New Explorations in the Application of Hydrogels for Electromagnetic Metamaterial Absorbers

Abstract Hydrogels are a class of polymer materials with a 3D network structure. Due to their flexibility, tunable dielectric properties, and high transparency, hydrogels have been extensively utilized in applications, including flexible electronics, smart materials, and biomedical engineering. This study successfully synthesized polyacrylamide (PAM) hydrogels exhibiting optical transparency and flexibility through chemical polymerization. The experimental results demonstrate that hydrogels, as hydrophilic polymers, contain a substantial number of water molecules. The polarity and mobility of these molecules confer dispersive dielectric properties upon the hydrogels, rendering them highly suitable for applications in electromagnetic metamaterials. Leveraging these properties, two types of electromagnetic devices are developed: a broadband metamaterial absorber and a frequency‐selective absorber, both utilizing hydrogel‐based components. The experimental and simulation results are consistent. The broadband absorber exhibited an absorption efficiency exceeding 90% in the 8.2–25 GHz range, while the frequency‐selective absorber maintained a low transmission loss of −1 dB in the 4.6–6.5 GHz range and achieved over 90% absorption in the 10.8−22.5 GHz range. This study explores the feasibility of using hydrogels in electromagnetic metamaterial applications. The designed metamaterial devices have advantages such as lightweight, reconfigurability, and flexibility, providing a new approach for the design of electromagnetic metamaterial devices.