The flow of crosslinking polymers through small channels determines success or failure in a range of engineered and natural processes. While these processes are critical in many applications, measuring the mechanical properties of gels in these spaces is challenging due to limited accessibility and small sample sizes. Consequently, there remains limited detailed characterization of how gel formation and the resulting mechanical properties affect important outcomes such as channel clogging. This work addresses this gap by investigating the flow of alginate solutions as they undergo calcium-induced crosslinking in a microfluidic device and characterizing the gels formed in the process. When alginate and calcium solutions meet in a microfluidic junction, an alginate gel deposits on the wall of the channel and begins to impede flow. Under specific conditions, increasing the driving pressure beyond a critical threshold results in the gel detaching from the channel wall and eluting from the device as a microscopic rod that retains the channel’s geometry. This phenomenon provides a novel microparticle fabrication approach that eliminates the need for oil-water emulsions typically required in conventional microfluidic manufacturing methods. Using a combination of fluorescent microscopy, atomic force microscopy, and a novel capillary bending assay, we characterize these microrods' morphological attributes (size, shape, porosity) and mechanical properties as functions of their formation conditions. Our findings establish parameters for controlled microrod manufacturing and explore how gel properties influence channel clogging during polymer crosslinking and deposition. The work highlights the rich dynamics in flows of crosslinking polymers and the ability to control them.
