Permeability Experiment and Unit Cell Numerical Model of Porous Membranes for Paper-based Diagnostics

Rate-of-rise experiments were performed to measure the permeability of nitrocellulose (NC) membranes for lateral flow tests. In order to characterize the microstructure of NC membranes, the porosity was measured using the weighting method. SEM images were then taken to statistically determine particle and pore size distributions. A novel particle-cubic unit cell model was proposed to represent the pore geometry of NC membranes. Based on the model, the theoretical relation between porosity, pore size and particle size was derived, which agreed well with the experimental data. Fluid flow in the particle-cubic model was numerically simulated with periodic boundary conditions to calculate the permeability. Results obtained using the present numerical model agreed well with experimentally measured permeability.