Field-Induced Structures in Ferrofluid Emulsions

Liu, Jing; Lawrence, Eric M.; Wu, Alicia; Ivey, Mark L.; Flores, G. A.; Javier, Kevin J.; Bibette, Jérôme; Richard, J.

doi:10.1103/physrevlett.74.2828

Cited by 261 publications

(164 citation statements)

References 12 publications

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“…These properties are dependent on the amplitude and frequency of the applied magnetic field, the shape and magnetic content of the beads, the concentration of the magnetic particles in the fluid, the temperature, etc. Despite the complexity of the aggregation process of a magnetic fluid into a SPS, the physical effects of a magnetic field on such a structure are now very well understood (Liu et al 1995;Flores et al 1999). When exposed to a strong, continuous magnetic field, the magnetic fluid will rapidly form a cross-linked network.…”

Section: Magnetic Supraparticle Structuresmentioning

confidence: 99%

“…In contrast, it was found that the application of a pulsed field (square wave alternating between field-on and field-off states) to a magnetic fluid did produce an energetically determined suspension structure (Promislow and Gast 1996;Promislow and Gast 1997). By allowing particle diffusion during the field-off state, a pulsed field enables the minimization of energy through structural rearrangements and the SPS consists of one-dimensional periodic patterns composed of high-concentration regions of magnetic particles (''columns''), aligned in the field direction and sharply separated from low-concentration regions (Wirtz and Fermigier 1994;Liu et al 1995;Wirtz and Fermigier 1995). Qualitatively, the dependence of the structure complexity on the tuning parameters can be understood from the time that it takes for the particles to aggregate together, which depends on the ratio of the magnetic interaction energy between particles relative to thermal energy.…”

Section: Magnetic Supraparticle Structuresmentioning

confidence: 99%

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Magnetic bead handling on-chip: new opportunities for analytical applications

Gijs

2004

Microfluid Nanofluid

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This review describes recent advances in the handling and manipulation of magnetic particles in microfluidic systems. Starting from the properties of magnetic nanoparticles and microparticles, their use in magnetic separation, immuno-assays, magnetic resonance imaging, drug delivery, and hyperthermia is discussed. We then focus on new developments in magnetic manipulation, separation, transport, and detection of magnetic microparticles and nanoparticles in microfluidic systems, pointing out the advantages and prospects of these concepts for future analysis applications.

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Section: Magnetic Supraparticle Structuresmentioning

confidence: 99%

Section: Magnetic Supraparticle Structuresmentioning

confidence: 99%

Magnetic bead handling on-chip: new opportunities for analytical applications

Gijs

2004

Microfluid Nanofluid

497

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show abstract

“…Earlier work by Liu et al [91] provided the initial impetus for the possible application of self-assembled ferrofluids as separation media. By comparing experiments and results from a mean field model, they indicated that the average post separation, d*, can be controlled by varying the height of the microchannel, L, and the ferrofluid volume fraction, and that in particular, post spacing is related to channel height via a power law of the form When DNA is placed in this array and an electric field is applied the polymer chain becomes hooked around a post in a pulley-like conformation, the escape time is dependent on the molecular weight of the DNA and separation is possible (inspired by [86]).…”

Section: Magnetic Self-assembling Sievesmentioning

confidence: 99%

Theory of DNA electrophoresis (∼ 1999 –2002 ½)

et al. 2002

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Over the last two decades, the introduction of new methods such as pulsed-field gel electrophoresis and capillary array electrophoresis has made it possible to map and sequence entire genomes, including our own. The development of these experimental methods has been helped by the progress of theoretical and computational sciences, and the interactions between these three modi operandi of modern science are still pushing the limits of our technologies. We now see a clear trend towards proteomics and microfluidic (even nanofluidic!) devices. In this review, we take a look at the progress of the field over the last 3 years using the glasses of the theoretical scientist and focusing mostly on new ideas and concepts. About a dozen different subfields are discussed and reviewed. We conclude by giving a commented list of some of the best review articles published over the last 2-3 years.

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“…However, this model as well as most existing theories, did not take into account interactions between magnetic nanoparticles that might lead to underestimation of the capture efficiency and even to unphysical results like particle concentrations above the limit of the maximum packing fraction. A few attempts [19,23,24] to account for interparticle interactions in the problem of magnetic separation were restricted to nonBrownian particles and did not predict condensation phase transition, which is often observed in magnetic colloids [25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

et al. 2014

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When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50µm) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces -the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter α ≥2), the Brownian motion seems not to affect the cloud behavior.

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Field-Induced Structures in Ferrofluid Emulsions

Cited by 261 publications

References 12 publications

Magnetic bead handling on-chip: new opportunities for analytical applications

Magnetic bead handling on-chip: new opportunities for analytical applications

Theory of DNA electrophoresis (∼ 1999 –2002 ½)

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

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