The material produced a clear image of the thumb

The coil array was placed between an object to be imaged, in this case one of the researcher's thumbs, and the receiver coil of an MRI device.

It helped to direct the magnetic flux from the thumb to the receiver coils to produce a clear image of the thumb's internal structure.

Professor Joseph Hajnal, of Imperial College School of Medicine, Hammersmith Hospital, London, said the research, reported in the journal Science, represented "a significant technological advance".

"In the future, we hope we will be able to make better MRI scanners than we have today," he told BBC News Online, "and so improve their power of medical imaging."

MRI scans

MRI is a technique that uses magnetic and radio waves to produce pictures of the body's tissues.

During MRI scanning, the patient lies inside a large, cylinder-shaped magnet which sends radio waves thousands of times stronger than the magnetic field of the Earth through the body.

This affects the body's atoms, distorting their nuclei and sending out radio waves of their own. The scanner picks up these signals and they are turned into an image by a computer.

The technique is used to detect brain tumours and heart defects or to examine the joints, spine and sometimes organs like the liver, kidneys and spleen.