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Title Αισθητήρες οπτικών ινών για ανίχνευση ατμών πτητικών οργανικών ενώσεων και αμμωνίας
Author Γραντζιώτη, Ελένη
Thesis advisor Κωνσταντάκη, Μαρία
Abstract Vapor sensors are devices that can detect the presence and concentration of specific substances. Several types of vapor sensors are available and their characteristics depend on the requirements of each application. The purpose of this study is the development and study of two optical fiber sensors for the detection of vapors of volatile organic compounds and aqueous ammonia, respectively. Optical fiber sensors offer specific advantages compared to electronic sensors such as high sensitivity, resistance to adverse conditions, immunity to electromagnetic interference, small size and weight and remote operation. Ammonia in gas (NH3) or aqueous (Ammonium hydroxide-NH4OH) phase is used in various applications including fertilizers, pharmaceutical products, cleaning fluids, plastics, and other industrial products. Despite its widespread use, ammonia is a toxic substance harmful to humans. The ammonia sensor developed in the frame of this work is based on a tilted fiber Bragg grating (TFBG) with a fluorinated graphene overlayer. When exposed to Ammonia vapors the properties of Graphene are modified alerting the guiding properties of the TFBG and thus allowing its detection. Volatile Organic Compounds, (VOCs), are organic chemicals with a high vapor pressure at room temperature. As a result, they readily evaporate into the atmosphere, creating potentially harmful conditions for humans and the environment. VOCs are emitted by a wide array of products such as dyes, pesticides, and fuels. The sensor for volatile organic compounds, specifically alcohols, that was developed, consists of a cavity of photopolymerizable resin at the end of a single-mode fiber, thus creating a Fabry-Pérot interferometer. The presence of alcohol vapors (Methanol, Ethanol and Isopropanol) induce changes in the refractive index and length of the cavity thus altering the spectral characteristics of the reflected light.
Language Greek
Issue date 2023-03-31
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
  Type of Work--Graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/e/e/a/metadata-dlib-1677656345-546189-27280.tkl Bookmark and Share
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