Optimising the design, cost, and performance of a distributed humidity and temperature fibre sensor

This paper presents the design, cost optimization and performance analysis of a distributed humidity and temperature fibre optic sensor for environmental monitoring. The sensor utilises a 1-metre spatial resolution phasesensitive Optical Time Domain Reflectometry (OTDR) interrogator and employs a pair of fibre optic cables as sensing elements. One cable is coated with polyimide for humidity sensing and the other is coated with acrylic for temperature sensing. The sensor is designed to be reliable, accurate and cost-effective, enabling its use in various industrial environments. New software was developed for fast data acquisition and processing, and the hardware was assembled to allow measurements to be taken at thousands of different locations over the same fibre optic. The cost of the current version and the acquisition time have been reduced by half compared to the reference version. The sensor’s performance was evaluated in both a controlled laboratory environment and in a real-world deployment. The results indicate that the sensor effectively measures relative humidity (RH) and temperature across a broad range of conditions while preserving the precision of the previous version. Additionally, it utilizes cost-effective hardware and has a significantly faster response time.