Nano-Ink for Glowing Holograms

Examples of printed europium-doped zirconia particles for glowing holographic coatings with a high degree of protection. (Source: ITMO)

Researchers at ITMO Univer­sity in Saint Peters­burg have unveiled a new approach to printing lumines­cent structures based on nano­particle ink. The unique optical proper­ties of the ink were achieved by means of euro­pium-doped zirconia. Particles of this material were proven to be useful in manu­facturing glowing holo­graphic coatings with a high degree of pro­tection. Notably, the developed approach enables the fabrication of custom holo­grams by means of a simple inkjet printer.

The idea of Inkjet printing using func­tional nano­particles has been gaining a lot of traction in recent years. Due to a number of advan­tages – lack of toxicity, high refrac­tion index and high quantum yield  – lumines­cent nano­particles are finding more applications in the fields of photonics, thera­nostics and bio­imaging; they are used to produce biosensors, visualize cancer cells and in security printing tech­nology. But to implement lab-made solutions on a bigger scale, a number of steps need to be taken to ensure proper func­tionality and stabi­lity during long-term storage of holograms.

The new ink possesses charac­teristics that address precisely these issues. In a series of experi­ments the material was used for printing mono­layers of lumines­cent-protected holograms and anti-counter­feiting objects with high stability and dura­bility. “Europium-doped zir­conium dioxide is a material that has been studied and used by researchers all over the world for decades. However, our research is novel in that it uses the material to protect the surface of rainbow holograms. To this end, we had to achieve certain features in the material. In particular, the nano­particles contained in the ink must be close to identical in size. Strict require­ments are also imposed by rheo­logical para­meters that deter­mine the visco­sity of the material – other­wise, the ink might not be suitable for inkjet printing. Our goal was to transform a material that was initially synthe­sized in a test tube into a stable colloid that could be printed and applied to any surface. Our study describes the exact process of creating such func­tional ink,” – comments Alexandr Vino­gradov, head of ITMO University’s Bio­chemistry Cluster.

This is far from the first research into inkjet printing of lumi­nescent optical nano­structures that has been done at ITMO University. The study builds on previous work conducted as part of a bigger project funded by the Russian Science Foun­dation. Earlier, the scientists developed the world’s first method of printing holo­graphic images using an inkjet printer. Back then, the team used ink based on titanium dioxide. One of the most promising appli­cations for the new ink is in the field of security printing – such as poly­graphic manu­facture of bills, bonds and documents. The new method makes it possible to create varied individual holo­grams on industrial scale – for instance, a specific pattern or a number sequence on a document that requires pro­tection. The ink is compatible with currently-existing print­head types and can be used with existing manu­facturing capa­bilities. (Source: ITMO)

Reference: A. D. Furasova et al.: Inkjet fabrication of highly efficient luminescent Eu-doped ZrO2 nanostructures, Nanoscale, in press (2017); DOI: 10.1039/C7NR03175K

Link: SCAMT Lab., ITMO University, St. Petersburg, Russia 

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