First Transistor That Mimics Brain Synapse
French researchers have created what they claim is the first transistor to mimic the connections in the human brain. It could lead to neurology-inspired computers, as well as provide a means for connecting artificial devices to existing biological tissue.
Schematic diagram illustrating how the NOMFET (bottom)
mimics a synapse (top). In a synapse, voltage spikes
(blue triangles) are converted to a chemical signal (orange arrow),
which flows across a gap. Once across, the chemical stimulates
the creation of new voltage spikes.
(Courtesy: Dominique Vuillaume))
The team, which includes scientists from the CNRS (the French National Science Agency) and CEA (the French Atomic Energy Commission), began by adding gold nanoparticles to the interface between an insulating layer (gate dielectric) and an organic transistor made of pentacene. They fixed the nanoparticles, which were 5, 10 and 20 nm in diameter, into the source-drain channel of the device using surface chemistry techniques and finished the structure by covering it with a 35 nm thick film of pentacene. The resulting device is called a nanoparticle organic memory field-effect transistor or "NOMFET".
A biological synapse transforms a voltage spike (action potential) arriving from a pre-synaptic neuron into a discharge of chemical neurotransmitters that are then detected by a post-synaptic neuron. These are subsequently transformed into new spikes, leading to a succession of pulses that either become larger or diminish in size. This fundamental property of synaptic behaviour is known as short-term plasticity, which is related to a neural network's ability to learn. It is this plasticity that Vuillaume and colleagues have succeeded in mimicking.
In the NOMFET, the pre-synaptic signal is simply the pulse voltage applied to the device and the output signal is the drain current, explains Vuillaume. The holes – the charge carriers in the p-type organic semiconductor employed – are trapped in the nanoparticles and act like the neurotransmitters. A certain number of holes are trapped for each incoming spike voltage and in the absence of pulses, the holes escape in a matter of seconds
This time delay is carefully adjusted by the researchers by optimizing nanoparticle number and device geometry. "The output of the NOMFET is thus able to reproduce the deceasing or amplifying behaviour typical of a synapse depending on the frequency of spikes," said Vuillaume.
Science fiction fans recall that Isaac Asimov, in his short story Reason, wrote about a similar idea:
All that had been done in the mid 20th century on "calculating machines" had been upset by Robertson and his positronic brain paths. The miles of relays and photocells had given way to the spongy globe of platinum iridium about the size of the human brain.
(Read more about the positronic brain)
A few years later, Philip K. Dick had fun with the idea of a Nexus-6 brain unit in his 1968 novel Do Androids Dream of Electric Sheep:
The Nexus-6 did have two trillion constituents plus a choice within a range of ten million possible combinations of cerebral activity. In .45 of a second an android equipped with such a brain could assume any one of fourteen basic reaction-postures. Well, no intelligence test could trap such an andy. But then, intelligence tests hadn't trapped an andy in years, not since the primordial, crude varieties of the 1970's.
From Physics World via Next Big Future.
Scroll down for more stories in the same category. (Story submitted 2/1/2010)
Follow this kind of news @Technovelgy.
| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
you like to contribute a story tip?
Get the URL of the story, and the related sf author, and add
Comment/Join discussion (Back On) ( 1 )
Related News Stories -
Millimeter-Scale Computing For 'Internet of Things'
'In their megalomania they thought to make the very sand beneath their feet intelligent...'- Stanislaw Lem, 1965.
Fujitsu Touchscreen Mixes Real And Virtual Worlds
'His hands flashed over the keyboard - it had not been there a moment before, but it was operative...'- Frederik Pohl, 1965.
Nanowire Memristor Networks Form 'Brains'
'He had constructed ... a brain, of metal... whose atomic structure he claimed was analogous to the atomic structure of a living brain.'- Edmond Hamilton, 1926.
US Census Will Be Online In 2020
'Most would be in English, but some would be in Spanish, some in Amerind languages, some in Chinese...'- John Brunner, 1975.
Technovelgy (that's tech-novel-gee!)
is devoted to the creative science inventions and ideas of sf authors. Look for
the Invention Category that interests
you, the Glossary, the Invention
Timeline, or see what's New.
Is Noam Chomsky As Paranoid As Philip K. Dick?
'I'm Bill Behren... Operator of fly 33408...'
Low-Cost, Implantable Electronics Get Closer
Better coatings need to become a reality.
'Marauder's Map' Created By Carnegie Melllon
'Is that Dumbledore in his study?'
Cheetah Cub Robot From PKD's Android Dreams
'What about an exact electric duplicate of your cat?'
Dead Cellphone? Try Solar-Powered Public Charging Stations
'Then he saw the geek ... leaning against one of the slender stalks of a sunshade-photocell collector...'
Hungry? Grow Nutritious Insects At Home
'...I balked when my wife served me termites.'
Snowboarding On Mars? Heinlein Was Ready
How long ago did Robert Heinlein write about skiing on dry alien worlds?
Orwell's '1984' Hits Bestseller Lists Thanks To PRISM
'There was of course no way of knowing whether you were being watched at any given moment.'
Roboroach Control? There's An App For That
'A cable, here, from the controller to the interface plug... wires from that to the brain.'
Court OK's DNA Collection Like 'Gattaca'
DNA sampling is not the same as fingerprinting.
Squid Vs. Whale Diorama Liked By Humans, Aliens
'Everything was ready, awaiting the Overlords' pleasure...'
Iceberg Harvesting Off Newfoundland's Coast
'Five hundred billion gallons worth of Antarctic iceberg had been towed into Santa Monica Bay.'
Sony's A4-Sized Flexible Digital Paper Notepad
'...he would plug his foolscap-sized Newspad into the ship's information circuit and scan the latest reports...'
Contact Lens Video Display Electronics Now Transparent
'He realized that it was not quite a clear lens. Speckles of colored brightness swirled and gathered in it...'
Tesla's Supercharge Station Plan
'To recharge the batteries, which can be done in almost every town and village...'
Millimeter-Scale Computing For 'Internet of Things'
'In their megalomania they thought to make the very sand beneath their feet intelligent...'
More SF in the News Stories
More Beyond Technovelgy science news stories