Focusing of active particles in a converging flow

Potomkin, Mykhailo; Kaiser, Andreas; Berlyand, Leonid; Aranson, Igor S.

doi:10.1088/1367-2630/aa94fd

Cited by 16 publications

(19 citation statements)

References 76 publications

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“…The flow in these regions seems to align the bacteria along the flow direction thus enhancing their mean transport velocity. Interestingly, the effect of stabilization by constriction was also described and discussed recently by Potomkin et al [33].…”

Section: Ii5 Rapid Downstream Migrationmentioning

confidence: 53%

Effect of motility on the transport of bacteria populations through a porous medium

et al. 2019

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The role of activity on the hydrodynamic dispersion of bacteria in a model porous medium is studied by tracking thousands of bacteria in a microfluidic chip containing randomly placed pillars. We first evaluate the spreading dynamics of two populations of motile and non-motile bacteria injected at different flow rates. In both cases, we observe that the mean and the variance of the distances covered by the bacteria vary linearly with time and flow velocity, a result qualitatively consistent with the standard geometric dispersion picture. However, quantitatively, the motiles bacteria display a systematic retardation effect when compared to the non-motile ones. Furthermore, the shape of the traveled distance distribution in the flow direction differs significantly for both the motile and the non-motile strain, hence probing a markedly different exploration process. For the non-motile bacteria, the distribution is Gaussian whereas for the motile ones, the distribution displays a positive skewness and spreads exponentially downstream akin to a Gamma distribution. The detailed microscopic study of the trajectories reveals two salient effects characterizing the exploration process of motile bacteria : (i) The emergence of an "active" retention effect due to an extended exploration of the pore surfaces, (ii) an enhanced spreading at the forefront due to the transport of bacteria along "fast-tracks" where they acquire a velocity larger than the local flow velocity. We finally discuss the practical applications of these effects on the large-scale macroscopic transfer and contamination processes caused by microbes in natural environments.

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Section: Ii5 Rapid Downstream Migrationmentioning

confidence: 53%

Effect of motility on the transport of bacteria populations through a porous medium

et al. 2019

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“…The description of the active stress σ a goes back to two seminal papers that demonstrated the active stress of wet rods to be proportional to the nematic order parameter with a sign depending on the forcing of the individuals, i.e. pusher or puller [130][131][132]. Recently, the representation of the active stress tensor similarly to the approach used in [133] was extended by including higher derivatives [55] via a Taylor expansion of point forces yielding…”

Section: A Nonequilibrium Dynamics Of Wet Self-propelled Rodsmentioning

confidence: 99%

Self-Propelled Rods: Insights and Perspectives for Active Matter

Bär

Großmann

Heidenreich

et al. 2020

Annu. Rev. Condens. Matter Phys.

240

182

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A wide range of experimental systems including gliding, swarming and swimming bacteria, in-vitro motility assays as well as shaken granular media are commonly described as self-propelled rods. Large ensembles of those entities display a large variety of self-organized, collective phenomena, including formation of moving polar clusters, polar and nematic dynamic bands, mobility-induced phase separation, topological defects and mesoscale turbulence, among others. Here, we give a brief survey of experimental observations and review the theoretical description of selfpropelled rods. Our focus is on the emergent pattern formation of ensembles of dry self-propelled rods governed by short-ranged, contact mediated interactions and their wet counterparts that are also subject to long-ranged hydrodynamic flows. Altogether, self-propelled rods provide an overarching theme covering many aspects of active matter containing well-explored limiting cases. Their collective behavior not only bridges the well-studied regimes of polar self-propelled particles and active nematics, and includes active phase separation, but also reveals a rich variety of new patterns. arXiv:1907.00360v1 [cond-mat.stat-mech]

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“…Through this mechanism of self-propulsion, these particles exhibit exciting behaviors mimicking that of its biological counterparts such as the ability to swim across flow streamlines, upstream migration, and wall accumulation. [22][23][24][25][26][27][28][29][30] In the absence of H 2 O 2 , the same particles are passive because no chemical reaction occurs.…”

mentioning

confidence: 99%

Self‐Propulsion and Shear Flow Align Active Particles in Nozzles and Channels

Rubio

Potomkin

Baker

et al. 2020

Advanced Intelligent Systems

Self Cite

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Active particles are capable of self-propelling by consuming energy from the environment. [1] The particles may be living, such as bacteria, or synthetic, such as bimetallic rods or spherical Janus particles. Due to persistent energy input, active materials are examples of out-of-equilibrium systems. They exhibit variety of intriguing phenomena such as the onset of collective behavior, [2,3] reduction of effective viscosity, [4-6] extraction of useful energy, [7-9] and enhanced mixing. [10-12] Typically, active microswimmers show a preferred orientation which determines the self-propulsion direction. Distribution of active particle orientation may have a significant impact on the macroscopic properties of the active material. It was shown in refs. [13-15] that reduction of effective viscosity in the suspension of active microswimmers, exemplified by bacteria, may be explained by a specific form of orientational distribution with respect to the background shear flow. In refs. [16,17] authors showed how the orientation of active microswimmers in the background shear flow leads to the formation of depletion regions, where particles' number density is significantly lower than the average value. Chemically-driven synthetic microswimmers, mimicking motility of living microorganisms , were first introduced by Paxton et al. [18] Since then the repertoire of synthetic microswimmers, as well as mechanisms which can be used to activate their self-propulsion, have significantly expanded. [1] The importance of synthetic microswimmers is twofold. On the one hand, their development leads to a variety of potential applications, for example in medicine [19,20] and materials science. [21] On the other hand, their study sheds new light on fundamental motility mechanisms and biological self-organization.

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Focusing of active particles in a converging flow

Cited by 16 publications

References 76 publications

Effect of motility on the transport of bacteria populations through a porous medium

Effect of motility on the transport of bacteria populations through a porous medium

Self-Propelled Rods: Insights and Perspectives for Active Matter

Self‐Propulsion and Shear Flow Align Active Particles in Nozzles and Channels

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