So called rainbow proteins (a spin-off from work into bioluminescence), which change colour in response to particular compounds, are also an option for detecting environmental toxins, or the potential agents of terrorism.

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Benetton, a fashion retailer, successfully standardised most of its products, except for their colour, which was added at the last minute in response to the latest tastes.

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Each bead is doped with a mixture of chemicals that become electrically charged in response to odour molecules and that charge alters the colour of the dye.

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The drawbacks of electrophoretic displays are that they have slow response times, since the pigment particles take time to move, and that colour versions are still in development.

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