Volume 246, 2023

Disentangling 1/f noise from confined ion dynamics

Abstract

Ion transport through biological and solid-state nanochannels is known to be a highly noisy process. The power spectrum of current fluctuations is empirically known to scale like the inverse of frequency, following the long-standing yet poorly understood Hooge's law. Here, we report measurements of current fluctuations across nanometer-scale two-dimensional channels with different surface properties. The structure of fluctuations is found to depend on the channel's material. While in pristine channels current fluctuations scale like 1/f1+a with a = 0–0.5, the noise power spectrum of activated graphite channels displays different regimes depending on frequency. Based on these observations, we develop a theoretical formalism directly linking ion dynamics and current fluctuations. We predict that the noise power spectrum takes the form 1/f × Schannel(f), where 1/f fluctuations emerge in fluidic reservoirs on both sides of the channel and Schannel describes fluctuations inside it. Deviations to Hooge's law thus allow direct access to the ion transport dynamics of the channel – explaining the entire phenomenology observed in experiments on 2D nanochannels. Our results demonstrate how current fluctuations can be used to characterize nanoscale ion dynamics.

Graphical abstract: Disentangling 1/f noise from confined ion dynamics

Associated articles

Article information

Article type
Paper
Submitted
08 fev 2023
Accepted
16 mar 2023
First published
16 mar 2023

Faraday Discuss., 2023,246, 556-575

Disentangling 1/f noise from confined ion dynamics

P. Robin, M. Lizée, Q. Yang, T. Emmerich, A. Siria and L. Bocquet, Faraday Discuss., 2023, 246, 556 DOI: 10.1039/D3FD00035D

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