Beads which change color: impact: reusable signage, posters, labels

Magnetochromatic Beads

RIVERSIDE, Calif., June, 18, 2009 – Microscopic polymer beads that change color instantly and reversibly when external magnetic fields acting upon the microspheres change orientation, have been discovered by a research team at the University of California, Riverside.

Applications of the new material include display type units such as rewritable or reusable signage, posters, papers and labels, and other magnetically activated security features. The new material also can be used to make environmentally friendly pigments for paints and cosmetics, as well as ink materials for color printing.

"Unlike many conventional approaches, the instantaneous color change occurs with no change in the structure or intrinsic properties of the microspheres themselves," said Yadong Yin, an assistant professor of chemistry who led the study that brought together chemists at UCR and engineers at Seoul National University, South Korea. "What changes instead are the magnetic fields acting externally on the orientation of these microspheres, these photonic crystals. Our work provides a new mechanism for inducing color change in materials. Now, for the first time, stable photonic materials with tunable colors can be fabricated on a large scale." "The new technology has a great potential for a wide range of photonic applications because the on/off switching of the diffraction color”

See the change in action: http://www.youtube.com/watch?v=LKsgzk5quZU
Read More at: http://www.photonics.com/Content/ReadArticle.aspx?ArticleID=38171