Flow-controlled densification and anomalous dispersion of E. coli through a constriction

Altshuler, E.; Miño, Gastón Leonardo; Pérez-Penichet, Carlos; Río, Laura del; Lindner, Anke; Rousselet, Annie; Clément, Éric

doi:10.1039/c2sm26460a

Cited by 51 publications

(49 citation statements)

References 31 publications

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“…Flow in a narrow channel is known to change the accumulation of cells on the walls and even to cause upstream swimming. Moreover, the response to flow depends upon the tumbling rate of the cells [12,41]. We could hypothesize that flow may lower the sorting efficiency when pointing in the easy ratchet direction (left-right) and enhance the efficiency otherwise, but this is something that deserves careful study.…”

Section: Discussionmentioning

confidence: 99%

“…These objects range from artificial microswimmers that can be actuated using applied magnetic fields [1] to motile cancer [2,3] and stem [4] cells, to motile bacteria [5,6] and spermatozoa [7,8]. The study of their properties in confined regions has been made possible by recent advances in microfabrication [9,10] and observation [11,12] techniques.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets

Berdakin¹,

Silhanek

Cortéz

et al. 2013

Open Physics

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Abstract:Suitable asymmetric microstructures can be used to control the direction of motion in microorganism populations. This rectification process makes it possible to accumulate swimmers in a region of space or to sort different swimmers. Here we study numerically how the separation process depends on the specific motility strategies of the microorganisms involved. Crucial properties such as the separation efficiency and the separation time for two bacterial strains are precisely defined and evaluated. In particular, the sorting of two bacterial populations inoculated in a box consisting of a series of chambers separated by columns of asymmetric obstacles is investigated. We show how the sorting efficiency is enhanced by these obstacles and conclude that this kind of sorting can be efficiently used even when the involved populations differ only in one aspect of their swimming strategy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets

Berdakin¹,

Silhanek

Cortéz

et al. 2013

Open Physics

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show abstract

“…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]. The case of semi-dilute to concentrated suspensions in confinement, however, has largely been unexplored but in a few studies.…”

Section: Introductionmentioning

confidence: 99%

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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“…The creation of inhomogeneous distributions of swimmer populations via asymmetric obstacles has been shown to be particularly efficient for run-and-tumble bacteria [16,[21][22][23]. Alternative ways of achieving nonuniform distributions have also been obtained combining symmetric funnels and flux [24]. Nowadays, numerous theoretical treatments are available to account for the effects of asymmetric obstacles on active particles distributions [25][26][27][28].…”

mentioning

confidence: 99%

Geometrical guidance and trapping transition of human sperm cells

et al. 2014

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The guidance of human sperm cells under confinement in quasi 2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations are performed with dilute sperm populations, for which effects of geometrical guidance and concentration are studied in detail. In particular, a trapping transition at convex angular wall features is identified and analyzed. We also show that highly efficient microratchets can be fabricated by using curved asymmetric obstacles to take advantage of the spermatozoa specific swimming strategy.PACS numbers: 87.17. Jj, 87.18.Hf, 87.17.Aa, 87.17.Rt Understanding sperm dynamics under confining microgeometries is a general problem and a major challenge both from the basic biophysics and the complex fluids points of view. It is also crucial for microfluidics and biomedical control applications. Our knowledge of the swimming cell motilities in unbounded media cannot be directly extrapolated to their behavior in complex environments such as those found in the oviduct or in the labon-a-chip microfluidic devices used to control and analyze small samples or for in-vitro reproduction procedures. In these cases, the characteristic length scales are of the same order as the cell size, i.e. a few micrometers. Under these circumstances, confined self-propelled microorganisms undergo substantial changes in their locomotion habits, adapting their dynamics to intricate porous media or to solid surfaces vicinity [1], reducing their speed close to boundaries [2] or adjusting their morphology and motility in very narrow channels [3].It has been shown that microswimmers with very different propulsion systems are similarly attracted to the walls and to swim parallel to the surface [2,[4][5][6][7][8][9][10][11]. It is believed that this attractive force has hydrodynamic origin although other possible mechanisms have been proposed [12][13][14]. Several models have been introduced to describe the swimming along surfaces (see Ref.[15] and references therein). Interestingly, the direct observation of the cell-wall attraction (see Fig. 1) have led to the design of ratchet devices that guide and sort self-propelled cells using asymmetric obstacles [16,17]. In particular, different microfluidic devices have been created to either increase sperm cell quality or enhance their concentration [18][19][20]. The creation of inhomogeneous distributions of swimmer populations via asymmetric obstacles has been shown to be particularly efficient for run-and-tumble bacteria [16,[21][22][23]. Alternative ways of achieving nonuniform distributions have also been obtained combining symmetric funnels and flux [24]. Nowadays, numerous theoretical treatments are available to account for the effects of asymmetric obstacles on active particles distributions [25][26][27][28]. Tumbles, rotational diffusion and collisions are efficient mechanisms for separating the cells from the surface, thus permitting bacteria to be reinserted into the bulk of the confining micro...

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Flow-controlled densification and anomalous dispersion of E. coli through a constriction

Cited by 51 publications

References 31 publications

Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets

Quantifying the sorting efficiency of self-propelled run-and-tumble swimmers by geometrical ratchets

Geometric control of active collective motion

Geometrical guidance and trapping transition of human sperm cells

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