COUPLED ELECTROHYDRODYNAMIC-DIELECTROPHORETIC MICROPUMPING OF COLLOIDAL SUSPENSIONS IN A MICROCHANNEL

摘要

Effective and versatile microfluidic pumps can be produced by utilizing various electrokinetic effects, such as electrohydrodynamics (EHD), induced-charge electroosmosis (ICEO) and dielectrophoresis (DEP). Among these, traveling-wave EHD (twEHD) has emerged as a powerful pumping mechanism due to its potential for miniaturization and the ability to pump a variety of liquids. However, when twEHD is used to deliver colloidal suspensions, the simultaneous presence of EHD effect may favorably or adversely influence the overall pumping performance, or vice versa. The net flow depends on the particle-fluid combination and the frequency range of the applied electric field. In this paper, the coupled EHD-twDEP flow was studied numerically in a microchannel with a three-phase interdigitated microelectrode array fabricated at the bottom surface. The results show that, depending on the frequency range of the traveling-wave electric field and the applied thermal boundary condition, the EHD-induced flow can significantly enhance or weaken the twDEP-induced flow.