Asymmetric capillary filling in nanoporous membranes

CLAUDIO BERLI, EMANUEL ELIZALDE, RAUL URTEAGA, ROBERTO KOROPECKI

Lucca

Conferencia; Microfluidics, Physics & Chemistry of; 2013

Gordon Research Conference

Nanoporous membranes 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. The capillary filling of conical channels exhibits counterintuitive results in comparison to the corresponding cylindrical channels. These novel results in nanoscale fluid dynamics have several potential applications in optofluidics, paper microfluidics, and nanofiltration. 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.