Scientists at Linköping University (LiU) in Sweden have developed an artificial organic neuron that is very similar to a real nerve cell. This artificial neuron has the ability to activate real nerves, making it a potentially useful medical tool in the future.

At the Laboratory for Organic Electronics, LOE, people are still trying to make artificial nerve cells that work better and better. A team of scientists headed by associate professor Simone Fabiano revealed in 2022 how an artificial organic neuron might be integrated into a live carnivorous plant to regulate its mouth opening and shutting. This artificial nerve cell had two of the twenty things that set it apart from a real nerve cell.

In their most recent study, which was published in the journal Nature Materials, the same LiU researchers created a new artificial nerve cell dubbed “conductance-based organic electrochemical neuron” or c-OECN, which closely mimics 15 of the 20 neural features that distinguish biological nerve cells, making its functioning significantly more similar to that of biological nerve cells.

“One of the key challenges in creating artificial neurons that effectively mimic real biological neurons,” according to professor Simone Fabiano, “is the ability to incorporate ion modulation.” 

“Traditional artificial neurons made of silicon can emulate many neural features but cannot communicate through ions. In contrast, c-OECNs use ions to demonstrate several key features of real biological neurons,” adds the author.

In 2018, they were among the first to successfully develop n-type conducting polymers, materials that can conduct negative charges, leading to the creation of printable complementary organic electrochemical circuits. The team has now taken this technology to the next level by optimizing the transistors for printing on a thin plastic foil using a printing press. This allows for the production of thousands of transistors on a flexible substrate, opening up the possibility of developing artificial nerve cells for a variety of applications.

The newly developed artificial neuron utilizes ions to control the flow of electronic current through an n-type conducting polymer, that spikes in the device’s voltage. This process mimics the behavior of biological nerve cells. The unique material used in the artificial neuron also allows for precise control of the current, with an almost perfect bell-shaped curve that closely resembles the activation and inactivation of sodium ion channels found in biology.

“Several other polymers show this behaviour, but only rigid polymers are resilient to disorder, enabling stable device operation,” adds Simone Fabiano.

In a collaboration with Karolinska Institute (KI), researchers have successfully connected the newly developed c-OECN neurons to the vagus nerve of mice. The experiments yielded promising results, as the artificial neuron was able to stimulate the nerves in the mice, resulting in a 4.5% change in their heart rate.

The ability of the new artificial neuron to stimulate the vagus nerve has the potential to revolutionize medical treatment in the long term. Organic semiconductors, such as the c-OECN neurons, have several advantages including biocompatibility, flexibility, and softness. Additionally, the vagus nerve plays a vital role in various bodily functions including the immune system and metabolism, making it a promising target for various medical applications.”

The next stage for the scientists will be to lower the artificial neurons’ energy consumption, which is still far greater than that of human nerve cells. It will take a lot of effort to artificially recreate nature.

“There is much we still don’t fully understand about the human brain and nerve cells. In fact, we don’t know how the nerve cell makes use of many of these 15 demonstrated features. Mimicking the nerve cells can enable us to understand the brain better and build circuits capable of performing intelligent tasks. We’ve got a long road ahead, but this study is a good start,” adds main author Padinhare Cholakkal Harikesh.

Source: 10.1038/s41563-022-01450-8

Image Credit: Thor Balkhed