Role of charge regulation and flow slip on the ionic conductance of nanopores: an analytical approach

Abstract

The number of precise conductance measurements in nanopores is quickly growing. In order to clarify the dominant mechanisms at play and facilitate the characterization of such systems for which there is still no clear consensus, we propose an analytical approach to the ionic conductance in nanopores that takes into account (i) electro-osmotic effects, (ii) flow slip at the pore surface for hydrophobic nanopores, (iii) a component of the surface charge density that is modulated by the reservoir $p$H and salt concentration $c_s$ using a simple charge regulation model, and (iv) a fixed surface charge density that is unaffected by $p$H and $c_s$. Limiting cases are explored for various ranges of salt concentration and our formula is used to fit conductance experiments found in the literature for carbon nanotubes. This approach permits us to catalog the different possible transport regimes and propose an explanation for the wide variety of currently known experimental behavior for the conductance versus $c_s$.

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Cited by in corpus (9)

• Fluids at the Nanoscale: from continuum to sub-continuum transport
• Interfacial transport with mobile surface charges and consequences for ionic transport in carbon nanotubes
• Chemi-sorbed versus physi-sorbed surface charge and its impact on electrokinetic transport: carbon versus boron-nitride surface
• Slippery and mobile hydrophobic electrokinetics: from single walls to nanochannels
• The Goldman-Hodgkins-Katz Equation, Reverse-Electrodialysis, and Everything in Between
• Electrical conductance of charged nanopores
• Revisiting the access conductance of a nanopore in a charged membrane
• Competition between Born solvation, dielectric exclusion, and Coulomb attraction in spherical nanopores
• Computational modeling of biological nanopores