Feasibility study of UV intensity monitoring in water disinfection systems using reverse-biased LED photometers†

Common ultraviolet (UV) photodiodes or detectors for measuring the intensity of UV-light-emitting diodes (LEDs) in UV disinfection systems are costly. This study explores the potential of using low-cost UV-LEDs as photometers for monitoring UV intensity in water systems. Reverse LEDs (rLEDs) generate a small current proportional to the incident light intensity on the p–n junction when operated in unbiased mode. rLEDs with different wavelengths and power levels were examined to find the optimal rLED for monitoring the intensity of a 275 nm LED strip, achieving less than 1% deviation from a calibrated spectroradiometer. The influence of temperature was also examined on rLED measurements and found non-negligible. This work demonstrates the feasibility of using rLEDs as intensity monitoring sensors for UV-C LED sources, offering a low-cost and reliable alternative for UV intensity monitoring in UV-LED water disinfection systems.