Figure 1.

(a) EDS spectrum from an Al₂O₃ membrane confirming the presence of only Al and O (Inset) TEM cross section of 40 nm thick Al₂O₃ membrane (Region 3) in which nanopores were formed (b) TEM phase contrast image of a 7 nm pore formed using a focused convergent electron beam (c) Linear IV characteristics from a 5.7 nm Al₂O₃ nanopore at KCl concentrations of 10 mM, 100 mM and 1 M (d) Schematic of DNA transport through a nanopore under an applied bias (e) Characteristic current blockades observed during DNA translocation of 5 kbp dsDNA through 7 nm pore at 500 mV (Inset) Control prior to the insertion of dsDNA does not shows steady, blockade free current.