  With the resistive-pulse technique (RPT), nanopores serve as the nanofluidic
sensors of various analytes for their many physical and chemical properties.
Here, we focus on the size measurement and its theoretical prediction for
sub-200 nm nanoparticles with RPT. Through systematical investigation of the
current blockade of nanoparticles across cylindrical nanopores with
simulations, Maxwell method considering the shape coefficient and access
resistances agrees well with simulation results. However, the widely used
integration method of the resistance has distinct deviations in various cases.
With the introduction of a correction factor \b{eta} to the integration method,
our revised equations can provide good predictions for simulation results.
\b{eta} shows a strong dependence on the diameter ratio (d over D) of the
nanoparticle and nanopore. Following the same strategy, modified equations are
provided for the accurate size prediction for nanoparticles across conical
nanopores, where the integration method is the default convenient way. The
correction factor \b{eta}' relates to \b{eta} in cylindrical nanopores.
\b{eta}' exhibits independence on the pore geometry parameters and diameters of
nanoparticles, but dependence on the surface charge density of conical
nanopores. Our improved equations can provide theoretical predictions for the
accurate size detection of 100-200 nm diameter nanoparticles across cylindrical
and conical nanopores.
