The most common method utilized for bottom-up fabrication is self-assembled monolayers (SAM). This method usually use biological materials to form a molecular monolayer on the substrate. Nano-channels can also be fabricated from the growth of carbon nanotubes (CNT) and quantum wires. The bottom-up methods usually give well-defined shapes with characteristic length about few nanometers. For these structures to be utilized as nanofluidic devices, the interconnection between nano-channels and microfluidic systems becomes an important issue.