Realising efficient and high-performance acoustic metamaterials within compact, constrained volumes represents a significant challenge in the field, often hindered by the inherent geometric constraints of fabricating intricate, high-aspect-ratio internal paths. To address this, we propose a high-dissipation-guided ultraslim meta-element design strategy, transitioning advanced acoustic theoretical designs into functional physical prototypes via additive manufacturing. This proposed concept leverages boundary-aligned cavity designs combined with internal segmentation to enhance dissipation by optimising thermoviscous losses. As a proof-of-concept, three cases of coiled-up channels are engineered within this design framework, featuring multiple structural orders, and demonstrating customisable sound absorption capabilities. Utilising Digital Light Processing (DLP) technology, we physically realised the modified non-uniform coiled-up channels (MNCC) with an ultraslim footprint of only 3.5 mm in the xy-plane. This high-resolution 3D printing approach circumvents the aforementioned geometric constraints, enabling the accurate fabrication of these deeply subwavelength features. Broadband, continuous, and efficient sound absorption is achieved spanning from 390 Hz to 875 Hz with an average absorptance of 0.91. This work provides a versatile framework for designing high-performance acoustic meta-elements, underscoring the critical role of 3D printing in realising complex structures for adaptive sound control in space-constrained environments.
Zeng et al. (Mon,) studied this question.