Assembly of magnetic spheres in strong homogeneous magnetic field

Messina, René; Stanković, Igor

doi:10.1016/j.physa.2016.08.079

Cited by 30 publications

(17 citation statements)

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“…When exposed to an external magnetic field, it has been demonstrated that nanoscopic magnetic rods form bundles ( [17]) or multimers when driven by ultrasound ( [8]). Although paramagnetic spheres form chains, they will form ribbon structures (connected, parallel chains) for chains exceeding 30 particles ( [18,19]) and flower-like patterns result when magnetic and non-magnetic beads are mixed with ferrofluids ( [20]). In the absence of an external magnetic field, a theoretical study of off-centered magnetic dipoles in spherical particles ( [21]) shows that lateral displacement of the dipoles results in structures that are more compact than chains.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic equivalence for microscopic motion in a turbulence driven three-dimensional self-assembly reactor

Hageman

Löthman

Dirnberger

et al. 2018

Journal of Applied Physics

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We built and characterised a macroscopic self-assembly reactor that agitates magnetic, centimeter-sized particles with a turbulent water flow. By scaling up the self-assembly processes to the centimeter-scale, the characteristic time constant scale also drastically increases. This makes the system a physical simulator of microscopic self-assembly, where the interaction of inserted particles are easily observable. Trajectory analysis of single particles reveals their velocity to be a Maxwell-Boltzmann distribution and it shows that their average squared displacement over time can be modelled by a confined random walk model, demonstrating a high level of similarity to Brownian motion. The interaction of two particles has been modelled and verified experimentally by observing the distance between two particles over time. The disturbing energy (analogue to temperature) that was obtained experimentally increases with sphere size, and differs by an order of magnitude between single-sphere and two-sphere systems (approximately 80 µJ versus 6.5 µJ, respectively). arXiv:1709.04978v1 [cond-mat.soft]

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Section: Introductionmentioning

confidence: 99%

Macroscopic equivalence for microscopic motion in a turbulence driven three-dimensional self-assembly reactor

Hageman

Löthman

Dirnberger

et al. 2018

Journal of Applied Physics

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“…is thought of as the result of an interplay between dipole-dipole interactions and short ranged excluded volume correlations. Similar results has been obtained for colloidal ribbon formation (Messina and Stankovic, 2017).…”

Section: -Theorysupporting

confidence: 88%

“…When exposed to an external magnetic field, it has been demonstrated that nanoscopic magnetic rods form bundles (Love et al, 2003) or multimers when driven by ultrasound (Tanaka et al, 2007). Although paramagnetic spheres form chains, they will form ribbon structures (connected, parallel chains) for chains exceeding 30 particles (Darras et al, 2016;Messina and Stankovic, 2017) and flower-like patterns result when magnetic and non-magnetic beads are mixed with ferrofluids (Erb et al, 2009). In the absence of an external magnetic field, a theoretical study of off-centred magnetic dipoles in spherical particles (Yener and Klapp, 2016) shows that lateral displacement of the dipoles results in structures that are more compact than chains.…”

Section: Introductionmentioning

confidence: 99%

“…Self-assembled 45 structures of dipolar particles (i.e., with electric or magnetic dipoles) are of great interest for several applications. Novel optical and stimuli-responsive materials are based on self assembly of magnetic particles (Messina and Stankovic, 2017). In the absence of an external magnetic field structure formation of magnetic spheres was investigated by Guo et al (2005).…”

Section: Introductionmentioning

confidence: 99%

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Macroscopic magnetic self-assembly

Löthman¹

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“…Although paramagnetic spheres form chains, they will form ribbon structures (connected, parallel chains) for chains exceeding 30 particles (Darras et al, 2016;Messina and Stankovic, 2017) and flower-like patterns result when magnetic and non-magnetic beads are mixed with ferrofluids (Erb et al, 2009). In the absence of an external magnetic field, a theoretical study of off-centred magnetic dipoles in spherical particles (Yener and Klapp, 2016) shows that lateral displacement of the dipoles results in structures that are more compact than chains.…”

Section: -Introductionmentioning

confidence: 99%

Observing magnetic objects in fluids

Hageman¹

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IntroductionIn the modern day world we can observe a trend towards miniaturization of technology. And this is not without reason, as this can lead to for instance more functionality in the same device and reduce the amount of resources used for their construction or consumed during operation. The future of integrated circuitsA well-known example is integrated circuits, pioneered by Jack Kilby in 1958, which have been subject to Moore's scaling law. These predominantly twodimensional architectures get more functionality over time by reducing the transistor dimensions so that more fit on the same chip, a process limited by the resolution of lithography processes. The industry has recently reached the 10 nm node for lithography, but cannot scale indefinitely due to the limits imposed by the size of atoms. To continue the trend of progress, besides changing the computational approach (such as quantum computing), we will eventually have to move to the third dimension. This is in need of new production methods as lithography-based methods like layer stacking and interference lithography are severely restricted in the third dimension. Self-assembly of colloidal particles with embedded electronics into regular 3D structures would be a solution (figure 1.1) (Abelmann et al., 2010). The formation of colloidal crystals has been studied by the likes of Alfons van Blaaderen (1997; and Albert Philipse (Philipse et al., 1994;Rossi et al., 2011), building on fundamental concepts of (molecular or macroscopic) selfassembly pioneered by George Whitesides (Grünwald et al., 2016;Whitesides and Grzybowski, 2002). The dynamics of microscopic self-assembly are difficult to observe due to the small size and short characteristic time constants involved, and therefore most publications are focused on reaction products. Yet, it is important to fully understand the particle-particle and particle-fluid interaction to optimize the assembly process and to minimize crystal defects. Computer simulations are a solution, but these scale unfavourable with the amount of particles FIGURE 1.1 -Three-dimensional electronics like memory chips could be constructed from smart building blocks, "smarticles" (A) (Abelmann et al., 2010), by forming regular structures via colloidal self-assembly (B) (Norris et al., 2004). Smart particles have been successfully self-assembled on macroscopic scale, forming electrically functional networks (C) (Gracias et al., 2000). Self-assembly dynamics may be simulated on macroscopic scale (D) (Ilievski et al., 2011b).involved. Analogue simulations in the form of a macroscopic self-assembly reactor can act as an alternative, greatly increasing visibility. For a proper analogy we need an interplay between the disturbing (temperature) and assembling (electrostatic, magnetic, van der Waals etc.) forces present on microscopic scale. Such forces could be respectively turbulence and magnetic dipole interaction, as explored before by Filip Ilievski (2011b). The future of microroboticsA second example of miniaturization is the use of...

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Assembly of magnetic spheres in strong homogeneous magnetic field

Cited by 30 publications

References 29 publications

Macroscopic equivalence for microscopic motion in a turbulence driven three-dimensional self-assembly reactor

Macroscopic equivalence for microscopic motion in a turbulence driven three-dimensional self-assembly reactor

Macroscopic magnetic self-assembly

Observing magnetic objects in fluids

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