Fine pattern printing without applying voltage to curved non-conductors
Dr. Seol Seung-Kwon’s smart 3D printing research team at KERI and Professor Lim-Doo Jeong’s team at the Ulsan National Institute of Science and Technology (UNIST) have developed a core technology for smart contact lenses that can implement augmented reality (AR)-based navigation. developed. in the 3D printing process.
Smart contact lenses are products that are worn on the human eye like normal lenses and provide a variety of information. Research into lenses is primarily for the purpose of health diagnosis and treatment. Recently, Google and others are developing Smart His Contacts His Lenses for displays that can implement AR. However, there are many obstacles to commercialization due to severe technical challenges.
In order to realize AR with smart contact lenses, an electrochromic1) display that can be driven with low power consumption is suitable, and as a lens material, “pure Prussian blue”, which has high price competitiveness and rapid contrast and color transition. Color is the focus. However, until now, colors have been applied to substrates in the form of films using an electroplating method2), which limits the ability to manufacture advanced displays capable of expressing various types of information (characters, numbers, and images). bottom. “
The result of KERI-UNIST is that it is a technology that can realize AR by printing fine patterns on the lens display with a 3D printer without applying voltage. What is important is the used ink meniscus. A meniscus is a phenomenon in which when a water drop is lightly pushed or pulled with a certain pressure, a curved surface is formed on the outer wall without the water drop bursting due to capillary action.
Prussian blue is crystallized by solvent evaporation at the meniscus formed between the micronozzle and the substrate. A meniscus of ferric acid ferricyanide ink is formed on the substrate when the ink-filled micronozzle contacts the substrate. Heterogeneous crystallization of FeFe(CN)6 occurs on the substrate within the meniscus via spontaneous reactions of precursor ions (Fe3+ and Fe(CN)3?) at room temperature. At the same time, solvent evaporation occurs at the meniscus surface. When water evaporates from the meniscus, water molecules and precursor ions move towards the meniscus surface by convection, preferentially accumulating precursor ions on the outer part of the meniscus. This phenomenon causes edge-enhanced crystallization of FeFe(CN)6. This is important to control the factors affecting FeFe(CN)6 crystallization during the printing process to obtain a uniformly printed PB pattern on the substrate. As with conventional electroplating, the substrate had to be a conductor when a voltage was applied, but when using the meniscus phenomenon, the solvent spontaneously evaporates and crystallization occurs, so there are no restrictions on the substrate that can be used. that is a big advantage. .
Precise movement of the nozzle continuously crystallizes Prussian blue to form a fine pattern. Patterns can be formed not only on flat surfaces but also on curved surfaces. The research team’s micropattern technology is so fine (7.2 micrometers) that it can be applied to smart contact lens displays for AR, and the colors are continuous and uniform.
The main expected application area is navigation. Just put on the lens and AR will unfold navigation in front of your eyes. Games such as the popular Pokémon GO can also be enjoyed with smart contact lenses instead of smartphones.
KERI’s Dr. Seol Seung-Kwon said: “It will greatly contribute to the miniaturization and versatility of AR devices,” he added.
The related research results were published in recognition of their excellence as the cover article of Advanced Science (IF 17.521/JCR 4.71%), a world-famous academic journal in the field of materials science.
The research team believes that this achievement will attract a great deal of attention not only from the AR field, but also from companies related to batteries and biosensors that require fine patterning of Prussian blue. We plan to proceed with
Original: A smart contact lens with a navigation function made with a 3D printer!
Than: Ulsan Institute of Science and Technology
