| With the rapid development of society and innovation of technology, people's life has been rich. The society wants development, and needs to consume more resourses of earth. Development of society has brought us a lot of convenience, but will bring a series of environmental pollution to us. Gas discharge in the production and decoration process, as well as automobile exhaust and other kinds of gas is increasing, in these gases, same are toxic and harmful.They are harm to human health and ecological environment. Therefore, it is very important to research and develop effective?safe?reliable and online method. Optical waveguide (OWG) chemical sensor can detect effectively toxic?hazardous?flammable and explosive gases. It has occupied to a very essential position in the field of chemical?biological detection because it has the advantages of high sensitivity, fast response and so on. The sensitive material as a sensitive part of OWG, it can directly affect the sensitivity of sensor. So the choice of sensitive materials properly,the Optical waveguide chemical sensor to achieve the best condition is the main purpose of this research project. Semiconductor metal oxide has good sensitive characteristics in optical waveguide(OWG) chemical sensor. Hence, the semiconductor gas sensitive material is one of the hot point of research in this work.In this paper, combined the unique performance of semiconductor gas sensitive material with superiority of chemical sensor, the doped ZnFe2O4 as a sensitive material, was studied by OWG sensor for volatile organic gas sensing property.The article began by describing the harm of atmosphere and indoor pollution, sensor and its development history, definition of sensor and it's classification, development trend, OWG sensor and it's classification, principle, advantages of semiconductor gas sensing materials etc. Finally, it puts forward the main contents of the subject and the research work of this thesis. In this dissertation some research work were done on planar OWG sensor system described below:1.V2O5 is a kind of transition metal oxides, it has a high sensitivity, low cost, high activity and good stability. In this chapter the V2O5 doped ZnFe2O4 solution was prepared by sol-gel methods and was regarded as a sensitive reagent. The V2O5 doped ZnFe2O4 solution was fabricated through the dip-pulling methods and was coated on to the surface of tin diffused glass optical waveguide,then we obtained the V2O5 doped ZnFe2O4 composed thin film/tin diffused optical waveguide sensor. Next, to detect xylene, styrene, benzene and other organic gases. The results show that the sensor has good response, higher selectivity and repeatability toward xylene gas in these gases. Minimum detectable gas concentration is 1×10-6(4.41mg/m3).2.Fe2O3 is a n type semiconductor, and it is a typical kind of anode materials for lithium ion batteries. It has low cost, none-toxic, good thermal and chemical stability. In this experiment,the Fe2O3 and Fe2O3 doped ZnFe2O4 solution was prepared by sol-gel method respectively. And through the dip-pulling methods coated on to the surface of tin diffused glass optical waveguide, then we obtained the two kinds of optical waveguide sensors. After that, tested with volatile organic gases and selected the response of optimum conditions. Learned from the experimental results, the pure sensor has a good selective response to xylene and styrene gases, as well as, can detected lowest concentrations were xylene 1×10-6(4.41mg/m3) and styrene 1×106(4.34mg/m3) respectively. Fe2O3 doped ZnFe2O4 changed gas's selective (mainly have a good selective to xylene and chlorobenzene), also increased the sensitivity to gases, sensor to detection range of xylene gas concentration is from 1×10-3(4.41×103mg/m3) to 1×10-7(0.44mg/m3), the detection range of chlorobenzene gas concentration is from 1×10-3(4.69×103mg/m3) to 1×10-7(0.47 mg/m3). Fe2O3 doped ZnFe2O4 sensor has a good linear relationship for xylene and chlorobenzene gases.The OWG system proved to be fast in response, reversible, high sensitive, and the sensor has the useful value. |
PDF Full Text Request