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)
Related Stories
An Anonymous Coward has provided a story entitled: This Tiny Electronic Chip Is Just 3 Atoms Thick
A tiny electronic chip just three atoms thick could yield advanced circuits that are powerful, flexible and transparent, researchers said in a new study. The scientists said the chip demonstrates a new way to mass-produce atomically thin materials and electronics.
These materials could be used to develop electronic displays on windows or windshields, along with powerful microchips in which circuitry spreads not just two-dimensionally but also rises three-dimensionally, the researchers said.
For more than 50 years, silicon has been the backbone of the electronics industry. However, as silicon transistors reach the limit of miniaturization, scientists worldwide are investigating new materials that could serve as the foundation of even tinier devices. In the past decade or so, researchers discovered that atomically thin materials could serve as the basis of electronic devices. For instance, sheets of graphene — a material related to the "lead" in pencils — are each just one carbon atom thick. Graphene is an excellent conductor of electricity, making it ideal for use in wiring.
[...] Instead of graphene, therefore, some researchers are exploring molybdenite, or molybdenum disulfide (MoS2), for use in advanced electronics. Molybdenum disulfide is a semiconductor, and the new study finds that molybdenum disulfide transistors "can be switched on and off significantly better than graphene and somewhat better than silicon," said study senior author Eric Pop, an electrical engineer at Stanford University in California.
[...] To create their ultrathin chip, the scientists incinerated small amounts of molybdenum and sulfur and then used the resulting vapor to form molecule-thin layers of molybdenum disulfide on a variety of surfaces, such as glass or silicon. "We went through a lot of painstaking trial and error to find the right combination of temperature and pressure to help grow these layers in a repeatable manner," Pop said.
Using this new technique, the researchers manufactured single-molecule-thick molybdenum disulfide chips measuring about 0.06 inches (1.5 millimeters) wide. These chips are each about 25 million times wider than they are thick, the researchers said.
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.
Submitted via IRC for SoyCow1984
Data use draining your battery? Tiny device to speed up memory while also saving power
Millions of new memory cells could be part of a computer chip and [provide] speed and energy savings, thanks to the discovery of a previously unobserved functionality in a material called molybdenum ditelluride. The two-dimensional material stacks into multiple layers to build a memory cell.
Chip-maker companies have long called for better memory technologies to enable a growing network of smart devices. One of these next-generation possibilities is resistive random access memory, or RRAM for short. [...] A material would need to be robust enough for storing and retrieving data at least trillions of times, but materials currently used have been too unreliable. So RRAM hasn't been available yet for widescale use on computer chips. Molybdenum ditelluride could potentially last through all those cycles.
"We haven't yet explored system fatigue using this new material, but our hope is that it is both faster and more reliable than other approaches due to the unique switching mechanism we've observed," Joerg Appenzeller, Purdue University's Barry M. and Patricia L. Epstein Professor of Electrical and Computer Engineering and the scientific director of nanoelectronics at the Birck Nanotechnology Center.
Electric-field induced structural transition in vertical MoTe2- and Mo1–xWxTe2-based resistive memories (DOI: 10.1038/s41563-018-0234-y) (DX)
(Score: 2) by exaeta on Tuesday December 18 2018, @10:40PM
The Government is a Bird
(Score: 2) by hendrikboom on Tuesday December 18 2018, @11:51PM (7 children)
What *is* a memristor? What electrical properties make it a memory device?
(Score: 2, Informative) by NPC-131072 on Wednesday December 19 2018, @01:19AM (5 children)
All answered here [arstechnica.com]
(Score: 2) by takyon on Wednesday December 19 2018, @01:06PM (3 children)
I have the sneaking suspicion you're building your account's hit points so you can take a few hits. :-)
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Wednesday December 19 2018, @07:26PM (1 child)
That would be a cool idea for a social media site. Karma > XP, every time you max out karma, get a new life (level), get demoted to level -1, no posting for a week.
(Score: 2) by takyon on Wednesday December 19 2018, @07:34PM
If karma was not capped at 50 here, I'd probably have well over 20,000. I could then use that accumulated karma to advance up and become a Lvl. 69 White Knight.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1) by NPC-131072 on Wednesday December 19 2018, @10:57PM
Hello fren, it's not easy being the vanguard against nazis and transmisogynists. Also, "electrical properties" is not straightforward as there are different implementations.
(Score: 2) by hendrikboom on Wednesday December 19 2018, @03:13PM
Thanks. That was helpful.
(Score: 0) by Anonymous Coward on Wednesday December 19 2018, @07:40PM
Is this 'injection' of lithium possible with mass manufacturing fabrication techniques, or only in a lab? And if it is possible in the former case, does this process actually function through entirely electrical means? If it cannot be controlled easily by electricity, or has a sufficiently low read/write life for the cells, then it won't matter if it works if it is effectively single use (not unlike a brain in fact.)
A followup question is if the current resistances of a particular memristor could be read by a conventional semiconduction circuit manufactured on the same substrate alongside it, and then be used to back up the state of each individual memristor in the design, or additionally be used to prep a particular memristor to a desired value without having to initialize all memristors with the same initial stimulus used to create the original memristor 'brain'.
Answer these questions and it might finally be possible to not only emulate a human-like brain using semiconductor processors, but also back up and restore it during the development and testing of such a design. Until all of these facets are in place, any produced synthetic brains would be just as useless as a human one for creating a reproducible artificial consciousness.