The end of nanochannels

TL;DR

This paper challenges existing nanochannel flow theories by demonstrating that end effects impose a fundamental limit on flow rates, even in frictionless channels, impacting both technological and biological transport systems.

Contribution

It introduces a reassessment of nanochannel flow models by incorporating end-effect friction, revealing limitations in current theories and providing revised flow-rate calculations.

Findings

End effects cause finite friction in nanochannels regardless of surface friction.

Flow rates are limited by end effects, contradicting previous no-boundary assumptions.

Revised models better predict experimental flow-rate and slip length measurements.

Abstract

Current theories of nanochannel flow impose no upper bound on flow rates, and predict friction through nanochannels can be vanishingly small. We reassess neglecting channel entry effects in extremely long channels and find violations at the nanoscale. Even in frictionless nanochannels, end effects provide a finite amount of friction. Hence, the speed at which nanochannels transport liquids is limited. Flow-rate and slip length measurements are reevaluated using calculations which include end-effect friction. End effects are critical for the design of new technological devices and to understand biological transport.