Evolution of metasurfaces for advanced elastic wave manipulation: a comprehensive review

Elastic waves exhibit fascinating yet complex physical phenomena because normal and shear deformations in elastic solid media characterize two different wave modes, longitudinal and transverse. Furthermore, elastic waves have a broad range of engineering applications, spanning industrial, geological, and medical fields. Recently, elastic metasurfaces, planar metamaterials typically made of thin, subwavelength-scale structures, have received significant attention. As they can surpass conventional technologies such as bulky metamaterials and wedge-type ultrasonic probes in wavefront control, they offer a new paradigm in wave manipulation. Intriguing and practical applications of metasurfaces include anomalous reflection, refraction, and wave steering with mode control. In this review, we outline the core concepts of elastic metasurfaces, detail their design strategies and implementation methods, and explore their transformative applications in engineering fields. We conclude by offering insights into future research directions and the advancements required to fully realize the potential of elastic metasurfaces.