Functional Human Brain Cells Made From Salt and Water Mark Significant Step in Iontronic Neuromorphic Computing

Since the development of ENIAC in the 1940s, computers have made amazing technological breakthroughs. In less than a century, computers that used to fill an entire room are now smaller, faster, more efficient, and can be worn by humans.

Although this immense progress is indeed a remarkable engineering achievement, computers still cannot be compared to the most impressive computational device of all: the human brain.

Challenges in Neuromorphic Computing

Neuromorphic computing is a nascent field which aims to imitate the structure and operation of the human brain. It is a method of computer engineering where artificial neurons and synapses are used to process information.

Replicating the information processing of the brain is very important due to the growth of the trend of energy consumption by computers. This drives experts to investigate new computing paradigms. Memristors (memory resistor) currently emerged as promising artificial analogues to biological synapses which allow brain-inspired circuit structures.

However, despite the successful implementation of memristors in different conventional platforms, most of these devices are composed of solid-state components which depend on a single information carrier that responds only to electric driving forces. Such limitations are in contrast with the synapses of the brain which has the ability to utilize ionic and molecular species in parallel. In light of this gap, an emerging approach seeks inspiration from the structure of the brain and from its aqueous medium and ionic signal carriers.

Complex Computer From Simple Recipe

At Utrecht University in the Netherlands, a group of scientists has successfully developed an artificial device which mimics the synapses of the human brain. This was achieved while the team was exploring the evolving field of iontronic neuromorphic computing.

Artificial synapses that can process complex information are known to exist based on solid materials. For the first time, the researchers were able to demonstrate that this can also be achieved using salt and water.

According to lead author Tim Kamsma, their team is effectively replicating neuronal behavior using a biological system that uses the same medium as the brain. The details of this study are described in the paper "Brain-inspired computing with fluidic iontronic nanochannels."

The device measures 150 to 200 micrometers across, almost double the thickness of the human hair. Known as an iontronic memristor, it is shaped like a cone and is packed with saline solution. As it receives an electrical impulse, the charged particles migrate through the channel which changes the ion environment around them. For particularly strong or long impulse, the channel adjusts its conductivity by strengthening or weakening neuron connection.

After analyzing the capabilities of the device, it was found that the length of the channel affects how long it takes for changes to scatter. According to Kamsma, this indicates that iontronic memristor can be customized to remember previous electrical charges.

A supercomputer from Australia known as DeepSouth aims to be the first machine to imitate the synapses of the human brain. Due to go online this year, this project focuses on conventional solid materials. The work of Kamsma and his colleagues demonstrate that an aqueous memristor can be better suited for reproducing the short-term synaptic plasticity of the human brain.