Design and Fabrication of Negative-Refractive-Index Metamaterial Unit Cells for Near-Megahertz Enhanced Acoustic Transmission in Biomedical Ultrasound Applications
Jiaying Wang, Florian Allein, Nicholas Boechler, James Friend, Oscar Vázquez-Mena
Abstract
Acoustic metamaterials with negative index of refraction offer great potential for improving resolution and signal transmission in biomedical ultrasound. Their potential has remained unrealized, however, for the lack of a fabrication technology that can create metamaterials compatible with biomedical imaging and operating at frequencies near 1 MHz. The authors report the simulation, fabrication, and characterization of integrated Helmholtz and membrane resonators with characteristic lengths less than 1 mm, produced by silicon-based clean-room microfabrication. Their work finally realizes a negative-index acoustic metamaterial that can be applied in ultrasound imaging and therapeutics.