New Scientist is reporting that Laxman Saggere of the University of Illinois at Chicago is working on an implantable retinal prosthesis that uses a photosensitive piezoelectric membrane to deliver a neurotransmitter to the retina.
Unlike other implants under development that apply an electric charge directly to retinal cells, the device does not cause the cells to heat up. It also uses very little power, so it does not need external batteries.
Now he has built a crucial component: a solar-powered actuator that flexes in response to the very low-intensity light that strikes the retina. Multiple actuators on a single chip pick up the details of the image focused on the retina, allowing some “pixels” to be passed on to the brain.
The prototype actuator consists of a flexible silicon disc just 1.5 millimetres in diameter and 15 micrometres thick. When light hits a silicon solar cell next to the disc it produces a voltage. The solar cell is connected to a layer of piezoelectric material called lead zirconate titanate (PZT), which changes shape in response to the voltage, pushing down on the silicon disc. In future, a reservoir will sit underneath the disc, and this action will squeeze the neurotransmitters out onto retinal cells.
Cool idea. A fundamental challenge will be figuring out how to re-fill those resevoirs of transmitter, though.
Hat tip: Gizmodo