the suitability of three vapor deposition techniques for pore size modification was evaluated using polycarbonate track etched membranes as model supports. a feature scale model was employed to predict the pore geometry after modification and the resulting pure water flux. physical vapor deposition (pvd) and pulsed plasma-enhanced chemical vapor deposition (pecvd), naturally, form asymmetric na...

We describe the fabrication of asymmetric nanopores sensitive to ultraviolet (UV) light, and give a detailed account of the divalent ionic transport through these pores using a theoretical model based on the Nernst-Planck equations. The pore surface is decorated with lysine chains having pH-sensitive (amine and carboxylic acid) moieties that are caged with photo-labile 4,5-dimethoxy-2-nitrobenz...

Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer...

Asymmetrically shaped nanopores have been shown to rectify the ionic current flowing through pores in a fashion similar to a p-n junction in a solid-state diode. Such asymmetric nanopores include conical pores in polymeric membranes and pyramidal pores in mica membranes. We review here both theoretical and experimental aspects of this ion current rectification phenomenon. A simple intuitive mod...

A nanoslot array with a uniform surface charge and height but with asymmetric slot entrances is shown to exhibit strong rectification, gating type current-voltage characteristics and a total current higher than the sum of isolated slots at a large voltage. Unlike previous reports of low-voltage current rectification within nanopores and nanochannels with a nonuniform surface charge and/or heigh...

The transport properties of single asymmetric nanopores in polyetheylene terephthalate ~PET! are examined. The pores were produced by a track etching technique based on the irradiation of the foils by swift heavy ions and subsequent chemical etching. Electrical conductivity measurements show that the nanopores in PET are cation selective and rectify the current with the preferential direction o...

Previous reports on Poisson-Nernst-Planck (PNP) simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dep...

The production of the track-etched membranes is well known in membrane science. Latent ion tracks are the result of the passage of swift ions through solid matter, they can be etched selectively in many materials. As a result, conical, cylindrical or other shape channels can be obtained. The increasing interest in polymer track-etched membranes with nano-channels is connected with the developme...

We describe the fabrication of a chemical-sensitive nanofluidic device based on asymmetric nanopores whose transport characteristics can be modulated upon exposure to hydrogen peroxide (H2O2). We show experimentally and theoretically that the current–voltage curves provide a suitable method to monitor the change of pore surface characteristics induced by H2O2 in solution from the electronic rea...