Conductance method for the determination of ion diffusion coefficient through a nanochannel

A method of using conductance measurements and its relation with concentration of the solution inside a nanochannel is applied to measure the diffusion coefficient of ions in the nanochannel for the first time. Extension of a conductance-based technique to the nanodomain is also validated. Using an analyte of 0.05 mol/l KCl solution at 296.15 K, the experimental results obtained show that the ion diffusion coefficient through a nanochannel decreases greatly to 1 of that through a microchannel. The results indirectly explain why the etching rate of thermal oxide in the nanochannel is much smaller than that in the microchannel. This study may be helpful for research on nanoscale diffusion, such as nanosized ion batteries and nanoscale diffusive properties in medicine. Surface forces are also analysed as possible reasons for the great deviation of ion diffusion coefficient through the nanochannel from that through the microchannel.