Design and Development of Intrinsic Fiber Optic Sensor for Simultaneous Measurement of Temperature and Humidity

Abstract

Simultaneous measurement of environmental parameters such as temperature newlineand humidity are an imperative demand for applications including meteorological newlineservices, biological and electronic manufacturing, chemical and food processing newlineindustries, indoor environmental control and structural health monitoring. Commercial newlinesensors that make use of electrical counterparts are greatly influenced by newlineelectromagnetic interference (EMI) and require frequent calibration in harsh and critical newlineapplications, including radiative and acidic environments. Environmental factors play a newlinesignificant role in Microbial Induced Corrosion (MIC) in sewage infrastructure, and the newlinedemand for sensors in such harsh conditions can be met with optical sensors. Intrinsic newlineFiber Optic Sensors (IFOSs) overcome these challenges due to the immunity to EMI, newlinecompact size, remote sensing capability with low propagation loss, and affordable price. newlineIn this thesis, an intrinsic fiber optic sensor is designed with a single-coated newlinegrating structure for the simultaneous measurement of temperature and humidity. Four newlinedifferent hygroscopic coating materials are investigated with Fiber Bragg Grating newline(FBG) structures to better choose the material for humidity transduction. An newlineexperimental investigation is carried out to analyze the proposed polyimide coating on newlinethe FBG sensor for humidity measurement and achieve a sensitivity of 2.1pm/%RH newlinewith an accuracy of 99.4747% newline