Quantum dots print tiniest inkjet image

By Leo Kelion
Technology desk editor

image copyrightETH Zurich
image captionThe tiny image requires a microscope to make out its detail

Researchers in Switzerland have created what has been classed as the world's smallest inkjet-printed picture.

They made a 0.08mm-by-0.115mm (0.003in-by-0.005in) colour photo of tropical clown fish, which is about as wide as a piece of photocopy paper is thick.

They printed it using "quantum dot" technology, an innovation also being deployed in new high-end TVs.

The nanotechnologists say their achievement has been verified by the Guinness World Records.

The photo of the fish - which are 3,333 times bigger in real life than in the picture - was printed at a resolution of 25,000 dots per inch (dpi).

There is 500 nanometres (0.0005mm) between each dot on each of the three colour layers deposited - red, green and blue.

Rather than squirt normal ink, "quantum dots" were used.

These are tiny particles that emit a different colour of light according to their size.

Smaller ones appear blue, mid-size ones are green and the bigger type are red.

The light generated by quantum dots is particularly intense, which makes them attractive to TV-makers, who have struggled to produce large OLED screens at affordable prices - another technology known for delivering colour-rich images.

One of the team suggested their technique could ultimately be adapted to "print" screens on demand.

"In a futuristic scenario, you could imagine having a plastic foil that goes into a printer and on the other side there is a display coming out," Dr Patrick Galliker told the BBC.

"You'd have all the functionality of a [video] screen, which has just been printed using nanomaterials that are in a liquid phase."

image copyrightGetty Images
image captionSamsung unveiled TVs using quantum dot technology at the CES trade show in January

Sony, Samsung and LG are among companies to have already shown off televisions using quantum dots, which they built using a different manufacturing technique.

Quantum dots have also been used elsewhere to create solar batteries and electron microscopes.

"This experiment was a very interesting gimmick, but a gimmick nonetheless," said Chris Green, a technology expert at the business consultancy Lewis.

"But as a technical exercise to demonstrate the sheer versatility of what quantum dot technology can do with regards to imaging, it's an absolutely fascinating demonstration of what can be achieved with what is not that expensive technology."

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