Characterisation of 3D printable material for an acoustic metamaterial cell with tuneable resonance

An industrially relevant challenge for acoustic meta-material (AMM) research is to incorporate frequency tuneability, with the aim of creating adjustable acoustic sensors and sound attenuators. The resonant frequencies of AMMs are largely fixed after manufacture, with adjustable mechanisms often requiring complex materials that are difficult to implement in AMM construction. This research presents an entirely 3D printable adjustable AMM device, with a bespoke magnetic resin developed for the adjustable mechanism. This device demonstrates significant potential for resonance tuneability at ultra-subwavelength dimensions for low-frequency audio bandwidths. The resin characterisation is documented, with different material weightings, magnetic nanoparticle sizes, and base polymers trialled to optimize the formula. The photo-responsive resin is developed specifically for stereolithography (SLA) 3D printers, and the superparamagnetic properties achieved ensure no postprocessing poling stage is needed, supporting ease of manufacture. Enabling simple and efficient manufacture of tuneable AMMs is the first step to introducing AMMs into widespread use for industry and academia alike.