Additive Manufacture of Small-Scale Metamaterial Structures for Acoustic and Ultrasonic Applications

Acoustic metamaterials are large-scale materials with small-scale structures. These structures allow for unusual interaction propagating sound and endow the material exceptional acoustic properties not found in normal materials. However, their multi-scale nature means that manufacture of these is trivial, often requiring micron-scale resolution over centimetre length scales. In this review, we bring together a variety metamaterial designs separately discuss ways to create them using latest trends additive manufacturing. We highlight advantages disadvantages different techniques act as barriers towards development realisable practical audio ultrasonic applications speculate on potential future developments.