Ink changing colour by breathing on it

Chinese scientists have developed ink which changes colour according to the level of humidity. One use for this could be ascertaining the authenticity of money simply by breathing on it. This would be a much more efficient and cheaper way than previous colour changing methods. The printing of colloidal and photonic crystals has up to now been very expensive. The Chinese scientists have found a way to do with via inkjet printing. The colour changes are affected by nitrogen and ethanol vapour and in principle could be affected by breathing on it. This would mean that ascertaining authenticity could be very fast and cheap. Bio sensors, optic communication and solar cells could also be candidates for this technology.

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