The sensitivity of CO2 sensor is linked to the equilibrium
constant (pKA) of the pH indicator used and to the nature of
surrounding buffer (Mills & Chang, 1994). An aqueous bicarbonate
buffer usually contained in first generation optical carbon dioxide
sensors. The aqueous buffer containing sensors have been replaced
by quaternary ammonium hydroxide containing solid sensor
membranes (Mills et al., 1992). Earlier, colorimetric leak indicators
in the form of sachets and tablets have been used for sensors
development in food packaging technology. Latest approaches, for
more compatible with industrial demand, would consist of printable
sensor membranes on the packaging material and should
provide information about analytes at any given stage in the
packaging and delivery process.