Revisiting, resolving and unifying the nanochannel-microchannel electrical resistance paradigm

TL;DR

This paper reviews and unifies models of nanochannel-microchannel electrical resistance, revealing the limitations of previous models and providing a comprehensive solution that aligns well with experimental data, enhancing nanofluidic system design.

Contribution

It introduces a unified model for nanochannel-microchannel resistance that corrects previous misconceptions and applies across various concentrations, simplifying system design.

Findings

The most popular existing model is shown to be incorrect.

The new unified model aligns well with simulations and experiments.

This model improves nanofluidic system design by providing clearer physics.

Abstract

Until recently, the accepted paradigm was that the Ohmic electrical response of nanochannel-microchannel systems is determined solely by the nanochannel while the effects of the adjacent microchannels are negligible. Two, almost identical, models were suggested to rationalize experimental observations that appeared to confirm the paradigm. However, recent works have challenged this paradigm and shown that the microchannels contribute in a non-negligible manner, and thus these two models are inadequate in describing realistic nanochannel-microchannel systems. Two newer nanochannel-microchannel models were suggested to replace the nanochannel-dominant models. These models were limited to either very low or very high concentrations. Here, we review these four leading models. The most popular is shown to be incorrect, while the remaining models are unified under a newly derived solution which shows remarkable correspondence to simulations and experiments. The unifying model can be used to improve the design of any nanofluidic based systems as the physics are more transparent, and the need for complicated time-consuming preliminary simulations and experiments has been eliminated.