Disclosed herein is a device for electrophoresis comprising: a separation channel in a substrate; and a plurality of capillary-well motifs cascading along the separation channel, each of the plurality of capillary-well motifs comprising a well and a plurality of non-intersecting capillaries, wherein the capillaries are downstream from the well and fluidly connected thereto, an interface between the well and the capillaries comprises a step profile. Also disclosed is a method comprising: obtaining a substrate comprising an insulator layer of an insulator material; forming a well and a plurality of trenches in the insulator layer so that only the insulator material is exposed to an interior of the well and the plurality of trenches; nonconformally depositing a film into the plurality of trenches until the film pinches off top openings of the trenches and forms a tubular void therein; transforming the tubular void into a capillary by annealing the film.
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