This paper describes the combined use of controlled nanoassembly and microfabrication (photolithography) to construct multi-walled, carbon, nanotube-based fluidic devices. The nanoassembly technique utilizes dielectrophoresis to position individual nanotubes across the gap between two electrodes patterned on a wafer. The dielectrophoretic migration process was studied theoretically and experimentally. Once a tube had been trapped between a pair of electrodes, photoresist was spun over the wafer and developed to form microfluidic interfaces. Liquid condensation in and evaporation from the nanotubes were observed with optical microscopy. The nanotube-based fluidic devices can be used for studies of fluid transport under extreme confinement and as sensitive sensors.