Influence of temperature and electroosmotic flow on the rectification behavior of conical nanochannels

Considering various potential applications of charged nanochannels, we studied theoretically the electric field driven ion transport in a conical nanochannel connecting two large, identical reservoirs filled with an aqueous KCl solution. Taking account of the effect of electroosmotic flow (EOF), the associated electrokinetic behaviors under various conditions are examined, focusing on the influences of the temperature and the bulk salt concentration on the degree of ionic current rectification (ICR) and the conductance. Assuming that the bulk salt concentration ranges from 1 to 1000 mM and temperature from 278 to 313 K, we show that neglecting the EOF effect will either underestimate or overestimate the ionic current, and can lead to ca. 90% deviation in the degree of ICR. In general, the higher the temperature the greater the conductance and the less significant the ICR effect, and the degree of this effect has a local maximum as the bulk salt concentration varies. A three dimensional plot correlating the ICR effect with the bulk salt concentration and the temperature is prepared for the design of the nanochannel-based thermal gates for ionic transport.