Gas monitoring instrument utilising fibre optic, piezoelectric and gas-sensitive polymer techniques

Abstract

The most usual form of instrument for the monitoring of gases such as carbon dioxide involves absorption bands in the infra-red spectrum, which in turn mandates the use of infra-red optics and sensors. The present instrument dispenses with the use of infra-red by employing visible light along with a gas-sensitive polymer which changes colour in the presence of CO 2, this being a reversible process. The instrument itself also utilises a novel realisation of the well-known double-beam-in-time principle in which fibre-optic light guides replace lens systems. The mechanical beam splitting is performed by a piezoelectric bimorph cantilever.