July 9, 2012
In July's Special Issue of Discover Magazine, author Adam Piore discusses the sophisticated cloaking devices that may soon hide objects from light, sound, water and even earthquakes! For the full DISCOVER Magazine article click here
Duke's Electrical and Computer Engineering (ECE) Assistant Faculty Yaroslav Urzhumov, a prominent member of the Center for Metamaterials and Integrated Plasmonics (CMIP) was higlighted in the July issue for a preliminary design for a mesh shield that would let submarines stealthily maneuver through the seas without leaving any wake. Urzhumov's research was in DISCOVER Magazine last August 2011 with Metamaterial Mesh Could Erase a Sub’s Tell-Tale Wake.
ECE Faculty member Steve Cummer's work with Sound Cloaks, a new acoustic invisibility cloak made of a plastic metamaterial that makes objects invisible to sound waves,Cummer and his group of researcher's tested the stacked sheets on a flat surface, placing a 4-inch block of wood underneath it. The block of wood could not “hear” the sound — there were no sound waves passing through — and “attempts to locate the object using sound waves would not find it,” BBC reports.
Adam readdresses the mystery behind cloaking in his latest installment for Discover Magazine discussing the Water Cloak and Sound Cloak;
SOUND CLOAK
"The Tech: Last year a Duke University team led by engineer Steven Cummer built a cloak that rendered an object “invisible” to sound waves.
What It's Made of: Stacked sheets of one-millimeter-thick perforated plastic (the actual engineering of these cloaks is difficult but unglamorous). The sheets’ holes and arrangement allow the cloak to manipulate sound waves.
How It Works: It hides an object much like Ergin’s light cloak does. Cummer placed the perforated sheets over a 10-centimeter-long block of wood. The cloak bent sound waves heading toward the block so that they avoided the cloaked area and rebounded as if it were not there. If the block had ears, it would not have heard any sound from outside the cloak.
Applications: Sonic cloaks could steer sound waves around beams and columns in a concert hall to give every seat perfect acoustics, or block the noise pollution from that chatty coworker in a neighboring cubicle. Such cloaks could also conceal submarines from the pulses of enemy sonar, although Cummer considers that a major challenge—he cannot just slap thick layers of plastic onto a military sub."
WATER CLOAK
"The Tech: Last year, Duke engineers Yaroslav Urzhumov and David Smith proposed a means of cloaking ships as they move through the water.
What It's Made of: A network of small water-deflecting blades and pumps encasing the bottom of the ship.
How It Works: As a ship chugs ahead, it drags water along with it and leaves a wake behind. Urzhumov’s contraption would scoop up water in front of the bow, steer it around the ship, and release it behind the stern. Water behind the ship would move at the same speed and in the same direction as at the front of the ship. The result: The ship would glide through the water without disturbing it.
Urzhumov says ships will not be getting fitted for cloaks for at least a decade, but the benefits are worth the wait. Cloaked ships could move faster, since they would encounter little friction from the surrounding water. They would also be harder to spot without a trail behind them. If that sounds like something that would make naval officers salivate, it is: The Navy helped fund the Duke study." - Adam Piore, DISCOVER contributing Editor
Reference: Yaroslav A. Urzhumov and David R. Smith. “Fluid Flow Control with Transformation Media.” Physical Review Letters, August 11, 2011. DOI: 10.1103/PhysRevLett.107.074501