Compact CO2 Gas Analyzer with Favourable Signal-to-Noise Ratio and Resolution Using Special Fluorescence Sensors (Optodes) Illuminated by Blue Led’s

Determination of carbon dioxide partial pressure (PCO2) can be performed with optical sensors called “optodes” (Lübbers and Opitz, 1975; Opitz et al., 1977). The measuring device incorporates a thin membrane-protected fluorescence indicator layer which is fixed on a radiation permeable plexiglass window. In analogy to the PCO2 electrode (Stow and Randall, 1954; Gertz and Loeschcke, 1958), the measuring principle is based on pH changes induced by the substance to be measured within a bicarbonate indicator buffer solution. These pH changes can be continuously monitored by means of suitable pH fluorescence indicators and various light detecting systems.