patterned the metallic leads can be deposited by a lift off technique after defining these conductive leads the substrate is coated with a layer of oxide which has a thickness equivalent to the desired channel depth in the preferred embodiment the thickness would be 200 nm to 800 nm in the second level of lithography the nanochannels are patterned and etched to the underlying electrical leads in an exemplary embodiment low cost patterning of 100 nm to 500 nm wide channels is done using conformable contact photolithography see j g goodberlet appl phys lett vol 76 2000 p 667 incorporated herein by reference the channels are etched in a reactive ion etcher by controlling the plasma etching conditions i e lowering the plasma bias increasing the pressure choosing an appropriate gas or gas mixture and using a polymer etch mask with a low etch selectivity sloped channel walls are formed when an etch mask exhibits low etch selectivity the mask itself will etch slowly while the substrate below is etching during the etching step the mask etches back exposing more area on the substrate to the etching plasma this results in sloped sidewalls rather than vertical walls as would be the case for a hard etch mask with high etch selectivity the sloping of the nanochannels 39 side walls facilitates the coating in subsequent processing steps also during the.