  Periodic arrays of micro- or nano-pillars constitute solid state matrices
with excellent properties for DNA size separation. Nanofabrication technologies
offer many solutions to tailor the geometry of obstacle arrays, yet most
studies have been conducted with cylinders arranged in hexagonal lattices. In
this report, we investigate the dynamics of single DNA collision with
elliptical nanoposts using hydrodynamic actuation. Our data shows that the
asymmetry of the obstacles has minor effect on unhooking dynamics, and thus
confirms recent predictions obtained by Brownian dynamics simulations. In
addition, we show that the disengagement dynamics are correctly predicted by
models of electrophoresis, and propose that this consistency is associated to
the confinement in slit-like channels. We finally conclude that elliptical
posts are expected to marginally improve the performances of separation
devices.
