The ionic conductance through an open solid-state nanopore can be modeled by $$ G_{o} = \sigma [\frac{4 t}{\pi d^2} + \frac{1}{d}]^{-1} $$ where $ \sigma $ is the solution conductivity, $t$ is the membrane thickness, and $d$ is the nanopore diameter. When a DNA molecule enters the pore, the molecule blocks a certain area of the pore and thus blocks some ionic current. We can think of the smaller effective area of the pore during translocation as having the diameter $$ d_{eff} = \sqrt{d^2 - d_{dna}^2} $$ We can calculate the change in conductivity as a DNA molecule enters an open pore. $$ \Delta G = G_{o} - G_{with dna} $$ $$ \Delta G = \sigma [\frac{4 t}{\pi d^2} + \frac{1}{d}]^{-1} - \sigma [\frac{4 t}{\pi d_{eff}^2} + \frac{1}{d_{eff}}]^{-1}$$ This $ \Delta G $ is the signal measured during DNA translocation experiments. Clearly, if we want to maximize the signal, we need to reduce the membrane thickness and reduce the pore diameter.

In the literature, there are a wide variety of salt solutions, membrane materials, and nanopore diameters used in experiments. This site is an attempt to compare different publications by looking at $ \Delta G $ for 1 M KCl solution conductivity at 23 °C.