Plasmonic nanopapers: flexible, stable and sensitive multiplex PUF tags for unclonable anti-counterfeiting applications

Abstract

Highly flexible and stable plasmonic nanopaper comprised of silver nanocubes and cellulose nanofibres was fabricated through a self-assembly-assisted vacuum filtration method.

Chemically stable fluorescent anti-counterfeiting labels achieved by UV-induced photolysis of nanocellulose

“…The building blocks (i.e., cellulose nano-bers) of the paper were extracted from garlic husk. [27][28][29] It is well known that natural garlic husk consists of cellulose, hemicellulose, lignin and ash. The hemicellulose and lignin residues were removed during the NaOH/NaClO treatment and H 2 SO 4 treatment, respectively.…”

“…The high-resolution C 1s XPS spectra of the same samples shows that there are four different types of carbon species with binding energy at 284.8 eV, 286.7 eV, 288.2 eV and 289.4 eV, which are assigned to the carbon in C-C/ C]C, C-O, C]O and O-C]O groups, respectively. 28,29 Interestingly, when using C-C peaks as a reference, the intensity of the C 1s XPS peaks at 286.7 eV, 288.2 eV and 289.4 eV increase slightly aer UV light exposure, indicating partial of hydroxyl groups were converted to C-O, C]O and O-C]O groups during the UV exposure. The increase of the amount of carboxyl acid groups on the area exposed to UV light can lead to the increased hydrophilia of the cellulose nanober paper, as carboxyl acid groups are more hydrophilic than hydroxyl groups.…”

“…Extraction of cellulose nanobers from garlic husk was conducted using a previously reported method with minor modi-cation. [27][28][29] In a typical procedure, 10 g of dried garlic husk was immersed in 400 g of NaOH solution (2 wt%) at 140 C for 5 h and then washed with ultrapure water. Subsequently, the obtained garlic skin was added to a mixture of 200 g of H 2 SO 4 solution (2 wt%) and 300 g of sodium hypochlorite (1.5 wt%) and stirred at 80 C for 6 h to remove the lignin.…”

Surface-enhanced Raman scattering-based molecular encoding with gold nanostars for anticounterfeiting applications

“…17 In addition, there were also examples of combining SERS labels with bar codes, quick response (QR) codes, or physically unclonable features. [27][28][29][30][31] In these studies, a SERS active substrate is a key component for the successful application of their materials in anticounterfeiting. While lithography methods were still widely used in making SERS-active plasmonic substrates, chemical syntheses of plasmonic nanomaterials have several advantages such as high tunability, easy processability, and low cost.…”

Improving the longevity of optically-read quantum dot physical unclonable functions

“…From a cryptographic standpoint, PUFs are classified as one-way functions, their unique nature prevents an attacker from deciphering how to recreate a particular PUF 4 . Methods of creating PUFs include stochastic processes 7 and nanomaterials 8 , in particular optically-active quantum dots 1 , 9 .…”