Synergy of Smart Materials and Structures Toward Intelligent Metamaterials

摘要

Metamaterials are artificially engineered systems in which the geometry and arrangement of designed unit cells give rise to effective properties that are not available in natural materials. Intelligent metamaterials extend this concept by integrating stimulus-responsive materials with programmable architectures, thereby creating functional matter that blurs the conventional boundary between materials and structures and enables dynamic, adaptive, and reconfigurable functionalities. These systems can respond to diverse stimuli such as thermal, electrical, optical, magnetic, and mechanical inputs, and convert them into tunable shape change, adaptive mechanical/optical responses, and other reconfigurable functionalities [1-5]. Through this synergy, they acquire lifelike and emergent behaviors, making them attractive platforms for next-generation applications in soft robotics, bioengineering, information encryption, and mechanical computation. Yet, without this integration, both components face intrinsic limitations. Standalone smart materials are typically constrained by specific modes, directionalities, and spatial complexities, restricting their use in multifunctional devices. Many promising material behaviors remain underutilized due to challenges in harnessing and controlling their properties at the system level. Likewise, mechanical structures alone are limited by their static configuration, which severely curtails their functional versatility. To overcome these challenges, a promising approach lies in the synergistic integration of smart materials with structural designs. Coupling programmable geometries with responsive materials not only surmounts the intrinsic limitations of each component but also unlocks emergent functionalities unattainable by either alone. Examples of these novel capabilities include programmable shape morphing, adaptive mechanical properties, and multimodal responses, all arising naturally from this codesign paradigm. This perspective elucidates this transformative paradigm by focusing on the integration of smart materials and structural architectures as a platform for intelligent metamaterials. We systematically review representative classes of smart materials and structural design and then highlight the fundamental principles underpinning material–structure coupling and discuss how structural design facilitates the full realization of material functionalities. Finally, we examine emerging applications and identify key challenges and future directions essential for developing the next generation of architected intelligent metamaterials. Figure 1 illustrates the core concept: the nexus of material properties, structural design, and emergent functionalities, where reconfigurability and dynamic operation arise from seamless integration, opening avenues to intelligent, reprogrammable metamaterials with profound technological impact. Synergistic integration of smart materials and structural design, highlighting how their coupling provides the foundation for intelligent metamaterials. One of the defining features of smart materials is their ability to actively respond to environmental stimuli. These responses originate from intrinsic molecular architectures, phase transitions, or energy conversion mechanisms [6], as illustrated in Figure 2A. Thermal responsiveness represents the most fundamental and widely applied category. Phase transitions provide the driving force: shape-memory polymers (SMPs) [7] and shape-memory alloys (SMAs) [8] recover their programmed configuration upon heating through reversible thermal transitions (glass transition or melting of crystalline domains) and reversible martensite–austenite transformation, which release the stored elastic strain energy and drive macroscopic shape recovery accordingly, whereas liquid-crystalline elastomers (LCEs) [9] actuate through the reorientation of mesogenic units, which directly drives macroscopic deformation. Electrical responsiveness can be clas