TORONTO—  Opalux   has patented a security features using tunable colour-changing photonic crystals and nano-scale technology. OpalPrint Polycarbonate, which creates a colour shifting image that overlays the image of the document holder in items such as passports.  ElastInk product changes colour in response to finger pressure and can be either reversible or irreversible; while Opalux Photonic Ink is RFID-activated and optically-variable .De La Rue of Britain has signed a partnership with Opalux to take it's developments world wide. De La Rue lay's claims to being the worlds largest security printer. They print banknotes, passports ,stamps and manufacture security paper. . Ulrich Walter, product director for De La Rue’s described Opalux’s technology as “exciting” in the face of the ongoing need to stay ahead of counterfeiters.