CONICET | Buscador de Institutos y Recursos Humanos

An experimental study on the capillary filling of nanoporous silicon with different fluids is presented. Thinnanoporous membranes were obtained by electrochemical anodization, and the filling dynamics was measured bylaser interferometry, taking advantage of the optical properties of the system, related with the small pore radius incomparison to light wavelength. This optical technique is relatively simple to implement and yields highly reproducibledata. A fluid dynamic model for the filling process is also proposed including the main characteristics of the porousmatrix (tortuosity, average hydraulic radius). The model was tested for different ambient pressures, porous layermorphology, and fluid properties. It was found that the model reproduces well the experimental data according to thedifferent conditions. The predicted pore radii quantitatively agree with the image information from scanning electronmicroscopy. This technique can be readily used as nanofluidic sensor to determine fluid properties such as viscosity andsurface tension of a small sample of liquid. Besides, the whole method can be suitable to characterize a porous matrix.