Microlattice Metamaterials for Tailoring Ultrasonic Transmission with Elastoacoustic Hybridization

Abstract

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.

Acoustic properties of porous microlattices from effective medium to scattering dominated regimes

“…In addition, we find a narrow band-gap for the intermediate porosity lattice, which stems from the hybridization with a bending mode of the truss. 33…”

Pathway towards Programmable Wave Anisotropy in Cellular Metamaterials

“…Lattice structures also display unique dynamic properties. They commonly feature Bragg-type bandgaps as a result of their periodicity and occasionally subwavelength bandgaps for special unit cell designs or in the presence of internal resonators, thus behaving as frequency-selective stop-band filters for acoustic [12], elastic [13][14][15][16][17][18][19] and electromagnetic waves [20]. They also display elastic wave anisotropy, which manifests as pronounced beaming of the energy according to highly directional patterns [13,[21][22][23][24][25][26][27][28][29][30].…”

Broadband and multiband vibration mitigation in lattice metamaterials with sinusoidally-shaped ligaments

“…Moreover, their design based on monophase cores allows producing lightweight phononic crystals with relatively simple fabrication procedures. Significant efforts have been devoted to exploring band gap properties in lattice materials with different topologies [31][32][33][34][35][36][37][38]. However, only triangular lattice configurations show a single locally resonant band gap [31].…”