Ionic conductivity in nanopipettes: experiment and model

This work investigates ion transport in glass nanopipettes with tip diameters in the range of 80–100 nm, filled with phosphate-buffered saline. A combination of experimental measurements and theoretical modeling is employed. A coupled Poisson-Nernst-Planck-Navier-Stokes model is used to describe the ion transport, incorporating electroosmotic flow, electrophoresis and interionic effects. The theoretical results are in good agreement with experimental current to voltage characteristics. Comparison between modeled and measured data enables estimation of nanopipette geometry with good accuracy. The simulations also reveal characteristic spatial distributions of ionic flow in the aperture area of the nanopipette tip, governed by electroosmosis and the tip shape. These findings provide insights into nanoscale ion transport phenomena relevant for analytical and biological applications.