London, Dec 25 (IANS) Nanotechnology experts in Britain have unveiled a Christmas card that is more than 8,000 times smaller than the size of a postal stamp.

The card designed by the school of engineering at the University of Glasgow is invisible to the naked eye and said to be the smallest in the world.

A total of 8,276 of the cards could be placed on an area the size of a stamp, the Daily Mail reported.

Professor David Cumming and Qin Chen etched the Christmas tree image on to a minute piece of glass.

"Our nanotechnology is among the best in the world but sometimes explaining to the public what the technology is capable of can be a bit tricky. We decided that producing this Christmas card was a simple way to show just how accurate our technology is, Cumming was quoted as saying by the paper.

"The process to manufacture the card only took 30 minutes. It was very straightforward to produce as the process is highly repeatable - the design of the card took far longer than the production."

Cumming said: "The card is 200 micro-metres wide by 290 micro-metres tall. To put that into some sort of perspective, a micrometre is a millionth of a metre; the width of a human hair is about 100 micro-metres.

"You could fit over half a million of them on to a standard A5 Christmas card - but signing them would prove to be a bit of a challenge."

The colours were produced by a process called plasmon resonance in a patterned aluminium film made in the university's James Watt Nanofabrication Centre.

The Christmas card is a simple demonstration of the nenotechnology which has significant applications in real world, the university said.

The electronics industry is taking advantage of micro and nano-fabrication technology by using it in bio-technology sensing, optical filtering and light control components.

The applications are critical in the future development of the digital economy and could eventually find their way into cameras, television and computer screens to reduce the manufacturing cost.