Metamaterials with microscale architectures, e.g., microlattices, can exhibit extreme quasi-static mechanical response and tailorable acoustic properties. When coupled with pressure waves in surrounding fluid, the dynamic behavior of microlattices in the long wavelength limit can be explained in the context of Biot’s theory of poroelasticity. In this work, we exploit the elastoacoustic wave propagation within 3D-printed polymeric microlattices to incorporate a gradient of refractive index for underwater ultrasonic lensing. Experimentally and numerically derived dispersion curves allow the characterization of acoustic properties of a fluid-saturated elastic lattice. A modified Luneburg lens index profile adapted for underwater wave focusing is demonstrated via the finite element method and immersion testing, showcasing a computationally efficient poroelasticity-based design approach that enables accelerated design of acoustic wave manipulation devices. Our approach can be applied to the design of acoustic metamaterials for biomedical applications featuring focused ultrasound.

具有微尺度结构的超材料，例如微晶格，可以表现出极端的准静态机械响应和可定制的声学特性。当与周围流体中的压力波耦合时，微晶格在长波长极限下的动态行为可以在 Biot 的多孔弹性理论的背景下进行解释。在这项工作中，我们利用 3D 打印聚合物微晶格内的弹性声波传播来结合水下超声透镜的折射率梯度。实验和数值导出的色散曲线允许表征流体饱和弹性晶格的声学特性。通过有限元方法和浸没测试证明了适用于水下波聚焦的改进的 Luneburg 透镜折射率分布，展示了一种计算效率高的基于多孔弹性的设计方法，可以加速声波操纵设备的设计。我们的方法可以应用于以聚焦超声为特色的生物医学应用的声学超材料设计。