Visitors try to pick counterfeit bills from the real ones displayed at the Money Museum in the Federal Reserve Bank of Chicago in 2011. Scientists have reported they had invented an invisible tag ... more 

Visitors try to pick counterfeit bills from the real ones displayed at the Money Museum in the Federal Reserve Bank of Chicago in 2011. Scientists have reported they had invented an invisible tag using the widely-used "quick response" code to help thwart banknote forgers and criminals who sell bogus drugs or fake vintage wine less