title: Osmotic flow through fully permeable nanochannels.
abstract: Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients across nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, we are able to measure the water flow rate inside single nanochannels to an unprecedented sensitivity of femtoliters per minute flow rates. Our results indicate the onset of a convective liquid motion under salinity gradients, from the higher to lower electrolyte concentration, which is attributed to diffusio-osmotic transport. To our knowledge, this is the first experimental evidence and quantitative investigation of this subtle interfacially driven transport, which need to be accounted for in nanoscale dynamics. Finally, diffusio-osmotic transport under a neutral polymer gradient is also demonstrated. The experiments highlight the entropic depletion of polymers that occurs at the nanochannel surface, resulting in convective flow in the opposite direction to that seen for electrolytes.
authors.affiliation: Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne Cedex, France and School of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang 412-791, Korea.
authors.forename: C
authors.initials: C
authors.lastname: Lee
authors.affiliation: Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Cottin-Bizonne
authors.affiliation: Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne Cedex, France.
authors.forename: A-L
authors.initials: AL
authors.lastname: Biance
authors.affiliation: CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse, France and Université de Toulouse, LAAS, F-31400 Toulouse, France.
authors.forename: P
authors.initials: P
authors.lastname: Joseph
authors.affiliation: Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne Cedex, France.
authors.forename: L
authors.initials: L
authors.lastname: Bocquet
authors.affiliation: Institut Lumière Matière, Université Claude Bernard Lyon 1-CNRS, UMR 5306, Université de Lyon, F-69622 Villeurbanne Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Ybert
mesh_terms: D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D061848:Optical Imaging; D009995:Osmosis
chemical_list: D005456:Fluorescent Dyes