A research team at the Korea Electrotechnology Research Institute (KERI) and Ulsan National Institute of Science and Technology (UNIST) has developed a smart contact lens with augmented reality (AR)-based navigation capabilities, using a 3D printing process.
The lens uses the technology to print functional micro-patterns on non-planar substrates, including curved contact lenses. This new technology is the first to use a meniscus phenomenon to crystallize Pure Prussian Blue (PB) color onto the lens, making it possible to produce advanced displays that can express various information, such as letters, numbers, and images. Prussian blue is a dark blue pigment that is commonly used in art and painting. It is also used in various other applications, including as a dye, a photographic toner, and a medical treatment for heavy metal poisoning.
The meniscus is the result of capillary action, where a curved surface forms on the outer wall when water droplets are gently pressed or pulled, without bursting.
Specifically, Prussian blue is formed on a substrate through the heterogeneous crystallization of FeFe(CN)6 via spontaneous reactions of precursor ions at room temperature in the meniscus formed between the ink-filled micronozzle and substrate.
Simultaneously, solvent evaporation occurs at the meniscus surface, inducing edge-enhanced crystallization of FeFe(CN)6. The meniscus phenomenon allows for the formation of uniformly printed Prussian blue patterns on any type of substrate, regardless of its conductivity. As a result, the process requires no voltage, unlike electroplating.
The team’s micro-pattern technology is very fine and uniform, making it possible to fabricate AR-powered smart contact lenses.
The expected application area is navigation, as well as gaming.
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