Departmental Papers (MEAM)

Document Type

Journal Article

Date of this Version



Suggested Citation:
Su, T. and Purohit, P.K. (2011). Entropically driven motion of polymers in nonuniform nanochannels. Physical Review E. 83, 061906.

© 2011 The American Physical Society


In nanofluidic devices, nonuniform confinement induces an entropic force that automatically drives biopolymers toward less-confined regions to gain entropy. To understand this phenomenon, we first analyze the diffusion of an entropy-driven particle system. The derived Fokker-Planck equation reveals an effective driving force as the negative gradient of the free energy. The derivation also shows that both the diffusion constant and drag coefficient are location dependent on an arbitrary free-energy landscape. As an application, DNA motion and deformation in nonuniform channels are investigated. Typical solutions reveal large gradients of stress on the polymer where the channel width changes rapidly. Migration of DNA in several nonuniform channels is discussed.



Date Posted: 15 June 2011

This document has been peer reviewed.