Swimming of magnetic micro-machines under a very wide-range of Reynolds number conditions

Ishiyama, K.; Sendoh, M.; Yamazaki, A.; Inoue, M.; Arai, Ken Ichi

doi:10.1109/20.951331

Cited by 25 publications

(8 citation statements)

References 6 publications

(4 reference statements)

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“…This phenomenon has already been reported multiple times. 23,87,94,100 From eqn (13) it is clear that the maximum T m,max is a function of the applied magnetic eld strength, the magnetization and the size of the magnetic material on the swimmer. The magnetic eld strength is the same for all microrobots, but the magnetization and size are Fig.…”

Section: Individual Control Of Surface-walkersmentioning

confidence: 99%

Bio-inspired magnetic swimming microrobots for biomedical applications

2013

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Microrobots have been proposed for future biomedical applications in which they are able to navigate in viscous fluidic environments. Nature has inspired numerous microrobotic locomotion designs, which are suitable for propulsion generation at low Reynolds numbers. This article reviews the various swimming methods with particular focus on helical propulsion inspired by E. coli bacteria. There are various magnetic actuation methods for biomimetic and non-biomimetic microrobots, such as rotating fields, oscillating fields, or field gradients. They can be categorized into force-driven or torque-driven actuation methods. Both approaches are reviewed and a previous publication has shown that torque-driven actuation scales better to the micro- and nano-scale than force-driven actuation. Finally, the implementation of swarm or multi-agent control is discussed. The use of multiple microrobots may be beneficial for in vivo as well as in vitro applications. Thus, the frequency-dependent behavior of helical microrobots is discussed and preliminary experimental results are presented showing the decoupling of an individual agent within a group of three microrobots.

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Section: Individual Control Of Surface-walkersmentioning

confidence: 99%

Bio-inspired magnetic swimming microrobots for biomedical applications

2013

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“…[40], the authors envisage micro machines moving in blood vessels and doing necessary repair work. The onearmed swimmer offers an interesting possibility to propel such micro machines.…”

Section: Discussionmentioning

confidence: 99%

Numerical study of a microscopic artificial swimmer

2006

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We present a detailed numerical study of a microscopic artificial swimmer realized recently by Dreyfus et al. in experiments [R. Dreyfus et al., Nature 437, 862 (2005)]. It consists of an elastic filament composed of superparamagnetic particles that are linked together by DNA strands. Attached to a load particle, the resulting swimmer is actuated by an oscillating external magnetic field so that it performs a non-reciprocal motion in order to move forward. We model the superparamagnetic filament by a bead-spring configuration that resists bending like a rigid rod and whose beads experience friction with the surrounding fluid and hydrodynamic interactions with each other. We show that, aside from finite-size effects, its dynamics is governed by the dimensionless sperm number, the magnitude of the magnetic field, and the angular amplitude of the field's oscillating direction. Then we study the mean velocity and the efficiency of the swimmer as a function of these parameters and the size of the load particle. In particular, we clarify that the real velocity of the swimmer is influenced by two main factors, namely the shape of the beating filament (determined by the sperm number and the magnetic-field strength) and the oscillation frequency. Furthermore, the load size influences the performance of the swimmer and has to be chosen as a compromise between the largest swimming velocity and the best efficiency. Finally, we demonstrate that the direction of the swimming velocity changes in a symmetry-breaking transition when the angular amplitude of the field's oscillating direction is increased, in agreement with experiments.

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“…For example, the role of hydrodynamic interactions in collective modes of locomotion has been the focus of much work [9][10][11][12][13]. In addition to their relevance to biology, the physical principles of cell locomotion has allowed for the design of synthetic swimming devices on small scales [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Locomotion by tangential deformation in a polymeric fluid

et al. 2011

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In several biologically relevant situations, cell locomotion occurs in polymeric fluids with Weissenberg number larger than one. Here we present results of three-dimensional numerical simulations for the steady locomotion of a self-propelled body in a model polymeric (Giesekus) fluid at low Reynolds number. Locomotion is driven by steady tangential deformation at the surface of the body (so-called squirming motion). In the case of a spherical squirmer, we show that the swimming velocity is systematically less than that in a Newtonian fluid, with a minimum occurring for Weissenberg numbers of order one. The rate of work done by the swimmer always goes up compared to that occurring in the Newtonian solvent alone, but is always lower than the power necessary to swim in a Newtonian fluid with the same viscosity. The swimming efficiency, defined as the ratio between the rate of work necessary to pull the body at the swimming speed in the same fluid and the rate of work done by swimming, is found to always be increased in a polymeric fluid.Further analysis reveals that polymeric stresses break the Newtonian front-back symmetry in the flow profile around the body. In particular, a strong negative elastic wake is present behind the swimmer, which correlates with strong polymer stretching, and its intensity increases with Weissenberg number and viscosity contrasts. The velocity induced by the squirmer is found to decay in space faster than in a Newtonian flow, with a strong dependence on the polymer relaxation time and viscosity. Our computational results are also extended to prolate spheroidal swimmers and smaller polymer stretching are obtained for slender shapes compared to bluff swimmers. The swimmer with an aspect ratio of two is found to be the most hydrodynamically efficient. * Electronic address: elauga@ucsd.edu † Electronic address: luca@mech.kth.se

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Swimming of magnetic micro-machines under a very wide-range of Reynolds number conditions

Cited by 25 publications

References 6 publications

Bio-inspired magnetic swimming microrobots for biomedical applications

Bio-inspired magnetic swimming microrobots for biomedical applications

Numerical study of a microscopic artificial swimmer

Locomotion by tangential deformation in a polymeric fluid

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