World's smallest Christmas card is so tiny you could fit 200 million on a postage stamp

Scientists have created the world's smallest Christmas card which is so tiny, you could fit more than 200 million of them onto a single postage stamp.

In fact, you would need a powerful microscope just to see the card – which measures just 15x20 microns in size - let alone read the festive message inside. It is 10 times smaller than the previous record-holder.

Researchers from the National Physical Laboratory (NPL) – the UK's National Measurement Institute – created the card from a material usually used in electronics called silicon nitride, which was also coated in platinum. The front cover design and message inside were carved using a focused ion beam – which is essentially a jet of charged particles.

The tools and technology used to make the tiny object are currently helping to understand materials on the microscopic scale, with implications for the miniaturisation of electronics and the development of new battery materials.

"While the card is a fun way to mark the festive season, it also showcases the progress being made in materials research on this scale," said David Cox, a research fellow at the NPL, who created the card with his colleague Ken Mingard.

"We are using the tools that created the card to accurately measure the thickness of extremely small features in materials, helping to unlock new battery and semiconductor technologies. It's a genuinely exciting development that could help to make new technologies and techniques a reality."

Aside from the important work of producing miniature Christmas cards, the NPL helps industry to better understand exciting new materials and how they can be used for new applications.