Clustering of Magnetic Swimmers in a Poiseuille Flow

Meng, Fanyu; Matsunaga, Daiki; Golestanian, Ramin

doi:10.1103/physrevlett.120.188101

Cited by 55 publications

(49 citation statements)

References 52 publications

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“…These results are expected to hold in higher dimensions as well. In recent works, chemical [60] and magnetic [61] interactions have been shown to compete against instabilities originating from hydrodynamic interactions. Therefore, it is important to examine how hydrodynamic effects modify the dynamics (especially in the case of bound states) that we have described in this work under more realistic geometries such as a Hele-Shaw cell.…”

Section: Discussionmentioning

confidence: 99%

Pairing, waltzing and scattering of chemotactic active colloids

2019

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We study theoretically an active colloid whose polar axis of self-propulsion rotates to point parallel (antiparallel) to an imposed chemical gradient. We show that the coupling of this 'chemotactic' ('antichemotactic') response to phoretic translational motion yields remarkable two-particle dynamics reflecting the non-central and non-reciprocal character of the interaction. A pair of mutually chemotactic colloids trap each other in a final state of fixed separation resulting in a selfpropelled active dimer. A second type of bound state is observed when the polar axes undergo periodic cycles leading to phase-locked circular motion around a common centre. A pair of swimmers with mismatched phoretic mobilities execute a dance in which they twirl around one another while moving jointly in a wide circle. For sufficiently small initial separation, the speed of self-propulsion controls the transition from bound to scattering states. Mutually anti-chemotactic swimmers always scatter apart. For the special case in which one of the two colloids has uniform surface activity we succeed in exactly classifying the fixed points underlying the bound states, and identify the bifurcations leading to transitions from one type of bound state to another. The varied dynamical behaviours are accessible by tuning the swimmer design and are summarised in state diagrams.

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Section: Discussionmentioning

confidence: 99%

Pairing, waltzing and scattering of chemotactic active colloids

2019

Self Cite

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“…In this process, the nano/micromotor will align first its magnetic anisotropy axis in the direction of the field (to minimize the torque T m = V m M × B ) and will eventually evolve toward accelerated motion because of the force. Accordingly, magnetic nano/micromotors exposed to such a magnetic field gradient will have their magnetic moments aligned in the same direction, such that dipolar interactions will emerge between them, creating groups of nano/micromotors, and thus forming aggregates or chains . The velocity reached by the nano/micromotors once propelled is determined by the so‐called magneto‐phoretic mobility, which depends on both the characteristics of the nano/micromotors (size and magnetic properties) and the medium (viscosity) .…”

Section: Externally Driven Nano‐ and Micromotorsmentioning

confidence: 99%

Recent Advances in Nano‐ and Micromotors

Fernández-Medina

Ramos-Docampo

Hovorka

et al. 2020

Adv Funct Materials

163

143

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Nano‐ and micromotors are fascinating objects that can navigate in complex fluidic environments. Their active motion can be triggered by external power sources or they can exhibit self‐propulsion using fuel extracted from their surroundings. The research field is rapidly evolving and has produced nano/micromotors of different geometrical designs, exploiting a variety of mechanisms of locomotion, being capable of achieving remarkable speeds in diverse environments ranging from simple aqueous solutions to complex media including cell cultures or animal tissue. This review aims to provide an overview of the recent developments with focus on predominantly experimental demonstrations of the various motor designs developed in the past 24 months. First, externally driven motors are discussed followed by considering fuel‐driven approaches. Finally, a short future perspective is provided.

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“…For example, the magnetic alignment, combined with a micro-aerotactic swimming response, qualifies such micro-swimmers as a promising vector for targeted drug therapy [32]. Recently, it was proposed, on theoretical grounds, that a suspension of such magnetotactic bacteria could display original magneto-rheological properties [33,34], novel pattern formation [35] and hydrodynamic instabilities [36,37].…”

Section: Introductionmentioning

confidence: 99%

Magnetotactic bacteria in a droplet self-assemble into a rotary motor

et al. 2019

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From intracellular protein trafficking to large-scale motion of animal groups, the physical concepts driving the self-organization of living systems are still largely unraveled. Self-organization of active entities, leading to novel phases and emergent macroscopic properties, recently shed new light on these complex dynamical processes. Here we show that under the application of a constant magnetic field, motile magnetotactic bacteria confined in water-in-oil droplets self-assemble into a rotary motor exerting a torque on the external oil phase. A collective motion in the form of a large-scale vortex, reversable by inverting the field direction, builds up in the droplet with a vorticity perpendicular to the magnetic field. We study this collective organization at different concentrations, magnetic fields and droplet radii and reveal the formation of two torque-generating areas close to the droplet interface. We characterize quantitatively the mechanical energy extractable from this new biological and self-assembled motor.

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Clustering of Magnetic Swimmers in a Poiseuille Flow

Cited by 55 publications

References 52 publications

Pairing, waltzing and scattering of chemotactic active colloids

Pairing, waltzing and scattering of chemotactic active colloids

Recent Advances in Nano‐ and Micromotors

Magnetotactic bacteria in a droplet self-assemble into a rotary motor

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