Dynamics near planar walls for various model self-phoretic particles

Bayati, Parvin; Popescu, M. N.; Uspal, William E.; Dietrich, S.; Najafi, Ali

doi:10.1039/c9sm00488b

Cited by 24 publications

(21 citation statements)

References 131 publications

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“…5), which take longer and can feature a reorientation of the swimmer. The underlying mechanisms could be similar to the reorientation mechanisms of self-diffusiophoretic swimmers [13,14] but this issue also requires future work.…”

Section: Discussionmentioning

confidence: 94%

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Surfactant-loaded capsules as Marangoni microswimmers at the air–water interface: Symmetry breaking and spontaneous propulsion by surfactant diffusion and advection

et al. 2021

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We present a realization of a fast interfacial Marangoni microswimmer by a half-spherical alginate capsule at the air–water interface, which diffusively releases water-soluble spreading molecules (weak surfactants such as polyethylene glycol (PEG)), which act as “fuel” by modulating the air–water interfacial tension. For a number of different fuels, we can observe symmetry breaking and spontaneous propulsion although the alginate particle and emission are isotropic. The propulsion mechanism is similar to soap or camphor boats, which are, however, typically asymmetric in shape or emission to select a swimming direction. We develop a theory of Marangoni boat propulsion starting from low Reynolds numbers by analyzing the coupled problems of surfactant diffusion and advection and fluid flow, which includes surfactant-induced fluid Marangoni flow, and surfactant adsorption at the air–water interface; we also include a possible evaporation of surfactant. The swimming velocity is determined by the balance of drag and Marangoni forces. We show that spontaneous symmetry breaking resulting in propulsion is possible above a critical dimensionless surfactant emission rate (Peclet number). We derive the relation between Peclet number and swimming speed and generalize to higher Reynolds numbers utilizing the concept of the Nusselt number. The theory explains the observed swimming speeds for PEG–alginate capsules, and we unravel the differences to other Marangoni boat systems based on camphor, which are mainly caused by surfactant evaporation from the liquid–air interface. The capsule Marangoni microswimmers also exhibit surfactant-mediated repulsive interactions with walls, which can be qualitatively explained by surfactant accumulation at the wall. Graphic Abstract

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Section: Discussionmentioning

confidence: 94%

“…[9,10]. A lot of different aspects of swimmer behavior have been studied for self-diffusiophoretic swimmers such as efficiency [11], confinement effects [6,8] cargo transport [7,12] or the rich behavior during collisions with walls [13,14].…”

Section: Introductionmentioning

confidence: 99%

Surfactant-loaded capsules as Marangoni microswimmers at the air–water interface: Symmetry breaking and spontaneous propulsion by surfactant diffusion and advection

et al. 2021

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“…These self-organized structures typically involve active colloids in close proximity, where near-field effects play a dominant role. From systematic experimental characterization of isolated catalytically active particles [29,30] and the flow-fields generated by them [31], it is known that various mechanistic details, such as ionic conditions [32,33] and interactions with nearby surfaces [34][35][36][37][38], are important ingredients for understanding the interactions in many-particle systems.…”

mentioning

confidence: 99%

Exact Phoretic Interaction of Two Chemically Active Particles

Nasouri

Golestanian

2020

Phys. Rev. Lett.

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We study the nonequilibrium interaction of two isotropic chemically active particles taking into account the exact near-field chemical interactions as well as hydrodynamic interactions. We identify regions in the parameter space wherein the dynamical system describing the two particles can have a fixed point-a phenomenon that cannot be captured under the far-field approximation. We find that, due to near-field effects, the particles may reach a stable equilibrium at a nonzero gap size or make a complex that can dissociate in the presence of sufficiently strong noise. We explicitly show that the near-field effects originate from a self-generated neighbor-reflected chemical gradient, similar to interactions of a selfpropelling phoretic particle and a flat substrate.

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“…The behavior of large collections of such motors has been frequently a topic of current research [22][23][24][25][26][27][28][29][30][31][32][33]. Although many of these investigations consider motor dynamics in simple fluid-phase systems or in the presence of walls [34], there have been investigations of motors in more complex media including those with inert and active obstacles as well as chemical patterns [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Active motion of synthetic nanomotors in filament networks

Qiao

Mei-Chun

Kapral

2020

Phys. Rev. Research

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The collective behavior of chemically powered nanomotors in complex filament networks is investigated. The synthetic motors are small oligomers and use self-diffusiophoresis for their active motion. Much like biological molecular machines, these motors attach to the filaments, which highly suppress orientational Brownian motion, and move along them. The collective motion is influenced by structure of the network and the forces that bind the motors to the filaments; it is characterized by strong clustering, especially near cross-links in the network, and differs substantially from that in a simple fluid phase where only weak clustering occurs. The features of the collective behavior are quantitatively examined through computations of the effective binding potentials and the dynamics of probe oligomers. The results are relevant for applications in the biological and materials sciences involving complex natural and synthetic networks activated by small chemically powered motors.

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Dynamics near planar walls for various model self-phoretic particles

Abstract: Dynamics of chemically active particles moving by self-phoresis near chemically inert walls is studied theoretically by employing various choices for the activity function.

Cited by 24 publications

References 131 publications

Surfactant-loaded capsules as Marangoni microswimmers at the air–water interface: Symmetry breaking and spontaneous propulsion by surfactant diffusion and advection

Surfactant-loaded capsules as Marangoni microswimmers at the air–water interface: Symmetry breaking and spontaneous propulsion by surfactant diffusion and advection

Exact Phoretic Interaction of Two Chemically Active Particles

Active motion of synthetic nanomotors in filament networks

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