Entropic rectification and current inversion in a pulsating channel

TL;DR

This paper investigates how pulsating channel geometries influence Brownian particle transport, revealing resonant current enhancement and inversion phenomena driven by shape oscillations and external forces, modeled via a time-dependent Fick-Jacobs equation.

Contribution

It introduces a novel model combining entropic barriers and dynamic diffusion to explain current resonances and inversions in pulsating channels.

Findings

Resonant increase in particle current with noise level.

Current inversion occurs at specific oscillation frequencies and forces.

Potential applications in microfluidic and biological transport optimization.

Abstract

We show the existence of a resonant behavior of the current of Brownian particles confined in a pulsating channel. The interplay between the periodic oscillations of the shape of the channel and a force applied along its axis leads to an increase of the particle current as a function of the noise level. A regime of current inversion is also observed for particular values of the oscillation frequency and the applied force. The model proposed to obtain these new behaviors of the current is based on the Fick-Jacobs equation in which the entropic barrier and the effective diffusion coefficient depend on time. The phenomenon observed could be used to optimize transport in microfluidic devices or biological channels.