Localized flow control in microchannels using induced-charge electroosmosis near conductive obstacles

Abstract

In this paper, we investigate the use of induced-charge electroosmosis (ICEO) as a means of providing localized flow control near conductive obstacles within bulk pressure-driven flow. In an experimental device, this ICEO flow was induced by an on/off switchable AC field applied across a section containing gold post(s). A simple numerical model, adapted from Levitan et al. (Colloids Surf A 267:122–132, 2005), was implemented and used to provide guidance for the design of the experimental devices. The induced flow was combined with an applied bulk pressure-driven flow to modify flow patterns. We have specifically observed single and multiple stream patterns downstream of the posts in the experimental devices, suggesting the presence of ICEO flow in the experimental system. The custom devices were obtained using a fabrication process that relies on relatively standard steps in the MEMS community, however, unlike other fabrication processes, it has been shown to create fully conductive posts with vertical sidewalls. Utilizing various combinations of number(s) of post(s), geometry and position, useful flow patterns can be created.