Dynamics of colloidal particles in microchannels under combined pressure and electric potential gradients

  • V. Lochab
  • A. Yee
  • M. Yoda
  • A. T. Conlisk
  • S. PrakashEmail author
Research Paper


Dynamics of charged sub-micron or colloidal particles in a microfluidic device through cross-stream migration under combined pressure gradients and electric potential gradients was demonstrated using confocal microscopy. The microfluidic device was a rectangular cross-section poly(dimethylsiloxane) or PDMS microchannel sealed with a borosilicate glass lid to form a hybrid PDMS-glass device. We postulate that the reported particle migration may arise in response to electrophoretic particle slip, i.e., the difference between the particle and fluid velocities, due to the applied electric potential gradient across the microchannel. Colloidal particle migration was observed either towards or away from the microchannel walls depending on the relative directions for the applied potential and pressure gradients. When pressure gradient driving the fluid flow and potential gradient were applied in the same direction, colloidal particles migrate away from the microchannel walls. In the case of opposite directions for the pressure and potential gradients, colloidal particles migrate towards the microchannel walls and subsequently assemble into distinct bands next to both the bottom glass and top PDMS walls. The results reported here demonstrate that the particle dynamics due to electrophoresis in Poiseuille flow within a microchannel result in non-uniform spatial distributions of colloidal particles via cross-stream migration, with the ability to assemble particles into distinct band structures at channel walls. Such manipulation, once fully realized, could lead to several microfluidics applications in material synthesis, particle separation, and biosensing.


Microfluidics Colloidal particles Particle assembly Spatial distribution Cross-stream migration Inertial migration Electrophoresis Confocal microscopy Directed assembly 



This work was funded by the US Army Research Office through Grant number W911NF-16-0278. Partial support for personnel from the National Institutes of Health via award RO1HL141941 is also acknowledged. We thank the staff of Nanotech West for helping with device fabrication and characterization. Images presented in this report were generated using the instruments and services at the Campus Microscopy and Imaging Facility, The Ohio State University. This facility is supported in part by Grant P30 CA016058, National Cancer Institute, Bethesda, MD.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Mechanical and Aerospace EngineeringThe Ohio State UniversityColumbusUSA
  2. 2.The George W. Woodruff School of Mechanical EngineeringGeorgia Institute of TechnologyAtlantaUSA

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