Plasmonic nanopillar arrays encoded with multiplex molecular information for anti-counterfeiting applications†
A major challenge in information security and the development of an anti-counterfeiting platform is to encode multiple identification features on a single platform where these features can be decoded with no interference. Here, we demonstrate a progressively complex anti-counterfeiting platform using a multiplex fabrication strategy. This multiplex strategy enabled us to realize a spatially selective encapsulation of dye molecules within an Ag nanopillar array embedding covert molecular information which was revealed using fluorescence, surface-enhanced Raman scattering (SERS), and signal intensities. A total of five identification layers were used to authenticate products in our nanopillar platform. Moreover, two spectroscopic techniques were required to fully decode the various covert layers encoded within the same nanopillar array, thereby greatly enhancing the security of the information. Hyperspectral imaging was used to precisely generate unique SERS fingerprints of molecules encapsulated in each nanopillar. This feature combined with the high ∼17 000 pillars per inch (ppi) information density of the platform make its use extremely effective against counterfeiting and forgery. In summary, our encoding platform enables high security, large information density and low-error decoding.