Flow-Induced Shift of the Donnan Equilibrium for Ultra-Sensitive Mass Transport Measurement Through a Single Nanochannel

Simon Gravelle (1) , Christophe Ybert (1)

1 iLM - L&I - iLM - Liquides et interfaces

Despite mass flow is arguably the most elementary transport associated to nanofluidics, its measurement still constitutes a significant bottleneck for the development of this promising field. Here, we investigate how a liquid flow perturbs the ubiquitous enrichment-or depletion-of a solute inside a single nanochannel. Using Fluorescence Correlation Spectroscopy to access the local solute concentration, we demonstrate that the initial enrichment-the so-called Donnan equilibrium-is depleted under flow thus revealing the underlying mass transport. Combining theoretical and numerical calculations beyond the classical 1D treatments of nanochannels, we rationalize quantitatively our observations and demonstrate unprecedented flow rate sensitivity. Because the present mass transport investigations are based on generic effects, we believe they can develop into a versatile approach for nanofluidics.

Mots clés: Fluorescence correlation spectroscopy; Nanochannels; Mass diffusion; Nanofluidics; Transport properties; Fluid flows

Domaines: Matière Molle [cond-mat.soft]

Simon Gravelle, Christophe Ybert. Flow-Induced Shift of the Donnan Equilibrium for Ultra-Sensitive Mass Transport Measurement Through a Single Nanochannel. Journal of Chemical Physics, 2019, 151 (24), pp.244503. ⟨10.1063/1.5133888⟩. ⟨hal-02335212⟩