Fluidic devices that possess structures less than 150 nm in one or two dimensions are generating great interest due to the unique properties afforded by this size domain not accessible at the microscale. As molecules travel through nanochannels, they undergo hydrophobic and van der Waals interactions with the channel walls at a degree that depends on the size of the channel, the surface chemistry of the wall and the debye length (governed by the ionic strength of the electrolyte solution). In this work, we report the fabrication of nanometer sized structures (nanoslits, nanochannels and nanoelectrodes) in thermoplastic and fused silica substrates for the analysis of dsNA. In the case of thermoplastics, mixed-scale micro- and nanofluidic networks were fabricated using a simple, high resolution, single-step thermal embossing process and the fluidic structures were enclosed via low temperature fusion bonding to a cover plate. Nanochannels were chemically modified and the associated electrokinetic parameters - surface charge density, zeta potential and electroosmotic flow - were evaluated. In the fused silica substrate, we developed an integrated nanosensing device comprising of a single nanochannel and two pairs of transverse electron-conducting (~50 × 50 nm) nanoelectrodes separated by a nanometer gap (nanogap) and poised at the input and output ends of the nanochannel. This device serves a foundation for a novel technique we developing for the sequencing of DNA molecule by measuring the transit time of the monomer units entering and exiting a nanochannel (5 to 50 nanochannels) after being clipped from a single polymer digested with an enzyme. Further experiments on single molecule electrophoresis will provide information on possible routes that can be adopted to engineer proper nanochannel wall chemistry for the enhancement or reduction of solute/wall interactions.