Most electronic information systems have
more sophisticated security than paper. It is not impossible, however,
to make paper secure and rewritable, to boot.
Researchers from the University of Tokyo, Tokyo University of
Science, Tokushima Bunri University and Japan Science and Technology Agency
have fabricated a rewritable security paper whose contents are only visible
under ultraviolet light.
The paper can be erased and reused by heating it above 50 degrees
Celsius. The paper can be used to handle confidential information, and
is environmentally friendly because it is reusable, according to the researchers.
The paper is coated with a clear plastic whose molecules contain
copper atoms. The plastic appears clear under regular light, and ordinarily
appears pink under ultraviolet illumination. When information is written
into the plastic by heating portions of it with a thermal printhead like
those used in fax machines, the connections between the branched molecules
that make up the plastic change, making those portions of the material
appear blue under ultraviolet illumination.
Images printed this way last as long as a year, according to the
The secure paper and plastic ink system could be used practically
within five years, according to the researchers. The work appeared in
the June 19, 2005 issue of Nature Materials (Rewritable Phosphorescent
Paper by the Control of Competing Kinetic and Thermodynamic Self-Assembling
Top 10 Stories
Letter to Readers
ink is rewritable
powers biochip gears
goes around bends
drives particle patterns
View from the High Ground Q&A
How It Works
News | Blog
Buy an ad link