Scientists 3D-Print Contact Lens With Built-In LED

LED contact lens
Tanya Padashenko holds the world's first one-day disposable ultra-violet (UV) radiation protective contact lens at it's launch in Sydney July 17. Australia was chosen as the first country in the world to be offered this type of contact lens due to its population being at a higher risk to developing eye damage as a result of a significant depletion of the ozone layer in the southern hemisphere. Reuters

Researchers at the University of Washington have created a contact lens with an LED display built into it. Whilst at present the contact lens device has only a single pixel of information, the researchers say it could be developed to display more complex information such as emails, creating a Google Glass-like contact lens, just one third of a millimeter in diameter.

Whilst theoretically it’s not difficult to build a display in a contact lens, actually fabricating the tiny, interrelated parts and then placing them on a miniature polymer disk is a very difficult task.

However, the 3D printer, or 3D quantum dot LED printer to be more precise, has made this task a lot easier for researchers. Rather than the standard ‘domed plastic light bulbs’ that we recognize LEDs to be, the 3D printer works by sandwiching together different layers of interacting material, each with a different task.

The emissive layer contains so-called ‘quantum dots’, nanocrystals of specific substances that have unique or useful electronic properties. These are sandwiched between a layer that donates electrons and and a layer that accepts electrons, the movement of which causes the quantum dots to radiate photons of light at very specific wavelengths or colour, as they pass through the emissive layer. This technology has the potential to create accurate displays of colours, and therefore images which the wearer will be able to see.

The whole thing is then fused to the surface of the lens via the adhesive layer, which is activated by UV light.

The process is problematic because it requires a lot of power, which is provided wirelessly via an antenna embedded in the lens. To store the energy, the lens also contains an integrated circuit only one thousandth of a human hair thick. This energy is then transferred to a chip containing a single blue LED.  

At present, the prototype for the 3D printer costs about $20,000 to create meaning that large scale production is still some way off. However, the implications of the research, published in the Journal of Micromechanics and Microengineering, are important - as well as contact lens displays, small and flexible LEDs like these could be used to improve the display technology of many small devices including smart glasses.