The Study Of Fiber Optical Oxygen Sensor Membrane And Sensor's Application In Environment Monitoring

This dissertation consists of three parts: 1. Literature summary, 2. Methods and principles, 3. The manufacture and investigation of fiber-optical oxygen sensor.In the first part, the article summarized the definition and importance about dissolved oxygen (DO), the general methods of measuring DO. The origin, development and excellence of usage in chemical sensor with fiber-optical technology, the characteristic of fiber optical chemical sensor are introduced. Those deferent fluorescence indicators have been used in oxygen sensors during more than twenty years and their deferent capability as fluorescence indicators. There have several methods of making sensor membrane including sol-gel process. And usage of the fiber-optical oxygen sensors in iatrology, biology, ocean inspect etc.The second part is about methods and principles of this experiment. The Stern-Volmer equation described the oxygen quenching progress. Sol-gel processes include basic theory, primary steps, and the influence of some parameters to the sol-gel membrane performance such as precursor, water, catalyzer, pH value, drying control chemical additives and temperature.The third part of this paper includes: 1. Experimental. 2. Results and discussion.The experimental introduces the instruments and reagents be used. The basic principle of the experiment including system composing, responding theory, making and installing of sensor membrane, establishing standard3curve, measuring, predicting results and confecting manual seawater etc.Optimizing the component of sd-gel membrane by chancing species and quantity of those parameters had mentioned content. The optode shows a satisfactory linear response for the dissolved oxygen in water (r = 0.9992, n =6)The relative standard deviations were 1.7% 5.0 %, the detection limit was 0.03 11 g/mL (SfN=3). The exposure time and recovery time of the optode membrane are 30s and 90s respectively. The reversibility of the fluorescence signal was evaluated by alternate measurements in oxygen saturated water and nitrogen-purged water. The relative standard deviation (n6) is found to be0.6%.The fluorescence intensity of the membrane in contact with flowing water was recorded over a period of 96h. From fluorescence intensity values taken every 4h (n=24) a RSD of 6% was obtained. After 3 month, the fluorescence signal of the membrane had decreased by 16%. The decrease may be due to washing out of fluoroprobe, but this was not an obstacle to its further use; the quantitative information (Fo I F) did not change significantly, where F0 and F are the fluorescence intensities in the absence and in the presence of oxygen, respectively. The sensor has good reproducibility and long-term stability. The interference was investigated and the selectivity of method in seawater was affirmed by a conventional method.