Optical oxygen sensor based on phosphorescence lifetime quenching and employing a polymer immobilised metalloporphyrin probe. Part 2. Sensor membranes and results

A gaseous oxygen sensor is described based on the measurement of phosphorescence lifetime of the dye palladium coproporphyrin, immobilised in a range of membrane materials including polyvinyl chloride, polymethylmethacrylate, polystyrene and silicone rubber. The lifetime of the dye in these materials is described, measured using a simple system consisting of a pulsed xenon flash lamp light source and a PC-based data acquisition system. The linearity of the sensing membranes over the 0-100 per cent oxygen range is presented together with data on temperature sensitivity, the effects of CO2, N2O, H2O and halothane, and the effects of ageing over a 90 day period. The sensors based upon polystyrene immobilised dye appear to provide the optimum characteristics for a gaseous oxygen sensor.