Fluidic cavities for on-chip layering and sealing of separation arrays

A method of fabricating a fluidic device, the method comprising:

• arranging a first pillar array on a substrate, the first pillar array comprising a plurality of pillars and a plurality of extraction columns, each extraction column comprising an access opening, each extraction column further comprising an inverted U-shaped structure defined by a single slit within a sidewall of the respective extraction column that provides unidirectional slit access to an exterior of the respective extraction column;
• arranging a sealing layer on the first pillar array to form a sealed fluidic cavity;
• and
• arranging an oxide layer on the sealing layer, the oxide layer having a plurality of vent holes aligned over the plurality of extraction columns.