Particle distribution and velocity in electrokinetically induced banding

Massimiliano Rossi (Corresponding Author), Alvaro Marin, Necmettin Cevheri, Christian J. Kähler, Minami Yoda

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

Colloidal particles may be repelled from/attracted to the walls of glass micro-channels when an electro-osmotic flow is combined with a Poiseuille flow. Under certain conditions, the particles assemble into bands after accumulating near the walls (Cevheri and Yoda in Lab Chip 14(8):1391–1394, 2014). The fundamental physical mechanisms behind these phenomena remain unclear and up to now only measurements within 1μm of the walls have been available. In this work, we applied a 3D particle-tracking technique, astigmatism particle tracking velocimetry, to measure the concentration and velocity distribution of particles across the depth of the entire micro-channel. The experiments show that the particles are depleted in the bulk as they become concentrated near the bottom and top walls and this particle redistribution depends strongly upon the bulk particle concentration. The results suggest that bands form in a region where particles are practically immobile and their volume fraction increases at least an order of magnitude with respect to the original volume fraction. Our results suggest that particle accumulation and band formation near the walls may be triggered by forces generated in the bulk since the banding and particle accumulation extends at least a few μ m into the channel, or at length scales beyond the range of surface forces due to wall interactions.

Original languageEnglish
Article number67
JournalMicrofluidics and nanofluidics
Volume23
Issue number5
DOIs
Publication statusPublished - 1 May 2019

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Volume fraction
Velocity distribution
Velocity measurement
Glass
Experiments
astigmatism
laminar flow
velocity distribution
chips
glass

Keywords

  • Astigmatic-PTV
  • Electro-osmotic flow
  • Electrokinetic banding
  • Micro-PIV
  • Micro/nanoparticles
  • Self-assembly

Cite this

Rossi, Massimiliano ; Marin, Alvaro ; Cevheri, Necmettin ; Kähler, Christian J. ; Yoda, Minami. / Particle distribution and velocity in electrokinetically induced banding. In: Microfluidics and nanofluidics. 2019 ; Vol. 23, No. 5.
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Particle distribution and velocity in electrokinetically induced banding. / Rossi, Massimiliano (Corresponding Author); Marin, Alvaro; Cevheri, Necmettin; Kähler, Christian J.; Yoda, Minami.

In: Microfluidics and nanofluidics, Vol. 23, No. 5, 67, 01.05.2019.

Research output: Contribution to journalArticleAcademicpeer-review

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