Localized electroosmosis (LEO) induced by spherical colloidal motors

Tso Yi Chiang, Darrell Velegol

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Experimental data show that the speed of colloidal (catalytic) motors decreases as the size of the motor particles increases. However, previous electrokinetic models have shown that the colloidal motor speed for spheres is independent of size, at least for the case of infinitesimally thin double layers and reaction-limited catalysis. Although a size dependence of motor speed has been calculated for diffusion-limited catalysis, most motor experiments are done in the reaction-limited regime. This apparent contradiction led us to examine how motor speed (U) changes with distance (δ) from a wall, starting from the usual electrokinetic equations. A key finding is that interactions between a colloidal motor and a nearby wall produce a localized electroosmotic (LEO) flow field that can significantly alter the motor speed near the wall. Because large motor particles typically settle closer to the wall than small motors, LEO thus provides at least one explanation of the size dependence of motor speed. Furthermore, LEO provides a new method of creating flow fields in capillaries and microchannels.

Original languageEnglish (US)
Pages (from-to)2600-2607
Number of pages8
Issue number10
StatePublished - Mar 18 2014

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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