| Oxygen is an important element in chemical and biochemical reactions. It has great impact on a large of research fields such as chemical industry, medicine, biology, environmental protection and so on. There is great interest in developing oxygen sensing technology over last years. A variety of photochemical planar sensors have been designed and evaluated by oversea research groups for laboratory applications and in-situ monitoring of marine sediments recently. Because of the planar optical chemical sensors are a new research field, there are no commercialization products available in the international market, and the theories and technologies are still need to be improved and explored. For example, the mechanical strength of the light-sensitive membrane, sensitivity, production process, stability, etc. are still need to be further improved. On the other hand, the methodologies of real-time image acquisition and processing are also need to be developed to meet real time applications.In this thesis, the researches on analytical chemistry, sol-gel film preparation process, correction method, sensor systems integrated are reported. An improved methodology is developed to fabricate large-area thin films based on the sol-gel technology, and an experimental system is developed for dissolved oxygen monitoring of sediment-water interface in-situ. The works are presented as follows:The first chapter is the review of the literature. A variety of methods of measuring the concentration of dissolved oxygen is presented, and we particularly emphasize on the research and development of fiber-optical chemical sensors. The advantages and disadvantages of the optical sensors are discussed. The exploration history of the fluorescent indicator is summarized, and several carrier's preparation methods of commonly used optical oxygen sensors are introduced. At last the prospect of the research and applications of the planar optical oxygen sensor are presented.The second chapter mainly discussed the theories of the optical oxygen sensor. The principles of oxygen quenching effect are reviewed and two indicators are chose in our study. The overall design of the planar-optic oxygen sensor is described. In the third chapter, the process of the sol-gel film preparation and the technical process are discussed. By making use of TEOS and MTEOS as precursors, DiMe-DMOS as organic modified reagent, DMF as drying control chemical additive, the process of fabricating the sensing film is presented. On the basis of repetitious experiments, the optimization of the combined material is carried out, and the sensing films are analyzed to determine the best ratios. The experimental results show that the best ratio of the these material is: (TEOS + MTEOS):DiMe-DMOS:DMF = (4+1):6:3.The last chapter reported the calibration and application of the planar-optic oxygen sensor. The dissolved oxygen of the marine sediment-water interface is measured in the laboratory. The experimental results show that the fluorescence intensity has a good linear relationship with the dissolved oxygen, and the linear range is 1.4mg/L, response time is below 30s, it has a good long-term stability.The contribution of this thesis is as following:1. Based on the experimental study, the ratio of the main material of the sol-gel fabrication is optimized, and the planar sensing films of the size of 150×150mm are fabricated. The sensing film can be used for oxygen monitoring in 2-dimension(2D). The works are beneficial to the next-generation planar-optic oxygen sensor development.2. Two metal indicators are embedded into films successfully, and experimental results show that these sensing films have good charateristics.3. By integrating an industrial CCD camera, light emitting diode and embedded system together, a prototype of benthic oxygen measurement is developed. |
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