| There are numerous applications of micro- and nano- scale apertures separating fluid reservoirs. Applications include patch-clamp type measurements, Coulter counting and DNA studies. Various techniques have been developed for the fabrication of nanoscale apertures, but the procedures contain steps that are incompatible with standard foundry processing. To overcome the drawbacks in the available methodologies a new procedure was developed to produce cylindrical solid-state nanopores that would be fully compatible with foundry production and be capable of customizable geometries.; Electron beam lithography (EBL) was used to pattern nanoscale apertures on device layer of a silicon-on-insulator (SOI) wafer. The nanopores were then etched using a reactive ion etch (RIE) tool using chlorine gas chemistry through the device layer to form the cylindrical aperture. Upon completion of the nanopore, a micropore was etched through the handle wafer using the Bosch process and a cavity was opened in the buried silicon dioxide (BOX) to complete the cavity. Thermal oxidation was then implemented to controllably passivate the silicon surface and reduce the diameter of the nanopore.; The electrolytic conductance of individual apertures of various diameters was measured using potassium chloride (KCI) electrolyte solution in the concentration range between one micromolar and one molar. The measured conductance was then compared with the theoretical conductance of a cylindrical impedance using the bulk solution conductivity. The measured conductance was found to follow the cylindrical approximation at high electrolyte concentration but was enhanced substantially at lower concentrations, less than one millimolar.; The origin of the enhanced conductance at the low electrolyte concentrations was accounted for by the accumulation of cations in the aperture to retain charge neutrality with the negatively charged silicon dioxide surface. A new theoretical model was developed, accounting for the cation accumulation, which resulted in a better fit of the measured conductance.; Upon completion of the characterization and modeling of the nanopores, Coulter counting experiments were conducted by introducing polystyrene nanoparticles of a known size into the wells adjacent to the aperture. While operating in a voltage clamp configuration, current fluctuations were observed due to the transition of the nanoparticles through the apertures. |
