Tilted post arrays for separating long DNA

Recent simulations by Chen and Dorfman [Electrophoresis 35, 405-411 (2014)] suggested that "tilting" the electric field with respect to the lattice vectors of a hexagonal post array would lead to a substantial improvement in electrophoretic DNA separations therein. We constructed such an array where the electric field is applied at an angle equidistant between the two lattice vectors. This tilted array leads to (i) baseline resolution of 20 kbp DNA and λ DNA (48.5 kbp) in a 4mm channel and (ii) measurable separation resolutions for electric fields up to 50 V/cm, both of which are improvements over untilted post arrays of the same post density. The predicted time required to reach a resolution of unity is approximately 5 min, independent of electric field. The separations are more reproducible at higher fields.