Abstract
Surface modification will change the surface
charge density (SCD) at the signal-limiting region of nanochannel
devices. By fitting the measured i−V curves in
simulation via solving the Poisson and Nernst−Planck
equations, the SCD and therefore the surface coverage can be
noninvasively quantified. Amine terminated organosilanes are
employed to chemically modify single conical nanopores.
Determined by the protonation−deprotonation of the functional
groups, the density and polarity of surface charges are
adjusted by solution pH. The rectified current at high
conductivity states is found to be proportional to the SCD
near the nanopore orifice. This correlation allows the noninvasive
determination of SCD and surface coverage of individual conical nanopores.