A programmable 3D-printed optofluidic platform for automated U(VI) determination in uranium mining wastewater.

Rapid determination of U(VI) in uranium mining wastewater is essential for environmental risk assessment and wastewater treatment control. Herein, we developed a compact 3D-printed optofluidic platform that translates uranium colorimetric chemistry into an automated and portable flow detection system. The platform integrates programmable flow injection, a serpentine mixer, a customized optofluidic detection module, fixed optical coupling, and spectral acquisition to enable reproducible mixing and stable optical signal collection. Key optical, fluidic, and reaction parameters were systematically optimized to improve signal stability and quantitative reliability. Under optimized conditions, the platform showed a linear response of 0.05 - 1.00 mg L-1, with a limit of detection of 0.013 mg L-1, precision better than 5%, and stable performance during repeated measurements. The platform was further validated using uranium mining wastewater, yielding results consistent with ICP-OES and recoveries of 97.7-105.9%. This work provides a practical route for automated field monitoring of uranium containing wastewater and bridges the gap between laboratory colorimetric assays and deployable analytical hardware.