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Title Ανάπτυξη και μελέτη αισθητήρων οπτικών ινών για μέτρηση υγρασίας
Author Πουμπουρίδης, Νικόλαος
Thesis advisor Κωνσταντάκη, Μαρία
Abstract The use of oak barrels for wine aging is a widespread technique due to the physical properties of oak wood. The oak barrel is an active, interactive container that releases aromatic compounds and tannin when wet, while allowing oxygen to penetrate and largely determines the characteristics of the produced wine. However, the release of aromatic compounds from oak, is limited resulting to the need for replacement of the barrel after prolonged use. Currently, the common practice of wine makers in the assessment of the condition of oak barrels is empirical and thus subjective. The release of compounds from the wood into the wine takes place due to the wetting of the wood, therefore the detection of the wetting condition in real time could give useful information about the condition of the barrel. A sensor able to accurately detect the wetting condition of an oak barrel in situ, would help to both reduce unnecessary costs and quantify the wine aging process. In order for the sensor to be functional in a restrictive environment such as a winery, it must be portable as well as have miniature size and weight, so that the disturbance in the barrel due to its placement is minimal. It must also have the ability of multiple uses (without reduction of its efficiency), have high efficiency and wide dynamic range. Optical fiber sensors are ideal for this application because they meet all of the above requirements. Additional advantages of such sensors are their low cost, fast response and durability. The two methods considered for the development of humidity sensors are Tilted Optical Fiber Bragg Gratings (TOFBG) and Fabry-Pérot cavities and relay on changes in the refractive index of hydroscopic materials under varying humidity. Specifically, in the first sensor, we coated the area surface of the TOFBG with agarose solution while for the second sensor, we formed a cavity of photo-polymerizable resin at the fiber end face. Different levels of ambient humidity, induce changes in the refractive index of the gel/resin thus altering the spectroscopic signature of the developed sensors.
Language Greek
Issue date 2021-11-19
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
  Type of Work--Graduate theses
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