A new simple pCO2 sensor with compact drifting buoy system for long term observation JAPANESE
Introduction Plan for development of CO2 sensor Theory CO2 sensor Anti-biofouling Data Observation systems
Theory
In our analytical system, we used an amorphous fluoropolymer tubing form of AF-2400 (AF Teflon) for the gas permeable membrane due to its high gas permeability coefficients.
In general, we use an air-water equilibrator and NDIR system for measuring pCO2 in sea water. This system needs some standard CO2 gas syringe, therefore the system become big size and high cost.

Plate1
Air-water equilibrator and
NDIR system
The measurement principle for the pCO2 sensor is based on spectrophotometry (e.g. Lefèvre et al., 1993; Degrandpre et al., 1995). The CO2 in the surrounding seawater equilibrates with the indicator solution across the gas permeable membranes. It is representing the change of pH, and the resulting change in optical absorbance. In our analytical system, we used an amorphous fluoropolymer tubing form of AF-2400 (AF Teflon) for the gas permeable membrane due to its high gas permeability coefficients (Fig.1).
Fig.1 The measurement principles for the pCO2 sensor