New work by engineers at Iowa State University have developed a new “meta-skin” which flexes and stretches while utilizing rows of liquid-metal built into the polymer to potentially mask an airplane employing the technology from radar operators.
Meta-skin as future of stealth technology
Somewhere between the Klingon’s cloaking device and Frodo’s cloak of invisibility lies the work with metamaterials that researchers from Iowa State recently published in the journal Scientific Reports. The work was partially funded by the China Scholarship Council and the National Science Foundation in addition to using the university’s resources.
Using composites that are by no means found in nature, the meta-skin created by the engineers in the electrical and computer engineering departments of Iowa State essentially allows the skin to trap radar signals. Radar’s effectiveness relies on the echo and return of a signal to the source of radar frequency emission and by trapping the signal the skin becomes “invisible.”
The lead authors of the paper were professors Liang Dong and Jimang Song with grad students Siming Yang, Peng Liu and Qiugu Wang along with undergrad Mingda Yang each being credited as co-authors.
“It is believed that the present meta-skin technology will find many applications in electromagnetic frequency tuning, shielding and scattering suppression,” the team wrote to describe their work.
Song specializes in electromagnetic waves while Dong’s expertise lies with using liquids and polymers at a micro and nanascale level. The collaboration between the two made perfect sense for the research.
By using tunable liquid-metal, the team devised a means by which to trap radar possible extending this to the shorter wavelengths of light necessary to make something nearly invisible to radar operators and their equipment.
Galinstan is the key
The team created the skin by connecting resonating rings with a diameter of 2.5 millimeters spaced a millimeter apart creating a segment of something best described as liquid wire. The rings were then embedded between layers of silicone sheets. Rather than using the very toxic mercury to fill the rings, the team opted to use galinstan to create the skin.
The inductors and the gaps between them create capacitors. By creating something stretchable, the metal rings are allowed to change shape and suppress radar at different frequencies. The team achieved a radar “trapping” success rate of roughly 75% in the 8 to 10 gigahertz range from all angles if an object is completely coated with the meta-skin.
“Therefore, this meta-skin technology is different from traditional stealth technologies that often only reduce the backscattering, i.e., the power reflected back to a probing radar,” the engineers observed.
Stealth is one thing, invisible is another and the team believes that further work, we’ll have just that.
“The long-term goal is to shrink the size of these devices,” Dong said. “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.”The material is quite light and wouldn’t overly burden an aircraft that was covered with the meta-skin. Working in conjunction with planes angled and designed to present a tiny radar signature the skin could ultimately lead to a nearly invisible plane, tank or ship.