Geometric pumping in autophoretic channels

Michelin, Sébastien; Montenegro‐Johnson, Thomas D.; Canio, Gabriele De; Lobato‐Dauzier, Nicolas; Lauga, Eric

doi:10.1039/c5sm00718f

Cited by 34 publications

(43 citation statements)

References 39 publications

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“…In this work, we demonstrated the emergence of spontaneous convective flows within a straight phoretic channel whose active walls drive a fluid flow in response to self-induced gradients of a chemical species. This mechanism, which is similar to a Bénard-Marangoni instability, identifies therefore a new route to the emergence of phoretic flows within a chemically-active micro-channel, in addition to asymmetric designs in chemical activity [16] or wall geometry [14], similarly to the dual problem of emergence of self-propulsion for phoretic colloids. A major difference between phoretic particles and channels need to be emphasized.…”

Section: Discussionmentioning

confidence: 90%

“…We first focus on the linear stability analysis of this system around the steady state from Eq. (14). Decomposing c =c + c and ψ = ψ , the linearized problem for c is obtained as…”

Section: Linear Stability Analysis Of the Steady Statementioning

confidence: 99%

“…This combination, often termed self-phoresis, has received much recent interest for self-propulsion applications [11][12][13]. Self-phoresis has also recently been considered as a potential alternative to macroscopically-actuated phoretic driving in microchannels [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Spontaneous onset of convection in a uniform phoretic channel

et al. 2020

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Phoretic mechanisms, whereby gradients of chemical solutes induce surface-driven flows, have recently been used to generate directed propulsion of patterned colloidal particles. When the chemical solutes diffuse slowly, an instability further provides active but isotropic particles with a route to self-propulsion by spontaneously breaking the symmetry of the solute distribution. Here we show theoretically that, in a mechanism analogous to Bénard-Marangoni convection, phoretic phenomena can create spontaneous and self-sustained wall-driven mixing flows within a straight, chemicallyuniform active channel. Such spontaneous flows do not result in any net pumping for a uniform channel but greatly modify the distribution of transport of the chemical solute. The instability is predicted to occur for a solute Péclet number above a critical value and for a band of finite perturbation wavenumbers. We solve the perturbation problem analytically to characterize the instability, and use both steady and unsteady numerical computations of the full nonlinear transport problem to capture the long-time coupled dynamics of the solute and flow within the channel. * Electronic address: sebastien.michelin@ladhyx.polytechnique.fr arXiv:1912.07667v1 [physics.flu-dyn]

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Section: Discussionmentioning

confidence: 90%

“…We first focus on the linear stability analysis of this system around the steady state from Eq. (14). Decomposing c =c + c and ψ = ψ , the linearized problem for c is obtained as…”

Section: Linear Stability Analysis Of the Steady Statementioning

confidence: 99%

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Spontaneous onset of convection in a uniform phoretic channel

et al. 2020

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“…The physico-chemical principles used for phoretic swimmers can in principle also be exploited to induce flow transport in confined devices such as microchannels, and therefore to create pumps [26][27][28][29]. Yet, the existing literature has only so far provided limited insight on the fundamental design principles of such pumps, and we propose here a detailed analysis of the link between pump design and performance.…”

Section: Introductionmentioning

confidence: 99%

Universal optimal geometry of minimal phoretic pumps

Michelin

Lauga

2019

Sci Rep

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Unlike pressure-driven flows, surface-mediated phoretic flows provide efficient means to drive fluid motion on very small scales. Colloidal particles covered with chemically-active patches with nonzero phoretic mobility (e.g. Janus particles) swim using self-generated gradients, and similar physics can be exploited to create phoretic pumps. Here we analyse in detail the design principles of phoretic pumps and show that for a minimal phoretic pump, consisting of 3 distinct chemical patches, the optimal arrangement of the patches maximizing the flow rate is universal and independent of chemistry.

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“…Moreover, the fact that in-and outlets rely on external pieces of equipment, importantly hampers the portability of the devices. A competitive approach is to induce stresses localized at the boundaries, through non-mechanical means which are driven typically by local fields [12][13][14][15][16]. This has shown to be especially efficient for miniaturizing fluidic pumps, due to the intrinsic large surface to volume ratio.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Pump Driven by Anisotropic Phoresis

2019

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Fluid flow along microchannels can be induced by keeping opposite walls at different temperatures, and placing elongated tilted pillars inside the channel. The driving force for this fluid motion arises from the anisotropic thermophoretic effect of the elongated pillars that generates a force parallel to the walls, and perpendicular to the temperature gradient. The force is not determined by the thermophilic or thermophobic character of the obstacle surface, but by the geometry and the thermophoretic anisotropy of the obstacle. Via mesoscale hydrodynamic simulations, we investigate the pumping properties of the device as a function of the channel geometry, and pillar surface properties. Applications as fluidic mixers, and fluid alternators are also outlined, together with the potential use of all these devices to harvest waste heat energy. Furthermore, similar devices can be also built employing diffusiophoresis or electrophoresis. arXiv:1808.05028v2 [cond-mat.soft]

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Geometric pumping in autophoretic channels

Cited by 34 publications

References 39 publications

Spontaneous onset of convection in a uniform phoretic channel

Spontaneous onset of convection in a uniform phoretic channel

Universal optimal geometry of minimal phoretic pumps

Microfluidic Pump Driven by Anisotropic Phoresis

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