A stretchable "meta-skin" cloaking technology uses rows of tiny ring resonators help to trap radar waves. Photo by Liang Dong/ISU

AMES, Iowa, March 7 (UPI) -- Engineers and materials scientists at Iowa State University have developed a new "meta-skin" capable of cloaking objects.

The stretchable polymer skin doesn't visually hide objects, but makes them invisible to radar. Rows of small, liquid-metal devices effectively trap radar waves, rendering the cloak and the cloaked undetectable.


The devices are split ring resonators, which have been lined up and sandwiched in layers of silicone sheeting. Inside the resonators is a liquid metal alloy called galinstan. Each resonator acts like a small curved piece of liquid wire. The resonators serve as electric inductors while the gaps between them act as electric capacitors.

Working in conjunction, the inductors and capacitors trap radar waves within a certain frequency. Because the meta-skin is stretchable, it can be pulled tight to augment the range of radar frequencies trapped by the resonators.

The new technology was described this week in the journal Scientific Reports.

"It is believed that the present meta-skin technology will find many applications in electromagnetic frequency tuning, shielding and scattering suppression," the study's authors wrote.

Unlike the cloaking technology used by the U.S. military's B-2 stealth bomber, which only negates direct reflection of radar waves, the new meta-skin traps and suppresses radar at all angles.

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Researchers believe their meta-skin could eventually replace the bomber's current stealth technology, but say the cloaking technology still needs further testing and tweaking.

"The long-term goal is to shrink the size of these devices," Liang Dong, associate professor of electrical and computer engineering at Iowa State, said in a news release. "Then hopefully we can do this with higher-frequency electromagnetic waves such as visible or infrared light."

"While that would require advanced nanomanufacturing technologies and appropriate structural modifications, we think this study proves the concept of frequency tuning and broadening, and multidirectional wave suppression with skin-type metamaterials," Dong added.