As the weather turns spring-like, winter's ice build-up on power lines, windshields, and airplane wings becomes a fading memory. Professor Victor Petrenko, of Thayer School of Engineering at Dartmouth College (Dartmouth, NH), hopes to keep it that way. The physicist discovered that applying a small electric voltage across an ice-metal interface can break the bond between ice and metal surfaces. Technically, Petrenko says, ice is a semiconductor--included in a small class of substances in which protons, rather than electrons, carry an electrical current. When an electrically-charged surface comes into contact with any other surface, the charged surface induces an opposite charge in the facing surface and, because opposites attract, the two surfaces are drawn together. "This simple attraction accounts for most of ice adhesion," says Petrenko. Breaking the bond between ice and metal, he reasoned, should be as simple as neutralizing the surface charge with an equal amount of its opposite. He tested his theory using a sheet of ice, a globule of mercury--which stays liquid until temperatures dip below -40F--and a small battery with two wires attached. He touched one wire to the ice, the other to the mercury. The mercury drew itself up and away from the ice. Petrenko repeated the experiment using steel and other solid metals. In each case, the electricity caused the ice to lose adhesion. The effect could also be reversed, causing a surface to stick more firmly to the ice. "It may be possible to prevent or significantly reduce icing on the wings of an airplane using a battery no bigger than the one in your car," Petrenko theorizes. Surface-to-surface interactions are also important in manufacturing and machinery. Call: (603) 646-2117.
Biomimicry has already found its way into the development of robots and new materials, with researchers studying animals and nature to come up with new innovations. Now thanks to researchers in Boston, biomimicry could even inform the future of electrical networks for next-generation displays.
Clean diesel continues to be the fuel of choice for transportation authorities in major U S cities, in spite of competitive options aimed at reducing emissions, according to a nonprofit agency that represents diesel engine and equipment manufacturers.
A panel at this year's Consumer Electronics Show in Las Vegas discussing upcoming FAA regulations for non-military drones brought out many of the issues that concern both industry and federal regulators.
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