Tumbling motion of magnetic particles on a magnetic substrate induced by a rotational magnetic field

Morimoto, Hisao; Ukai, Tomofumi; Nagaoka, Yutaka; Grobert, Nicole; Maekawa, Taira

doi:10.1103/physreve.78.021403

Cited by 59 publications

(52 citation statements)

References 32 publications

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“…The graph in Fig. 1(c) shows the existence of two distinct types of dynamics: for low ellipticity (β < 0.2), the chains rotate as a whole, performing a 3D "walkinglike" motion as observed in previous works [43,44]. In contrast, for larger values of β > 0.…”

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confidence: 78%

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

et al. 2015

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We study propulsion arising from microscopic colloidal rotors dynamically assembled and driven in a viscous fluid upon application of an elliptically polarized rotating magnetic field. Close to a confining plate, the motion of this self-assembled microscopic worm results from the cooperative flow generated by the spinning particles which act as a hydrodynamic "conveyor belt." Chains of rotors propel faster than individual ones, until reaching a saturation speed at distances where induced-flow additivity vanishes. By combining experiments and theoretical arguments, we elucidate the mechanism of motion and fully characterize the propulsion speed in terms of the field parameters. DOI: 10.1103/PhysRevLett.115.138301 PACS numbers: 82.70.Dd, 87.85.gj Propulsion in viscous fluids plays a key role in many different contexts of biology, physics, and chemistry. From a fundamental perspective, the transport of microscopic objects in a liquid medium poses the appealing challenge to find an adequate swimming strategy due to the negligible role of inertial force compared to viscous one. At low Reynolds number the Navier-Stokes equations become time reversible [1], and any strategy based on reciprocal motion, i.e., a motion composed by symmetric backward and forward displacements, will fail to produce net propulsion [2].Facing this challenge, the last few years have witnessed the theoretical propositions of several suitable geometries and procedures to propel micromachines in viscous fluids [3][4][5][6][7][8][9]. Parallel advances in miniaturization have led to the generation of new classes of chemically powered [10,11] or externally actuated [12][13][14][15] prototypes with exciting applications in emerging fields such as microsurgery [16,17] or lab-on-a-chip technology [18,19].In contrast to reaction driven microswimmers, actuated magnetic micropropellers do not present the autonomous behavior that distinguishes force-and torque-free motion of biological organisms [20], but instead avoid efficiency reduction due to fuel shortage or directional randomization. To date, three main approaches have been developed to transport microscopic particles in a viscous fluid using uniform magnetic fields [21], namely, by actuating flexible magnetic tails [12,22], by rotating helical shaped structures [23,24], or by using the close proximity to a bounding wall [25,26]. In the latter case, it is well established that in the Stokes regime the rotational motion of a body close to a surface can be rectified into net translation due to the hydrodynamic interaction with the boundary [27]. Surface rotors are optimal to work in confined geometries such as microfluidic channels or biological networks characterized by narrow pores.In this Letter we show that an ensemble of rotors dynamically self-assembled via attractive dipolar interactions can be propelled by a hydrodynamic "conveyor-belt" effect generated by the cooperative flow of the spinning particles close to a surface. Recent theoretical works [28][29][30] have addressed the rich dynamic...

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confidence: 78%

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

et al. 2015

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“…One attractive scheme that has gained considerable interest lately is to use surfaces to locally hinder the mobilities of particles near the surface (19). Very recently this approach has been used to move, in a controlled fashion, irreversibly-bound dimers (18) and slightly longer chains on paramagnetic substrates to enhance friction (20). A simple way to understand this concept is to think of the lower bead (the one closest to the surface) as a hinge on which the rest of the chain rotates.…”

Section: Resultsmentioning

confidence: 99%

Controlled surface-induced flows from the motion of self-assembled colloidal walkers

Sing

Schmid

Schneider

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

226

206

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Biological flows at the microscopic scale are important for the transport of nutrients, locomotion, and differentiation. Here, we present a unique approach for creating controlled, surface-induced flows inspired by a ubiquitous biological system, cilia. Our design is based on a collection of self-assembled colloidal rotors that "walk" along surfaces in the presence of a rotating magnetic field. These rotors are held together solely by magnetic forces that allow for reversible assembly and disassembly of the chains. Furthermore, rotation of the magnetic field allows for straightforward manipulation of the shape and motion of these chains. This system offers a simple and versatile approach for designing microfluidic devices as well as for studying fundamental questions in cooperative-driven motion and transport at the microscopic level.Biological flows | Cilia | Magnetic | Microfluidics | Transport

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“…1). In comparison to other approaches with electromagnets on planar glass surfaces with magnetic films and in the absence of fluidic flow (Morimoto et al 2008), we use a single rotating permanent magnet to generate the rotating magnetic field. Furthermore, this single magnet at the same time provides the field gradient required to attract the beads towards the channel wall.…”

Section: Introductionmentioning

confidence: 99%

Controlled counter-flow motion of magnetic bead chains rolling along microchannels

Karle

Wöhrle

Miwa

et al. 2010

Microfluid Nanofluid

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We demonstrate controlled transport of superparamagnetic beads in the opposite direction of a laminar flow. A permanent magnet assembles 200 nm magnetic particles into about 200 lm long bead chains that are aligned in parallel to the magnetic field lines. Due to a magnetic field gradient, the bead chains are attracted towards the wall of a microfluidic channel. A rotation of the permanent magnet results in a rotation of the bead chains in the opposite direction to the magnet. Due to friction on the surface, the bead chains roll along the channel wall, even in counter-flow direction, up to at a maximum counter-flow velocity of 8 mm s -1 . Based on this approach, magnetic beads can be accurately manoeuvred within microfluidic channels. This counter-flow motion can be efficiently be used in Lab-on-a-Chip systems, e.g. for implementing washing steps in DNA purification.

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Tumbling motion of magnetic particles on a magnetic substrate induced by a rotational magnetic field

Cited by 59 publications

References 32 publications

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

Controlled surface-induced flows from the motion of self-assembled colloidal walkers

Controlled counter-flow motion of magnetic bead chains rolling along microchannels

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