Applications of magnetic and electromagnetic forces in micro-analytical systems

Suwa, Masayori; Tsukahara, Satoshi; Watarai, Hitoshi

doi:10.1039/d2lc00702a

Cited by 2 publications

(3 citation statements)

References 298 publications

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“…This extra contribution arises from the magnetic mismatch between the non-magnetic particles and the magnetic suspension. A clear example of them in soft matter occurs in the magnetophoresis of spheres of weakly magnetic materials, where the sum of all these forces onto single particles immersed in a medium can be resumed in the following expression [ 127 ]:

where,

and

represent the volume magnetic susceptibilities of the particle and the medium, respectively. V is the volume of the particle, and

, being M the magnetization and

the permeability of the vacuum.…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Force Profiles For H >mentioning

confidence: 99%

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Depletion Interactions at Interfaces Induced by Ferromagnetic Colloidal Polymers

Cerdà,

Batle,

Bona-Casas

et al. 2024

Polymers

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The pair-interaction force profiles for two non-magnetic colloids immersed in a suspension of ferromagnetic colloidal polymers are investigated via Langevin simulations. A quasi-two-dimensional approach is taken to study the interface case and a range of colloidal size ratios (non-magnetic:magnetic) from 6:1 up to 20:1 have been considered in this work. Simulations show that when compared with non-magnetic suspensions, the magnetic polymers strongly modify the depletion force profiles leading to strongly oscillatory behavior. Larger polymer densities and size ratios increase the range of the depletion forces, and in general, also their strength; the force barrier peaks at short distances show more complex behavior. As the length of the ferromagnetic polymers increases, the force profiles become more regular, and stable points with their corresponding attraction basins develop. The number of stable points and the distance at which they occur can be tuned through the modification of the field strength H and the angle θ formed by the field and the imaginary axis joining the centers of the two non-magnetic colloids. When not constrained, the net forces acting on the two colloids tend to align them with the field till θ=0∘. At this angle, the force profiles turn out to be purely attractive, and therefore, these systems could be used as a funneling tool to form long linear arrays of non-magnetic particles. Torsional forces peak at θ=45∘ and have minimums at θ=0∘ as well as θ=90∘ which is an unstable orientation as slight deviations will evolve towards θ→0∘. Nonetheless, results suggest that the θ=90∘ orientation could be easily stabilized in several ways. In such a case, the stable points that the radial force profiles exhibit for this orthogonal orientation to the field could be used to control the distance between the two large colloids: their position and number can be controlled via H. Therefore, suspensions made of ferromagnetic colloidal polymers can be also useful in the creation of magnetic colloidal tweezers or ratchets. A qualitative explanation of all the observed phenomena can be provided in terms of how the geometrical constraints and the external field modify the conformations of the ferromagnetic polymers near the two large particles, and in turn, how both factors combine to create unbalanced Kelvin forces that oscillate in strength with the distance between the two non-magnetic colloids.

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where,

and

represent the volume magnetic susceptibilities of the particle and the medium, respectively. V is the volume of the particle, and

, being M the magnetization and

the permeability of the vacuum.…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Force Profiles For H >mentioning

confidence: 99%

Depletion Interactions at Interfaces Induced by Ferromagnetic Colloidal Polymers

Cerdà,

Batle,

Bona-Casas

et al. 2024

Polymers

View full text Add to dashboard Cite

show abstract

“…35 Similarly, by implementing two or more bifurcating junctions, several other magnetic microfluidic devices separate particles based on size, shape, and magnetic susceptibility. 36–40 In addition, such devices are also highly explored for on-demand mixing and quantifying ferrofluid using a micro wall mixer and magnetic actuation, as reported by Broeren group. 41 The application of such devices includes mixing, isolating, trapping, and extracting functionalized magnetic particles, cells, RBC/WBC, and bioactive molecules.…”

Section: Introductionmentioning

confidence: 99%

A magnetically controlled microfluidic device for concentration dependent in vitro testing of anticancer drug

Yadav,

Ganguly,

Mishra

et al. 2023

Lab Chip

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Applications of magnetic and electromagnetic forces in micro-analytical systems

Abstract: This review summarizes the recent attractive developments in the application of magnetic and electromagnetic forces in micro-analytical systems.

Cited by 2 publications

References 298 publications

Depletion Interactions at Interfaces Induced by Ferromagnetic Colloidal Polymers

Depletion Interactions at Interfaces Induced by Ferromagnetic Colloidal Polymers

A magnetically controlled microfluidic device for concentration dependent in vitro testing of anticancer drug

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