Dear colleagues and friends
On April 25, 2024, in the newsletter of the University of Utrecht (UU), this article was published, which a dear colleague shared with us and which we translated for this space. Let's check what they tell us...
Theoretical physicists from Utrecht University, together with experimental physicists from Sogang University in South Korea, have succeeded in building an artificial synapse. This synapse works with water and salt and provides the first evidence that a system that uses the same medium as our brain can process complex information.
The results appear in the journal Proceedings of the National Academy of Sciences (PNAS).
In the quest to improve the energy efficiency of conventional computers, scientists have long turned to the human brain for inspiration. Their goal is to emulate their extraordinary ability in a number of ways.
These efforts have led to the development of brain-like computers, which move away from traditional binary processing to adopt analog methods similar to our brains. However, while our brains work using water and dissolved salt particles called ions as a medium, most current brain-inspired computers rely on conventional solid materials.
This begs the question: couldn't we achieve a more faithful replica of brain functioning by adopting the same medium? This intriguing possibility lies at the heart of the burgeoning field of iintronic neuromorphic computing.
Artificial synapses
In the latest study published in the PNAS, scientists have demonstrated, for the first time, a system dependent on water and salt that exhibits the ability to process complex information, reflecting the functionality of our brain. A central element of this discovery is a tiny device measuring 150 by 200 micrometers, which mimics the behavior of a synapse, an essential component of the brain responsible for transmitting signals between neurons.
Tim Kamsma, a doctoral candidate at the Institute of Theoretical Physics and the Institute of Mathematics of the University of São Paulo and lead author of the study, expresses his enthusiasm and states: “Although there are already artificial synapses based on solid materials capable of processing complex information, we now show for the first time that this feat can also be achieved using water and salt. We are effectively replicating neural behavior using a system that employs the same environment as the brain.”
Ion migration
The device, developed by scientists in Korea and called iintronic memristor, consists of a cone-shaped microchannel filled with a solution of water and salt. Upon receiving electrical impulses, the ions within the liquid migrate through the channel, causing alterations in the ion concentration.
Depending on the intensity (or duration) of the pulse, the channel's conductivity is adjusted accordingly, reflecting the strengthening or weakening of the connections between neurons. The degree of change in conductance serves as a measurable representation of the input signal.
An additional finding is that channel length affects the length required for concentration changes to dissipate. “This suggests the possibility of adapting channels to retain and process information for varying durations, similar to the synaptic mechanisms observed in our brain,” Kamsma says.
The genesis of this discovery dates back to an idea conceived by Kamsma, who began his doctoral research not long ago. He transformed this concept, focused on the use of artificial ion channels for classification tasks, into a solid theoretical model.
“By chance, during that period our paths crossed with the South Korean research group,” Kamsma says. “They welcomed my theory with great enthusiasm and quickly began experimental work based on it.”
Surprisingly, the initial findings materialized just three months later, closely aligned with the predictions outlined in Kamsma's theoretical framework. “I thought wow!” he reflects. “It's incredibly rewarding to witness the transition from theoretical conjectures to tangible results in the real world, which ultimately result in these beautiful experimental results.”
An important step forward
Kamsma underlines the fundamental nature of the research and highlights that iintronic neuromorphic computing, while experiencing rapid growth, is still in its infancy. The expected result is a computer system that is far superior in efficiency and energy consumption compared to current technology. However, at this time it remains speculative whether this vision will materialize. However, Kamsma believes that the publication is an important step forward.
“It represents a crucial advance towards computers capable not only of imitating the communication patterns of the human brain but also of using the same medium,” he says. “Perhaps this will ultimately pave the way for computer systems that more faithfully reproduce the extraordinary capabilities of the human brain”
