Moth-Wing-Inspired Multifunctional Metamaterials

To evade ultrasonic predation by bats, moths have evolved wing scale architectures capable of absorbing and scattering high-frequency acoustic signals. Drawing inspiration from this natural defense strategy, a bioinspired multifunctional metamaterial is presented that integrates broadband sound absorption, thermal insulation, and mechanical energy dissipation within a unified structural framework. Inspired by the graded pore architecture of moth scales, acoustic performance is first optimized via genetic algorithm-driven pore design and the structures using 3D printing. The resulting metamaterial exhibits broadband acoustic absorption with an average coefficient of 0.742 across the 1000-6000 Hz frequency range. When implemented in helmet-based noise reduction systems, the proposed metamaterial outperforms conventional commercial foams in suppressing environmental noise. In addition, the metamaterial retains a negative Poisson's ratio under large deformation, which enhances its mechanical energy dissipation and impact resilience. Furthermore, the alternating architecture of polymer layers and internal air cavities reduces the effective thermal conductivity to 30.2 mW m^-1 K^-1, ensuring excellent thermal insulation. This work demonstrates that leveraging biological architectures enables the simultaneous integration of acoustic, mechanical, and thermal functionalities in lightweight metamaterials, offering a new paradigm for multifunctional design.