In a bid to thwart counterfeiters, scientists have developed tiny organic electronic circuits that can be fabricated directly onto banknotes.
Banknotes already incorporate up to 50 different anti-counterfeiting features, such as watermarks, holograms, raised printing, embedded foil strips and fluorescent inks. Yet counterfeiting is still rife, with the Bank of England taking 566,000 fake notes, with a face value of £11.1 million, out of circulation in 2009.
To tackle the problem, authorities have explored the possibility of supplementing these passive security features with active electronic anti-counterfeiting and tracking in the form of silicon integrated circuits but have been stymied because the chips are too thick.
Now, a team of Japanese and German boffins have developed organic thin-film transistors (TFTs) less than 250 nanometres thick, printing gold, aluminium oxide and organic molecules onto the notes through a patterned mask. The resulting notes hold around 100 TFTs which can be turned on and off with just three volts that could be transmitted by a reader.
Impressive, cutting-edge technology in the ongoing battle against the counterfeiters but never underestimate the ability of humans to negate such advances. In 2008 a woman managed to dupe a cashier into accepting a hand-made fake £20 note that stated it was from the 'Santa Christmas Bank'. The note featured a picture of Santa and his reindeer and promised to pay the bearer nothing. Santa himself was listed as chief operating officer with a North Pole address.