Synchronous Electrokinetic-Inertial Focusing in Microfluidic Devices

The application of electric fields to inertial focusing presents a rare interplay of electrokinetic and inertial phenomenon. It has also attracted considerable attention for its potential application for particle separation based on differences in electric properties at high throughput. A considerable challenge to its widespread practical implementation is the difficulty of maintaining large electric fields over long channel lengths, which are typically required for inertial focusing. Furthermore, the proposed mechanisms and scaling laws of electrokinetically enhanced migration are yet to be rigorously tested. Here, we present an experimental approach that attempts to address both of these challenges by synchronously applying oscillatory flow and an AC electric field in a microfluidic device. The dependence of particle migration on oscillation frequency and phase difference between the applied fields will be discussed.