Magic Ink: Now available for full colour Printing

Borrowing an idea from nature could lead to technology capable of producing full-colour A4 prints in a fraction of a second, according to South Korean engineers.

Many insects and birds owe their bright colours to the interaction of light with finely-patterned surface textures, rather than relying on pigments. The iridescent colours of a peacock's tail are largely a result of the interaction of light with just one biological material – melanin rods.

Engineers have long experimented with replicating these so-called structural colours in synthetic materials, and now Sunghoon Kwon's team at Seoul National University in South Korea has managed it.

Their M-Ink can be used to produce any colour in the visible spectrum and could lead to a new method of cheap and fast full-colour printing, Kwon says.

Just add nanoparticles

M-Ink contains three ingredients: magnetic nanoparticles 100 to 200 nanometres across, a solvation liquid, and a resin.

The nanoparticles disperse throughout the resin, giving the ink a brown appearance. But when an external magnetic field is applied, the nanoparticles immediately snap to the magnetic field lines, forming chain-like structures.

The regularly-spaced nanoparticle chains interfere with incoming light, so that the light reflected from the surface is of a particular colour. Adjusting the magnetic field strength shifts the spacing of the field lines and changes the colour, says Kwon.