DNA separation on surfaces

Recent experimental work on DNA separation on surfaces reveals a power law behavior of the mobility with size. We employed a simple model that elucidates the observed power law trend. When the external electric field is barely larger than the critical value required for initiating translational motion, the mobility is approximately inversely proportional to the DNA size. At larger fields, mobility scales as N^-α with 0<α<1, while showing oscillatory structure. Finally, at very large fields, mobility becomes size independent. Our model provides insight into separation mechanisms and presents numerical results that explain power law scaling.