University of Missouri researchers designed a prototype of a small, lightweight active 'metamaterial' that can control the direction and intensity of energy waves.

Professor Guoliang Huang of the University of Missouri has developed a prototype metamaterial that can control the direction and intensity of energy waves using electrical signals. The innovative material has potential applications in the military and commercial sectors, and can also be used to monitor the structural health of bridges and pipelines.

For more than 10 years, Guoliang Huang, the Huber and Helen Croft Chair in Engineering at the University of Missouri, has been investigating the unconventional properties of "metamaterials" — an artificial material that exhibits properties not commonly found in nature as defined by Newton's laws of motion — in his long-term pursuit of designing an ideal metamaterial.

Huang's goal is to help control the "elastic" energy waves traveling through larger structures — such as an aircraft — without light and small "metastructures."

Now, Huang's one step closer to his goal. In a new study published in the Proceedings of the National Academy of Sciences (PNAS) on May 18, Huang and colleagues have developed a prototype metamaterial that uses electrical signals to control both the direction and intensity of energy waves passing through a solid material.

Potential applications of his innovative design include military and commercial uses, such as controlling radar waves by directing them to scan a specific area for objects or managing vibration created by air turbulence from an aircraft in flight.

"This metamaterial has odd mass density," Huang said. "So, the force and acceleration are not going in the same direction, thereby providing us with an unconventional way to customize the design of an object's structural dynamics, or properties to challenge Newton's second law."

This is the first physical realization of odd mass density, Huang said.

"For instance, this metamaterial could be beneficial to monitor the health of civil structures such as bridges and pipelines as active transducers by helping identify any potential damage that might be hard to see with the human eye."