RUI: Electrohydrodynamic Flow in Microchannels

Franklin W. Olin College Of Engineering, Needham MA

Investigators

Abstract

Electrically driven flows with significant conductivity gradients are critical to a variety of on-chip assays such as field amplified sample stacking, isoelectric focusing, and electrophoretic assays where conductivities of various sample and buffer streams are either unknown or poorly controlled. In some applications, such as low Reynolds number microchannel mixing, the instability is desirable and in other applications, such as field amplified sample stacking (FASS) the instability is undesirable. The work performed under this grant will build upon the understanding of the basic instability mechanisms in regular flow channels and focus on developing new computational tools for evaluating electrokinetic flows in more complex and realistic geometries. The three main research thrusts are: (1) Performing high fidelity, direct numerical simulations (DNS) of electrokinetic flows in order to explore the statistics of the transport. These DNS will serve as a baseline comparison for more tractable and computationally efficient models, (2) Extending current numerical methods to include geometries other than simple channel flows using commercial finite element software, and (3) Optimization and control of mixing rates through AC electric fields, surface modification, or channel geometry. These combined mechanisms hold promise as a rapid, passive mechanism for low Reynolds number mixing. This research program will be implemented at the Franklin W. Olin College of Engineering, a new undergraduate college, in which 44% of the students are female. A significant broader impact of this grant is direct involvement of these students in carrying out the research objectives. Undergraduate students will be involved in modifying the existing computational models, developing analysis and visualization tools for large sets of computational data, and helping to expand this research to new application areas using commercial finite element software. The project will also afford undergraduates the opportunity to experience research, and to enhance their interest in graduate study.