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We demonstrate a new method of fabricating in-plane cylindrical glass nanocapillaries (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.

We demonstrate monolithic integration of fine cylindrical glass microcapillaries (diameter ∼1 μm) on silicon and evaluate their performance for electrophoretic separation of biomolecules. Such microcapillaries are achieved through thermal reflow of a glass layer on microstructured silicon whereby slender voids are moulded into cylindrical tubes. The process allows self-enclosed microcapillaries with a uniform profile. A simplified method is also described to integrate the microcapillaries with a sample-injection cross without the requirement of glass etching. The 10-mm-long microcapillaries sustain field intensities up to 90 kV/m and limit the temperature excursions due to Joule heating to a few degrees Celsius only.