Si la cape d’invisibilité pour les personnes est encore un fantasme, bien que des avancées existent en ce sens, des ingénieurs ont développé une « méta-peau » capable de rendre invisible aux radars n’importe quel objet.
Ce sont des ingénieurs et des étudiants en ingénierie de l’Université Iowa State, aux États-Unis, qui sont parvenus à mettre un point un matériau flexible et extensible, sorte de « méta-peau ». Celle-ci est capable non pas de rendre invisibles les objets, mais en tout cas de les rendre indétectables par les radars, comme le rapporte le site Phys.org.
Ce matériau polymère est composé de petits anneaux faits de galinstan, un métal issu de l’alliage eutectique de gallium, d’indium et d’étain. Ces petits anneaux ont un diamètre de 2,5 mm pour une épaisseur de 0,5 mm, avec un interstice d’un millimètre, le tout étant lié par une membrane en silicone. Ils ont ainsi une fonction d’inducteurs électriques, alors que les interstices jouent le rôle de condensateurs, pour une combinaison agissant comme un résonateur capable de neutraliser la plupart des ondes radars qui les atteint.
Selon les ingénieurs, cette « méta-peau » est capable d’absorber 75 % des fréquences radars situées entre 8 et 10 Ghz. Ainsi, quel que soit l’angle de provenance des ondes radars, les objets équipés disparaîtraient des écrans radars. Une fonction qui pourrait évidemment trouver des applications militaires. « Un jour, cette méta-peau pourrait recouvrir la surface de la prochaine génération d’avions furtifs », a d’ailleurs déclaré Jiming Song, ingénieur sur le projet.
Ce sont des ingénieurs et des étudiants en ingénierie de l’Université Iowa State, aux États-Unis, qui sont parvenus à mettre un point un matériau flexible et extensible, sorte de « méta-peau ». Celle-ci est capable non pas de rendre invisibles les objets, mais en tout cas de les rendre indétectables par les radars, comme le rapporte le site Phys.org.
Ce matériau polymère est composé de petits anneaux faits de galinstan, un métal issu de l’alliage eutectique de gallium, d’indium et d’étain. Ces petits anneaux ont un diamètre de 2,5 mm pour une épaisseur de 0,5 mm, avec un interstice d’un millimètre, le tout étant lié par une membrane en silicone. Ils ont ainsi une fonction d’inducteurs électriques, alors que les interstices jouent le rôle de condensateurs, pour une combinaison agissant comme un résonateur capable de neutraliser la plupart des ondes radars qui les atteint.
Selon les ingénieurs, cette « méta-peau » est capable d’absorber 75 % des fréquences radars situées entre 8 et 10 Ghz. Ainsi, quel que soit l’angle de provenance des ondes radars, les objets équipés disparaîtraient des écrans radars. Une fonction qui pourrait évidemment trouver des applications militaires. « Un jour, cette méta-peau pourrait recouvrir la surface de la prochaine génération d’avions furtifs », a d’ailleurs déclaré Jiming Song, ingénieur sur le projet.
Engineers develop flexible skin that traps radar waves, cloaks objects
Iowa State University engineers have developed a new flexible, stretchable and tunable "meta-skin" that uses rows of small, liquid-metal devices to cloak an object from the sharp eyes of radar.
The meta-skin takes its name from metamaterials, which are composites that have properties not found in nature and that can manipulate electromagnetic waves. By stretching and flexing the polymer meta-skin, it can be tuned to reduce the reflection of a wide range of radar frequencies.
The journal Scientific Reports recently reported the discovery online. Lead authors from Iowa State's department of electrical and computer engineering are Liang Dong, associate professor; and Jiming Song, professor. Co-authors are Iowa State graduate students Siming Yang, Peng Liu and Qiugu Wang; and former Iowa State undergraduate Mingda Yang. The National Science Foundation and the China Scholarship Council have partially supported the project.
"It is believed that the present meta-skin technology will find many applications in electromagnetic frequency tuning, shielding and scattering suppression," the engineers wrote in their paper.
Dong has a background in fabricating micro and nanoscale devices and working with liquids and polymers; Song has expertise in looking for new applications of electromagnetic waves.
Working together, they were hoping to prove an idea: that electromagnetic waves - perhaps even the shorter wavelengths of visible light - can be suppressed with flexible, tunable liquid-metal technologies.
What they came up with are rows of split ring resonators embedded inside layers of silicone sheets. The electric resonators are filled with galinstan, a metal alloy that's liquid at room temperature and less toxic than other liquid metals such as mercury.
Those resonators are small rings with an outer radius of 2.5 millimeters and a thickness of half a millimeter. They have a 1 millimeter gap, essentially creating a small, curved segment of liquid wire.
The rings create electric inductors and the gaps create electric capacitors. Together they create a resonator that can trap and suppress radar waves at a certain frequency. Stretching the meta-skin changes the size of the liquid metal rings inside and changes the frequency the devices suppress.
Tests showed radar suppression was about 75 percent in the frequency range of 8 to 10 gigahertz, according to the paper. When objects are wrapped in the meta-skin, the radar waves are suppressed in all incident directions and observation angles.
"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 wrote in their paper.
As he discussed the technology, Song took a tablet computer and called up a picture of the B-2 stealth bomber. One day, he said, the meta-skin could coat the surface of the next generation of stealth aircraft.
But the researchers are hoping for even more - a cloak of invisibility.
"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."
Explore further: Array of perfect nanometer-scale spheres that can control the flow of visible light may find use in invisibility cloaks
More information: Siming Yang et al. From Flexible and Stretchable Meta-Atom to Metamaterial: A Wearable Microwave Meta-Skin with Tunable Frequency Selective and Cloaking Effects, Scientific Reports (2016). DOI: 10.1038/srep21921
Journal reference: Scientific Reports search and more info website
Provided by: Iowa State University search and more info website
Iowa State University engineers have developed a new flexible, stretchable and tunable "meta-skin" that uses rows of small, liquid-metal devices to cloak an object from the sharp eyes of radar.
The meta-skin takes its name from metamaterials, which are composites that have properties not found in nature and that can manipulate electromagnetic waves. By stretching and flexing the polymer meta-skin, it can be tuned to reduce the reflection of a wide range of radar frequencies.
The journal Scientific Reports recently reported the discovery online. Lead authors from Iowa State's department of electrical and computer engineering are Liang Dong, associate professor; and Jiming Song, professor. Co-authors are Iowa State graduate students Siming Yang, Peng Liu and Qiugu Wang; and former Iowa State undergraduate Mingda Yang. The National Science Foundation and the China Scholarship Council have partially supported the project.
"It is believed that the present meta-skin technology will find many applications in electromagnetic frequency tuning, shielding and scattering suppression," the engineers wrote in their paper.
Dong has a background in fabricating micro and nanoscale devices and working with liquids and polymers; Song has expertise in looking for new applications of electromagnetic waves.
Working together, they were hoping to prove an idea: that electromagnetic waves - perhaps even the shorter wavelengths of visible light - can be suppressed with flexible, tunable liquid-metal technologies.
What they came up with are rows of split ring resonators embedded inside layers of silicone sheets. The electric resonators are filled with galinstan, a metal alloy that's liquid at room temperature and less toxic than other liquid metals such as mercury.
Those resonators are small rings with an outer radius of 2.5 millimeters and a thickness of half a millimeter. They have a 1 millimeter gap, essentially creating a small, curved segment of liquid wire.
The rings create electric inductors and the gaps create electric capacitors. Together they create a resonator that can trap and suppress radar waves at a certain frequency. Stretching the meta-skin changes the size of the liquid metal rings inside and changes the frequency the devices suppress.
Tests showed radar suppression was about 75 percent in the frequency range of 8 to 10 gigahertz, according to the paper. When objects are wrapped in the meta-skin, the radar waves are suppressed in all incident directions and observation angles.
"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 wrote in their paper.
As he discussed the technology, Song took a tablet computer and called up a picture of the B-2 stealth bomber. One day, he said, the meta-skin could coat the surface of the next generation of stealth aircraft.
But the researchers are hoping for even more - a cloak of invisibility.
"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."
Explore further: Array of perfect nanometer-scale spheres that can control the flow of visible light may find use in invisibility cloaks
More information: Siming Yang et al. From Flexible and Stretchable Meta-Atom to Metamaterial: A Wearable Microwave Meta-Skin with Tunable Frequency Selective and Cloaking Effects, Scientific Reports (2016). DOI: 10.1038/srep21921
Journal reference: Scientific Reports search and more info website
Provided by: Iowa State University search and more info website