Development of a UV meter using the sensor AS7331 and a Raspberry Pi 4B

This work presents the design, construction, and calibration of a low-cost instrument developed for measuring UVA, UVB, and UVC radiation in the city of Arequipa, Peru. The system integrates an AS7331 spectral sensor with a Raspberry Pi 4B, and its operation is managed using a Python program that was adapted and corrected to ensure accurate data acquisition. Calibration was performed through a direct comparison method, by comparing the digital counts obtained from the AS7331 with measurements from a Black Comet C-SR-50t spectrometer, a UVA meter model 4.0, and a UVB meter model 6.0. Measurements were performed under clear-sky conditions over three days at various times, with all instruments aligned directly to the sun. Calibration relationships were established between the sensor’s digital counts and the physical measurements in mW/cm² by direct comparison. The constructed instrument is suitable for performing solar UV radiation measurements, as it exhibits errors comparable to the measurement precision of commercial UVA and UVB radiation meters.