Dynamics of suspended colloidal particles near a wall: Implications for interfacial particle velocimetry

Interfacial transport due to surface forces is significant in many microfluidic devices with their relatively large surface areas and small volumes. Recently, velocimetry methods where evanescent waves illuminate fluorescent particles less than 1 mu m in radius have been used to obtain fluid velocities within 500 nm or less of the wall. This review considers some of the phenomena affecting the dynamics of suspended colloidal particles near a wall. The measurement of interfacial flow velocities using such particles as tracers, illustrated by studies of Poiseuille and electrokinetically driven flows, is then discussed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662005]