Invisible nano-barcodes could track explosives, drugs, and more

When forensic investigators first started using sophisticated ballistics analysis to identify criminals, it was viewed as an incredible insight. Just a pattern of scratches on a hunk of half-destroyed metal could link a gun to a bullet — amazing! Today, impressing people is much more difficult; DNA evidence in particular has given us the sense that physical evidence can be analyzed to almost unlimited effect. Still, investigators often have trouble tracing evidence back to its source in any useful way, often in the most serious of cases. But what if trace amounts of explosive, say, could be identified and tracked as easily as a firearm? That’s the goal of new research published this week, which uses nanoparticles to put an invisible, indestructible barcode in just about any object imaginable.