A new class of transformable kirigami metamaterials for reconfigurable electromagnetic systems

Abstract

The rapid development of radio frequency (RF) components requires smart multifunctional materials that can adapt their physical shapes and properties according to the environment. While most current reconfigurable systems provide limited flexibility with high manufacturing cost, this research proposes to harness the transformable properties of kirigami-inspired multistable mechanical metasurfaces that can repeatedly deform and lock into different configurations to realize a novel class of low-cost reconfigurable electromagnetic structures with a broad design space. The metasurfaces are formed by designing kinematic-based unit cells with metallised coating that can provide adjustable resonant electromagnetic (EM) properties while rotating with respect to each other. Tailoring the cut length and geometry parameters of the patterns, we demonstrate programming of the topologies and shapes of different configurations. The influence of critical parameters on the structural multistability is illustrated by means of both a simplified energy model and finite element simulations. As examples of the reconfigurable electromagnetic devices that can be realized, we report the development of a tuneable half-wave dipole and two frequency selective surface (FSS) designs featuring isotropic and anisotropic responses. While the kirigami dipole can be tuned by mechanically stretching its arms, the FSSs exhibit distinct transmittance and reflectance spectra in each of the kirigami patterns stable states. The functionality of these kirigami devices is validated both by full-wave EM simulations and experiments. The proposed transformable structures can be mechanically actuated to tune the EM response in frequency or induce anisotropies for wave propagation.

Design and Characterization of Deformable Superstructures Based on Amine‐Acrylate Liquid Crystal Elastomers

“…They have broad application prospects in national defense, military, aerospace, biomedicine, etc. A variety of practical reconfigurable electromagnetic devices (systems) have been developed using deformable superstructures, [ 1 ] including variable curvature wings, [ 2 ] biaxial thermal‐shrinking promoting wound‐healing dressings. [ 3 , 4 ] The unique multiscale structural configuration of metamaterials exhibits unconventional deformation behaviors, such as negative Poisson's ratio, [ 5 , 6 ] negative stiffness, [ 7 , 8 ] compression‐torsion coupling response, [ 9 ] and negative thermal expansion, [ 10 , 11 ] exhibiting potential applications in flexible components and smart robots.…”

Frequency selective surface with a bistable auxetic geometry

“…Frequency selective surfaces (FSSs) belong to this family of periodic metamaterials and despite their introduction in the early 70's there is still a thriving activity in this field. Examples of elastomeric origami and kirigami structures have been recently studied for tuning FSSs [3]. Auxetic surfaces are a particular type of metamaterials that are increasing or expanding as they are stretched (the term auxetic has been taken from the Greek verb 'afksano, αυξ άνω' which means to increase).…”