Geometric dependence of the conductance drop in a nanopore due to a particle.

We study the effect of a neutral particle on the ionic flow through a nanopore using a basic uniform field theory and the coupled Poisson-Nernst-Planck and Navier-Stokes (PNP-NS) equations. We consider hourglass and cylindrical pore profiles and examine how the difference in pore shape changes the position dependence of the current change due to the particle. Good quantitative agreement between both calculations is seen, though we find that the simple theory is unable to correctly capture the change in the access resistance of the pore if a particle is placed at the pore entrance. Finally, we examine the spatial variations in the solutions of the PNP-NS equations, finding that the electro-osmotic flow through the pore is completely disrupted for sufficiently large particles.