Strongly Non-Linear Pressure-Induced Ion Currents in Conical Nanopores
Summary
This research project investigates the non-linear behavior of pressure-induced currents in conical nanopores under influence of hydraulic and electric driving. This was hypothesized to be caused by space charge outside of the electric double layer. Numerical calculations were done to investigate the source of this non-linearity. Our data, however, point towards the conduction current as the cause of this transistor-like behavior, which is not related to charge inside the cone. We developed an analytical theory, based on a Poisson-Boltzmann framework for the electric double layer, to describe the salt concentration profile in the channel, which is directly related to the conduction current. A salt flux caused by a pressure difference counteracts the depletion or accumulation of salt in the channel. We conclude that this influence of the pressure on the concentration profile fully explains the observed current response.