Airport security checks could soon be hassle free after the invention of a scanning device capable of detecting more potentially dangerous materials than today's X-ray machines.

Scientists at the US Department of Energy's Argonne National Laboratory, along with collaborators in Turkey and Japan, have created a compact device that could lead to portable, battery-operated sources of T-rays, or Terahertz radiation.

Unlike more energetic X-rays, T-rays do not have sufficient energy to 'ionize' an atom and cause cellular damage that can lead to radiation sickness or cancer.

But T-rays are capable of penetrating many common materials, such as leather, fabric, cardboard and paper.

These qualities make terahertz devices one of the most promising new technologies for airport and national security.

Today's metal or X-ray detectors can identify only a few obviously dangerous materials, but T-ray absorption patterns could detect and identify a much wider variety of hazardous or illegal substances.

T-rays can also penetrate the human body by almost half a centimetre, and have already been used by doctors to detect and treat certain types of cancers, especially those of the skin and breast.

Research leader Ulrich Welp, of Argonne's Materials Science Division, said that scientists and engineers have produced microwave radiation using conventional electric circuits for more than 50 years.

But terahertz radiation could not be generated this way because of the physical limitations of the semiconducting circuit components.

"Right around 1 terahertz, you have a range of frequencies where there have never been any good solid-state sources," he explained.

"You can make those frequencies if you are willing to put together a whole ta ble full of expensive equipment, but now we've been able to make a simple, compact solid-state source."