A microfluidic separation device includes a microchannel formed in a substrate and being defined at least by a bottom surface, a first side wall, and second side wall. Fluid containing particles or cells is flowed through the microchannel from an upstream end to a downstream end. The downstream end terminates in a plurality of branch channels. A plurality of vertically-oriented electrodes are disposed on the first wall and on the second wall opposite to the first wall. A voltage source is connected to the plurality of opposing electrodes to drive the electrodes. The opposing, vertically-oriented electrodes may be used to focus a heterogeneous population of particles or cells for subsequent downstream separation via additional electrodes placed on one of the side walls. Alternatively, the opposing, vertically-oriented electrodes may be used to spatially separate a heterogeneous population of particles or cells for later collection in one or more of the branch channels.