Fig. 1.

General nanopore characteristics at 1 M salt. (a) Current–voltage characteristics of six individual nanopores with nanopore diameters as indicated. All curves show a linear I–V dependence. (Inset) A transmission electron microscopy image of the 15.6-nm-diameter nanopore. (b) Resistance values of 28 individual nanopores as a function of nanopore diameter. The red line represents the resistance of a 25-nm-long cylinder. Resistance values larger than 2.5 times the resistance indicated by the red line are shown in grey. (c) Current recordings and histograms of two nanopores (at 100 mV) with substantially different resistance values, illustrating clear differences in current noise. The nanopores diameters are 20.8 nm (bottom traces) and 22.0 nm (top traces). The current was filtered at 10 and 1 kHz, as indicated. The black, grey, and blue histograms, shown on the right, are magnified along the x axis to be visible on the same scale. (d) Current power spectral densities of the two nanopores used in c, showing 1/f low-frequency noise of different magnitude and comparable high-frequency noise.