Dielectrophoretic microbead sorting using modular electrode design and capillary-driven microfluidics

Multiplexing assays using microbeads in microfluidics offers high flexibility and throughput, but requires the ability to sort particles based on their physical properties. In this paper, we present a continuous method for separating microbeads that is compact, modular and adaptive, employing an optimized electrode layout that alternates sorting and concentration of microbeads using dielectrophoresis and a nested design. By simulating the combined effects of the hydrodynamic drag and dielectrophoresis forces on polystyrene beads, the parameters of the electrode layout and voltage configuration are optimized for maximum separation based on particle size with a small number of slanted planar electrodes. Experimental verification confirms the efficient separation of 10 μm and 5 μm beads, with ~98% of all concentrated beads sorted in two separate streams and only ~2% of 5 μm beads leaking into the 10 μm bead stream. In addition, this method is implemented on capillary-driven microfluidic chips for maximum portability and ease of use.