Asymmetric Capillary Filling of Nanoporous Membranes

CLAUDIO L.A. BERLI; EMANUEL ELIZALDE; RAÚL URTEAGA; ROBERTO R. KOROPECKI

Lucca, Barga

Conferencia; Microfluidics, Physics & Chemistry of Gordon Research Conferences; 2013

Gordon Research Conferences

Nanoporous anodized alumina membranes (NAAM) are studied by measuring the dynamics of capillary-driven fluid imbibition on both sides of the substrate by laser interferometry. The membranes considered contain a well-ordered array of straight nanopores with conical geometry. It is found that the filling times present a strong asymmetry depending on which side of the membrane is wet. We show by theory and experiments that, for a given fluid, the asymmetric filling is determined by the ratio of the inlet to outlet pore radii. These novel results in nanoscale fluid dynamics have several potential applications. On the other hand, the optofluidic model used allows one to determine the pore radius variation across the membrane, which is of great interest in the characterization of nanoporous substrates.