A fibre-optic oxygen (O2) sensor monitoring at a wavelength of 400 nm has been successfully developed for the determination of gaseous O2. Its working principle is based on the contact charge-transfer absorption of N,N-dimethyl-p-toluidine and O2. The response to changes in O2 concentrations is reversible and in good agreement with the Beer-Lambert law. The response and recovery times are 12 and 26 min, respectively.
The sensor can detect a wide range of O2 concentrations, ranging from 4.3 to 100% O2. The precision is 1.45% (n=5) in a gas mixture of 95% O2 in N2 and the limit of detection is 4.3% O2 (3σb). The sensor is stable with a 0.53% change in sensitivity per hour. There is a 0.25% °C−1 decrease of the sensitivity of the sensor to O2 in the range 20–34°C. Water vapour and nitrogen dioxide interfere slightly, whereas hydrogen sulphide and hydrogen chloride have moderate interference on the sensor. However, chlorine and sulphur dioxide seriously interfere with the sensor.
Choi, M.F. and Hawkins, P., 1996. A fibre-optic oxygen sensor based on contact charge-transfer absorption. Sensors and Actuators B: Chemical, 30(3), pp.167-171.
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Categories: Material & Chemical