Researchers at the University of Missouri-Rolla are using nano-sized glass microspheres to trace explosives back to their manufacturers and help law enforcement authorities thwart terrorists.
The glass microsphere’s chemical composition becomes a signature and can provide the name of company, the plant location, and the day it was manufactured. If the explosive is then used illegally, the information in the microsphere tags can be used to narrow down the suspects who may have purchased the material.
Glass was chosen as it will not cause the explosive to detonate prematurely, nor will it more dangerous but also because they are already deliberately added to explosives to improve performance.
After an explosion, the highly durable tags are found in and around the explosion site. The microspheres are then detected using a variety of methods depending on what was added to the spheres when they were formed. For example, if a certain chemical is added, the microspheres will glow when exposed to low-level radiation. They can also be made magnetic and a magnet can be used at the explosion site to pick up the microspheres.