Revertible wideband hydrogel-based meta-structure absorber

Multiple bending can have detrimental effect on the performance of the microwave absorber as it may cause fractures and fatigues in the materials it is composed off. Consistency in absorption performance requires performance revertibility along with flexibility. Hydrogels with semi-liquid behavior are found to exhibit reversibility. Herein, meta-structure-based revertible absorbers have been proposed  using PVA–borate cross-linked hydrogel popularly known as slime embedded in silicone rubber. Resonators are shaped into cuboidal and hexagonal–prism structures. Dual resonating structure technique has been employed to achieve a wide – 10 dB absorption bandwidth almost covering the entire X-band. The hydrogel with dielectric properties close to water assists in more than 90% absorption over the whole operating band. Simulation shows that the structures are bendable up to a bending radius of 10 mm without compromising on the absorption bandwidth. The self-healing property of slime further aids revertibility of the developed MSAs. Performance restoration is observed after 24 h of continuous application of deformation force for maximum bending. The absorption mechanism in the MSAs are discussed by vector field distribution. Polarization insensitive absorption is found over \(\pm 90^\circ\) $\pm {90}^{\circ }$ .