Fabrication of nano-channels is categorized into top-down and bottom-up methods. Top-down methods are the conventional processes utilized in the IC industry and Microelectromechanical systems research. It begins with photolithography on a bulk silicon wafer. Bottom-up methods, in contrast, starts with atoms or molecules with intrinsic nano-scaled dimension. By organize and combine these building blocks together, it is able to form a nanostructures as small as only a few nanometers.