An “artificial retina” developed at the University of Sydney may one day restore sight to the blind, according to its creator, Matthew Griffith of the Australian Centre for Microscopy & Microanalysis and the School of Aerospace, Mechanical and Mechatronic Engineering. The electrical device acts like a retina, using absorbed light to fire neurons to transmit signals. It was created using multicolored carbon-based semiconductors. The device is a type of neural interface; it interacts with a person’s nervous system to record or stimulate activity, and it functions like the actual retina. It receives light taken in through the eye, which it converts into neural signals that are sent to the brain for processing. Matthew Griffith’s low-cost, printed device. Courtesy of the University of Sydney. “Among other functions, neurons are the body's signal conductors. A missing neuron link, which can be caused by, for example, a spinal cord injury, can cause severe problems. It can also be debilitating if neurons misfire. This can cause blindness and deafness, as well as diseases like Parkinson’s and epilepsy, for which there is no cure,” Griffith said. “Neural interfaces can bridge this neuronal divide, or, in the case of misfiring, reprogram the neurons.” In the case of Griffith’s artificial retina, the device is implanted into the retina through a surgical procedure. “Similar technologies are being intensively developed, though our device differs in that it is made of carbon — the same building block as human cells,” he said. “Other devices tend to be rigid and usually made of silicon or metal, which can present problems integrating with the human body that is soft and flexible. Our organic device is designed with this in mind.” The device is designed to be printed — in a similar, low-cost method to newspapers — onto soft and flexible surfaces from water-based inks that contain nerve growth factors. Once the device is implanted, the relevant neurons begin to reconnect, returning lost function to the retina as it is stimulated with light. Early tests examined the growth of neuronal cells from mice onto the semiconductors in a petri dish, after which the electrical activity was tested. “Not only did these cells survive — they grew and maintained neural functionality,” Griffith said. “The next step is to control where they grow by printing nanopatterns. This is so in the future we can direct them to grow into specific bodily locations, like a spinal cord or retina.” Comparable technologies are attempting to replicate both the eye and the brain in an effort to restore sight. “Patients do get some vision back, which is definitely life-changing for those without sight. However it’s not what you or I would think of as high-fidelity vision. Current state-of-the-art produces large blurry shapes in black and white,” Griffith said. Another key difference is that Griffith’s device does not require electricity; rather, it is powered internally by light from the outside world. “If successful, our device will help us progress toward solving one of the great scientific challenges of the 21st century: communicating with the human body’s sensory network,” Griffith said. “We hope to achieve this using nothing but light, which opens up some really exciting prospects for the future of bioelectronics technology.”
