Collision of a field-driven polymer with a post: Electrophoresis in microlithographic arrays

We study the collision of a DNA or other polyelectrolyte chain with a point obstacle in the presence of an electric field via computer simulation. We find a very strong dependence of the average collision time, [t(c)], acid the average distance traveled during a collision, [z(c)], upon the impact parameter, b. Despite the complexities of the chain-post interaction, [t(c)] and [z(c)] follow universal curves over a large range of molecular weights and field strengths. This result provides analytic formulas for the chain's mobility in an array of posts and yields insight into the effect of post spacing.