New frontiers in acoustic and elastic metamaterials and metasurfaces

Acoustic metamaterials and metasurfaces are a kind of artificially structured materials to manipulate advanced or unprecedented functions for acoustic waves in air, liquid, and solid from macroscale to nanoscale. Metasurfaces act as a slice of a metamaterial with subwavelength thickness being like a surface, benefitting scenarios that especially require compact design in space. In the past two decades, we witnessed significant advancements of this field as an integrative process as “design–fabrication–verification” for innovations include extreme effective parameters, invisible cloak, non-reciprocal propagation, topological insulators, among others, and for interdisciplinary research in physics, materials, engineering, and artificial intelligence. Driven by new manufacturing technologies and strong applicable demands, such as noise and vibration control, aerospace, signal processing, sensors, and non-destructive testing, the study of acoustic metamaterials and metasurfaces attracts increasing attention from both academic and industrial parts.