Enhanced UV-C photolysis using microscale concave reflector arrays

초록

This study explores the enhancement of UV-C-induced photolysis using concave micro-reflector arrays, with methylene blue (MB) serving as a model compound. Twelve reflector configurations-including flat, scattering, gapped, and gapless concave designs with diameters ranging from 1 to 45 mu m-were fabricated via wet-etching, anodization, photoresist reflow, and PDMS molding. Photolysis experiments were performed using four 270 nm UV-C LED boards at controlled source-specimen distances (15 and 30 mm) to decouple the effects of light intensity and exposure time under constant total energy. The results revealed that light intensity had a greater influence on MB degradation than exposure time. Concave micro-reflectors with diameters of 15-30 mu m achieved at least twice the removal ratio of flat reflectors within the first 30 min, with the gapless 25 mu m design showing the highest performance-up to a 3.09x improvement at 15 min and 83 % MB removal at 60 min without catalysts. The enhancement was most significant during the initial 30 min of irradiation, aligning with typical sterilization timeframes. These findings demonstrate that integrating optimally dimensioned, gap-minimized concave micro-reflectors into UV-C LED systems provides a simple, scalable, and catalyst-free strategy to substantially improve sterilization efficiency.

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