| Air pollution as one of the four environmental pollution caused worldwide concernof the majority of researchers. Volatile organic compounds （VOCs） are a class ofatmospheric pollutants. and decoration materials, life, work items, and they areclosely related to people’s daily life and work. Inhalation of excessive amount ofVOCs can cause various diseases. Therefore, in order to detect pollution and toprevent disasters effectively, the safe, reliable, continuous, effective methods of rapiddetection of trace gases or new type sensors have very important significance. In thispaper, combining with the unique properties of nanomaterials and the superiority ofoptical waveguide sensor, yttrium oxide and its adulterant as sensitive reagent, xylene,styrene and other volatile organic gas were studied. This paper is composed by thefollowing several parts:The first chapter is the introduction part, the environment pollution and pollutionsources, the harm to human beings. We overview sensor technology and introducedclearly the characteristics of optical waveguide chemical, development status,classification and application of sensitive materials，the principle of optical waveguide.Sensors finally, the topic sources and contents of this study work were put forward.The second chapter is the gas sensing properties of yttrium oxide thin films/tindiffusued glass composite optical waveguide element. The yttrium oxide as sensitivereagent, it is fixed on the tin diffusued glass waveguide surface by dip coater, yttriumoxide thin film/tin diffusued composite glass waveguide sensor is prepared. Theinfluence of optical properties of refractive index, thickness and light transmittance ofyttrium oxide thin film were studied, the best conditions for the preparation ofsensitive film of the optical waveguide were filter out. The yttrium oxide thin film/tindiffusued glass waveguide sensor is fixed in the detection system, detection of thesensing element for various volatile organic gas sensing property was studied. Thesensitive mechanism was explained by optical properties change of the sensitive film.The results showed that the sensor has high sensitivity towards xylene andclorobenzene vapors, and fast response, good reversibility, it can detect to the volumefraction1×10-5（44.1mg/m3） of xylene and clorobenzene vapors at room temperature.The third chapter is on the basis of Y2O3sensitive film in the the second chapter wasmodified. Becase of various amount of the TiO2dopant, TiO2-Y2O3composite film on gas sensitivity is also different. In this chapter, three kinds of doping amount of1%,2%,3%TiO2-Y2O3as a sensitive reagent were screen out respectively, and were fixedon tin diffusued glass waveguide surface, TiO2-Y2O3composite film/tin diffusuedglass waveguide sensors were developed for volatile organic compounds detection ofxylene, styrene and chlorobenzene gases. Among them, doped2%TiO2-Y2O3composite film/tin diffusued glass optical waveguide sensor has best sensitivity andselectivity to xylene gas, and has good reversible response, the minimum detection toxylene to the volume fraction1×10-7（0.44mg/m3）, the linear response range was from1×10-3to1×10-7.The fourth chapter is for the screening of four kinds of doping amount of1%,2%,3%,4%Al2O3-Y2O3as a sensitive reagent respectively, and were fixed on tindiffusued glass waveguide surface, Al2O3-Y2O3composite film/tin diffusued glasswaveguide sensors were developed for detection of xylene, styrene and chlorobenzenegases. Among them, doped with3%Al2O3-Y2O3composite films/tin diffusued glassoptical waveguide sensor has best sensitivity and selectivity to xylene gas, and hasgood reversible response, the minimum detection to xylene to the volume fraction1×10-5（44.1mg/m3）,The linear response range of1×10-3to1×10-5.The fifth chapter, polyvinyl carbazole （PVK） is a variant of the gusset material, theexcellent properties has great significance in optical chemical sensor. From that point,PVK （PVK） as the sensitive material, PVK film/K+-exchanged glass opticalwaveguide sensor was fabricated by the rotation-rejection coating and will be fixedin potassium ion-exchanged glass waveguide surface, and will detect volatile organicgases.The selective response of the sensing element to various gases with differentPVK percentage content of different. As PVK percentage of0.5%, the gas sensitivityof the sensing element is well, PVK film/K+-exchanged glass waveguide gas sensorhas good selectivity to xylene vapor. And the minimum detection to xylene to thevolume fraction1×10-6（4.41mg/m3）, its linear response range of1×10-3to1×10-6.The sixth chapter is the concluding part, a summary of the main content of ourresearch study. |
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