Polarization insensitive multiband metamaterial absorber for bio-plastic sensing application

This article introduces a microwave multiband metamaterial absorber (MA) with high potential for bio-plastic sensing applications. The innovative design is realized through a compact unit cell dimension of 1.33 lambda omicron x 1.33 lambda omicron x 0.22 lambda omicron, employing a state-of-the-art split-ring resonator structure. Strikingly, this absorber demonstrates polarization insensitivity and can be characterized by five distinct absorption peaks at 18.69 GHz, 23.34 GHz, 25.72 GHz, 32.94 GHz, and 35.40 GHz. The corresponding absorption rates are exceptionally high, ranging from 92.82% to 99.95%. To elucidate the underlying absorption mechanism, detailed analyses of the electric field, magnetic field, surface current distribution, and input impedance are provided, showcasing the absorber's effective MA structure. The designed MA sensor exhibits outstanding performance metrics for bio-plastic detection, including an average quality factor (Q-factor) of 210 and sensitivity of 0.888 GHz/RIU (refractive index unit), marking a significant advancement in the field. Additionally, the sensor's linearity, output variation, and sensitivity are considerably improved for bio-plastic sensing. The research confirms the proposed MA absorber's functionality by comparing measured results and simulation outcomes, indicating a high degree of accuracy and reliability. The potential applications of this MA are manifold, extending to microwave absorption and enhanced plastic sensing techniques. Its compact and thin design facilitates seamless integration with various sensor equipment, broadening the scope of its utility. Furthermore, the article delves into the relevance of this research to several Sustainable Development Goals (SDGs), particularly highlighting its alignment with SDG 9 (Industry, Innovation, and Infrastructure), SDG 12 (Responsible Consumption and Production), and SDG 14 (Life Below Water). Thus, the innovative MA design signifies a technological leap in the field of metamaterial absorbers and contributes to the pursuit of sustainability and environmental protection.