KRYPTEN and scientists from ITMO University (St. Petersburg, Russia) have developed NANOPRINT inkjet printing technology for covert colour polarized images based on nanocrystalline cellulose. The latent images are invisible in regular light conditions and visualized in polarized light from a smartphone display. 

The joint project combined the developments of KRYPTEN’s Holographic Laboratory in the field of polarized hidden images (HIT® and SMART-HIT® (Hidden Image Technology)) and studies of ITMO University connected with the invention of ink-based on cellulose nanoparticles. As a result, a technology of commercial inkjet printing of hidden images was obtained.

Technology secrets

NANOPRINT technology uses special methods for the chemical synthesis of inks and their application to a surface. Ink feed algorithms control the orientation of cellulose nanoparticles during printing to create an optical effect of colour images visible in polarized light.

The new ink consists of special particles about 10 nanometres wide and around 200 nanometres long. In the initial solution, they are organized chaotically. NANOPRINT technology modifies the properties of nanoparticles in solution (a charge, ionic force) so that the particle dynamics arranges them parallel to each other. As a result, cellulose nanoparticles are arranged on the surface not in a random order but along the axis and form a specific ordered structure. 

After drying, the ink creates an optically active coating. A certain thickness of the image is set to create the polarized effect. The interference effect is obtained when the coating thickness is at least 10 microns.

The technology allows the printing of high-resolution objects including digits, letters, logos, and patterns.

How to use

NANOPRINT offers new opportunities for protecting goods against counterfeiting. The manufacturer gets a new secure and cost-efficient method of fast application of security features to the products. Nanocrystalline cellulose ink reduces considerably the cost of hidden image printing as compared to expensive liquid crystals featuring similar optical effects.

Hidden images are easily visualized in polarized light from a smartphone, LCD screen, or ordinary polarizer. Product identification does not require any complex devices or equipment. The effect of invisible image attracts the buyer’s attention engaging in product authentication.

The cost-saving method of printing based on cellulose nanoparticles enables using NANOPRINT technology in the serial production of security features. NANOPRINT polarized images can be used to protect documents, packaging or be applied to security labels. NANOPRINT covert symbols are suitable for the labeling of goods.

Andrey Smirnov, the Head of KRYPTEN’s Holographic Laboratory: “In Russia, the mandatory labeling is implemented for a whole group of goods to trace their circulation from manufacturing to sale. However, this system does not guarantee package integrity and does not protect it against the replacement of its contents. We actively cooperate with the leading Russian universities, study new methods of optical protection of goods against counterfeit and develop security features ensuring the authenticity of goods. The project with our colleagues from ITMO’s Chembio Cluster offers new prospects for applying polarized latent images in goods protection. NANOPRINT is a robust and cost-efficient technology manufacturers can use to protect their goods against counterfeiting”.