Miniaturized Fluorescence-Based Optical Sensor for Real-Time Oxygen Monitoring During Respiration

The increasing demand for real-time oxygen monitoring during respiration is driven by applications in both healthcare and sports, where accurate measurements support medical diagnostics and performance optimization. In this paper, we present the development of a compact optical oxygen sensor. The sensor is based on the principle of fluorescence quenching, in which the fluorescence emission intensity decreases in the presence of oxygen. A pyrene fluorophore embedded in an ethyl cellulose matrix serves as the oxygen-sensitive dye. This work introduces a novel sensing unit designed for seamless integration into a standard T-piece in the field of respiratory medicine. The sensor parts (LED, photodetector and sample holder) were fabricated from aluminum with a base area of 15 mm diameter. The pyrene-ethyl cellulose sensing layer was deposited directly on a cylinder also made of aluminum. This enables easy integration due to the same materials and eliminates the need for a separate glass plate as carrier. The achieved detection resolution is 0.31 vol. % of oxygen during laboratory tests, providing a basis for future research to improve reliability, enhance performance, and explore practical applications in respiratory monitoring.