Methane detection approach based on THz wave absorber

A simple and efficient methane detection approach has been developed in this paper. A THz wave absorber sensitive to refractive index is designed. The proposed absorber mainly uses nested graphene rings and continuous graphene sheets. Two scenarios are followed in this paper. Firstly, a simple single layer including graphene rings on top of the Kapton dielectric and backside coated gold is suggested. The graphene rings face free space or polluted air with a known refractive index in this situation. The second scenario considers the sample (probably toxic polluted air) in the middle layer and also in free space. Both states are mathematically modeled in terms of referred impedance. Additionally, full-wave simulations are also performed. The equivalent impedance can reveal the absorption response of the structure with the aim of impedance matching or maximum power transmission theorem. Interestingly, the impedance modeling converges to the numerical full-wave simulation, verifying efficient mathematical modeling. Furthermore, ample simulation results are provided to investigate the robustness and reliability of the proposed methane optical detector. Based on the findings, the proposed detector is highly appropriate for gas detection, specifically for the healthcare industry due to using Kapton which makes it flexible and wearable.