Intelligent Inks for Oxygen
4 February 2008, 12:34
Categories: smt-chromism-color-change coatings
Semiconductors can absorb light. Some absorb light in the visible range, appearing colored, and others absorb light in the UV range, appearing white or colorless. This light-absorbing feature is used to drive electrons around a circuit in photovoltaic cells, but it can also be used to drive chemical reactions at the surface. A good example of the latter is the use of 15 nm thin film coatings on self-cleaning glass. Upon absorbing UV light in sunlight, these titanium dioxide films are able to reduce oxygen, present in air, to water and oxidize any organic material on its surface to its minerals, thereby keeping the surface clean.
Researchers at the University of Strathclyde in Glasgow, UK, have used this oxidation feature to developed an irreversible solvent-based blue ink, which upon activation with UV light, loses all its color and becomes oxygen sensitive. It will only gain its original color upon exposure to oxygen. A major application area for this oxygen ink is in food packaging where it could be used to detect a modified atmosphere inside food containers.
Posted by: The Editors
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