Abstract

Industrial applications of fibre optic sensors have been limited to situations where they provide technical advantage (1) over conventional sensors. This has primarilily been due to their significantly higher costs and the reluctance of industry to depart from tried and tested technology. In the present case an inexpensive, passive, fibre optic sensor was fabricated to monitor concentrations of CO₂ gas with applications ranging, for example, from the medical to food processing industries. By selection of appropriate materials the technique can be extended to detect a range of acidic or alkaline gases. Because the operating wavelength is 590 nm. the fibre optic sensor can be used remotely at greater distances than fluorescence based fibre sensors which operate in the UV and have high fibre losses. Moreover, these sensors are: easy to implement, cost effective, insoluble in water, unaffected by relative humidity, and do not need covering with a diffusion membrane.

© 1996 IEEE