Earlier this month, it came to light that the new high-tech U.S. $100 bill was so difficult to counterfeit that even the U.S. mint couldn't properly master the production process, causing printing problems that eventually led the Treasury Department to quarantine $110 billion in new currency. But rather than incorporating sophisticated printing tricks like 3-D security strips, watermarks, and color-shifting inks, a team of German and Japanese researchers have come up with an easier and potentially more effective way to secure banknotes: stamp tiny organic circuitry directly onto the bills.