Recent advances in optochemical sensors for the detection of H2, O2, O3, CO, CO2 and H2O in air

Optochemical sensors have numerous advantages over electricity-based sensors. This review summarizes recent advances in optochemical sensors that detect H2, O2, O3, CO, CO2 and H2O in air. Optochemical sensors can be divided into seven categories; this report focuses on those based upon changes in absorbance and reflectance or refractive index. In addition, it briefly mentions sensors based upon changes in photoluminescence, photothermal effect and photoacoustic effect.