Self-assembly and novel planetary motion of ferrofluid drops in a rotational magnetic field

Chen, Ching‐Yao; Hsueh, Hao Chung; Wang, Sheng Yan; Li, Yan Hom

doi:10.1007/s10404-014-1472-1

Cited by 20 publications

(15 citation statements)

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“…If their line of centers is initially perpendicular to the external static field, the drops repel while rotating around each other so that their line of centers aligns with the field. Meanwhile the radial force becomes attractive and the two approach each other and may even coalesce (Chen et al 2015). A similar scenario occurs in the equivalent problem of two bubbles interacting in a ferrofluid (Lee et al 2010).…”

Section: Introductionmentioning

confidence: 71%

“…The experiment of Chen et al (2015) differs from the solid-particle studies in that the drops are large (radius r 0 ∼ 1 mm); they deform and are subject to inertial effects. Can their planetary motion be explained by the same dipole model, or does it involve distinct mechanisms?…”

Section: Introductionmentioning

confidence: 92%

“…For a pair of ferrofluid drops in a rotating magnetic field, Chen et al (2015) observed an intriguing "planetary motion", illustrated in figure 1 and Movie 1 in the Supplementary Material online. In their experiments, the millimeter-sized drops elongate in the field direction into an ellipsoidal shape and then spin in phase with the rotating field.…”

Section: Introductionmentioning

confidence: 98%

“…The letter "R" marks the drop initially on the right. Reproduced from Chen et al (2015) with permission, c Springer. See also Movie 1 in the Supplemental Material online.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of a pair of ferrofluid drops in a rotating magnetic field

et al. 2018

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We use two-dimensional numerical simulation to study the interaction between a pair of ferrofluid drops suspended in a rotating uniform magnetic field. Numerical results show four distinct regimes over the range of parameters tested: independent spin, planetary motion, drop locking and direct coalescence. These are in qualitative agreement with experiments, and the transition between them can be understood from the competition between magnetophoretic forces and viscous drag. We further analyse in detail the planetary motion, i.e. the revolution of the drops around each other while each spins in phase with the external magnetic field. For drops, as opposed to solid microspheres, the interaction is dominated by viscous sweeping, a form of hydrodynamic interaction. Magnetic dipole–dipole interaction via mutual induction only plays a secondary role. This insight helps us explain novel features of the planetary revolution of the ferrofluid drops that cannot be explained by a dipole model, including the increase of the angular velocity of planetary motion with the rotational rate of the external field, and the attainment of a limit separation between the drops that is independent of the initial separation.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 98%

“…The letter "R" marks the drop initially on the right. Reproduced from Chen et al (2015) with permission, c Springer. See also Movie 1 in the Supplemental Material online.…”

Section: Introductionmentioning

confidence: 99%

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Interaction of a pair of ferrofluid drops in a rotating magnetic field

et al. 2018

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“…(iii) Chen et al . investigated the effect of the rotational field on self-assembly of FFD53 and ordered FFD formation54. (iv) Di Carlo et al ., demonstrated magnetic droplet generation rate, and size control by a magnetically driven technique, consisting of a gradient magnetic field of a permanent magnet55.…”

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confidence: 99%

Droplet Merging on a Lab-on-a-Chip Platform by Uniform Magnetic Fields

Varma

Ray

Wang

et al. 2016

Sci Rep

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Droplet microfluidics offers a range of Lab-on-a-chip (LoC) applications. However, wireless and programmable manipulation of such droplets is a challenge. We address this challenge by experimental and modelling studies of uniform magnetic field induced merging of ferrofluid based droplets. Control of droplet velocity and merging was achieved through uniform magnetic field and flow rate ratio. Conditions for droplet merging with respect to droplet velocity were studied. Merging and mixing of colour dye + magnetite composite droplets was demonstrated. Our experimental and numerical results are in good agreement. These studies are useful for wireless and programmable droplet merging as well as mixing relevant to biosensing, bioassay, microfluidic-based synthesis, reaction kinetics, and magnetochemistry.

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Flexible Ferrofluid as Soft Robotic Agents

2023

Untethered Miniature Soft Robots

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Self-assembly and novel planetary motion of ferrofluid drops in a rotational magnetic field

Cited by 20 publications

References 50 publications

Interaction of a pair of ferrofluid drops in a rotating magnetic field

Interaction of a pair of ferrofluid drops in a rotating magnetic field

Droplet Merging on a Lab-on-a-Chip Platform by Uniform Magnetic Fields

Flexible Ferrofluid as Soft Robotic Agents

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