SEM-based analysis of pore uniformity: effects of pore positions and sizes

Pore characterization is a critical aspect in materials science, where precise geometrical and morphological features significantly impact material performance. Accurate pore metrology, encompassing size, depth and spatial distribution, is essential for optimizing material performance in applications such as catalysis, membrane filtration, biomedical engineering etc. However, in cases where surfaces exhibit nanoscale features or complex geometries, traditional image analysis techniques, particularly thresholding, often fail to capture the inherent heterogeneity of pore structures observed in pore microscopy images. In this study, we present a contour-based centroid analysis framework aiming to quantify variability in pore arrangement, size and depth. Our method systematically explores the full grayscale threshold range to employ contour extraction of the pores and compute their centroids. We incorporate the Nearest Neighbour Index and pore density as base of comparison metrics, being applied to both simulated images for various levels of pore randomness, and experimental images of zirconium-based MOFs grown on nanoporous alumina surfaces. The framework demonstrates enhanced sensitivity to structural nuances, providing a reproducible and informative methodology for porous material characterization. • The work provides a framework on how pore analysis reveals variations in pore shape, depth, and spatial uniformity. • Utilizes the Nearest Neighbour Index (NNI) to quantify spatial uniformity in pore distributions. • Framework is applied to both simulated and experimental images of zirconium-based MOFs grown on nanoporous alumina surfaces.