California universities, lab develop "world's lightest" material

The University of California Irvine, the California Institute of Technology and HRL Laboratories have developed a lattice-structured material that consists of 99.99 percent air.

A team of researchers from the University of California Irvine (UCI, Irvine, Calif., USA), HRL Laboratories (Malibu, Calif., USA) and the California Institute of Technology (Pasadena, Calif., USA) reported on Nov. 17 that they have developed the world’s lightest material – with a density of 0.9 mg/cc – about one hundred times lighter than expanded polystyrene. Their findings appear in the Nov. 18 issue of Science.

The new material features a “micro-lattice” cellular architecture. The researchers were able to make a material that consists of 99.99 percent air by designing the 0.01 percent solid at the nanometer, micron and millimeter scales. “The trick is to fabricate a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair,” said lead author Dr. Tobias Schaedler of HRL.

The material’s architecture allows unprecedented mechanical behavior for a metal, including complete recovery from compression exceeding 50 percent strain and extraordinarily high energy absorption.

“Materials actually get stronger as the dimensions are reduced to the nanoscale,” explained UCI mechanical and aerospace engineer Lorenzo Valdevit, UCI’s principal investigator on the project. “Combine this with the possibility of tailoring the architecture of the micro-lattice and you have a unique cellular material.”

Developed for the Defense Advanced Research Projects Agency, the novel material could be used for battery electrodes and acoustic, vibration or shock energy absorption. William Carter, manager of the architected materials group at HRL, compared the new material to larger, more familiar edifices: “Modern buildings, exemplified by the Eiffel Tower or the Golden Gate Bridge, are incredibly light and weight-efficient by virtue of their architecture. We are revolutionizing lightweight materials by bringing this concept to the nano and micro scales.”