Electrokinetic Behavior of Large Polystyrene Particles in Insulator Based Dielectrophoresis

Dielectrophoresis is a microscale electrokinetic technique that has been successfully employed for the manipulation and assessment of a wide array of bioparticles, from proteins, to DNA to cells. This work is focused on insulator-based dielectrophoresis (iDEP), a technique where dielectrophoretic forces are generated by creating non-uniform electrify fields using insulating structures embedded between two external electrodes. It was recently observed that “larger” (>5 µm diameter) polystyrene spheres did not exhibit a clear negative dielectrophoresis (DEP) behavior when working with a microfluidic channel with insulating posts in insulator-based dielectrophoresis (iDEP) experiments. DEP theory predicts that larger particles will experience much stronger trapping than smaller particles, which have been easily manipulated under identical conditions. Cells in the 5-10 µm range have also been successfully manipulated using iDEP. Understanding the deviation of large polystyrene particles from predictions of current DEP theory may lead to novel applications and methods for DEP based manipulation and separation of particles.