The effects of the electrical double layer on giant ionic currents through single-walled carbon nanotubes

We developed a computational model for investigating the cause for the high ionic current through a single-walled carbon nanotube nanofluidic device by considering the electrical double layer at a solid–liquid interface. With this model, we were able to examine the influence of the Gouy–Chapman–Stern electrical double layer and the solution concentration on the ionic conductance in the device. Results showed that the conductance–concentration relationship predicted from our model agreed well with experimental observation. Moreover, our model showed that the compact layer thickness increased with the increase of the bulk solution concentration, reducing the internal volume of the nanotube channel available for fluid transport. Fluid within the channel had an enhanced concentration and a net charge which increased the electroosmotic and electrophoretic transport properties of the device, increasing the total ionic conductance of the system. (paper)