Pink noise of ionic conductance through single artificial nanopores revisited 

We report voltage-clamp measurements through single conical nanopore
obtained by chemical etching of a single ion-track in polyimide
film. Special attention is paid on the pink noise of the ionic current
(i.e. 1/f noise) measured with different filling liquids. The relative
pink noise amplitude is almost independent of concentration and pH for
KCl solutions, but varies strongly using ionic liquids. In particular,
we show that an appropriate ionic liquid enhances the conductivity and
decreases the pink noise amplitude by 2 orders of magnitude. These
results show that the origin of the pink noise cannot be imputed
neither to fluctuations of the pore geometry nor to the pore wall
charges but rather to a cooperative effect on ions mobility.