MIT innovates a novel framework for controlling ultrasound waves using microscale acoustic metamaterials, advancing imaging and computing technologies.
Researchers at the Massachusetts Institute of Technology (MIT) have developed a design framework that enables precise control of ultrasound wave propagation within microscale acoustic metamaterials. Their innovative approach focuses on strategically positioning microscopic spheres within a three-dimensional lattice, which will be a promising application in medical imaging and mechanical computing.
Acoustic metamaterials are materials engineered to manipulate sound waves, exhibiting unique properties due to their structural design. While theoretical studies and computer models have long predicted their potential, practical development has been limited to larger structures and low-frequency sound waves. MIT’s new framework pushes the boundaries, enabling these materials to operate at ultrasonic frequencies.
“The multifunctionality of metamaterials — being simultaneously lightweight and strong while having tuneable acoustic properties — makes them ideal for extreme-condition engineering,” said Carlos Portela, assistant professor of mechanical engineering, MIT. However, miniaturisation and high-frequency characterisation have posed significant challenges in advancing their development.
Targeted applications for this technology range across various sectors. Medical professionals, particularly those working in ultrasound imaging, could benefit from the enhanced precision and efficiency in imaging devices. Similarly, engineers involved in mechanical computing and signal transmission may find these metamaterials invaluable for creating compact, efficient systems. The design’s scalability also appeals to researchers exploring advanced materials for industrial and scientific uses.
Portela’s team, including Rachel Sun, Jet Lem, and Yun Kai from MIT, alongside Washington DeLima of the U.S. Department of Energy, tackled these issues by embedding microscopic spherical masses into metamaterial lattices. “Our work shows how simple geometrical changes in a lattice can alter ultrasound wave velocities, guiding or focusing them as needed,” Portela explained.
Using laser-ultrasonics, the researchers demonstrated tuneable wave velocities within these materials, allowing spatial and temporal control of wave propagation. They also developed an acoustic demultiplexer—a device capable of separating a single acoustic signal into multiple outputs. These advancements pave the way for efficient devices useful in ultrasound imaging and data transmission.
The findings highlight a significant leap in acoustic metamaterial research, making way for possibilities in fields requiring precision in wave control and offering insights into wave mechanics at microscopic scales.
