The three dimensional structures of the micrometer and nanometer rocks have great potential for many applications. An efficient and accurate process for printing such structures from different materials has already been presented by researchers at the Karlsruhe Technological Institute (KIT) and Carl Zeiss AG in Scientific Achievements: they integrated a microfluidic camera into a 3D laser lithographic device. They then use this system to produce multicolour, fluorescent security features to protect banknotes, documents and branded counterfeit products.
From components for processing data from light to optical microwaves, mechanical metamaterials or artificial cell scaffolds to banknote or branded security features, three-dimensional micro- and nanostructured prints have a wide range of applications. 3D laser lithography has become an established, reliable and flexible process for their production. The laser beam passes through a liquid photoresist in a computer controlled manner and the material is exposed and hardens only at the focal point of the laser beam. This results in highly precise filigree structures for many applications, including optics and photonics, materials science, biotechnology, or security technologies. Almost all micro- and nanostructures produced by 3D laser lithography so far consist of one material. But they can also be made of several materials by successively applying and curing various photoresists, whereby the unexposed resistor is washed in a subsequent bath. Such a process, however, takes a lot of time and is complicated and its precision decreases with increasing number of materials and repetitions.
Within the framework of the 3D Body of Excellence Cluster, scientists from the KIT Institute of Nanotechnology (API), Applied Physics (APH), Chemical Technology and Chemistry of Polymer (ITCP), and the Chemical Faculty of the University of Queensland Technologies (QUT) in Brisbane / Australia, together with researchers from Carl Zeiss AG, have already developed a new system for efficient and precise production of printed micro- and nanostructures from several materials. They integrated a microfluidic fluid chamber in the smallest space directly into a 3D laser lithographic device.
In their publication & quot; Multimaterial 3D Laser Microspray Using an Integrated Microfluidic System & quot; Scientific AchievementsResearchers report using the integrated system for producing three-dimensional microstructured security features of seven different liquids: a non-fluorescence photoresist such as a backbone, two photoresists with different fluorescence quantum dots, two photoresist with different fluorescent dyes and two liquids. protect banknotes, documents and branded products against counterfeiting. The security element consists of a three-dimensional grid enclosed by supporting walls and fluorescent markers in different colors.
For their system, scientists used a 3D laser lithographic device developed and commercialized by Nanoscribe GmbH, spinoff on KIT, and integrated it into a self-developed microfluidic chamber. A ten millimeter glass roof is provided on which 3D structures can be printed. The camera is connected to electronic pressure control, up to ten containers for various photoresists and developers, and a star selection valve. The selected fluid is transferred to the sample holder via an overpressure valve. Finally, it flows into a waste container. "All steps to produce three-dimensional micro- and nanostructures from several materials can be integrated into one system," says Professor Martin Wegener, who heads the APH Task Force. "This system paves the way for the production of multimaterial micro- and nanoscale supplements."
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