The wobbling-to-swimming transition of rotated helices

Man, Yi; Lauga, Eric

doi:10.1063/1.4812637

Cited by 45 publications

(60 citation statements)

References 39 publications

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“…Due to the symmetry, the resistance matrix D has the same nonzero elements as the mobility matrix in the x, y, z bases, Where P = P/R and lx = Cl/Ci-The mobility matrix is the inverse of the resistance matrix. Our resistance matrix differs from that reported in Man and Lauga [40], since, according to their Eq. (1), their origin is located at one end of the helix, while ours is located along the symmetry axis in the center of the helix.…”

Section: Discussioncontrasting

confidence: 99%

“…Man and Lauga [40] showed that during wobbling the precession angle scales as inverse frequency using nu merics and asymptotics of nearly straight helices. Ghosh e t a l. [39,41] and Morozov and Leshansky [42] investi gated the transition of stability from tumbling to wobbling behavior as frequency increases by treating the rotational dynamics as that of ellipsoids numerically and analytically, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Magnetization directions and geometries of helical microswimmers for linear velocity-frequency response

Jabbarzadeh

Meshkati

2015

Phys. Rev. E

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Recently, there has been much progress in creating microswimmers or microrobots capable of controlled propulsion in fluidic environments. These microswimmers have numerous possible applications in biomedicine, microfabrication, and sensing. One type of effective microrobot consists of rigid magnetic helical microswimmers that are propelled when rotated at a range of frequencies by an external rotating magnetic field. Here we focus on investigating which magnetic dipoles and helical geometries optimally lead to linear velocity-frequency response, which may be desirable for the precise control and positioning of microswimmers. We identify a class of optimal magnetic field moments. We connect our results to the wobbling behavior previously observed and studied in helical microswimmers. In contrast to previous studies, we find that when the full helical geometry is taken into account, wobble-free motion is not possible for magnetic fields rotating in a plane. Our results compare well quantitatively to previously reported experiments, validating the theoretical analysis method. Finally, in the context of our optimal moments, we identify helical geometries for minimization of wobbling and maximization of swimming velocities.

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Section: Discussioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetization directions and geometries of helical microswimmers for linear velocity-frequency response

Jabbarzadeh

Meshkati

2015

Phys. Rev. E

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“…Since = ω, the direction of ω also sets the swimmers rotation axis as well as the direction of average swimming translation. Frequency dependent rotational axes have also been observed and modeled for magnetically actuated swimmers and gyroscopes both in bulk fluids and near surfaces [26,43,[51][52][53]. Together, these considerations make qualitative predictions that can be checked experimentally.…”

Section: Qualitative Predictions and Experimentsmentioning

confidence: 85%

Minimal geometric requirements for micropropulsion via magnetic rotation

et al. 2014

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Controllable propulsion of microscale and nanoscale devices enhanced with additional functionality would enable the realization of miniaturized robotic swimmers applicable to transport and assembly, actuators, and drug delivery systems. Following biological examples, existing magnetically actuated microswimmers have been designed to use flexibility or chirality, presenting fabrication challenges. Here we show that, contrary to biomimetic expectations, magnetically actuated geometries with neither flexibility nor chirality can produce propulsion, through both experimental demonstration and a theoretical analysis, which elucidates the fundamental constraints on micropropulsion via magnetetic rotation. Our results advance existing paradigms of low-Reynolds-number propulsion, possibly enabling simpler fabrication and design of microswimmers and nanoswimmers.

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“…Before considering the dynamics of swimmer-particle interaction, we briefly explain the dynamics of a single swimmer, propelled by a rotating magnetic field. It is a well known result that magnetically actuated artificial swimmers only exhibit meaningful locomotion for a certain range of driving frequencies of the oscillating field [21][22][23]. Specifically, there exist three distinct frequency-dependent motion regimes.…”

Section: Simulation Resultsmentioning

confidence: 99%