3D-Printed Prussian Blue Ink Drives This Arduino Uno-Powered Augmented Reality Smart Contact Lens

Researchers from the Korea Electrotechnology Research Institute (KERI) and the Ulsan National Institute of Science and Technology (UNIST) have developed "core technology" for 3D-printed smart contact lenses based on low-power monochrome displays — and have proven its capabilities for augmented reality systems, including live navigation.

"Our achievement is a development of 3D printing technology that can print functional micro-patterns on non-[planar] substrate that can commercialize advanced smart contact lenses to implement AR [Augmented Reality]," says Seol Seung-Kwon, PhD, of the team's work. "It will greatly contribute to the miniaturization and versatility of AR devices."

Smart contact lenses are the "holy grail" of augmented reality technology. Rather than relying on often-bulky glasses with micro-displays and complex optics, or the clip-on monocle design recently released by Brilliant, a smart contact lens simply sits on the surface of the eye and overlays information on the user's vision.

Creating a smart lens thin enough and capable of running at a very low power, though, is a challenge — which is where the team's 3D printing approach comes in. The researchers have demonstrated the ability to print micro-patterns of Prussian blue ink on the lenses, which then crystallizes when the solvent evaporates.

In testing, the printing system was able to create patterns as fine as 7.2 micrometers, suitable for augmented reality display use, with a continuous and uniform color — and the team is hopeful the technology will prove suitable for augmented reality displays. To prove that, a prototype was developed of an augmented reality smart lens with live navigation capabilities — projecting direction arrows, as well as "stop" and "go" signs, over the user's vision to guide them to a location via an external GPS receiver built using an Arduino Uno microcontroller board.

The technology has some way to go to commercialization, however: the prototype AR navigation lens was tested on a 3D-printed replica eyeball, with a hole cut in the rear to provide a means to see what a user would see, but has not yet found its way onto a living human's eye.

The team's work has been published under open-access terms in the journal Advanced Science.