Scientists improve the design of security sensors

Feb 11, 2008 10:43 GMT  ·  By

If it's light manipulation, then we're talking about metamaterials. Researchers report to have improved the design of T-ray sensors with the help of a metamaterial that guides T-ray light across the surface of the detector. T-ray sensors are thought to become the next generation of explosive and poison detection devices, that emit and detect electromagnetic radiation in the far infrared wavelength.

This particular electromagnetic light spectrum has a wavelength about 500 times longer than that of visible light, meaning that it is absorbed by most of the molecules used in explosives and biological substances, such as anthrax, for example. Metametarials, on the other hand, represent composite materials created out of intricate metal structures, which most of the time are used into light and sound manipulation experiments, such as electromagnetic or acoustic cloaks.

By using a metamaterial, scientists claim to have guided the weak fields of radiation into a very strong field less than a millimeter above the surface of the sensor, enhancing the electromagnetic absorption. Usually T-ray radiation weak fields extend some centimeters above the surface of the material, which disables the possibility of an accurate detection.

The creators of the new metamaterial design, a team of physicists from the UK and Spain led by Dr Stefan Maier from the Imperial College London's Department of Physics, say that the T-ray sensors could eventually become standard devices for detecting hazardous materials, like explosives, ability that has been greatly restricted so far by the fact that such radiation could not be control and guided in a way to make it useful for real world applications. Now, on the other hand, we are capable of concentrating more T-ray radiation along the detector, to increase the range of possible future applications.

The newly created metamaterial represents a metallic structure consisting in a two-dimensional array of pits, which are scaled so that they match the wavelength of T-ray radiation in order to draw it closer to the surface of the actual detector. Nonetheless, Dr. Steve Andrews writes that T-ray detectors still require much optimization until they can be used in real life applications. For example, scientists have to increase the spectrum of frequencies currently used by T-ray and captured by the metamaterial, which will ultimately result in an increase of possible detected molecules.