Peculiar Functions and Potential Applications of Acoustic Metamaterials in Wave Manipulation: A Review

Abstract Acoustic metamaterials (AMs), including phononic crystals, have revolutionized wave manipulation through artificially engineered microstructures that show unprecedented control over elastic and sound waves. These materials exhibit unique properties such as bandgap formation, wave localization, and anomalous wavefront control, which are unattainable in natural materials. This review presents a comprehensive survey with analysis of AMs for the fundamental mechanism of wave attenuation, such as Bragg scattering and local resonance, and highlights advanced techniques for bandgap widening, multi-band resonance, and inertial amplification. The role of defects in achieving wave localization and waveguiding is discussed, alongside innovative concepts like gradient refractive index (GRIN) AMs and metasurfaces for precise wavefront manipulation. The integration of topological phases into AMs has led to the development of topological acoustic metamaterials (TAMs), supporting robust wave propagation and energy localization at interfaces. Recent advances in actively controllable AMs are also reviewed, leveraging multi-field coupling materials and mechanically reconfigurable structures to achieve real-time tunability. Despite significant progress, challenges remain in the fabrication, scalability, and practical implementation of AMs, particularly in complex engineering environments. The review concludes with an outlook on future research directions, emphasizing the need for novel fabrication technologies, optimization strategies, and the integration of artificial intelligence for future advancement of the field.