Sensing of volatile organic compounds in indoor atmosphere and confined areas of industrial environments

A chemical vapour sensor working with a monochromatic light source and based on optical
fibre coated with a thin siloxane polymer film has been developed for in situ monitoring of
volatile organic compounds, such as ethylbenzene, xylene (o-xylene), heptane, octane,
chloroform, carbon tetrachloride, ethanol and butanol in indoor atmosphere and confined
areas of industrial environments. The sensor consists on a monomode optical fibre with an
end surface coated with a thin polymeric film by dip-coating technique. The light source
utilized was a stabilized laser diode at 1550 nm and the light power changes were measured
with a photodiode. The sensor was tested for different VOCs and for different individual
concentrations regarding stability, sensitivity, repeatability and reversibility of the analytical
signal. The response and desorption time have been found to be 30 seconds and good
reproducibility and accuracy have been also obtained. Finally, the analytical performance of
the developed sensor was also evaluated and found adequate for actual monitoring on indoor
atmospheres.