Design of a plasmonic optical sensor probe for humidity-monitoring

High performance surface plasmon resonance (SPR) sensor is proposed for relative humidity (RH) monitoring. The structure is based on widely used 2S2G chalcogenide glass and gold as SPR active metal applied with silica-based porous film. The angular interrogation method has been used to study the performance of the sensor in terms of intrinsic sensitivity (SI) that includes the width and shifts of SPR curve for the entire RH-range between 0% and 100%. The effect of temperature is also studied on the proposed sensorʹs performance. Any possibility of oxidation problem to the proposed SPR sensor due to constantly being in contact with humid environment may be addressed by using a stable buffer layer. Intrinsic sensitivity of the proposed sensor is significantly high for almost entire range of RH values. The proposed sensor has a good resolution of the order of 10−2% RH.