A microfluidic device for size-based particle separation and methods for its use, where the microfluidic device comprises: (a) an inlet reservoir, where the inlet reservoir is configured for communication with an inlet electrode, (b) an insulator constriction coupled to the inlet reservoir via a microchannel, where the insulator constriction comprises an insulating material, and (c) a plurality of outlet channels each defining a first end and a second end, where the first end of each of the plurality of outlet channels is coupled to the insulator constriction, where the second end of each of the plurality of outlet channels is coupled to one of a plurality of outlet reservoirs, and where the plurality of outlet reservoirs are configured for communication with one or more outlet electrodes.