Active Particles Powered by Quincke Rotation in a Bulk Fluid

Das, Debasish; Lauga, Eric

doi:10.1103/physrevlett.122.194503

Cited by 28 publications

(21 citation statements)

References 35 publications

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“…The ability of such artificial microscale swimmers to self-propel through the surrounding viscous medium is essential to the emergence of nontrivial collective dynamics or for technological applications, and can be forced externally using acoustic vibrations [10] or electromagnetic fields [11][12][13]. Alternatively, direct interactions of individual particles with their immediate environment can convert physicochemical energy to set the fluid into motion and self-propel [14,15].…”

Section: Introductionmentioning

confidence: 99%

Hydrochemical interactions in dilute phoretic suspensions: From individual particle properties to collective organization

Traverso

Michelin

2020

Phys. Rev. Fluids

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Janus phoretic colloids (JPs) self-propel as a result of self-generated chemical gradients and exhibit spontaneous nontrivial dynamics within phoretic suspensions, on length scales much larger than the microscopic swimmer size. Such collective dynamics arise from the competition of (i) the self-propulsion velocity of the particles, (ii) the attractive/repulsive chemically mediated interactions between particles, and (iii) the flow disturbance they introduce in the surrounding medium. These three ingredients are directly determined by the shape and physicochemical properties of the colloids' surface. Owing to such link, we adapt a recent and popular kinetic model for dilute suspensions of chemically active JPs where the particle's far-field hydrodynamic and chemical signatures are intrinsically linked and explicitly determined by the design properties. Using linear stability analysis, we show that self-propulsion can induce a wave-selective mechanism for certain particles' configurations consistent with experimental observations. Numerical simulations of the complete kinetic model are further performed to analyze the relative importance of chemical and hydrodynamic interactions in the nonlinear dynamics. Our results show that regular patterns in the particle density are promoted by chemical signaling but prevented by the strong fluid flows generated collectively by the polarized particles, regardless of their chemotactic or antichemotactic nature, i.e., for both puller and pusher swimmers.

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Section: Introductionmentioning

confidence: 99%

Hydrochemical interactions in dilute phoretic suspensions: From individual particle properties to collective organization

Traverso

Michelin

2020

Phys. Rev. Fluids

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“…A suspension of Quincke rotors can exhibit lower effective viscosity [11][12][13] or increased conductivity [14] compared to the suspending fluid. More complex electrorotation dynamic arises from field nonuniformity [15] or nonspherical particle shape [16][17][18][19], for example, shape anisotropy created by chirality [20] or deformation as in the case of an elastic filament attached to a sphere [21] converts the Quincke rotation into particle translation. Drops while rotating can also deform and appear as if "breathing" [7,[22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Quincke rotor dynamics in confinement: rolling and hovering

2019

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The Quincke effect is an electrohydrodynamic instability which gives rise to a torque on a dielectric particle in a uniform DC electric field. Previous studies reported that a sphere initially resting on the electrode rolls with steady velocity. We experimentally find that in strong fields the rolling becomes unsteady, with time-periodic velocity. Furthermore, we find another regime, where the rotating sphere levitates in the space between the electrodes. Our experimental results show that the onset of Quincke rotation strongly depends on particle confinement and the threshold for rolling is higher compared to rotation in the hovering state.

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“…It is also worth mentioning that the QR instability was utilised to study suspensions of artificial swimmers made of QR particles that achieved locomotion by rolling near a rigid solid boundary (Bricard et al 2013). In addition, the recent work of Das & Lauga (2019) shows theoretically and numerically that a dielectric particle with particular geometrical asymmetry (e.g. a helix) under a DC electric field is able to convert QR into spontaneous translation in an unbounded domain.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…It is also worth mentioning the assumption of neglecting electrohydrodynamic effect of the filament. The electric torque exerted on a slender QR structure scales with a 2 L (Das & Lauga 2019), and that on a sphere scales with A 3 (see (B 1)). By assuming that the filament and particle have similar dielectric properties and realising α = A/L = O(1), the ratio of the former to the latter torque is of the order of 2…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Harnessing elasticity to generate self-oscillation via an electrohydrodynamic instability

Zhu

Stone

2020

J. Fluid Mech.

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Under a steady DC electric field of sufficient strength, a weakly conducting dielectric sphere in a dielectric solvent with higher conductivity can undergo spontaneous spinning (Quincke rotation) through a pitchfork bifurcation. We design an object composed of a dielectric sphere and an elastic filament. By solving an elasto-electrohydrodynamic (EEH) problem numerically, we uncover an EEH instability exhibiting diverse dynamic responses. Varying the bending stiffness of the filament, the composite object displays three behaviours: a stationary state, undulatory swimming and steady spinning, where the swimming results from a self-oscillatory instability through a Hopf bifurcation. The onset of this instability is predicted by a linear stability analysis incorporating an elastohydrodynamic model and the predicted critical conditions agree well with the numerical counterparts. We find that the elastoviscous response of the filament transforms the pitchfork bifurcation into the Hopf bifurcation. Our results imply a new way of harnessing elastic media to engineer self-oscillations, and more generally, to manipulate and diversify the bifurcations and the corresponding instabilities. These ideas will be useful in designing soft, environmentally-adaptive machines.

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Active Particles Powered by Quincke Rotation in a Bulk Fluid

Cited by 28 publications

References 35 publications

Hydrochemical interactions in dilute phoretic suspensions: From individual particle properties to collective organization

Hydrochemical interactions in dilute phoretic suspensions: From individual particle properties to collective organization

Quincke rotor dynamics in confinement: rolling and hovering

Harnessing elasticity to generate self-oscillation via an electrohydrodynamic instability

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