Mew-Bing Wan, YongSeok Jho
Previous work shows that a net directed motion arises from a system of individual particles undergoing run-and-tumble dynamics in the presence of an array of asymmetric barriers. Here, we show that when the individual particle is replaced by a chain of particles (polymers) linked to each other by spring forces, the rectification is enhanced. Introducing a chain of particles, we have an additional control parameter of n which represents the aspect ratio of the elongated chain. In particular, when the length of the chain is not negligible compared to the size of the opening between barriers, l_o, the conformal entropy of the chain induces a force to enhance rectification. Analyses based on flux balances and intensive molecular simulations, are presented. It is found that the rectification increases when the number of particles in each polymer, as well as its length, increases. In addition, the rectification increases when l_o, decreases. Interestingly, if the conformal entropic difference exceeds the thermal diffusion, net directed motion is observed even when the run length is small, that is, when the run-and-tumble dynamics approaches Brownian motion. Also, when the inelastic collisions between the particles and the barriers are replaced by elastic collisions, a reversed rectification is observed.
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http://arxiv.org/abs/1209.2343
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