Design and analysis of prism-based surface plasmon resonance optical sensor for detection of ammonia gas

Abstract

Surface plasmon resonance (SPR) sensors are extensively used in a variety of applications. In the proposed investigation, SPR phenomena are used to detect toxic gases by employing a multilayer sensing chip. A glass prism is coated with a nano composite thin film based on different materials: gold (Au), titanium dioxide (TiO2), and molybdenum disulfide (MoS2). The ammonia gas is applied to the MoS2 sensing layer of the multilayer optical sensing chip. As the ammonia gas concentration rises around the multilayer sensing structure, the resonance angle increases, indicating that the MoS2 layer refractive index has gone up significantly due to absorption of the increasing ammonia gas concentration. The measured ammonia gas concentration is based on an angle interrogation approach. The sensor performance has also been optimized for varied MoS2 and Au layer thicknesses. This article has all the mathematical equations that are needed, and MATLAB software is used to check the results.