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Cambridge University Science Magazine
Colleagues from UC Irvine, HRL Laboratories and the California Institute of Technology created the metal structure, which consists of 99.99% air, by constructing a “lattice of interconnected hollow tubes with a wall thickness 1000 times thinner than a human hair”.

The micro-lattice has a density of 0.9 milligrams per cubic centimetre, compared to the world’s existing lightest solid, silica aerogel, which has a density limited to 1.0 milligram per cubic cm. The ordered structure of the micro-lattice makes the material stiffer, stronger and better able to absorb and conduct energy than metal aerogels or foams, which have random cellular structures.

William Carter, the manager of architected materials at HRL, compared the new material to the Eiffel Tower or the Golden Gate Bridge, which “are incredibly light and weight-efficient by virtue of their architecture”. As their dimensions become smaller, materials actually become stronger. The group have combined weight-efficient architecture with nano and micro scale engineering, making the resulting metal structure extremely tough. Following compression to half thickness in strength tests, the lattices returned to 98% of their height and to their original shape. Although repeating the test for a second time resulted in the lattice becoming less stiff and strong, the team say that further compressions made very little difference.

The material has been developed for the Defence Advanced Research Projects Agency, and could be used for thermal insulation, battery electrodes and products designed for sound and shock absorption.

Written by Joanna-Marie Howes

DOI: 10.1126/science.1211649