All-liquid frequency selective absorber design with flexibility and wide-angle stability

Abstract An all-liquid flexible metamaterial crossing the ultrabroadband range of S, C, X, and Ku bands is reported. This work demonstrates for the first time a frequency selective absorber (FSA) using all-flexible materials, which enables a transmission band of 2.4–4 GHz and a 6–20 GHz ultrawideband absorption. Firstly, liquid metal (LM) as a new functional material with self-healing capability and high reflectivity, based on its metasurface can realize the minimum insertion loss of 0.72 dB at 3.2 GHz. Then, utilizing dielectric resonance and diffraction grating effects of the water-based metasurface, the design can achieve greater than 90% absorption in the frequency band of 6–20 GHz, with a relative bandwidth of 107%. Furthermore, by miniaturizing the design, the FSA exhibits high stability in TM mode with oblique incidence up to 60° and TE mode at 45°. Our design can be fabricated using polydimethylsiloxane lithography and encapsulated with water and LM with a thickness of only 8 mm. Finally, the fabricated FSA are tested by bending to different curvatures, and the good performance indicates its promising applications in electromagnetic stealth, compatibility and wearable devices.