A new process for embedding a liquid crystal display (LCD) screen into contact lenses promises the development of applications for medical and beauty purposes not far down the road.
Among the range of system-connected ‘wearables’ being developed, we can now include contact lenses. Researchers at the University of Washington, in conjunction with Aalto University, had already developed a contact lens able to display an image that can be perceived by the eye. In the same vein, work is being done at the Centre for MicroSystems Technology (CMST), a laboratory affiliated with the Interuniversity Microelectronics Centre (IMEC), a micro- and nanoelectronics research centre headquartered in Leuven, Belgium. Their adapted contact lens surface can on the one hand modulate incoming light and, on the other, externally display an image using LCD technology. This process could be used for medical purposes, for example by creating an artificial iris to control light travelling towards the eye's retina when the iris is damaged. It could also be used to give the iris a ‘tuneable’ colour, allowing the user to change it to suit his/her mood. The process works by using a new spherical curved LCD display, which can be embedded in contact lenses. The first prototype the researchers created was a dollar sign, a clear nod to the common cartoon trick where the characters appear to have dollar signs in their eyes.
Moulding the screen shape
In contrast to light-emitting diode (LED)-based displays forcontact lenses, where the display resolution is limited to only a small number of pixels, IMEC’s LCD-based technology enables the entire display surface to be used. The images projected are not intended for the wearer of the lens to view him/herself, as the human eye would be unable to focus on such a close-up object. They would only be seen by others. However the display aspect is not the project’s main objective. One application would be where the contact lenses act as adaptable sunglasses. Explaining the technical innovation, Jelle De Smet, the chief researcher on the project, pointed out that:“Normally, flexible displays using liquid crystal cells are not designed to be formed into a new shape, especially not a spherical one.” The main challenge was therefore to create a very thin, spherically curved substrate with active layers that could withstandthe extreme moulding processes.“We had to use very thin polymer films, and their influence on the smoothness of the display had to be studied in detail,” underlined De Smet.
By using new kinds of conductive polymers and integrating them into a smooth spherical cell, the researchers were able to construct a new LCD-based contact lens display. In future, the new system might also be used for a head-up display, in a car for example, by superimposing an image on to the user’s normal sight. Research is currently underway to resolve the focusing issue and see whether a display which is integrated into the contact lens could actually be seen by the contact lens wearer him/herself. The researchers are also now looking at how to power the display autonomously, by for example integrating flexible solar cells and microbatteries into the surface layer.