In situ assembly of linked geometrically coupled microdevices

Sawetzki, Tobias; Rahmouni, Sabri; Bechinger, Clemens; Marr, David W. M.

doi:10.1073/pnas.0808808105

Cited by 57 publications

(45 citation statements)

References 35 publications

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“…[93] In another study, the in-situ assembled colloidal clusters were used as valves for microfluidic devices. [94] An intriguing idea is to realize complex colloidal assembly in a programmed manner. Inspired by DNA replication, a fundamental process for biological heredity, a road map was given to illustrate how colloidal self-replication may be realized in a similar fashion (Figure 16).…”

Section: Magnetic Fieldsmentioning

confidence: 99%

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

2010

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Colloidal particles may be considered as building blocks for materials, just like atoms are the bricks of molecules, macromolecules, and crystals. Periodic arrays of colloids (colloidal crystals) have attracted much interest over the last two decades, largely because of their unique photonic properties. The archetype opal structures are based on close-packed arrays of spheres of submicrometer diameter. Interest in structuring materials at this length scale, but with more complex features and ideally by self-assembly processes, has led to much progress in controlling features of both building blocks and assemblies. The necessary ingredients include colloids, colloidal clusters, and colloidal "molecules" which have special shapes and the ability to bind directionally, the control over short-range and long-range interactions, and the capability to place and orientate these bricks. This Review highlights recent experimental and theoretical progress in the assembly of colloids larger than 50 nm.

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Section: Magnetic Fieldsmentioning

confidence: 99%

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

2010

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“…[5][6][7] In industrial operations such as heavy oil transportation in pipes, 8 the internal mechanism involved in filtration processes 9 or microfluidics, particle motion is also encountered in laminar flows. The template-assembly of microparticles, 10 the assembly of coupled microdevices in confined structured geometries 11 or the intrinsic particleinduced lateral transport in microchannels, 12 are examples of applications at low Reynolds numbers. Even in natural phenomena as in the last phase of outburst floods, the process is characterized by a viscous regime and dominated by channel bed friction.…”

Section: Introductionmentioning

confidence: 99%

How do neighbors affect incipient particle motion in laminar shear flow?

2014

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We experimentally study how neighboring particles affect the incipient motion of particles on regular substrates and exposed to a laminar shear flow. To this end, we determine the critical Shields number and determine whether the particle rolls or slides. The substrates consist of a monolayer of fixed spheres of uniform size that are regularly arranged in triangular and quadratic configurations. Neighboring particles influence the incipient motion by shielding to the shear flow and may inhibit continuous motion once they are in direct contact with the particle. At the low particle Reynolds numbers studied, neighboring spheres on the monolayer only affect the incipient particle motion if they are closer than about 3 particle diameters. Direct contact inhibits continuous motion and results in a strong increase of the critical Shields number. For identical beads, we found two different regimes for the onset of continuous motion. Depending on the substrate geometry, the upstream particle may start to roll like a single particle passing the downstream neighbor or it may push its downstream neighbor forward. In the latter case, the downstream sphere rolls while the upstream bead slides in contact with the downstream neighbor. Both regimes yield about the same critical Shields number although the critical Shields number for single particle motion differs by about 50%. If particle contact is avoided by a sudden jump in the Shields number, the critical Shields number for onset of continuous particle motion can be reduced considerably. Finally, the lowest critical Shields numbers for dislodging buried beads in the configurations studied coincides with the critical Shields number for incipient motion of irregular granular beds.

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“…1,2 It is also the initial process of several natural situations, i.e., sediment transport in rivers and coastal flows, granular beds erosion, or dune formation. [3][4][5] Consequently, over the past decades, numerous studies have been dedicated to study the basics of incipient motion.…”

Section: Introductionmentioning

confidence: 99%

Incipient motion of a single particle on regular substrates in laminar shear flow

Agudo

Wierschem

2012

Physics of Fluids

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We study experimentally the critical conditions for incipient motion of a single spherical particle deposited on a regular substrate under laminar flow conditions. The substrates are triangular and quadratic arrangements of identical glass spheres. For the latter configuration, the distance between the substrate spheres is varied, resulting in different partial shielding of the deposited particle to the shear flow. For the studied particle Reynolds numbers range between 3 × 10−4 and 3, the critical Shields number is independent from the particle density and from the particle Reynolds number but it depends significantly on the geometry of the substrate. Depending on the spacing between the substrate beads and thus on the exposure of the particle to the flow, we have observed an increase of about 50 percent in the critical Shields number. Studying the onset of particle motion as a function of the orientation of the substrate to the flow direction we find that the critical Shields number changes by up to a factor of 2, which is mainly due to the fact that the particle travels through the troughs of the substrate and hence the shear force in travel direction diminishes if not in line with the flow direction. Besides the critical Shields number we study the initial stage of particle motion by detecting the minimum time that is necessary for maintaining a certain Shields number to change the position of a single particle on the regular substrates. In the range studied, the initial stage of motion on the scale of the substrate's periodicity is mainly governed by the equilibrium particle motion.

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In situ assembly of linked geometrically coupled microdevices

Cited by 57 publications

References 35 publications

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

How do neighbors affect incipient particle motion in laminar shear flow?

Incipient motion of a single particle on regular substrates in laminar shear flow

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