Researchers devise new printing technology for invisible images

In a new development, researchers at ChemioBio Cluster, University of ITMO have developed an inkjet printing technology. This technology makes it possible to produce images that are visible only in polarized light, such as the one produced using a smartphone screen. Using this technology, manufacturers can protect their products from forgery.

Meanwhile, to obtain the results, researchers worked for five years on a way to use solution chemistry methods to apply high-resolution organized structures. Broadly, the ability to generate images invisible to the naked eye is due to the manufacture of special colloidal ink based on nanoscale cellulose particles. These particles can orient themselves on a surface in a special manner.

To that end, the demand for printing materials that can protect products from counterfeiting and forgery is expanding at a geometric rate. As such, manufacturers use a number of QR codes and data signals. However, it is preferable to have techniques that are easy to access and don’t require large investments. The use of inkjet printing can make the process of launching the manufacture of packaging material significantly simpler. “Nonetheless, it calls for serious research for multiple years for the chemical composition of the ink.”

Under regular conditions, the distribution of nanoparticles is disorderly, using this special inkjet printing technique results in a nanoarchitecture. In a nanoarchitecture, the particles are strictly positioned parallel to each other. Meanwhile, the thickness of such coatings is chosen that allows certain optical phenomena noticed under polarized light. Thus, using a LCD screen, this allows to observe colorful optical response from the printed image, including that of a smartphone.

The programming of nanoparticles contained within the solution enables this effect.