Cylindrical solid-state nanopores with 40 nm diameter were fabricated in silicon-on-insulator substrates using standard cleanroom semiconductor processing techniques. Here we report on a fabrication sequence which consistently produced robust nanopores with control over the final diameter. The electrolyte concentration dependence of ion transport through a single nanopore was measured over the range of 0.316 mM to 1 M. Experimentally measured values follow the bulk linear behavior at high concentrations but deviate from the simple model at lower concentrations. These deviations were modeled using a surface charge conduction mechanism. (C) 2007 Elsevier Ltd. All rights reserved.