  We propose a new method for electrophoretic separation of DNA in which
adsorbed polymers are driven over a disordered two-dimensional substrate which
contains attractive sites for the polymers. Using simulations of a model for
long polymer chains, we show that the mobility increases with polymer length,
in contrast to gel electrophoresis techniques, and that separation can be
achieved for a range of length scales. We demonstrate that the separation
mechanism relies on steric interactions between polymer segments, which prevent
substrate disorder sites from trapping more than one DNA segment each. Since
thermal activation does not play a significant role in determining the polymer
mobility, band broadening due to diffusion can be avoided in our separation
method.
