Numerical and Analytical Studies of Electrothermally Induced Flow And Its Application For Mixing and Cleaning in Microfluidic Systems

摘要

This paper presents both analytic and simulation results of electrothermal flow in microfluidic systems. It also considers the application of this phenomenon to microscale mixing and cleaning. The basic operation requires application of an alternating electric field at high frequency and moderate amplitude to create thermal gradients. This in turn will induce both Columbic and dielectric forces to the bulk fluid due to the variation of electrical permittivity and conductivity of the buffer solution with respect to temperature. First, electrothermal flow in a simple two-electrode structure is investigated via analytical means. Subsequently, the detailed framework for a full-scale multiphysics simulation of electrothermal flow in complex devices is described. Using simulations, it is revealed that mixing can be increased dramatically due to the presence of electrothermal flows. Chaotic nature is established via exponential growth of the interface. Orders of magnitude improvement in the time required to washout contaminants trapped in microcavities is also demonstrated.