Abstract
The phenomena of AC electroosmosis (ACEO) and dielectrophoresis (DEP) which are AC electrokinetics (ACEK) phenomenon but the earlier is always referred as AC electrohydrodynamic (AC EHD), have been used for many years to study, manipulate, trap, separate and collect particles of different scales and origins. The techniques have been adopted by builders of Microelectromechanical systems (MEMS) for Lab on a Chip (LOC) and Micro Total Analysis System (μTAS) for developing microfluidic devices. In this work, electrodes have been used to investigate these phenomena, to understand and optimise electroosmotic (EO) trapping. The effect of medium viscosity, medium density and temperature has been examined. It has been shown that medium viscosity is dominant over medium density as factor that affects EO trapping. It is also has ruled out centrifugal force as the dominant factor of EO trapping. Additionally, this work has investigated the effect of chamber height and electrode size on the efficiency of EO trapping. It has also been shown that there is an optimal height for optimum collection. Inadequate vertical space will result in inefficient collections, and over the optimal heights it will cause the vertical collections to be influenced by sedimentation. Furthermore, a model has been developed for particle trapping where the space above the electrode can be treated as two spaces, one trapping zone and a second region in which particles exhibit a linear descent into the trapping zone due to sedimentation.