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Eco-friendly electronics that self-degrade and vanish By Amy Norcross Researchers at Scandinavian research organization SINTEF have made progress in developing components that dissolve in water. They are made of a combination of magnesium, silicon, or silicon with a magnesium additive; are water-soluble; and disappear after a few hours. One of the obstacles to creating a final working product is the need for a coating that can protect the circuits. When external fluids reach the inside of the packaging, the circuits will begin to degrade. The job for which the circuit is designed must be complete before that step occurs. SINTEF researchers gave an example, a circuit package designed to be used in seawater and fitted with sensors for measuring oil spills. The film must be made so that it remains in place for the weeks during which the measurements are being taken. “It’s important to make it clear that we’re not manufacturing a final product, but a demo that can show that an electronic component can be made with properties that make it degradable,” says Karsten Husby, a research scientist in SINTEF’s Information and Communication Technology (ICT) division. “Our project is now in its second year, but we’ll need a partner active in the industry and more funding in the years ahead if we’re to meet our objectives. There’s no doubt that eco-friendly electronics is a field which will come into its own, also here in Norway. And we’ve made it our mission to reach our goals.” Researchers in the United States have been working on biocompatible electronic devices that can be implanted in the body for various uses — pain management, for example, or to combat infection — and then dissolve over time. “We make no secret of the fact that we are putting our faith in the research results coming out of the USA,” Husby adds. “The Americans have made amazing contributions both in relation to medical applications, and towards resolving the issue of waste. We are far from this, but we want to try to find alternative approaches to the same problem.” Along similar lines, other researchers have created what they call the world’s first “biological” drone built with biodegradable material that, should the drone crash, will start breaking down upon impact, leaving no evidence of its existence. A team of 15 Stanford University, Brown University, and Spelman College students developed the drone in collaboration with New York-based biomaterials company Ecovative Design for the iGEM (International Genetically Engineered Machine competition) 2014 Giant Jamboree, held Oct 30 to Nov 3 in Boston. An unmanned aerial vehicle made entirely of biological materials would be able to fly in sensitive areas, for numerous purposes, and leave no trace of its existence in the event of a crash. “No one would know if you’d spilled some sugar water or if there’d been an aircraft there,” Lynn Rothschild, lead scientist at NASA’s Ames Research Center and an adviser for the student team that created the drone, told New Scientist. In a recent Tech Times article, author Jim Algar says, “Drones have been used to explore and observe remote locations, some for scientific purposes and some for military operations, but the crash of a science drone could contaminate a sensitive environment, while that of a military drone could give away the fact someone’s been spying.” “The greatest part of the biological prototype drone,” Algar adds, “consists of a plant-root-like material known as mycelium, part of a fungus, often grown for use as a sustainable, lightweight material for wine packaging or in surfboard cores.” Other materials used in the drone’s construction included a protective covering for the fungal body — comprising sticky cellulose “leather” sheets grown by bacteria in the lab — proteins cloned from the saliva of paper-wasps, and silver nanoparticle ink for printing the circuits. Nonbiological components of the drone were the controls and propellers borrowed from a standard quadcopter, as well as a standard battery. The team plans to eventually be able to make all parts of the drone, including the sensors, biodegradable. Printed on a silicon wafer, the components contain extremely thin circuits — only a few nanometres thick — that are designed to transfer energy. Source: Werner Juvik, SINTEF The bio-drone’s chassis, made of mycelium, the vegetative part of a fungus, was modelled and 3D-designed by a team of students for the 2014 iGEM design contest and produced by Ecovative Design. Source: iGEM.org www.electronics-eetimes.com Electronic Engineering Times Europe February 2015 25


EETE FEB 2015
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