Resumen de A new game of tag
Voxtel, a firm in Beaverton OR, has won a US Air Force contract to develop a drone-based tagging system. Voxtel makes tagging materials--taggants--that can be used to discreetly label vehicles carrying smuggled goods, or people who are involved in civil disobedience or attempting to cross international borders illegally. Interest in tagging technology has been driven in part by growing pressure on the White House over civilian deaths in US drone attacks. Tagging by drones would allow people to be tracked for subsequent arrest. Voxtel's taggants are based on quantum dots--semiconductor nanocrystals less than 50 atoms across. Because of quantum effects, they absorb and emit light at specific wavelengths. The company has demonstrated a taggant powder that, when illuminated with an invisible ultraviolet laser, can be detected by infrared cameras 2 kilometers away. The powder is delivered as an aerosol that clings to metal, glass and cloth, and batches can be engineered to have distinct spectral signatures.
