Brains and computers might have similarities in some functions, namely calculating and organizing stuff, but they are very different. And their differences are structural. Computers are not built like brains – but could they be? This idea has been around for a while and researchers have now taken an important step forward. They built a device that acts like a synapse.

The central nervous system is largely made of neurons or nerve cells. These send signals between one another using synapses, which are junctions between neurons where the information being carried is both transmitted and processed. They are fundamental to the function of brains.

Synapses do that using ions, electrically charged atoms or molecules, dissolved in water. New work shows that it is possible to create an artificial synapse that also works with water and salts. Crucial to this is a device that's only as wide as two sheets of paper, called an iontronic memristor.

Despite the complex name, its shape and behavior are straightforward. It is shaped like a cone and filled with a solution of water and salts. When it receives an electrical impulse the ions in the water move, changing the salt concentration. This is akin to what a real brain synapse does.

"While artificial synapses capable of processing complex information already exist based on solid materials, we now show for the first time that this feat can also be accomplished using water and salt," lead author Tim Kamsma, a graduate researcher at Utrecht University, said in a statement. "We are effectively replicating neuronal behaviour using a system that employs the same medium as the brain."

The ionotronic memristor was developed by South Korean scientists and a chance encounter with Kamsma led to the collaboration. Together, they saw the possibility of using the device as a computational synapse. This is not a functioning computer, but it shows that it might be possible to construct a computer-like device that not only has synapses, but synapses that behave just like our own do.

"It represents a crucial advancement toward computers not only capable of mimicking the communication patterns of the human brain but also utilizing the same medium," Kamsma added. "Perhaps this will ultimately pave the way for computing systems that replicate the extraordinary capabilities of the human brain more faithfully."

The study is published in Proceedings of the National Academy of Sciences.