Non-integer-dimensional architected materials enabling synergistic acoustic, mechanical, and fluid coupling

Architected materials have long struggled to achieve true multifunctionality, as attempts to combine acoustic insulation, mechanical robustness, and ventilation often rely on hybridized or modular designs that compromise scalability. Here we introduce a dimension-driven strategy that exploits non-integer-dimensional architected materials (NDAMs) to achieve multifunctional integration within a single topological framework. As a proof of concept, Menger sponge-inspired NDAMs were fabricated by high-resolution additive manufacturing, demonstrating three capabilities: broadband acoustic insulation through self-similarity induced scattering and resonance, tunable mechanical energy absorption via stress redistribution, and enhanced airflow efficiency enabled by drag-reducing multiscale channels. These functionalities arise intrinsically from fractal hierarchy, without reliance on material heterogeneity or external hybridization. Crucially, the dimensional parameter serves as a scalable and fabrication-accessible handle, bridging abstract fractional geometry with real-world engineering. This work establishes NDAMs as a powerful design axis for next-generation multifunctional metamaterials, with potential applications in aerospace, transport, and biomedical systems.