Additive manufacture of small-scale metamaterial structures for acoustic and ultrasonic applications

Abstract

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