June 16, 2009 3:38:28 pm
Scientists have created a new type of metamaterial that could be used to create high-definition ultrasound images of babies in-utero,help doctors find tiny tumours or hide submarines from enemy sonar.
Our focus is not about dampening noise,but to guide sound waves around structures, Nicholas Fang,a professor at the University of Illinois at Urbana Champaign,told ABC News.
He added,If we have a coating on a submarine that bends acoustics waves before they hit the surface,guiding them around the submarine smoothly,then you wont be able to detect a submarine using sonar.
Sound waves are larger than electromagnetic waves. To manipulate either wave requires structures many times smaller than the size of the wave.
Because the properties of the material are determined by their physical structure and not their chemical make-up,they are called metamaterials.
If you need to build an ultrasonic metamaterial,the dimension of the physical structure is tens or hundreds of microns, said Fang.
Compare that with optical metamaterials,and you are talking about hundreds of nanometers. That makes it a lot more amenable for research, he added.
The sonic metamaterial uses cubes and octagons to create holes that can then bend the wave around the structure.
The most obvious application would be as a coating for submarines that want to avoid detection from enemy sonar.
Besides bending waves around a structure,the metamaterial can also focus sound waves into a sub-millimetre-sized area,an area smaller than traditional ultrasound machines can currently see.
Known as a super lens,it could enable doctors to see babies in-utero in much higher definition or detect tumours that are currently too small for ultrasonic detection.
We have seen some very exciting demonstrations, said Fang. But to make this as a practical structure we need another three to five years, he added.