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How do you find non-metal explosive devices like plastic landmines—or
even shoe bombs? Johns Hopkins University in Maryland suggests taking a
reference sample of an explosive, like the C4 used by the alleged Al-Qaida shoe
bomber Richard Reid, and imprinting the shape of its molecules on the ends of a
bundle of optical fibres. If the air contains trace levels of the explosive’s
molecules that match the shape of the pits, the fluorescence from the end of the
illuminated fibres will be diminished. Light sensors register this and raise the
alarm. The fibres could also be used to relay a rough image of the shape of the
explosive body.