A deterministic platform for engineering interfacial phenomena in porous media using artificially structured rough surfaces.

The role of surface roughness in controlling interfacial phenomena is ubiquitous across natural and engineered porous media, governing core processes in energy recovery, carbon sequestration, and water purification. However, a mechanistic understanding has been hindered by the inability to systematically control and replicate complex surface topographies in the laboratory. Here, we introduce a versatile materials platform that offers deterministic control over surface roughness in these media. Our approach is based on the thermal sintering of glass beads into artificial thin sections, combined with an innovative semi-immersion technique that enables precise sectioning and reliable interfacial measurements. We establish quantitative scaling laws, demonstrating that bead size directly determines roughness amplitude and morphology-from fine, high-frequency textures to pronounced, wavy undulations. This controlled topography sets wettability states, triggering transitions between Wenzel and Cassie-Baxter regimes, and governs contact-line pinning that leads to hysteresis and capillary trapping. By bridging the gap between stochastic natural surfaces and idealized models, our tunable and reproducible platform paves the way for systematic study and tailored engineering of multiphase flow across a wide range of applications, from subsurface hydrology to advanced material design.