Study On TiO₂and Composite Optical Waveguide Chemical Sensor

In recent years, the ecological environment pollution is becoming more and moreserious. All kinds of industrial wastewaters, wastes directly discharged into the water andair. To cause the extremely serious environmental pollutions, become the gas that doharm to people’s normal life, survival and development. It is very serious problem thattreatment the causes environmental pollution gases that Volatile organic gases. With thedeveloping of the human economic life, people pay more attention to interior decoration,a luxury car to enjoy a happy life. The increasing of people demands brought a lot oftrouble. Volatile organic gases of the source is indoor decoration and was exhausted bycar that daily life has brought us a lot of convenience of bus is accumulation to a certainextent harmful to human survival and development and the normal work. Sensitivereagent of optical waveguide sensor is quite flexible, so effective, fast, safe, andconvenient to play a great role in detection a trace of volatile gas.In this paper, first and second chapter embarks on characteristics of sensitive reagent,summarizes the further used research in other disciplines of sensitive materials and thewhole sensor applications history. Introduced the development of sensor status andNecessity of the national economy development, Classification, working principle andapplication characteristics, chemical sensors. Evaluated the development of opticalwaveguide sensor is one types are photochemical sensor, and focus on describe theclassification of optical waveguide sensors, characteristics and work principle.This thesis conducted in following research work:1TiO₂films with higher refractive index, higher photo catalytic activity, goodphotoelectric conversion properties. In this chapter, the screening of TiO₂as a sensitivematerial, preparation by sol-gel method and were characterized by X-ray diffraction TiO₂,and the coating in the tin doped glass waveguide fabricated TiO₂thin film/tin dopedglass waveguide devices, study the optical response of the sensing element, and gassensitivity of styrene on this condition detection. The uses of molecular absorption of light power changes explain the sensitive mechanism. Research results show that, thesensor can detect the concentration ratio of Styrene Steam1×10^-6volume fraction.2. Select has good selectivity of spinel composite oxide ZnFe₂O₄for the sensitivematerial, ZnFe₂O₄sol was prepared by sol-gel method and fixed on the optical waveguidedetection system, to detect volatile organic gas. And explain the sensitive mechanism.From the results obtained, ZnFe₂O₄thin film/tin doped glass waveguide sensing elementhas larger response to styrene (2×10^-10volume ratio)vapor, than xylene (2×10^-6volumeratio) higher than104, chlorobenzene (1×10^-5volume ratio) higher than105. And in acertain range has linear relation between concentration and output light intensity variation.This glass optical waveguide has characteristics of reversible，high sensitivity, simple ofpreparation, superior etc.3. Modifications the method of preparation of TiO₂thin films. ZnFe₂O₄dopedpreparate ZnFe₂O₄-TiO₂sol and characterization. Using the dip-coating method which isfixed on the tin doped glass optical waveguide surface developed ZnFe₂O₄-TiO₂film/tindoped glass waveguide components. Study on the optical conditions of the sensingelement, further use sensitive element that prepared on in the best response preparationconditions to test the sensitivity. Research shows that, after doping ZnFe₂O₄, theselectivity of pure TiO₂never changed. But the sensitivity is high, the sensitive elementto could detect1×10^-7volume ratio of styrene steam.4. ZnFe₂O₄spinel structure is used in magnetic materials and catalysts, but the sensorhas not obtained the widespread application. So this thesis on ZnFe₂O₄doped TiO₂prepared the TiO₂-ZnFe₂O₄sol. and in order to characterize were used to X-raydiffraction. Using the dip-coating method the sol coating on the tin doped glass opticalwaveguide surface,and use detected the volatile gas. The results show that: after ZnFe₂O₄doping TiO₂the selectivity was changed, but the sensitivity was decrease.TiO₂-ZnFe₂O₄thin film/tin doped glass waveguide components has better response toxylene（1×10-5volume ratio） steam. The last chapter is the conclusion part of the Experiment–summary.