Related Experiment Video
Updated: Jun 22, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Hydrodynamic mobility of chiral colloidal aggregates.
Eric E Keaveny1, Michael J Shelley
1Applied Mathematics Laboratory, Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012, USA.
Summary
Magnetic aggregation forms helical micro-particle clusters. Hydrodynamic calculations reveal how cluster geometry couples rotation and translation, crucial for microfluidic device design.
Area of Science:
- Colloidal science
- Microfluidics
- Soft matter physics
Background:
- Recent advances in colloidal technology enable magnetic aggregation of micron-scale beads.
- These aggregates form helical structures with potential applications in controlled transport and separation.
- Understanding hydrodynamic properties is key for designing microfluidic devices.
Purpose of the Study:
- To quantify the coupling between rotation and translation in magnetically aggregated helical micro-particle clusters.
- To establish parametrized expressions for bead positions based on size ratio.
- To determine the relationship between applied torque and translation along the helical axis.
Main Methods:
- Parametrized geometric modeling of bead positions within aggregates.
- Hydrodynamic calculations to determine mobility matrix entries.
- Analysis of the relationship between torque and translation for varying aggregate structures.
Main Results:
- Established parametrized expressions for aggregate geometry based on bead size ratio.
- Calculated hydrodynamic properties, including mobility matrix entries.
- Observed a sign change in the rotation-translation coupling with increasing aggregate size for larger particle radius ratios.
Conclusions:
- The study quantifies the crucial hydrodynamic coupling in helical micro-particle clusters.
- Findings indicate a complex superhelical structure in these aggregates.
- Results provide essential data for the design of microfluidic devices utilizing such self-assembled structures.
Related Concept Videos
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...
03:22Colloids
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
01:17Colloids and Suspensions
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
01:09Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
01:34Fluid Mosaic Model
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.LipidsThe most...
02:30Chirality in Nature
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid. The...