In situ evaluation of 3D polymeric microstructures integrated into a microfluidic channel

We investigate the applicability of photoluminescence (PL) mapping technique for in situ evaluation of the polymeric microstructures fabricated by direct laser writing in pre-polymers (DLW-PP), both in open and closed (fully three-dimensional) microfluidic channels, where conventional characterization is often challenging. The technique utilizes quenching of photo-initiator emission in polymerized regions, enabling visualization of fabricated features prior to development. PL mapping enables accurate three-dimensional localization before sample development and can be repeatedly applied during fabrication without damaging the structures. The detected PL signal consistently exhibits a footprint smaller than the final developed structure. These results extend the applicability of PL mapping to fused silica microfluidic platforms and demonstrate its potential as a practical in situ tool for monitoring, alignment, and quality assessment of DLW-PP-fabricated microstructures.