Living on the edge: transfer and traffic of E. coli in a confined flow

Figueroa-Morales, Nuris; Miño, Gastón Leonardo; Rivera, A.; Caballero, Rogelio; Clément, Éric; Altshuler, E.; Lindner, Anke

doi:10.1039/c5sm00939a

Cited by 70 publications

(73 citation statements)

References 26 publications

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“…Continuum modeling as performed in this work proves to be a valuable tool for the understanding and prediction of these flows and could also play a useful role in the design of microfluidic devices for bioengineering applications involving bacteria. c(r) = A 1 + A 2 I 0 (Ωr), m r (r) = A 2 I 1 (Ωr), (27) where the constants A 1 and A 2 are expressed in terms of incomplete Bessel functions as…”

Section: Periodic Channels: Racetracksmentioning

confidence: 99%

“…In dilute systems, it is well known that self-propelled particles accumulate at boundaries [24][25][26][27] as a result of both kinematic [25,[28][29][30][31] and hydrodynamic mechanisms [24,32,33]. In complex geometries, transport of the particles along curved boundaries has also been exploited to design ratchets for concentrating microswimmers or directing their motion [34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

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Geometric control of active collective motion

2017

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Recent experimental studies have shown that confinement can profoundly affect selforganization in semi-dilute active suspensions, leading to striking features such as the formation of steady and spontaneous vortices in circular domains and the emergence of unidirectional pumping motions in periodic racetrack geometries. Motivated by these findings, we analyze the two-dimensional dynamics in confined suspensions of active self-propelled swimmers using a mean-field kinetic theory where conservation equations for the particle configurations are coupled to the forced Navier-Stokes equations for the self-generated fluid flow. In circular domains, a systematic exploration of the parameter space casts light on three distinct states: equilibrium with no flow, stable vortex, and chaotic motion, and the transitions between these are explained and predicted quantitatively using a linearized theory. In periodic racetracks, similar transitions from equilibrium to net pumping to traveling waves to chaos are observed in agreement with experimental observations and are also explained theoretically. Our results underscore the subtle effects of geometry on the morphology and dynamics of emerging patterns in active suspensions and pave the way for the control of active collective motion in microfluidic devices.

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Section: Periodic Channels: Racetracksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geometric control of active collective motion

2017

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“…The effects of confinement to narrow flow channels are less well understood; see, e.g., [10][11][12][13][14] and references therein. Recent experiments on driven droplets [3,[15][16][17] and self-propelled colloids [18,19] in quasi two-dimensional (Hele-Shaw type) channels show the emergence of traveling density waves, including density shocks at the wave front.…”

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confidence: 99%

Density Shock Waves in Confined Microswimmers

Tsang

Kanso

2016

Phys. Rev. Lett.

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Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from 'subsonic' with compression at the back to 'supersonic' with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a non-trivial interplay between hydrodynamic interactions and geometric confinement, and is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechanisms for controlling the emergent density distribution and average population speed, with potentially profound implications on various processes in industry and biotechnology such as the transport and sorting of cells in flow channels. , and pathogens in the urinary tract [6]. The ability to control the density distribution and group velocity of micro-particles in flow would therefore have numerous applications in physics and biology. This letter analyzes, via discrete particle simulations and macroscopic models, the emergent patterns in populations of motile particles driven by an external flow in a rectangular micro-channel.The dynamics of single and many-swimmer systems are typically studied in unconfined settings [7][8][9]. The effects of confinement to narrow flow channels are less well understood; see, e.g., [10][11][12][13][14] and references therein. Recent experiments on driven droplets [3,[15][16][17] and self-propelled colloids [18,19] in quasi two-dimensional (Hele-Shaw type) channels show the emergence of traveling density waves, including density shocks at the wave front. Similar observations are reported in simulations of confined self-propelled particles [20], albeit with density shocks forming at the back of the wave. The primary mechanism responsible for the emergence of these density waves is attributed to hydrodynamic interactions (HI) among the confined particles [18,20]. Confinement in Hele-Shaw type geometries induces a distinct hydrodynamic signature; the particle far-field disturbance is that of a source dipole irrespective of the details of the particle transport mechanism, driven or self-propelled, pusher or puller [3,15,16,21,22]. Additional confinement to a narrow channel does not alter the nature of hydrodynamic interactions but imposes impenetrability conditions on the lateral boundaries of the channel. These effects are properly accounted for in the model used in [20], and, * corresponding author: kanso@usc.edu thus, do not explain the discrepancy in the location of the shock ...

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“…This detachment from surfaces by imposed flows has been demonstrated recently in experiments [43]. In figure 4, the minimum flow strength required to detach a swimmer from the bottom wall is shown as a function of dipole moment k and source doublet moment s. Note the asymmetry-a pusher can be washed off more easily than its equivalent puller.…”

Section: Flow-induced Peelingmentioning

confidence: 88%

Hotspots of boundary accumulation: dynamics and statistics of micro-swimmers in flowing films

Mathijssen¹,

Doostmohammadi²,

Yeomans³

et al. 2016

J. R. Soc. Interface.

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Biological flows over surfaces and interfaces can result in accumulation hotspots or depleted voids of microorganisms in natural environments. Apprehending the mechanisms that lead to such distributions is essential for understanding biofilm initiation. Using a systematic framework, we resolve the dynamics and statistics of swimming microbes within flowing films, considering the impact of confinement through steric and hydrodynamic interactions, flow and motility, along with Brownian and run-tumble fluctuations. Micro-swimmers can be peeled off the solid wall above a critical flow strength. However, the interplay of flow and fluctuations causes organisms to migrate back towards the wall above a secondary critical value. Hence, faster flows may not always be the most efficacious strategy to discourage biofilm initiation. Moreover, we find run-tumble dynamics commonly used by flagellated microbes to be an intrinsically more successful strategy to escape from boundaries than equivalent levels of enhanced Brownian noise in ciliated organisms.

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Living on the edge: transfer and traffic of E. coli in a confined flow

Cited by 70 publications

References 26 publications

Geometric control of active collective motion

Geometric control of active collective motion

Density Shock Waves in Confined Microswimmers

Hotspots of boundary accumulation: dynamics and statistics of micro-swimmers in flowing films

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