Biomimetic Water‐Based Metamaterial Absorber for Ultrabroadband Radar Stealth

Inspired by the hierarchical porous architecture of Pachliopta aristolochiae butterfly wings and leveraging the intrinsic dielectric dispersion of water, it proposes a biomimetic water-based metamaterial absorber. Breaking conventional compactness-bandwidth trade-offs, this work integrates aqueous metamaterials with bio-inspired architecture, combining butterfly-derived hierarchical porosity and water's dielectric dispersion to achieve unprecedented microwave absorption. The absorber employs hexagonal water cavities in a polydimethylsiloxane (PDMS) matrix, mimicking butterfly-wing multiscale pores to extend wave paths through cascaded resonances. Water serves as "artificial melanin," enabling tunable dielectric loss via molecular relaxation, with absorption dynamically adjusted through water column height/temperature for frequency-shifting and bandwidth broadening. The centrosymmetric geometry ensures polarization insensitivity and wide-angle stability. Optimized aqueous unit coupling achieves >95% experimentally verified absorption (17.11-35.74 GHz) and >10 dB simulated radar cross section (RCS) reduction. Experimental validation shows that the measured absorptivity is in high agreement with the simulation results. Unlike rigid multilayered alternatives, this water-PDMS architecture offers optical transparency, flexibility, and inherent fluidic tunability for functional reconfiguration. With advantages in ultra-broadband performance, angular stability, and scalable fabrication, the proposed absorber opens new avenues for adaptive camouflage, electromagnetic shielding, and multispectral stealth technologies.