Korean researchers have unveiled a smart contact lens they say is capable of implementing augmented reality-based navigation

With the advent of the Metaverse era, there have been growing expectations that virtual reality (VR) and augmented reality (AR) technologies will likely enhance convenience in everyday life, as well as improve industry productivity and performance.

A joint research team, affiliated with Ulsan National Institute of Science and Technology (UNIST) has introduced core technology for smart contact lenses that can implement AR-based navigation through a 3D-printing process. 

According to the research team, the new smart contact lenses can be worn inside the eye of a person, like a normal contact lens.

The breakthrough has been jointly led by Professor Im Doo Jung in the Department of Mechanical Engineering at UNIST and Dr Seung Kwon Seol from the Smart 3D-Printing Research Team at Korea Electrotechnology Research Institute (KERI).

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Severe technical challenges


Some of the disadvantages of existing AR devices include high cost, experimental technology, and bulky appearance, making them difficult to get access to the market.

Smart contact lenses, on the other hand, have the advantages of being affordable and convenient, as it can be worn inside the eye of a person.

Leading companies throughout the world, such as Google, are currently working on creating smart contact lenses, capable of implementing AR.

Still, there exists barriers that impede the effective and efficient commercialisation of research due to severe technical challenges.

In implementing AR with smart contact lenses, energy-saving electrochromic (EC) displays that can be driven with low power are suitable.

Prussian blue (PB) has been regarded as one of the attractive EC materials due to its uniform colouration, fast kinetics, high optical contrast, multiple colour states (blue, white, green), environmental friendliness, and cost competitiveness. 

However, this method has limitations in displaying words or images that are needed for a display on AR smart contact lenses because of the difficulty of micro-patterning PB on the contact lens, the research team noted.



Lens displays


The joint research team studied how to not use an electroplating process, and as a result, they developed a simple and effective printing strategy to produce micro-patterns of PB using the meniscus-guided printing of an acidic-ferric-ferricyanide ink composed of FeCl3, K3Fe(CN)6, and HCl. The key to this is the meniscus of the acidic-ferric-ferricyanide ink.

As with the conventional electroplating approach, the substrate used must be a conductor when voltage is applied. However, with the meniscus phenomenon, there is no restriction on the substrate that can be used because crystallisation occurs by natural evaporation of the solvent.

The micro-pattern technology is very fine (7.2 micrometres) that can be applied to smart contact lens displays for AR, and the colour is continuous and uniform.

The role of smart contact lenses is most anticipated in fields such as navigation. Through experiments, researchers successfully demonstrated PB-based EC displays in a smart contact lens with a navigation function. 

The device was able to display directions to the destination to the user on the EC display by receiving GPS co-ordinates in real time, noted the research team.

The research team said: “Although thin glass ITO was used for the EC display in this study, it can be further developed as a method of patterning transparent electrodes, such as graphene on flexible materials and printing EC materials.

“We believe that our novel strategy will serve as an attractive method for realising PB-based EC displays as well as diverse functional devices with micro PB patterns.”

The research is published in Advanced Science.

Image 1: איתן טל CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/legalcode).

Image 2: Electrochromic (EC) display for navigation system embedded in a contact lens. © UNIST.