A family of portable and modular UV spectrometers for liquid and gaseous analytes monitoring in agro-environmental fields is proposed. The systems comprise one or more LEDs, a chemical interaction chamber with application-specific features, and a Silicon Carbide (SiC) based detector. The systems are completed by custom on-board electronics for LED driving, control, data readout, and transmission, which, despite using low-cost components, can measure currents in the pA range. The technology has been validated for sulfur dioxide (SO₂) monitoring in volcanological contexts, achieving TRL 6 ÷7 with sensitivity < 2 ppm. A TRL 4 has been reached for methyl salicylate (MeSa) detection, a volatile organic compound emitted by plants under stress, where preliminary tests revealed sensitivity on the order of ppb. A TRL ~3 system targets nitrates and nitrites (LOD within/ approaching legal limits for drinking water) in post-filtration agricultural waters.
The proposed systems feature modularity, low cost, equipped with commercial LEDs as light sources and SiC detectors insensitive to visible light, offering large active area, high sensitivity, and low dark current even at room temperature. This results in low-power devices with high sensitivity. Their compactness enables in situ measurements, and they support remote management. The SiC detector eliminates false positives from chemical interferents that de-excite in the visible range; its thermal stability minimizes free parameters, which are critical in harsh environments. Competitive advantages include robustness and insensitivity to ambient temperature and humidity. For SO₂ sensing, compared to electrochemical sensors, the system avoids saturation, periodic recalibration, short lifespan, and issues in extreme conditions such as volcanic environments.