Entropic pulling and diffusion diode

Biological environments at micrometer scales and below are often crowded, and experience incessant stochastic thermal fluctuations. The presence of membranes/pores, and multiple biological entities in a constricted space can make the damping/diffusion inhomogeneous. This effect of inhomogeneity is presented by the diffusion becoming coordinate-dependent. In this paper, we analyze the consequence of inhomogeneity-induced coordinate-dependent diffusion on Brownian systems in thermal equilibrium under the It\ᵒ's interpretation. We argue that the presence of coordinate-dependent diffusion under It\ᵒ's formulation gives rise to an effective diffusion potential that can have substantial contribution to system's transport. Alternatively, we relate this to the existence of an emergent force of entropic origin that dictates the transport near interfaces.