The fluorescence‑based dissolved oxygen meter operates on the principle of fluorescence quenching.

Blue light irradiates the fluorescent substance to excite it, causing the substance to emit red light. Since oxygen molecules carry away energy (the quenching effect), the duration and intensity of the emitted red light are inversely proportional to the oxygen concentration. The oxygen concentration is calculated by measuring the phase difference between the excited red light and the reference light, which is then compared against internal calibration values.

For more than 50 years, the amperometric and polarographic methods have been used to measure dissolved oxygen. These techniques once played a vital role in dissolved‑oxygen monitoring for municipal and industrial wastewater. Nevertheless, conventional electrochemical methods rely on membranes, electrodes and electrolyte solutions, which give rise to numerous problems. Accurate readings cannot be guaranteed even with regular maintenance.

For water quality monitoring, the online dissolved‑oxygen sensor developed by Hybono is recommended. Adopting the fluorescence measurement principle, the Hybono dissolved‑oxygen analyser requires no reagents and is eco‑friendly with zero pollution, enabling real‑time online monitoring. It consumes no oxygen and has no flow‑rate requirements. No electrolyte is needed, eliminating maintenance and frequent calibration. Free from hydrogen sulphide interference, it delivers excellent stability. A built‑in temperature sensor provides automatic temperature compensation. Equipped with RS485 output and MODBUS protocol support, the sensor can be easily integrated into water‑quality monitoring systems to meet customer requirements.