Brownian transport of finite size particles in a periodic channel coexisting with an energetic potential.

Abstract

Transport of particles with different sizes moving in a two-dimensional periodic channel is studied in the presence of an unbiased external force and a periodic energetic potential. While particles are going through entropic barrier resulting from the geometric restraints, the transport is also influenced by the energetic potential. For the case of an unbiased external force, the competition between the energetic potential and entropic barrier leads to different transport direction of particles, which sensitively depends on the particles radius. Particles move to the left when smaller than a critical radius and larger than another critical radius, whereas particles move to the right in the range of two critical radii. Therefore, the results we have presented can contribute further to the invention of machines for particle separation.