Large-scale reconfigurable metamaterials

Abstract Metamaterials have opened unprecedented avenues for controlling wave propagation, mechanical response, and dynamic behavior. Some of these metamaterials are capable of reconfigurability, in the sense that they can be modulated in response to external stimuli. Whether the application is passive or reconfigurable, the vast majority of reported research on metamaterials has been at the nano- and micro-scales, attributable to fabrication costs and capabilities, and to the desire to study and leverage enhanced properties at smaller scales. The aim of this review paper is to generate a discussion at the meter scale and beyond, for example energy systems, civil infrastructures, and aerospace structures. Because we postulate that the capability to modulate would be a key enabler for large-scale applications, the review focuses on reconfigurable metamaterials, synthesizing the information by emphasizing on functional capabilities, challenges, and opportunities in the large-scale context. We start by introducing key concepts and discuss fabrication methods, and highlight multi-materials engineering and hybrid manufacturing as promising paths to fabricating large-scale metamaterials. After, we review reconfigurability mechanisms for metamaterials, and comment on the particular promise of semi-active mechanisms, because of their capability to operate using limited power. Hence, we follow with nine case studies on semi-active metamaterials, and demonstrate promises of the semi-active technology yet at small scales. Lastly, we review large-scale metamaterial applications, here including passive applications given the highly limited literature, and point to key directions that could facilitate field deployment of large-scale reconfigurable metamaterials. Ultimately, we conclude that there is a need for integrative cross-disciplinary frameworks capable of bridging laboratory-scale developments and field-deployment demands, thereby advancing the maturation of reconfigurable metamaterials for large-scale engineering applications.