Microlattice Metamaterials for Tailoring Ultrasonic Transmission with Elastoacoustic Hybridization

Materials with designed microscale architectures, like microlattices, can achieve extreme mechanical properties. Most studies of microlattices focus on their quasistatic response, but their structural dimensions naturally prime them for ultrasonic applications. Here we report that microlattices constitute a class of acoustic metamaterials that exploit elastoacoustic hybridization to tailor ultrasonic wave propagation. Selecting the microlattice geometry allows the formation of hybridization band gaps that effectively attenuate (by >2 orders of magnitude) acoustic signals. The hybridization gaps stem from the interaction of pressure waves in a surrounding medium (e.g., water) with localized bending modes of the trusses in the microlattice. Outside these band gaps, the microlattices are highly transmissive (>80%) because their acoustic impedance is close to that of water. Our work can have important implications in the design of acoustic metamaterial applications in biomedical imaging, cell-based assay technology, and acoustic isolators in microelectromechanical systems.