Electro-viscous effects in capillary filling of nanochannels

TL;DR

This paper theoretically investigates electro-viscous effects in nanochannel capillary filling, concluding that such effects are minimal, contributing at most 1% to the apparent viscosity in realistic scenarios.

Contribution

It provides a detailed theoretical analysis including Debye-layer corrections, showing electro-viscous effects are negligible in typical nanochannel experiments.

Findings

Electro-viscous effects peak when channel size is comparable to screening length.

The maximum electro-viscous contribution is about 1% of apparent viscosity.

Electro-viscous effects are insignificant for realistic parameters.

Abstract

We theoretically examine the widespread hypothesis of an electro-viscous origin of the increase in apparent viscosity observed in recent experiments on capillary filling of nanochannels. Including Debye-layer corrections to the hydraulic resistance we find that the apparent viscosity reaches a maximum in the mesoscopic regime where the channel height (or more generally the hydraulic radius) is comparable to the screening length. However, for realistic estimates of central parameters, we find that the electro-viscous contribution to the apparent viscosity is at most a 1% effect.