Asymmetric properties of ion current 1/f noise in conically shaped nanopores

We study ion currents in single rectifying conically shaped nanopores of various opening diameters and analyze the 1/f spectral behavior of the current fluctuations. The 1/f noise characteristics show an asymmetry with respect to the externally applied voltage. When in the high conductance state, the normalized 1/f noise associated with ion current signals increases with applied voltage, while in the low conductance state the 1/f noise shows equilibrium, voltage-independent fluctuations. The pore diameter and salt concentration play a direct role in defining these noise properties and influence the frequency range of the 1/f noise occurrence. We describe this behavior for a range of nanopore diameters and electrolyte concentrations. (C) 2010 Elsevier B.V. All rights reserved.