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Biomimetic and Bioinspired designs have been investigated due to the advances in modeling, mechanics and experimental characterization of structural features of living organisms. To accomplish bioinspiration for fields such as robotics, adhesives and smart materials, it is required to comprehend how Nature accomplished enhanced mechanical behavior. Among the plethora of complex organisms spanning at different lengthscales, the deep sea sponge Euplectella Aspergillum has been of particular interest due to its lattice structure that can be the framework to design mechanical metamaterials. However, despite its intriguing morphology, constraints in the fabrication and modeling of scalable and nonuniform materials has hindered the study of its mechanical performance and how to harness it. Moreover, a comprehensive FEA model that encompasses the whole spectrum of its constitutive and structural performance has not been reported. In this study, it is aimed to characterize and model the mechanical behavior of this sponge from a structural standpoint. Utilizing various experimental techniques, an FEA mechanical model is developed to study the nonlinear buckling analysis of the sponge’s lattice structure and its resilience to failure. Finally, through topology optimization and sensitivity analysis, a new mechanical metamaterial is proposed. Our results elucidate how mechanical characterization and FEA modeling can be employed for a deeper understanding of Nature’s tailored hierarchy and the design of metamaterials. 

Abstract Recent advancements in manufacturing, finite element analysis (FEA), and optimization techniques have expanded the design possibilities for metamaterials, including isotropic and auxetic structures, known for applications like energy absorption due to their unique deformation mechanism and consistent behavior under varying loads. However, achieving simultaneous control of multiple properties, such as optimal isotropic and auxetic characteristics, remains challenging. This paper introduces a systematic design approach that combines modeling, FEA, genetic algorithm, and optimization to create tailored mechanical behavior in metamaterials. Through strategically arranging 8 distinct neither isotropic nor auxetic unit cell states, the stiffness tensor in a 5 × 5 × 5 cubic symmetric lattice structure is controlled. Employing the NSGA-II genetic algorithm and automated modeling, we yield metamaterial lattice structures possessing both desired isotropic and auxetic properties. Multiphoton lithography fabrication and experimental characterization of the optimized metamaterial highlights a practical real-world use and confirms the close correlation between theoretical and experimental data. 

Abstract Cardiac tissues are able to adjust their contractile behavior to adapt to the local mechanical environment. Nonuniformity of the native tissue mechanical properties contributes to the development of heart dysfunctions, yet the current in vitro cardiac tissue models often fail to recapitulate the mechanical nonuniformity. To address this issue, a 3D cardiac microtissue model is developed with engineered mechanical nonuniformity, enabled by 3D‐printed hybrid matrices composed of fibers with different diameters. When escalating the complexity of tissue mechanical environments, cardiac microtissues start to develop maladaptive hypercontractile phenotypes, demonstrated in both contractile motion analysis and force‐power analysis. This novel hybrid system could potentially facilitate the establishment of “pathologically‐inspired” cardiac microtissue models for deeper understanding of heart pathology due to nonuniformity of the tissue mechanical environment.