pH-Regulated Ionic Conductance in a Nanochannel with
Overlapped Electric Double
Layers
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Abstract
Accurately and rapidly analyzing
the ionic current/conductance
in a nanochannel, especially under the condition of overlapped electric
double layers (EDLs), is of fundamental significance for the design
and development of novel nanofluidic devices. To achieve this, an
analytical model for the surface charge properties and ionic current/conductance
in a pH-regulated nanochannel is developed for the first time. The
developed model takes into account the effects of the EDL overlap,
electroosmotic flow, Stern layer, multiple ionic species, and the
site dissociation/association reactions on the channel walls. In addition
to good agreement with the existing experimental data of nanochannel
conductance available from the literature, our analytical model is
also validated by the full model with the Poisson–Nernst–Planck
and Navier–Stokes equations. The EDL overlap effect is significant
at small nanochannel height, low salt concentration, and medium low
pH. Neglecting the EDL overlap effect could result in a wrong estimation
in the zeta potential and conductance of the nanochannel in a single
measurement