Study On Fiber Optic Oxygen, Acetylene Sensing Materials And Their Sensors

The detection of the gaseous oxygen and the dissolved oxygen is very important in many fields such as medicine, industrial analysis and environmental monitoring. Therefore, the researches of fiber optic oxygen sensors have gotten much attention of people in recent years. Fiber optic oxygen sensor have many advantages such as intrinsic safety and high sensitivity, high detection precision, quick response, anti-disturbance of electromagnetism, and it can be used for long-distance, successive and on-line monitoring of the gaseous oxygen and the dissolved oxygen in dangerous environment. In this thesis, Ru(phen)3Cl2 and Ru(bathophen)3Cl2 are used as fluorescent indicators, which are immobilized in poly(vinyl) chloride(PVC) and polystyrene(PS) respectively, to form the fiber optic oxygen sensing membranes. Using the lock-in technology, these membranes have many advantages such as high sensitivity, fast response and good stability and reproducibility when they are used in fiber optic oxygen sensors to detect the concentration of the gaseous oxygen and the dissolved oxygen.It is also very important to detect the concentration of the gaseous acetylene on-line in many fields such as power industry and petrifaction. This sensor in this paper is based on the characteristic absorption spectrum of acetylene to detect acetylene content and utilizes the optical waveguide all through the process, so it has the intrinsic anti-explosion function, fast response time and good repeatability.Main contents of this paper include two aspects: the synthesis of fluorescent indicator and the preparation of oxygen sensing membrane and the research of their characteristics; the design of the absorptive-type fiber optic acetylene sensor and the use of it in detecting gaseous acetylene.(1) Through the polymer membrane method, the indicators such as Ru(phen)3Cl2, Ru(phen)3Cl2 are immobilized in polyvinyl chloride, and the PVC sensing membrane is formed. For the detection of gaseous oxygen, themembrane has these merits: the fast respond time less than 30s, detection limit up to 5ppm and detection precision 0.5% and good repeatability and stability.(2) RuCl3-3H2O and the ligand, 4,7-diphenyl-l,10-phenanthroline, are used as raw materials to synthesize the new fluorescent indicator, Ru(bathophen)3Cl2, which is characterized by infrared spectroscopy(IR) and fluorescence spectroscopy(FS), and then is immobilized into PS to form the PS sensing membrane. Because of the intrinsic nonaquaeous of this indicator, the network size of PS membrane can be controlled and the leaking of the fluorescent indicator in water can also be prevented by adjusting the appropriate proportion among the matrix, solvent and the indicator.(3) The fiber optic acetylene sensor based on spectrum absorbing has been designed. During the development of it, the author has been mainly engaged in the task of the research of the materials such as the light resource, the air-chamber and the light detector. The sensor has a good response time less than 3s and a detecting limitation up to 157ppm by combining the chromatography of gases in detecting the gaseous acetylene. And it can be used to measure the concentration of the gaseous acetylene on-line through suitable light source and air-chamber.