A Foldable Ultraviolet Light Box for Smartphone-Based Fluorescence Spectroscopy Experiments

This work describes the design, assembly, and applications of the TechGlow, a foldable ultraviolet light box for smartphone-based fluorescence imaging. The device is fabricated from heavyweight black cardstock using consumer-grade desktop paper-cutting machines, avoiding the need for 3D printing, laser cutting, specialized machining, custom electronics, or optical alignment. The TechGlow uses an inexpensive LED strip for top-down excitation and holds up to five cuvettes in fixed positions for simultaneous visual comparison and image-based fluorescence measurements. Two quinine-based activities illustrate different levels of quantitative complexity. An introductory activity explores the relationship between dilution and fluorescence intensity, while a more advanced assay uses smartphone images and blue-channel intensity values to construct calibration curves and determine quinine concentrations. The rapidly assembled, portable design provides a reproducible platform for introducing fluorescence, solution preparation, calibration, and graphical analysis in teaching laboratories and outreach settings with limited access to conventional fluorescence instrumentation.