A Piezoelectric Sensor for Dissolved Careon Dioxide

Abstract
Piezoelectric crystals undergo a change in vibrational frequency proportional to a change in their mass. A sensor based on this microweighing principle was investigated for use in continuous monitoring of dissolved CO2. The crystal coated with a primary amine was sealed into a compartment covered with a gas permeable membrane. A probe utilizing a didodecylamine coated crystal and a microporous Teflon filter membrane measured dissolved carbon dioxide in aqueous samples. A differential mode of measurement with a reference probe referred to water vapor was used to compensate for water vapor interference.