UK scientists have discovered a fingerprint' “developer' which can highlight invisible prints on almost any surface – and read the text of a letter just from the envelope it was sent in. Paul Kelly and colleagues at Loughborough University found that a disulfur dinitride (S2N2) polymer turned exposed fingerprints brown, as the polymer reaction was initiated from the near-undetectable remaining residues. Traces of inkjet printer ink can also initiate the polymer.
The detection limit is so low that details of a printed letter previously in an envelope could be read off the inside of the envelope after being exposed to S2N2. (more)
