Researchers create acoustic metamaterial ‘superlens’
A team at the University of Illinois, Chicago, has developed the world’s first acoustic ‘super lens’. It is proposed that this innovation could be used for high-resolution ultrasound imaging, non-destructive structural testing of buildings and bridges, and underwater stealth technology or "acoustic cloaking".
Professor of mechanical science and engineering, Nicholas X. Fang, leads the team which successfully focused ultrasound waves through a flat metamaterial lens on a spot roughly half the width of a wavelength at 60.5 kHz using a network of fluid-filled Helmholtz resonators.
Prof Fang said the acoustic imaging, while not quite as convenient or accurate as optical imaging, is improving. Presently, however, acoustic imaging can’t detect objects smaller than a few millimeters. Prof Fang said the best tool for tumor detection is still optical imaging but exposure to electromagnetic radiation, like those found in x-rays, does pose health risks, especially when used on pregnant women. Acoustic images don’t rely on electromagnetic radiation.
Acoustic images may prove useful when detecting tumors in the body that are often surrounded by hard tissues and don’t permit clear detection by traditional optical imaging methods.
Prof Fang said that the application of acoustic imaging technology could lead to other possibilities. Buildings and bridges could be checked for hairline cracks or other deeply embedded defects that are undetectable by optical imaging.
He added that the technology might even extend to underwater stealth technology, what he termed an “acoustic cloak” that would act as camouflage for submarines.
Prof Fang and his team are currently working at developing a practical device that will allow them to use the acoustic imaging technology outside of the lab in a variety of situations.