Controlled disassembly of colloidal aggregates confined at fluid interfaces using magnetic dipolar interactions

Martínez‐Pedrero, Fernando; Ortega, Francisco; Codina, Joan; Calero, Carles; Rubio, Ramón G.

doi:10.1016/j.jcis.2019.10.008

Cited by 13 publications

(29 citation statements)

References 56 publications

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“…[11] They show specific structures and dynamics not observable in the bulk of liquids. [20,58] The strategy of transport introduced in this work, easily implemented but unique to strongly confined suspensions, takes advantage of the higher affinity of the particles to one of the media and the anisotropic character of the magnetic dipolar interaction to transport colloids or molecules onto fluid interfaces, through loosely packed self-assembled lattices. In contrast to other experimental realizations, which require of sophisticated prefabricated substrates or optical ratchets, [6,8,59] here the active control over colloids is dynamically achieved thanks to the driven potential generated by the adsorbed particles themselves.…”

Section: Resultsmentioning

confidence: 99%

“…In a binary system of paramagnetic particles of different size, with radius R B and R s , adsorbed onto a fluid interface, the particle centers are confined to planes separated by a distance Δ z , According to the SEM images of the magnetic particles obtained with the gel trapping technique (GET) (see inset in Figure a and ref. [ 20 ] ), the affinity of the two types of particles is preferentially to the water phase, and Δ z ≈ R B − R s = 0.9 µm. The application of a field parallel to the interface in the X direction, H x , induces the formation of linear aggregates, composed by small and big particles aligned along the X axis.…”

Section: Resultsmentioning

confidence: 99%

“…The subsequent application of a field perpendicular to the interface, H z , modulates the magnetic dipole–dipole interaction between colloidal particles, promoting the fragmentation of the linear aggregates and the generation of a set of new states, determined by the field strength

H_{0} = \sqrt{H_{x}^{2} + H_{z}^{2}}

and tilt angle γ = a tan ( H z / H x ) (see Figure S1 in the Supporting Information and ref. [ 20 ] ). In the range 54.7° < γ < (asin (Δ z /( R B + R s )) + 54.7°), equally sized magnetic particles repel one another, whereas pairs of big and small particles, can attract and form heterodimers directed along the X axis.…”

Section: Resultsmentioning

confidence: 99%

“…The experimental set‐up was custom built and originally described in ref. [ 20 ] . The loaded interface is placed in the middle of two pairs of orthogonal coils, aligned along the X and Y axes, while a third coil is placed under the sample, aligned along the optical axis of the microscope.…”

Section: Methodsmentioning

confidence: 99%

“…x z and tilt angle γ = atan (H z /H x ) (see Figure S1 in the Supporting Information and ref. [20]). In the range 54.7° < γ < (asin (Δz/(R B + R s )) + 54.7°), equally sized magnetic particles repel one another, whereas pairs of big and small particles, can attract and form heterodimers directed along the X axis.…”

Section: = + H H Hmentioning

confidence: 99%

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Collective Transport of Magnetic Microparticles at a Fluid Interface through Dynamic Self‐Assembled Lattices

Martínez‐Pedrero

Ortega

Rubio

et al. 2020

Adv Funct Materials

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The transport of confined micron-sized particles plays an important role in a range of phenomena in biology, colloidal science, and solid-state physics. Here, an easily implementable strategy that allows for the collective and monitored transport of magnetic colloidal particles along fluid-fluid interfaces is introduced. Adsorbed microparticles are carried on time-dependent magnetic potentials, generated by dynamic self-assembled lattices of different-sized particles confined onto a parallel plane. In such binary system, the synchronized inversion of the precessing applied field allows for the ballistic and directional transport of the motile components along prescribed directions. The transportation mode can be tuned through the stoichiometry or the strength and orientation of the applied field. The described methodology can be used in the capture and manipulation of drugs or pollutants adsorbed on liquid surfaces, the segregation of colloidal mixtures or the assisted mixture of surface active molecules.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

H_{0} = \sqrt{H_{x}^{2} + H_{z}^{2}}

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: = + H H Hmentioning

confidence: 99%

See 3 more Smart Citations

Collective Transport of Magnetic Microparticles at a Fluid Interface through Dynamic Self‐Assembled Lattices

Martínez‐Pedrero

Ortega

Rubio

et al. 2020

Adv Funct Materials

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Study on self‐assembly of colloidal particles at high ionic strength with stimulated emission depletion microscopy

Neupane

Zhong

Wang

2020

Engineering Reports

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Understanding the spatial organization of nano-and micro-sized particle is very important in the fabrication of complex structures having unprecedented properties. Study on self-assembly of submicroscopic colloidal particles at high ionic strength solution at single particle resolution can provide new insight into the nanoscale interactions. In this study, we studied the self assembly behavior of negatively charged 0.2 and 1 μm colloidal particles at high ionic strength on glass-solution interface that is, in situ environment. The self-assembled 0.2 μm particles could not be resolved with conventional confocal and epi-fluorescent microscopy, so a home-built continuous wave stimulated emission depletion (STED) microscope was used for the study. We found that particles self-assemble into ordered and disordered structures at higher and lower ionic strength solution, respectively. The optical imaging methods allowed us to measure inter-particle gap at second energy minimum directly. Interestingly, we found that the inter-particle gap in the wet self-assembly higher than the classical Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory predicted. The in situ investigation of particle self-assembly at high ionic strength will provide more insight for the understanding nanoscale interactions.

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Static and Dynamic Self‐Assembly of Pearl‐Like‐Chains of Magnetic Colloids Confined at Fluid Interfaces

Martínez‐Pedrero

González-Banciella

Camino

et al. 2021

Small

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Understanding the aggregation of magnetic particles is also essential for their use in the fabrication of metamaterials, [8] as magnetic separation agents in, e.g., protein purification protocols, [9] as contrast agents in magnetic resonance imaging, [10] or as cell manipulation operators [11] among others.Floating magnetic particles have also been extensively used in the bottom-up fabrication of different dynamic selfassemblies, which develop order at the same time as dissipate energy. The strong confinement of a system of particles can dramatically influence both the nature of their interactions and the long-range order possible, permitting the existence of new structures and phases both in equilibrium [12,13] and out of equilibrium. [12,14] Besides, the quasi 2D nature of these systems facilitates the experimental analysis of the structure and dynamics. In this regard, magnetic colloids adsorbed at liquid-liquid interphases have been proven to be suitable model systems to investigate the formation of static and dynamic arrangements of particles, and promising candidates to engineer novel functional planar structures unfeasible in bulk dipolar systems. [15,16,17] Grzybowski et al. studied disparate dynamic structures formed by rotating millimeter-sized magnetic disks, in processes ruled by the equilibrium between

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Controlled disassembly of colloidal aggregates confined at fluid interfaces using magnetic dipolar interactions

Cited by 13 publications

References 56 publications

Collective Transport of Magnetic Microparticles at a Fluid Interface through Dynamic Self‐Assembled Lattices

Collective Transport of Magnetic Microparticles at a Fluid Interface through Dynamic Self‐Assembled Lattices

Study on self‐assembly of colloidal particles at high ionic strength with stimulated emission depletion microscopy

Static and Dynamic Self‐Assembly of Pearl‐Like‐Chains of Magnetic Colloids Confined at Fluid Interfaces

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