ABSTRACT
The use of electrokinetics for both biological and synthetic particle manipulations, including particle separation, assembly, sorting, focusing, and characterization in microfluidic devices, has recently gained significant attention. Microfluidic devices in general have complex geometries, giving rise to spatially nonuniform electric fields. Even in a straight uniform microchannel, finite-size particles distort the electric field, yielding spatially nonuniform electric fields around them. Arising from the spatially nonuniform electric fields and the surface charges on the particle surfaces and the microchannel walls, electroosmosis, electrophoresis, and dielectrophoresis typically coexist in the process of the electrokinetic particle transport in a microfluidic device. The particles experience both hydrodynamic and dielectrophoretic (DEP) forces and distort both electric and flow fields, which in turn affect the mentioned forces acting on the particles. Therefore, the full fluid-particle-electric field interactions as well as dielectrophoresis should be taken into account in the mathematical model to predict the electrokinetic particle transport in a microfluidic device accurately.
