Cylindrical glass nanocapillaries patterned via coarse lithography (>1 μm) for biomicrofluidic applications

We demonstrate a new method of fabricating in-plane cylindrical glass nanocapillaries (<100 nm) that does not require advanced patterning techniques but the standard coarse photolithography (>1 μm). These nanocapillaries are self-enclosed optically transparent and highly regular over large areas. Our method involves structuring μm-scale rectangular trenches in silicon, sealing the trenches into enclosed triangular channels by depositing phosphosilicate glass, and then transforming the channels into cylindrical capillaries through shape transformation by the reflow of annealed glass layer. Extended anneal has the structures shrunk into nanocapillaries preserving their cylindrical shape. Nanocapillaries ∼50 nm in diameter and effective stretching of digested λ-phage DNA in them are demonstrated.