Electrolytic conduction properties of single conical nanopores

Single conical nanopores were fabricated by etching single-ion-irradiated poly(ethylene terephthalate) (PET) films. The etching process was monitored by measuring the transmembrane current. A series of conical nanopores with decreasing tip sizes (decreasing conductivity) were obtained at different maximum etching currents, I-max. Results showed that it was possible to control the tip diameter by terminating etching at a certain I-max. The current-voltage characteristic of the nanopores in KCl solution was investigated. The current rectification coefficient, gamma = vertical bar I(U-)/I(U+)vertical bar, depended significantly on the tip size: a nanopore with small tip diameter could expect a larger gamma. gamma was also influenced by electrolyte concentration, and reached its maximum at KCl concentration of 0.3 M. (C) 2008 Elsevier Ltd. All rights reserved.