T-rays searching for disease or bombs

Scientists have made a development that could improve the detecting and sensing of objects ranging from biological cell abnormalities to explosives.

The discovery in the United Kingdom involves the harnessing of electromagnetic terahertz waves (T-rays). T-rays could be directed to "search' the interior of objects " useful for medical applications such as endoscopic probing for cancerous cells " as well as detecting explosives at airports or anywhere that could be a security risk area.

Researchers at the University of Bath, western England, working in cooperation with colleagues in Spain, say the discovery came about after they found a way to control the flow of terahertz radiation along a metal wire.

Materials interact with radiation at T-ray frequencies in different ways compared with radiation in other parts of the spectrum, making T-rays potentially important in detecting and analysing chemicals by analysing how they absorb T-rays fired at them.

Possible benefits could be quality control of prescribed drugs and easier detection of explosives since many complex molecules have distinctive signatures in this part of the electromagnetic spectrum.

"This is a significant development that would allow unprecedented accuracy in studying tiny objects and sensing chemicals [by] using T-rays," said Dr Stefan Maier, who leads the research at Bath's department of physics.

T-rays are emitted by all objects around us but they cannot be seen by humans. They can go through almost everything except metal and water. This ability " the result of their short wavelengths " makes them ideal candidates for certain types of medical imaging.

The rays can be used in the detection of concealed weapons, explosives and drugs because they have the ability to penetrate a variety of materials such as clothing, wood, masonry, plastics and ceramics.

Other potential uses include safer versions of X-rays; scanning bags and luggage; identifying biological molecules such as proteins, viruses and bacteria; communications; quality control; even measuring the effectiveness of facial moisturisers.

The rays also have the capability of identifying mutations in DNA (deoxyribonucleic acid) matter and could help clinicians identify pharmaceutical therapies that would be compatible with individual patients' DNA information.

T-rays, whose frequency is about one thousand billion cycles a second, bridge the gap between the microwave and infrared parts of the electromagnetic spectrum. Today, their applications are limited by the relatively poor ability to focus the rays with conventional lenses and mirrors. The smallest spot size of focused T-rays with this method is still a substantial fraction of a millimetre, making studies of small objects such as biological cells with high resolution virtually impossible.

The Bath researchers found that ordinary metal wire would not guide T-rays very well but if a series of tiny grooves were cut into the wire it would do so much more effectively. If the corrugated wire is then tapered to a point it becomes possible to transport radiation very efficiently to a point as small as a few millionths of a metre across.

"In this way, the T-rays can be focused to the tip of the wire and guided into confined spaces or used to detect small objects, with important implications for disease detection or finding explosives that are hidden," said Maier.