October_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 1 7 7 KNITTING ELECTRICITY WITH ENERGY-HARVESTING YARNS An international research team led by scientists at The University of Tex- as at Dallas and Hanyang University in South Korea has developed high-tech yarns that generate electricity when stretched or twisted. Researchers say the “twistron” yarns have potential for numerous applications, such as harvesting energy from the motion of ocean waves or from temperature fluc- tuations. “The easiest way to think of twistron harvesters is, you have a piece of yarn, you stretch it, and out comes electricity,” says Carter Haines, asso- ciate research professor in the Alan G. MacDiarmid NanoTech Institute at UT Dallas. The yarns are made of carbon nanotubes, which the researchers first twist-spin into high-strength, light- weight yarns and then twist to make them highly elastic. In order to generate electricity, yarns must be either sub- merged in or coated with an ionically conducting material, such as a mixture of table salt and water. Even though the investigators used very small amounts of twistron yarn in the current study, they have shown that harvester perfor- mance is scalable, both by increasing the twistron diameter and by operating many yarns in parallel. utdallas.edu . BENDABLE CRYSTALS KNOT A JOKING MATTER Australian scientists report that single crystals, commonly thought of as brittle, are flexible enough to be Are you working with or have you discovered a material or its properties that exhibit OMG - Outrageous Materials Goodness? Send your submissions to Frances Richards at frances.richard s@asminternational.org. OMG! OUTRAGEOUS MATERIALS GOODNESS The Foster + Partners | Branch Technol- ogy teamwith their 3D-printed dome structure. Courtesy of NASA/Joel Kowsky. Flexible crystal knot. Courtesy of Universi- ty of Queensland. pressure sensors and electronic devic- es.” www.qut.edu.au, www.uq.edu.au . NASA HOLDS 3D-PRINTED HOUSING CHALLENGE NASA is in the midst of a multi- phase, $2.5 million 3D-Printed Habitat Challenge designed to advance the construction technology needed to create sustainable housing for Earth and beyond. Teams were required to develop the fundamental 3D printing technology necessary to produce a structurally sound habitat, including the printer itself and construction ma- terials. Competitors then had to print beams, cylinders, and domes that were analyzed and compressed to failure to determine team scores. First place and a prize of $250,000 went to Team Fos- ter + Partners | Branch Technology of Chattanooga, Tenn., and second place to Pennsylvania State University with a prize of $150,000. Challenge activities were held during August at Caterpil- lar’s Edwards Demonstration and Learning Center in Edwards, Illinois. nasa.gov/winit. repeatedly bent and even tied in a knot. Researchers from Queensland University of Technology (QUT) and The University of Queensland (UQ) measured the structural mechanism behind the elas- ticity of the crystals down to the atomic level. The team grew bendable crystals about the width of a fishing line and up to 5 cm long from a common metal com- pound—copper (II) acetylacetonate. They mapped changes in the atomic scale structure when the crystals were bent using x-ray measurements per- formed at the Australian Synchrotron. Crystals from six other structurally re- lated compounds, some containing copper and other metals, were also tested and found to be flexible. Professor Jack Clegg in UQ’s School of Chemistry and Molecular Biosciences says the experiments show that the crystals can be repeatedly bent and return quickly to their origi- nal shape with no signs of breaking or cracking when the force bending them is removed. “Under strain, the mole- cules in the crystal reversibly rotate and reorganize to allow the compression and expansion required for elasticity and still maintain the integrity of the crystal structure,” he explains. “Flexible crystals could lead to new hybrid ma- terials for applications from aerospace components to parts for motion or SEM image of coiled carbon nanotube yarns that generate electrical energy when stretched or twisted.