Density dependent speed-up of particle transport in channels

TL;DR

This paper reveals that in microfluidic channels, the velocity of actively driven particles increases with density due to hydrodynamic interactions, leading to a speed-up effect that impacts understanding of biological and synthetic transport systems.

Contribution

It demonstrates a novel density-dependent speed-up in particle transport driven by hydrodynamic effects, supported by experimental and numerical evidence.

Findings

Particle velocity increases with density in driven transport.

Hydrodynamic piston-like effect causes the speed-up.

Implications for biological channels and sensor design.

Abstract

Collective transport through channels shows surprising properties under one-dimensional confinement: particles in a single file exhibit sub-diffusive behavior, while liquid confinement causes distance-independent correlations between the particles. Such interactions in channels are well studied for passive Brownian motion, but driven transport remains largely unexplored. Here, we demonstrate gating of transport due to a speed-up effect for actively driven particle transport through microfluidic channels. We prove that particle velocity increases with particle density in the channel due to hydrodynamic interactions under electrophoretic and gravitational forces. Numerical models demonstrate that the observed speed-up of transport originates from a hydrodynamic piston-like effect. Our discovery is fundamentally important for understanding protein channels and transport through porous materials and for designing novel sensors and filters.