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Emergence of reconfigurable wires and spinners via dynamic self-assembly.

Kokot G, Piet D, Whitesides GM, Aranson IS, Snezhko A - Sci Rep (2015)

Bottom Line: The energy injection rate, and properties of the environment are important control parameters that influence the outcome of dynamic self-assembly.The spinners emerge via spontaneous breaking of the uniaxial symmetry of the energizing magnetic field.Demonstration of the formation and disaggregation of particle assemblies suggests strategies to form new meso-scale structures with the potential to perform functions such as mixing and sensing.

View Article: PubMed Central - PubMed

Affiliation: Complex Matter Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubliana, Slovenia.

ABSTRACT
Dissipative colloidal materials use energy to generate and maintain structural complexity. The energy injection rate, and properties of the environment are important control parameters that influence the outcome of dynamic self-assembly. Here we demonstrate that dispersions of magnetic microparticles confined at the air-liquid interface, and energized by a uniaxial in-plane alternating magnetic field, self-assemble into a variety of structures that range from pulsating clusters and single-particle-thick wires to dynamic arrays of spinners (self-assembled short chains) rotating in either direction. The spinners emerge via spontaneous breaking of the uniaxial symmetry of the energizing magnetic field. Demonstration of the formation and disaggregation of particle assemblies suggests strategies to form new meso-scale structures with the potential to perform functions such as mixing and sensing.

No MeSH data available.


Related in: MedlinePlus

Self-assembly of dynamic magnetic wires.(a) Consecutive formation of the dynamic wire from a compact cluster at 36 Oe, 240 Hz in-plane magnetic field. Formation of a dynamic wire proceeds along the axis of the applied field. (b) Time evolution of the rescaled dynamic wire length. The wire was assembled at 35 Oe, 260 Hz applied field. Wire formation proceeds through deformation of the cluster of particles rather than aggregation phenomenon. Insert: dependence of the wire formation characteristic time on the amplitude of in-plane magnetic field. The frequency of excitations was fixed at 260 Hz. (c) Parallel arrays of particle-thick dynamic wires assembled with 54 Oe and 200 Hz in-plane field. Additional 20 Oe static magnetic field was applied perpendicular to the interface to stabilize the pattern.
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f2: Self-assembly of dynamic magnetic wires.(a) Consecutive formation of the dynamic wire from a compact cluster at 36 Oe, 240 Hz in-plane magnetic field. Formation of a dynamic wire proceeds along the axis of the applied field. (b) Time evolution of the rescaled dynamic wire length. The wire was assembled at 35 Oe, 260 Hz applied field. Wire formation proceeds through deformation of the cluster of particles rather than aggregation phenomenon. Insert: dependence of the wire formation characteristic time on the amplitude of in-plane magnetic field. The frequency of excitations was fixed at 260 Hz. (c) Parallel arrays of particle-thick dynamic wires assembled with 54 Oe and 200 Hz in-plane field. Additional 20 Oe static magnetic field was applied perpendicular to the interface to stabilize the pattern.

Mentions: The formation of dynamic wires proceeds through an elongation of the initial cluster of particles along the axis of the applied magnetic field (see Fig. 2a). During its growth, the wire shows imperfections (e.g. kinks and perforations). These are eventually eliminated by the rearrangements of near-by particles. The extension of a wire continues until it becomes one-particle thick (see Supplementary Video 5). Since all dynamic phases are reversible and controlled by the parameters of the applied a.c. field, the formation of a wire is also possible from the initial spinner phase by adjustment of the a.c. field frequency. In this case, growth of the wire proceeds by successive attachments of individual particles and merging of linear chain fragments (see Supplementary Video 6).


Emergence of reconfigurable wires and spinners via dynamic self-assembly.

Kokot G, Piet D, Whitesides GM, Aranson IS, Snezhko A - Sci Rep (2015)

Self-assembly of dynamic magnetic wires.(a) Consecutive formation of the dynamic wire from a compact cluster at 36 Oe, 240 Hz in-plane magnetic field. Formation of a dynamic wire proceeds along the axis of the applied field. (b) Time evolution of the rescaled dynamic wire length. The wire was assembled at 35 Oe, 260 Hz applied field. Wire formation proceeds through deformation of the cluster of particles rather than aggregation phenomenon. Insert: dependence of the wire formation characteristic time on the amplitude of in-plane magnetic field. The frequency of excitations was fixed at 260 Hz. (c) Parallel arrays of particle-thick dynamic wires assembled with 54 Oe and 200 Hz in-plane field. Additional 20 Oe static magnetic field was applied perpendicular to the interface to stabilize the pattern.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4374141&req=5

f2: Self-assembly of dynamic magnetic wires.(a) Consecutive formation of the dynamic wire from a compact cluster at 36 Oe, 240 Hz in-plane magnetic field. Formation of a dynamic wire proceeds along the axis of the applied field. (b) Time evolution of the rescaled dynamic wire length. The wire was assembled at 35 Oe, 260 Hz applied field. Wire formation proceeds through deformation of the cluster of particles rather than aggregation phenomenon. Insert: dependence of the wire formation characteristic time on the amplitude of in-plane magnetic field. The frequency of excitations was fixed at 260 Hz. (c) Parallel arrays of particle-thick dynamic wires assembled with 54 Oe and 200 Hz in-plane field. Additional 20 Oe static magnetic field was applied perpendicular to the interface to stabilize the pattern.
Mentions: The formation of dynamic wires proceeds through an elongation of the initial cluster of particles along the axis of the applied magnetic field (see Fig. 2a). During its growth, the wire shows imperfections (e.g. kinks and perforations). These are eventually eliminated by the rearrangements of near-by particles. The extension of a wire continues until it becomes one-particle thick (see Supplementary Video 5). Since all dynamic phases are reversible and controlled by the parameters of the applied a.c. field, the formation of a wire is also possible from the initial spinner phase by adjustment of the a.c. field frequency. In this case, growth of the wire proceeds by successive attachments of individual particles and merging of linear chain fragments (see Supplementary Video 6).

Bottom Line: The energy injection rate, and properties of the environment are important control parameters that influence the outcome of dynamic self-assembly.The spinners emerge via spontaneous breaking of the uniaxial symmetry of the energizing magnetic field.Demonstration of the formation and disaggregation of particle assemblies suggests strategies to form new meso-scale structures with the potential to perform functions such as mixing and sensing.

View Article: PubMed Central - PubMed

Affiliation: Complex Matter Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubliana, Slovenia.

ABSTRACT
Dissipative colloidal materials use energy to generate and maintain structural complexity. The energy injection rate, and properties of the environment are important control parameters that influence the outcome of dynamic self-assembly. Here we demonstrate that dispersions of magnetic microparticles confined at the air-liquid interface, and energized by a uniaxial in-plane alternating magnetic field, self-assemble into a variety of structures that range from pulsating clusters and single-particle-thick wires to dynamic arrays of spinners (self-assembled short chains) rotating in either direction. The spinners emerge via spontaneous breaking of the uniaxial symmetry of the energizing magnetic field. Demonstration of the formation and disaggregation of particle assemblies suggests strategies to form new meso-scale structures with the potential to perform functions such as mixing and sensing.

No MeSH data available.


Related in: MedlinePlus