Tuning chemotactic and diffusiophoretic spreading <i>via</i> hydrodynamic flows

Chu, Henry; Garoff, Stephen; Tilton, Robert D.; Khair, Aditya S.

doi:10.1039/d2sm00139j

Cited by 11 publications

(15 citation statements)

References 74 publications

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“…These observations are in accordance with a recent more complex expression for the phoretic velocity proposed in Menolascina et al (2017) and Salek et al (2019). Thus, depending on the species considered and its concentration, a drift velocity of the type v dp = α∇S can also be observed in practice (corresponding to D dp ∝ S), as discussed in Chu et al (2022); this is the expression we consider in this article. Note finally that in a view of simplicity, in the following we mainly refer to diffusiophoresis.…”

Section: Introductionsupporting

confidence: 89%

“…One may wonder if such behaviours as enhanced dispersion or blockage could be observed in practice. In the case of chemotaxis, because of the very large values of the drift coefficient α involved (Chu et al 2022), a situation of blockage would be likely to happen in such flow configurations, where the separatrices would become real transport barriers (Berman et al 2021). However, when the nutriments would lack, and the gradient G would decrease sufficiently, the motile organisms would become free to leave their cell and perhaps find some food somewhere else.…”

Section: Discussionmentioning

confidence: 99%

“…In the case of chemotaxis, because of the very large values of the drift coefficient involved (Chu et al. 2022), a situation of blockage would be likely to happen in such flow configurations, where the separatrices would become real transport barriers (Berman et al. 2021).…”

Section: Discussionmentioning

confidence: 99%

“…Note finally that in a view of simplicity, in the following we mainly refer to diffusiophoresis. However, other mechanisms such as chemotaxis (for instance, movement of a motile organism in a direction corresponding to a gradient concentration of a nutriment) lead to a similar expression for the drift velocity, but with a much larger drift coefficient α, as also discussed in Chu et al (2022).…”

Section: Introductionmentioning

confidence: 92%

“…Thus, depending on the species considered and its concentration, a drift velocity of the type can also be observed in practice (corresponding to ), as discussed in Chu et al. (2022); this is the expression we consider in this article. Note finally that in a view of simplicity, in the following we mainly refer to diffusiophoresis.…”

Section: Introductionmentioning

confidence: 92%

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Phoresis in cellular flows: from enhanced dispersion to blockage

et al. 2022

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In this article, we study numerically the dispersion of colloids in a two-dimensional cellular flow in the presence of an imposed mean salt gradient. Owing to the additional scalar, the colloids do not follow exactly the Eulerian flow field, but have a (small) extra-velocity proportional to the salt gradient, $\boldsymbol {v}_{dp}=\alpha \boldsymbol {\nabla } S$ , where $\alpha$ is the phoretic constant and $S$ the salt concentration. We study the demixing of an homogenous distribution of colloids and how their long-term mean velocity $\boldsymbol {V_m}$ and effective diffusivity $D_{eff}$ are influenced by the phoretic drift. We observe two regimes of colloids dynamics depending on a blockage criterion $R=\alpha G L/\sqrt {4 D_cD_s}$ , where $G$ is the mean salt gradient amplitude, $L$ the length scale of the flow and $D_c$ and $D_s$ the molecular diffusivities of colloids and salt. When $R<1$ , the mean velocity is strongly enhanced with $V_m \propto \alpha G \sqrt {Pe_s}$ , ${Pe}_s$ being the salt Péclet number. When $R > 1$ , the compressibility effect due to the phoretic drift is so strong that a depletion of colloids occurs along the separatrices inhibiting cell-to-cell transport.

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Section: Introductionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 92%

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Phoresis in cellular flows: from enhanced dispersion to blockage

et al. 2022

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The role of variable zeta potential on diffusiophoretic and diffusioosmotic transport

Lee

Ault

2023

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Diffusioosmotic dispersion of solute in a long narrow channel

Teng,

Rallabandi,

Ault

2023

J. Fluid Mech.

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Solute–surface interactions have garnered considerable interest in recent years as a novel control mechanism for driving unique fluid dynamics and particle transport with potential applications in fields such as biomedicine, the development of microfluidic devices and enhanced oil recovery. In this study, we will discuss dispersion induced by the diffusioosmotic motion near a charged wall in the presence of a solute concentration gradient. Here, we introduce a plug of salt with a Gaussian distribution at the centre of a channel with no background flow. As the solute diffuses, the concentration gradient drives a diffusioosmotic slip flow at the walls, which results in a recirculating flow in the channel; this, in turn, drives an advective flux of the solute concentration. This effect leads to cross-stream diffusion of the solute, altering the effective diffusivity of the solute as it diffuses along the channel. We derive theoretical predictions for the solute dynamics using a multiple-time-scale analysis to quantify the dispersion driven by the solute–surface interactions. Furthermore, we derive a cross-sectionally averaged concentration equation with an effective diffusivity analogous to that from Taylor dispersion. In addition, we use numerical simulations to validate our theoretical predictions.

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Tuning chemotactic and diffusiophoretic spreading via hydrodynamic flows

Abstract: The transport of microorganisms by chemotaxis is described by the same ``log-sensing'' response as colloids undergoing diffusiophoresis, despite their different mechanistic origins. We employ a recently-developed macrotransport theory to analyze...

Cited by 11 publications

References 74 publications

Phoresis in cellular flows: from enhanced dispersion to blockage

Phoresis in cellular flows: from enhanced dispersion to blockage

The role of variable zeta potential on diffusiophoretic and diffusioosmotic transport

Diffusioosmotic dispersion of solute in a long narrow channel

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