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Ink takes caffeine hit

Monday, 22 August 2011
By Print 21 Online Article

New printing techniques and ink formulas emerge from studies into the coffee-ring effect, the future of print could be under a cappuccino.

According to Arjun Yodh’s research published in the British science journal, Nature, the important factor in creating this pattern is the shape of the particles in the liquid, and the way these particles respond to surface tension.

"This work gives us a new idea about how to make a uniform coating, relatively simply,” he says. “If you change the particle shape, you can change the way a particle is deposited. You can also make mixtures. In some cases, even just a small amount of ellipsoids can change the way the particles deposit when they dry.”

A uniform coating can be achieved by changing the shape of the particles in the solution, removing the coffee-ring effect. The ring is formed by round molecules of coffee, ink or dye gathering at the perimeter of the drop.

Changing the shape of the particles will make it easier to smooth them across the entire surface. The research team at the University of Pennsylvania will explore drying and deposition of different types of fluids in future studies.

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