This study addresses the challenges of high-power consumption and complexity in conventional infrared (IR) gas sensors by integrating metamaterials and gold coatings into IR radiation sources to reduce radiation loss. In addition, emitter design optimization and material selection were employed to minimize conduction loss. Our metasurface exhibited superior performance, achieving a narrower full width at half maximum at 4197 and 3950 nm, resulting in more confined emission spectral ranges. This focused emission reduced energy waste at unnecessary wavelengths, improving efficiency compared to traditional blackbody emitters. At 300 °C, the device consumed only 6.8 mW, while maintaining temperature uniformity and a fast response time. This enhancement is promising for the operation of such sensors in IoT networks with ultra-low power consumption and at suitably low costs for widespread demands in high-technology farming.

This study explores the design and performance of a bilayer graphene metamaterial absorber (MA) operating in the GHz range. The structure is developed based on a single-layer MA, which consists of graphene ink layer on an FR-4 dielectric substrate, backed by a continuous copper plate. To enhance absorption performance, a second graphene-FR4 layer with identical dimensions is added, forming a bilayer configuration. Our proposed bilayer graphene MA structure achieves an absorption exceeding 90% with an impressive bandwidth of 8.43 GHz, covering the frequency range from 6.07 GHz to 14.5 GHz. The structure maintains high absorption even at large incident angles and remains insensitive to polarization angles due to its symmetrical design. Additionally, we analyze the absorption mechanism of the bilayer metamaterial structure through surface current distribution and magnetic field investigations. These comprehensive analyses provide valuable insights into the underlying mechanisms responsible for the enhanced absorption in bilayer metamaterial structures. Furthermore, we have successfully fabricated this material, demonstrating its potential for applications in electromagnetic wave shielding technologies and GHz-range devices.

This paper introduces a vanadium dioxide-integrated broadband metamaterial absorber designed for the terahertz frequency range. The simulation results for the proposed structure demonstrate a wide 90% absorption bandwidth of 8.23 THz, corresponding to a fractional bandwidth of 89.5%. By leveraging the phase-transition properties of VO₂, the absorber demonstrated dynamic adjustability by modulating the absorption from 3% to 98.74%. The absorption mechanism was analyzed through the impedance matching theory and electromagnetic field distributions, confirming the role of magnetic resonance and interference. Furthermore, machine learning algorithms, specifically Linear Regression, Support Vector Regression, and Random Forest (RF), were applied to accelerate the design process and optimize the structural parameters. Among these, the RF model demonstrated superior prediction accuracy. The machine learning-assisted optimization successfully extended the effective absorption bandwidth to 9 THz, representing an improvement by 9.4% compared to the traditional optimization methods. These results validate the efficacy of combining electromagnetic simulation with data-driven techniques for advanced metamaterial design.