Shape Discrimination with Hexapole−Dipole Interactions in Magic Angle Spinning Colloidal Magnetic Resonance

Tierno, Pietro; Schreiber, Steffen; Zimmermann, Walter; Fischer, Thomas M.

doi:10.1021/ja808888g

Cited by 11 publications

(10 citation statements)

References 12 publications

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“…In this case the magnetic dipoledipole interactions have to be taken into account. Magic angle spinning may suppress the magnetic dipole or multipole interactions [25] such that the hydrodynamic interactions dominate.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Hydrodynamic attraction and repulsion between asymmetric rotors

2010

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At low Reynolds numbers, the hydrodynamic interaction between dumbbells driven by an external rotating field can be attractive or repulsive. Dumbbells of dissimilar asymmetric shape or different coupling to the external field undergo conformational rearrangements that break the time reversal symmetry. The parameter ranges leading to attraction or repulsion are explored numerically. The results of our simulations suggest that rotating fields may be a useful avenue for the assembly, disassembly, and sorting of particles of different shape as well as for the study of collective micro-swimmers.

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Section: Conclusion and Discussionmentioning

confidence: 99%

“…They form dynamically induced self-organized structures depending on the particles' contours [7]. Magnetic dipolehexapol interactions may be used for separating rotors with respect to their shape [25]. Rotors also play an important role for bacterial motion such as the propulsion of Escherichia coli [3] with its rotating flagella.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic attraction and repulsion between asymmetric rotors

2010

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“…Particles that have isotropic magnetizations, such as spherical paramagnetic particles (n = 1), interact solely with their dipoles. For ϑ = 0 • , time-averaged dipolar interactions are repulsive when Ψ is smaller than the magic angle 54.7º 20,21 , and attractive for Ψ > 54.7º. In contrast, chains (n > 1) additionally have higher-order magnetic moments due to spatially separated dipoles positioned at centers of particles that form the chains 20,22,23 .…”

Section: Pairwise Magnetic and Hydrodynamic Interactionsmentioning

confidence: 99%

“…For ϑ = 0 • , time-averaged dipolar interactions are repulsive when Ψ is smaller than the magic angle 54.7º 20,21 , and attractive for Ψ > 54.7º. In contrast, chains (n > 1) additionally have higher-order magnetic moments due to spatially separated dipoles positioned at centers of particles that form the chains 20,22,23 . For doublets (n = 2), the dominant repulsive multipolar interaction is the hexapole-dipole for Ψ < 61.5º, which decays rapidly with r -6 compared to the r -4 decay rate of the attractive dipolar interaction forces 20 .…”

Section: Pairwise Magnetic and Hydrodynamic Interactionsmentioning

confidence: 99%

“…In contrast, chains (n > 1) additionally have higher-order magnetic moments due to spatially separated dipoles positioned at centers of particles that form the chains 20,22,23 . For doublets (n = 2), the dominant repulsive multipolar interaction is the hexapole-dipole for Ψ < 61.5º, which decays rapidly with r -6 compared to the r -4 decay rate of the attractive dipolar interaction forces 20 . Similar multipolar interactions are also in play for chains with n > 2 (Fig.…”

Section: Pairwise Magnetic and Hydrodynamic Interactionsmentioning

confidence: 99%

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Cohesive self-organization of mobile microrobotic swarms

2020

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Mobile microrobots are envisioned to be useful in a wide range of high-impact applications, many of which requiring cohesive group formation to maintain self-bounded swarms in the absence of confining boundaries. Cohesive group formation relies on a balance between attractive and repulsive interactions between agents. We found that a balance of magnetic dipolar attraction and multipolar repulsion between self-assembled particle chain microrobots enable their selforganization into cohesive clusters. Self-organized microrobotic clusters translate above a solid substrate via a hydrodynamic self-propulsion mechanism. Cluster velocity increases with cluster size, resulting from collective hydrodynamic effects. Clustering is promoted by the strength of cohesive interactions and hindered by heterogeneities of individual microrobots. Scalability of cohesive interactions allows formation of larger groups, whose internal spatiotemporal organization undergoes a transition from solid-like ordering to liquid-like behavior with increasing cluster size. Our work elucidates the dynamics of clustering under cohesive interactions, and presents an approach for addressing operation of microrobots as localized teams.

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Actuation of Iron Oxide‐Based Nanostructures by External Magnetic Fields

Vach

2016

Iron Oxides

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Iron oxide nanoparticles can be used for the actuation of nanostructures with external magnetic fields. Most commonly the iron oxides magnetite or maghemite are used. Iron oxides are advantageous for actuation, as they have a high permanent magnetic moment, are nontoxic and relatively stable. External magnetic fields can exert forces and torques on the particles, which can be used to actuate individual nanostructures or to guide the self-assembly of large numbers of magnetic nanostructures. The external magnetic fields can thus act as a fuel for nanomachines or can provide the energy needed to drive a system of interacting nanostructures out of thermal equilibrium. Many interesting discoveries have been made along these lines in recent years, some of which are reviewed in this chapter

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Shape Discrimination with Hexapole−Dipole Interactions in Magic Angle Spinning Colloidal Magnetic Resonance

Cited by 11 publications

References 12 publications

Hydrodynamic attraction and repulsion between asymmetric rotors

Hydrodynamic attraction and repulsion between asymmetric rotors

Cohesive self-organization of mobile microrobotic swarms

Actuation of Iron Oxide‐Based Nanostructures by External Magnetic Fields

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