Collaboration between researchers at University of California (San Diego) and Nanovision Biosciences (La Jolla, CA) has produced a method for constructing wirelessly powered high-resolution retinal prostheses that interface directly with retinal cells. A rat retina interfacing with a prototype of the device in vitro demonstrated the ability of the device to restore the ability of retinal neurons to respond to light.
Silicon nanowire arrays simultaneously sense light and electrically stimulate the retina accordingly. These nanowires give the prosthesis higher resolution than anything achieved by other devices—closer to the dense spacing of photoreceptors in the human retina. A wireless device transmits power and data to the nanowires over the same wireless link at record speed and energy efficiency.
Existing retinal prostheses require a vision sensor outside of the eye to capture a visual scene and then transform it into alternating signals to sequentially stimulate retinal neurons. In the new device, silicon nanowires mimic the retina’s light-sensing cones and rods to directly stimulate retinal cells. Nanowires are bundled into a grid of electrodes, directly activated by light and powered by a single wireless electrical signal. The design affords a much simpler—and scalable—architecture for the prosthesis.
The implant is wirelessly powered through an inductive powering telemetry system which transmits both power and data over a single pair of inductive coils. One pair emits from outside the body and the other on the receiving side in the eye. One bit of data is sent and received for every two cycles of the 13.56 megahertz RF signal; other two-coil systems need at least 5 cycles for every bit transmitted.
The researchers plan to develop and translate the technology into clinical use, with the goal of restoring functional vision in patients with severe retinal degeneration. Animal tests with the device are in progress, with clinical trials following.
