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Study On Fiber Bragg Grating Based PH Sensor And Its Sensitivity Improvement

Posted on:2015-07-07Degree:MasterType:Thesis
Country:ChinaCandidate:X C LiangFull Text:PDF
GTID:2298330452951442Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
With advantages of high sensitivity, wavelength encoding and reflective measurement, etc., fiberBragg gratings have been proved to be high performance sensors in detecting physical quantities,such as the train, temperature, displacement, acceleration. However, the fiber Bragg grating(FBG)sensors designed for chemical detection, such as in environmental field and meteorological field,are still in the stage of exploration, and related studies are becoming the current researchhotspots of FBG.Aiming at the focus of FBG-based pH sensing technology, a kind of FBG-based pH sensor isproposed and studied. The key factor of the sensitivity in the FBG-based pH sensor is analyzedin detail by theory analysis and experimental tests. First, the principle of FBG-based pH sensors,as well as the sensitive cover of FBG is discussed. Then the fabrication of the FBG-based pHsensors is studied deeply from aspects of hydrogel preparating, FBG writing, hydrogel coatingand testing. Finally, the key factor of the sensitivity improving of the FBG-based pH sensor isanalyzed in detail, and a FBG-based pH sensor with good performance is achieved by sensitivityimproving and optimizing.The key method that increasing the radius of the gel layer coated on fiber Bragg gratings bya cylindrically symmetrical way is worked out to improve the sensitivity of FBG-based pHsensors. A multi-thin-layer structure of gel coated cover is proposed to ensure the cylindricalsymmetry along the fiber axis when the coater layer is getting thicker, which is implemented viaour special “coating over curing” process. A good performance FBG-based pH sensor with thegel layer thickness of580μm is achieved, of which the sensitivity is52pm/pH in the pH range of6~12.
Keywords/Search Tags:Fiber Bragg gratings, Hydrogel, pH sensor, Sensitivity improving
PDF Full Text Request
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