A nanochannel system fabricated by MEMS microfabrication and atomic force microscopy

A silicon nanochannel system with integrated transverse electrodes was designed and fabricated by combining MEMS microfabrication and AFM nanolithography. The fabrication process began with the patterning of microscale reservoirs and electrodes on an oxidized silicon chip using conventional MEMS techniques. A nanochannel, approximately 30μm long with a small semi-circular cross-sectional area of 20nm by 200nm, was then mechanically machined on the oxide surface between the micro reservoirs by applying AFM nanolithography with an all-diamond probe. Anodic bonding was used to seal off the nanochannel with a matching Pyrex cover. Continuous flow in the nanochannel was verified by pressurizing a solution of fluorescein isothiocyanate (FITC) in ethanol through the channel in a vacuum chamber. It was further demonstrated by driving carboxyl-modified FluoSpheres^® (diameter ~ 20 nm) through the nanochannel with an external electric field. Presence of the FluoSpheres^® in the channel was indicated by a sharp increase in current between the transverse electrodes.