Development Of Optical Oxygen Sensor And Its Application In Environmental Monitoring

Determination of dissolved oxygen levels is of great importance to many different applications such as industrial, biological, medical and environmental monitoring. In the past years, several methods for oxygen measurement have been reported. Fiber optic oxygen sensor has attached much attention of people in recent years for its intrinsic safety, high sensitivity, fast response and anti-disturbance of electromagnetism. In this thesis, Ru( II ) complex Ru(dpp)3DS2 is used as fluorescent indicator and copolymer of styrene and 2,2,3,3-tetrafluoropropyl methacrylate as the matrix, tributyl phosphate as plasticiser to form the oxygen sensing membrane. Using the minisize CCD detector, LED light source and a fiber optic, a fiber optic oxygen sensor based on fluorescence quenching has been developed.This dissertation consists of the following three chapters.The first chapter is the review of the literatures. We summarizes a variety of methods of measuring the concentration of dissolved oxygen, particularly emphasizing on the research and development of fiber-optical chemical sensors. Several polymer for optical oxygen sensors were discussed in this chapter. At last the signification purpose and the main content of the dissertation are put forward.The second chapter is about theories and design of the optical oxygen sensor. The theory of fluorescence quenching and design of the optical oxygen sensor are described in detail.The third chapter introduces the fabrication of the sensing film. In this chapter, copolymer of styrene and 2,2,3,3-tetrafluoropropyl methacrylate is used as matrix, tributyl phosphate as plasticiser, Ru( II )complex(Ru(dpp)3DS2) is immobilized in the copolymer matrix and a sensing film is formed. By adjusting the proportion of each component of the film, a sensing film with best response to oxygen can be prepared.In the last chapter, application of the optical oxygen sensor is investigated. The perfomence, stability and ablity of anti-disturbance of the sensor arereviewed. For the detection of dissolved oxygen, the respond time of the sensor is less than 85 seconds, detection limit of 0.2 mg/1. Good repeatability and photostability are also observed. Moreover, the sensor is not affected by ions, pH value in water as well as salinity. The sensor has been used to detect the dissolved oxygen in seawater samples. There is no obvious difference between the results got by the sensor and the Winkler tradition method, and the measure deviation of the sensor is less than 4%, which indicates it will be possible for this sensor to be used for the on-line monitoring of seawater.