Fake versions of real money have been around ever since people first stopped bartering for goods and began exchanging representations of wealth for items and it remains a bigger problem than you might think. It’s estimated, for example, that over 200 million fake US dollars are currently in circulation around the globe. As a result, the government has dedicated significant resources to continually updating security features on bills in an effort to make them more difficult to copy.
Counterfeit money confiscated by law enforcement.
Image courtesy of Johnson City Press
However, the increasing availability of powerful technologies combined with simple ingenuity have given counter-counterfeiting measures a run for their money. Tarshema Brice took advantage of a Hewlett-Packard, a degreasing formula, and a toothbrush to create somewhere between 10 and 20 thousand fake US bills before being caught in 2013. Albert Talton used printers he bought at Staples and sheets of newspaper to create his faux currency, pumping out more than $7 million worth before landing himself a spot in prison in 2009. But the record is held by Canadian counterfeiter Frank Bourassa who was ultimately found to have printed $250 million with only a $300,000 initial outlay.
The latest effort to address the production of funny money comes from the Karlsruher Institut Für Technologie (KIT) in Germany, where researchers have developed a method for 3D printing microstructures onto bills. The structures themselves are no longer than about 100 μm (one millionth of a meter) and nearly invisible to the naked eye. Instead, the structures would be read by a machine, also developed by the team at KIT. The development was described by Professor Martin Wegener, expert in 3D printing of microstructures at the Institute of Nanotechnology at KIT:
“Today, optical security features, such as holograms, are frequently based on two-dimensional microstructures. By using 3D printed fluorescent microstructures, counterfeit protection can be increased. Security fetaures produced in this way are not only of individual character, but also very complex in manufacture. This makes life difficult [for] forgers.”
A complete discussion of the technique has been proposed in the journal of Advanced Materials Technologies, but concisely stated, the microstructure consists of a 3D cross-grid of fluorescent dots that can be arranged in any number of combinations on the three dimensional grid. Precise and rapid laser lithography is used to produce and print the microstructures by building them up layer by layer from non-fluorescent and two fluorescent photoresists. The point at which the liquid photoresist is touched by the laser beam is hardened, creating a filigree structure which can then be encased in a transparent polymer that provides protection from damage.
Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures, on products or packagings. [Image courtesy of Frederik Mayer/KIT]
You can access the full study here.
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