KIT and ZEISS declare war on product piracy. Printed, fluorescent 3D microstructures offer increased protection against counterfeiting.
Leather goods, works of art, jewelry - there is hardly an area in which product counterfeiting has not become commonplace. In 2017 alone, German customs removed 3,295,600 counterfeit items worth 196 million euros from circulation. According to estimates by the consulting firm Ernst & Young, the German economy suffers annual damage of 56 billion euros as a result. However, not only manufacturers are almost powerless in the face of declining market shares and image losses; customers also have to contend with the negative consequences of product piracy. There is a clear need for action, especially when the products affected are those for which safety and reliability are in question, for example in the case of automotive spare parts.
One solution could be to continue developing security features that clearly distinguish originals from counterfeits. "Today, most optical security features are based on two-dimensional structures, such as holograms. However, is has already been possible to imitate these processes in the past and transfer them to counterfeits as stamps. Science and product counterfeiters are in a permanent race to develop new security features and imitate them," says Professor Martin Wegener, group leader at the Institute of Applied Physics and director of the Institute of Nanotechnology at KIT.
After Carl Zeiss AG inquired if it would be possible to produce such a security feature, he joined forces with scientist Frederik Mayer and ZEISS employees to develop an innovative process based on three-dimensional microstructures. These consist of a stable three-dimensional support framework in which quantum dots of fluorescent materials can be variably arranged. Layer by layer, a structure consisting of one non-fluorescent and two or more fluorescent photoresists is thus applied. This process is significantly safer than existing methods. "On the one hand, the addition of any number of different fluorescent materials enables a high number of variants, and on the other hand, it is very complex to manufacture due its multiple layers. This construct makes life difficult for counterfeiters," explains Frederik Mayer.
A high-resolution laser lithography device from Nanoscribe GmbH, a spin-off of KIT in which ZEISS also holds a stake, is used for printing. The laser beam of the printer passes through the liquid photoresist. The material is only exposed at the focal point of the laser beam and hardens. What is special here is the small size of the optical security features with a side length of 100 micrometers, which corresponds roughly to the thickness of an 80g/m² paper page. The advantage of this is that they are not visible to the human eye and can therefore be permanently applied to high-value products such as jewelry. The number of possible applications is endless. "One could conceivably integrate the filigree structure into security labels, which are used, for example, to distinguish pharmaceuticals or original spare parts from counterfeits. But it would also be possible to use the process in the field of document protection, for example as a security mark on ID cards and passports," says Professor Wegener. "However, a special reader that makes the fluorescent 3D structures visible is needed to read them out. Currently, we use a special confocal laser-scanning microscope for this purpose. To make the step into industrial use, the goal would be to develop a handy and significantly cheaper readout device for end users."
Stefan Richter, an employee in the Corporate Research & Technology department at ZEISS, emphasizes, "Our interest is currently focused primarily on research. Here, we see ourselves as a sparring partner and consultant, offering support in the area of measurement technology or the provision of optical components, for example. In the long term, of course, we also want to examine what a possible business model might look like, who potential customers are, and whether corresponding write and read-out devices meet with demand."