From miscibility development to microbial biomineralization: visualization of pore scale process in microfluidic porous medium.

Pore-scale processes govern the emergence of macroscopic patterns in porous media. Direct experimental access to these coupled processes at the pore scale, however, remains limited by the opacity and structural heterogeneity of natural geomaterials. Microfluidic porous media offer real-time visualization of flow, interfacial phenomena, and chemical reactions within well-defined pore networks.

Here, we present a microfluidic platform that bridges pore-scale physical chemistry and biologically mediated precipitation process. The device architecture was originally developed to quantify multiple-contact miscibility in CO₂-enhanced oil recovery, providing direct measurements of phase behaviour and interfacial dynamics in a controlled pore network. We now extend this same framework to investigate microbial biomineralization as a precipitation-driven reactive process in porous media.

Using an optically transparent microfluidic porous medium, we resolve microbial transport, attachment, and growth, together with spatially localized mineral precipitation within individual pores and throats. This enables quantitative analysis of nucleation sites, precipitation kinetics, and pore-scale clogging. We apply the platform to study fungal-induced calcium carbonate precipitation, a biologically mediated mineralization pathway relevant to soil stabilization and the development of bio-based construction materials.

Our results demonstrate that a single microfluidic porous medium can be used to transition from physicochemical multiphase flow studies to biologically driven dissolution–precipitation processes. This approach provides a versatile experimental framework for reactive transport research, with implications for biomineralization, subsurface engineering, and biomaterial design based on microbially controlled mineral formation.