Engineering news
The technology, built from nanowires and wireless electronics, works by restoring the ability in neurons in the retina to respond to light.
A team of engineers at the University of California San Diego and startup Nanovision Biosciences successfully tested this response to light in a rat retina using a prototype of the device in vitro (placed outside of the rat’s body).
The technology could help tens of millions of people worldwide suffering from incurable, debilitating diseases that affect eyesight, including macular degeneration, retinitis pigmentosa and loss of vision due to diabetes, said the researchers.
Scott Thorogood, co-founder of Nanovision Biosciences said that the team had made “rapid progress” with the development of the “world’s first nano-engineered retinal prosthesis.”
While there have been advances in the development of retinal prostheses in the last two decades, the performance of devices to help the blind regain functional vision is still “severely limited” and well under the threshold of 20/200 that defines legal blindness.
"We want to create a new class of devices with drastically improved capabilities to help people with impaired vision," said Gabriel A. Silva, one of the senior authors of the work and professor in bioengineering and ophthalmology at UC San Diego.
The new prosthesis relies on two technologies. One consists of arrays of silicon nanowires that simultaneously sense light and electrically stimulate the retina to respond to it. The nanowires give the prosthesis higher resolution than anything achieved by other devices, according to the researchers, and is “closer to the dense spacing of photoreceptors in the human retina”.
The second technology is a wireless device that can transmit power and data to the nanowires over the same wireless link at what the researchers claim is “record speed and energy efficiency”.
Unlike current retinal prostheses the prototype doesn’t use a vision sensor outside of the eye to capture an image of the scenery and transform it in to signals, which then stimulate the retinal neurons. Instead, the silicon nanowires mimic the retina's light-sensing cones and rods to directly stimulate retinal cells.
Nanowires are bundled into a grid of electrodes, activated by light and powered by a single wireless electrical signal. “This makes for a much simpler and scalable architecture for the prosthesis,” said the researchers.
The power provided to the nanowires from the single wireless electrical signal gives the light-activated electrodes their high sensitivity while also controlling the timing of stimulation.
"To restore functional vision, it is critical that the neural interface matches the resolution and sensitivity of the human retina," said Gert Cauwenberghs, the paper's senior author.
Power is delivered wirelessly, from outside the body to the implant, through an “inductive powering telemetry” system developed by the team.
The device can minimise energy loss in wireless power and data transmission and in the stimulation process. This is achieved by recycling electrostatic energy circulating within the device. Up to 90% of the energy is used for stimulation, which means less radio frequency (RF) wireless power being lost through heat, and less heating of the surrounding tissue.
The telemetry system can transmit both power and data over a single pair of inductive coils, one emitting from outside the body, and another on the receiving side in the eye. The link can send and receive one bit of data for every two cycles of the 13.56 megahertz RF signal; other two-coil systems need at least 5 cycles for every bit transmitted.