform hydrodynamic conditions resulting from flow cell geometry (square and rectangular cross-section) on Pseudomonas aeruginosa 01 (PAO1) biofilm formation, location, structure were investigated for nominally similar using a combination confocal scanning laser microscope (CSLM) computational fluid dynamics (CFD). thickness surface coverage PAO1 biofilms observed to vary depending the location in thus also local wall shear stress. 5:1 (width height) aspect ratio was...

Dense suspensions of motile bacteria, possibly including the human gut microbiome, exhibit collective dynamics akin to those observed in classic, high Reynolds number turbulence with important implications for chemical and biological transport, yet this analogy has remained primarily qualitative. Here, we present experiments which a dense suspension Bacillus subtilis bacteria was flowed through microchannels velocity statistics flowing were quantified using recently developed velocimetry...

ABSTRACT Most microbial life on Earth is found in localized microenvironments that collectively exert a crucial role maintaining ecosystem health and influencing global biogeochemical cycles. In many habitats such as biofilms aquatic systems, bacterial flocs activated sludge, periphyton mats, or particles sinking the ocean, these experience sporadic continuous flow. Depending their microscale structure, pores channels through permit flow shifts relative importance of diffusive advective mass...

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly prevalent pathogen capable of causing severe vascular infections. The goal this work was to investigate the role shear stress in early adhesion events. Methods Human umbilical vein endothelial cells (HUVEC) were exposed MRSA for 15-60 minutes and stresses 0-1.2 Pa a parallel plate flow chamber system. Confocal microscopy stacks captured analyzed assess number MRSA. Flow parameters validated using...

One of the main features backward-facing step (BFS) low frequency pulsatile flow is unsteadiness due to convection vortical (coherent) structures, which characterize dynamics in shear layer. The physics field analyzed by looking at energy redistribution between mean and pulsating obtained via a particle image velocimeter (PIV) using concept triple decomposition. total fluctuating kinetic budget calculated discussed for Reynolds number 100 0.035 ≤ St 2.19. effects that these coherent...

This work is concerned with the behavior of pulsatile flows over a backward-facing step geometry. The paper mainly focuses on effects pulsation frequency vortex development 2:1 for mean Reynolds number 100 and 0.035 ≤ St 2.19. dependence flow field (Re = 200) was also examined constant Strouhal number, 1. A literature survey carried out it found that modifies pattern compared to steady flow. It shown in present inlet generally leads differences although bulk velocity same due energy...

A Backward-Facing Step (BFS) is widely used as an in-vitro model to investigate the influence of flow separation and recirculation observed in biomedical devices, arterial bifurcations stenoses. In this study we numerically over a BFS with expansion ratio 2 pulsed velocity at inlet. The main objective effects oscillation frequency amplitude on evolution interaction between vortices. pulsatile leads breakdown primary vortex generation secondary upper wall instability lower Reynolds numbers...

Microfluidics is a relatively novel interdisciplinary research area with broad applications in chemistry, physics, material science, and biology. Despite the rapid growth of field, students' exposure to microfluidic technologies still limited often insufficient appreciate advantages over other commonly used technologies. To this end, we designed five-day course, "Microfluidics for microbial ecology," which students very different backgrounds learn basics sample range ecology. The course was...

The appearance of highly resistance bacterial strains or ldquosuper bugsrdquo is a major challenge in both the community and hospital environment. Manipulating laboratory based devices order to generate correct environmental conditions study these biofilms requires through comprehension hydrodynamics surrounding biofilm. In this study, MBECtrade biomedical were used biofilm antibiotic response susceptibility at different rotational speeds an orbital shaker. fluid motion was modeled with...

We demonstrate a method for the generation of controlled, dynamic chemical pulses―where localized chemoattractant becomes suddenly available at microscale―to create micro-environments microbial chemotaxis experiments. To pulses, we developed system to introduce amino acid sources near-instantaneously by photolysis caged acids within polydimethylsiloxane (PDMS) microfluidic chamber containing bacterial suspension. applied this chemotactic bacterium, Vibrio ordalii, which can actively climb...

Abstract While a variety of active and passive techniques have been proposed for steady flows, pulsatile flow has received much less attention. Pulsation makes more control parameters available methods enables them to separate particles. The purpose this work is determine the effects phase shift between two entering flows (only one includes particles) on particle separation inside double Y-microchannel. Numerical simulations were carried out both pulsating conditions. results showed that...

Ejector Refrigeration Systems (ERS) offer the use of low grade energy sources. These systems are simple in principle; however, suffer from relatively COP, mainly due to inefficient exchange between primary and secondary fluid flows ejector. The two chemically distinct fluids forward reversed Rankine cycles such has been shown improve COP. known as Binary Fluid ERS (BFERS). This paper focuses on application BFERS for purpose water distillation. First, a model an ideal ejector was developed...

Wall shear stress acting on arterial walls is an important hemodynamic force determining vessel health. A parallel-plate flow chamber with a 127 μm-thick channel used as in vitro system to study the fluid mechanics environment. It essential know how well this performs emulating physiologic regimes especially when cultured cells are present. Hence, objectives of work computationally and experimentally characteristic providing defined regime map wall distributions presence endothelial cell...

The hydrodynamics in flow systems is known to induce phenotypic changes associated with bacterial biofilms, including increased tolerance antimicrobial agents and biocides. Results obtained cells commonly used biological medical studies on the influence of biofilm behavior susceptibility are sometimes contradictory. It thus hypothesized that discrepancies results may be related cell geometry. In this study, shear stress distribution substrate concentration were numerically simulated inside...

Abstract Most microbial life on Earth is found in localized microenvironments that collectively exert a crucial role maintaining ecosystem health and influencing global biogeochemical cycles. In many habitats such as biofilms aquatic systems, bacterial flocs activated sludge, periphyton mats, or particles sinking the ocean, these experience sporadic continuous flow. Depending their microscale structure, pores channels through permit flow shifts relative importance of diffusive advective mass...