New research from the University of Washington shows that metal detectors at security checkpoints were able detect and count smuggled stacks of banknotes.
According to an article published by Gizmodo, “physicists Christopher Fuller and Antao Chen found that ordinary handheld metal detectors were ale to recognize magnetic ink in a single dollar bill from just over an inch away. As multiple bills were stacked, the size of their magnetic field also increased, allowing the researchers to not only detect them from a greater distance, but also count how many there were.”
Magnetic ink in currency typically allows vending machines to verify the authenticity of banknotes.
The discovery is not without its challenges. Currently, metal detectors cannot detect the dollar value of stacks because each denomination uses the same amount of magnetic ink. According to the research, metal detectors would have to be vastly improved so they could automatically differentiate the magnetic ink from other sources.
Fuller and Chen are scheduled to present their work at an upcoming Defense, Security and Sensing conference in Baltimore, Maryland.