Scientists report they have successfully developed and tested the world's first ultrathin artificial retina that could vastly improve on existing implantable visualization technology for the blind. The flexible device, based on very thin 2-D materials, could someday restore sight to the millions of people with retinal diseases. And with a few modifications, the device could be used to track heart and brain activity.
The researchers are presenting their work today at the 256th National Meeting & Exposition of the American Chemical Society (ACS).
"This is the first demonstration that you can use few-layer graphene and molybdenum disulfide to successfully fabricate an artificial retina," Nanshu Lu, Ph.D., says. "Although this research is still in its infancy, it is a very exciting starting point for the use of these materials to restore vision," she says, adding that this device could also be implanted elsewhere in the body to monitor heart and brain activities.
[...] Diseases such as macular degeneration, diabetic retinopathy and retinitis pigmentosa can damage or destroy retinal tissue, leading to vision loss or complete blindness. There is no cure for many of these diseases, but silicon-based retinal implants have restored a modicum of vision to some individuals. However, Lu says these devices are rigid, flat and fragile, making it hard for them to replicate the natural curvature of the retina. As a result, silicon-based retinal implants often produce blurry or distorted images and can cause long-term strain or damage to surrounding eye tissue, including the optic nerve. Lu, who is at the University of Texas at Austin, and her collaborator Dae-Hyeong Kim, Ph.D., who is at Seoul National University, sought to develop a thinner, more flexible alternative that would better mimic the shape and function of a natural retina.
The researchers used 2-D materials, including graphene and molybdenum disulfide, as well as thin layers of gold, alumina and silicon nitrate to create a flexible, high-density and curved sensor array. The device, which resembles the surface of a flattened soccer ball or icosahedron, conforms to the size and shape of a natural retina without mechanically disturbing it.
Source: https://phys.org/news/2018-08-artificial-retinas-based-d-materials.html.
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Toward brain-like computing: New memristor better mimics synapses
A new electronic device developed at the University of Michigan (U-M) can directly model the behaviors of a synapse, which is a connection between two neurons.
For the first time, the way that neurons share or compete for resources can be explored in hardware without the need for complicated circuits.
"Neuroscientists have argued that competition and cooperation behaviors among synapses are very important. Our new memristive devices allow us to implement a faithful model of these behaviors in a solid-state system," said Wei Lu, U-M professor of electrical and computer engineering and senior author of the study in Nature Materials.
[...] The memristor is a good model for a synapse. It mimics the way that the connections between neurons strengthen or weaken when signals pass through them. But the changes in conductance typically come from changes in the shape of the channels of conductive material within the memristor. These channels—and the memristor's ability to conduct electricity—could not be precisely controlled in previous devices.
Now, the U-M team has made a memristor in which they have better command of the conducting pathways.They developed a new material out of the semiconductor molybdenum disulfide—a "two-dimensional" material that can be peeled into layers just a few atoms thick. Lu's team injected lithium ions into the gaps between molybdenum disulfide layers.
They found that if there are enough lithium ions present, the molybdenum sulfide transforms its lattice structure, enabling electrons to run through the film easily as if it were a metal. But in areas with too few lithium ions, the molybdenum sulfide restores its original lattice structure and becomes a semiconductor, and electrical signals have a hard time getting through.
Related: This Tiny Electronic Chip Is Just 3 Atoms Thick
A New Generation of Artificial Retinas Based on 2-D Materials
Purdue University Researchers Identify Molybdenum Ditelluride as a Material for Next-Gen Memory
Ionic modulation and ionic coupling effects in MoS2 devices for neuromorphic computing (DOI: 10.1038/s41563-018-0248-5) (DX)
(Score: 0) by Anonymous Coward on Monday August 20 2018, @11:13PM
N/T
(Score: 1, Interesting) by Anonymous Coward on Monday August 20 2018, @11:13PM (1 child)
Goodbye Retinal scans!
(Score: 2, Funny) by Anonymous Coward on Monday August 20 2018, @11:26PM
You wish. They'll print a QR code on it.
(Score: 4, Interesting) by requerdanos on Tuesday August 21 2018, @12:27AM (2 children)
I suppose 2-D materials that are "very thin" are similar to 1-D materials that are "almost line-like".
A surprise for me was the potential appeal to advertisers--I note in TFA [phys.org] that, quote:
I mean what company wouldn't say "Hey that's much better than tracking cookies. Shut up and take my money!"
I suppose they are calling them 2-D to simply mean "really really thin" but I note that they curve into a third dimension to conform to the spheroid shape of the back of the eyeball.
I want to stress that bionic retinae that restore vision are very, very cool, even if there be parts that I don't understand or misunderstand.
(Score: 1) by beernutz on Tuesday August 21 2018, @06:08AM (1 child)
Maybe in this case they mean surfaces that are a single atom thick?
(Score: 2) by requerdanos on Tuesday August 21 2018, @11:30AM
That seems about right. I think if you go beyond the two dimensions of length and width and into the realm of a third dimension of thickness, however many atoms (or Planck lengths) thick, 2D stops being a descriptive term and starts being a metaphor.