Humidity sensor based on fibre bragg grating for predicting microbial induced corrosion

Abstract

Humidity is among the most important environmental factors which enhance the biogenic acidic corrosion in concretes of sewers structures. Deterioration of concrete structures is a significant issue that requires special focus in massive structures such as wastewater treatment plants. The impact of deterioration on structural integrity necessitates distinctive consideration in examining the external factors supporting microbial degradation. External environmental factors such as humidity and temperature enhances the process of microbial degradation demands special monitoring. An Optical based humidity sensor was proposed for deployment in harsh environments like sewer structures. In this study, Bragg Grating coated with polyimide has been experimented with different humidity conditions and sensitivity has been analyzed over a wide range of humidity. It shows the linear Bragg shifts over the range of 11% to 97% with the sensitivity of 2.0 pm/%RH which is an optimum value for sewer environment deployment. Assessment metrics such as resolution, sensitivity, response time and limit of detection(LOD) were also analyzed.