2D retinas could cure blindness

Materials World magazine
,
24 Sep 2018

Developments in a new 2D artificial retina promise not only significant improvements on current optical implants, but also 2D pacemakers applied to the heart and even a cure for blindness. Khai Trung Le reports.

Presently, there is no cure for retinitis pigmentosa, diabetic retinopathy, or many ailments that can lead to macular degeneration, destroying retina and resulting in severe loss of eyesight. However, a 2D artificial retina developed by the Seoul National University, South Korea, and the University of Texas at Austin, USA, promises not only vast improvements on current visualisation technology, but also the potential to track heart and brain activity, and even a cure for blindness.

Today, electrooculography (EOG) sensors are able to restore a small degree of vision but are rigid, flat, and fragile. Silicon implants can produce distorted or imprecise images, and may result in long-term strain or damage to surrounding eye tissue. The Texas electrooculography sensor system is referred to as a non-invasive graphene electronic tattoo (GET) comprising 2D layers of graphene and molybdenum disulphide, with thin layers of gold, alumina, and silicon nitrite.

The study, Imperceptible electrooculography graphene sensor system for human–robot interface, published in 2D Materials and Applications, specifies that the EOG sensor system can be laminated around the eyes without the use of adhesives or placing any constraints on blinking or facial expressions.

Laboratory and animal studies show the GET photodetectors are able to absorb light and pass it through a soft external circuit board that houses the electronics required to digitally process light and stimulate the retina, which the research team claims reveals the tattoo’s biocompatibility and successfully mimics the structural features of the human eye.

Other tests include connecting the GET sensors to a wireless transmitter to control a quadcopter. The paper stated, ‘To guide the eye movement, we placed a signalling board with five individually controllable LEDs in front of the subject. To measure the EOG of a specific eye movement, the subject was asked to move his eyes toward the only LED that was on at a given time […] We observed clear voltage steps for successive eye movement of 4˚ in both horizontal and vertical directions.’

In a statement to Materials World, Dr Nanshu Lu, Associate Professor of Biomedical Engineering at the University of Texas at Austin, said, ‘This is the first demonstration that you can use few-layer graphene and molybdenum disulphide to successfully fabricate an artificial retina. Although this research is still in its infancy, it is a very exciting starting point for the use of these materials to restore vision.’

Although materials from Texas at Austin claim the device may one day lead to a cure for blindness, Lu did not comment further to Materials World on this potential.

Lu is now looking to investigate functionalising the GET for other means, including mechanically and optically imperceptible tattoos laminated on a person’s skin to monitor real-time health information, requiring the addition of transistors to support amplifying signals from the brain or heart, or even applying it directly to the heart to detect arrhythmias or to be programmed to operate as pacemakers.