Mechanical Metamaterials: Emerging Trends in Fabrication, Geometry, Properties, and Functionalities

ABSTRACT Mechanical metamaterials have attracted significant attention due to their unprecedented properties arising from architectural design and material combinations. In recent years, accelerating trends have pushed metamaterials beyond conventional structures toward increasingly complex geometries and unexplored regions of the material property space, largely driven by technological advancements such as additive manufacturing and artificial intelligence. This review highlights recent advances and emerging trends in mechanical metamaterials, with particular emphasis on the interplay among fabrication techniques, structural geometry, mechanical properties, and functionalities. The discussion begins with recent progress in additive manufacturing techniques, targeting high resolution, high throughput, scalability, material diversity, and sustainability. Building on this, innovations in geometry design, informed by both physical principles and artificial intelligence, are examined. The resulting remarkable mechanical properties are then summarized, including extreme performance, controlled instabilities, enhanced fracture resistance, mitigation of trade‐offs, and unconventional responses. This review further emphasizes the growing focus on multifunctional integration, advancing metamaterials that are not only mechanically robust but also capable of sensing, actuation, and even information processing. Finally, this review concludes by highlighting current challenges and future opportunities, providing a timely perspective on the evolving landscape of mechanical metamaterials and aiming to inspire future innovations.