Simultaneous monitoring of pH, CO2 and O-2 using an optical imaging fiber

The interdependence of pH, CO2 and O-2 during chemical and biochemical processes has driven the need to monitor them simultaneously, continuously and in situ, in order to exert better control over such reactions. We present the fabrication and performance of a multi-analyte imaging fiber sensor that allows pH, CO2 and O-2 to be monitored simultaneously with rapid response. Sensing elements are fabricated by covalently immobilizing, fluorescent indicators within polymer matrices via photopolymerization, resulting in the formation of distinct regions of analyte-sensitive polymer at the fiber's distal end. The multianalyte sensor's working range is 0%-100% for O-2 and 0%-10% for CO2 in the pH range 5.5-7.5. The sensor was used to monitor the pH, CO2 and O-2 changes during a beer fermentation.