Nano Fingerprints...

The process of producing anti-counterfeit nano-fingerprints based on randomly distributed silver nanowires.
[1] Silver nanowires (AgNWs) are prepared by the self-seeding method and an amorphous silica shell is coated on the surface using tetraethyl orthosilicate (TEOS).
[2] Fluorescein isothiocyanate (FITC) and rhodamine B-isothiocyanate (RITC) are attached covalently to the surface of the pre-formed silica shell by allowing the formation of covalent bonds between the silica surface and 3-aminopropyltrimethoxysilane (APTMS).
[3] A photolithographic process is used to inscribe the direction and target markers on the surface of the PET film. The orientation marker (“KAIST”) can be used to determine the correct direction of the PET film. The target marker (“X”) has an empty space in its central region where AgNWs are loaded to generate fingerprints.

Counterfeiting is a steady and increasingly important problem that occurs in nearly every trade and industry. Recognizing the difficulty in distinguishing counterfeit goods from genuine products, new nanoscale technologies are being developed to prevent and identify this illegal practice. Using dye-coated one-dimensional (1D) nanowires, researchers at the Korea Advanced Institute of Science and Technology (KAIST) in South Korea have demonstrated that randomly distributed nanowires can generate unique and simple barcode patterns readily applicable by many to anti-counterfeiting.

Reporting in Nanotechnology, nanoscale fingerprint patterns are generated by simply casting fluorescent dye-coated silver nanowires onto a transferrable flexible polyethylene terephthalate (PET) film. The direction and target markers ("KAIST" and "X") are patterned by a photolithographic technique to provide positional information for identification and the nanowires are cast onto it. Then, using an optical microscope, the resulting unique fingerprint patterns can be visually authenticated in a simple and straightforward manner, as shown fully in the figure above.

Nano Tech Web: Combatting counterfeit goods with nanoscale fingerprints