A technique relates sorting biopolymers. The biopolymers are introduced into a nanopillar array, and the biopolymers include a first population and a second population. The nanopillar array includes nanopillars arranged to have a gap separating one from another. The biopolymers are sorted through the nanopillar array by transporting the first population of the biopolymers less than a predetermined bumping size according to a fluid flow direction and by transporting the second population of the biopolymers at least the predetermined bumping size according to a bumped direction different from the fluid flow direction. The nanopillar array is configured to employ the gap with a gap size less than 300 nanometers in order to sort the biopolymers.