Simultaneous separation and concentration of micro- and nano-particles by optically induced electrokinetics

This paper presents our work on the automated and parallel manipulation, separation, and concentration of micro- and nano-particles utilizing a hydrogenated, amorphous silicon (a-Si:H)-based optically induced electrokinetics (OEK) chip. A theoretical analysis and calculation of the crossover frequency spectrum characteristic of polystyrene beads is first presented. Then, we use different optically induced dielectrophoresis (ODEP) force directionalities, i.e., positive and negative components, to separate polystyrene beads with diameters of 10 μm and 1 μm, respectively. Furthermore, we have also demonstrated experimentally that polystyrene beads with three different diameters, i.e., 500 nm, 1 μm, and 10 μm, can also be simultaneously separated and concentrated by combining different directionality and magnitudes of the ODEP force. We elucidated the dominate factors governing the operating regimes for rapid and simultaneous separation of micro-/nano-particles using OEK in this paper, and concluded that OEK is an extremely useful technology for the rapid sorting of micro-/nano-particles.