Noise in Ultrashort Elastic Membrane Nanotube

Abstract

Fluctuations of the ion current in elastic nanopores are studied in a wide frequency range and a complete description of their noise characteristics is presented. The lumen of ultrashort (<200 nm) lipid nanotubes (usNT) filled with an electrolyte solution was used as a model of an elastic nanopore. It is shown that at low frequencies (f < 300 Hz) the 1/f noise type prevails. This low frequency noise was analyzed at different salt concentrations and nanopore geometries and it was found that the 1/f noise power is proportional to the reciprocal of the number of charge carriers, which is in good agreement with the empirical Hooge relation. Linear approximation showed that the Hooge parameter for elastic nanopores is (2.5 ± 0.5) × 10^–3, which turned out to be an order of magnitude higher than for solid analogs. In the high-frequency regime (f > 1 kHz), white noise becomes dominant, the power density of which depends linearly on the signal bandwidth and, as the length of the usNT decreases and the ionic strength increases, it is in good agreement with its representation as the sum of the Johnson–Nyquist thermal noise and the Schottky shot noise.