Since the beginning of recorded time, humans have used materials found in nature to improve their lot. Since the turn of this century, scientists have studied metamaterials, artificial materials engineered to bend electromagnetic, acoustic and other types of waves in ways not possible in nature.
Now, Hao Xin, a professor of electrical and computer engineering at the University of Arizona, has made a discovery with these synthetic materials that may take engineers one step closer to building microscopes with superlenses that see molecular-level details, or shields that conceal military airplanes and even people.
Xin reported his findings with co-authors in an article, "Microwave Gain Medium With Negative Refractive Index," just published in the online journal Nature Communications.
In the UA's Millimeter Wave Circuits and Antennas Laboratory, Xin uses a 3-D printer to make metamaterials from metals, plastics and other substances. Resembling porous plastic bowling balls and tiny copper wire circuit boards, these objects are configured in precise geometrical patterns to bend waves of energy in unnatural ways. In particular, they exhibit a property called negative refraction, meaning they can bend a wave backward.
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