Computers come alive

Neil Phillips often stops at the greengrocer's for mushrooms on the way to his workplace. Vendors inform Phillips when they get a fresh stock. Phillips, however, has no ordinary interest in mushrooms — he uses them to design computer circuits.

Phillips and his collaborators at the Unconventional Computing Laboratory at the University of the West of England (UWE), Bristol, are exploring fungi as a tool for computing. In a recent study published in Fungal Ecology, the UWE group demonstrated the role of mushrooms in making futuristic computers (bit.ly/Fungi-tronics). Back in 2001, recognising the urgent need for computers that would be effective in the 22nd century and beyond, Andrew Adamatzky, a co-author of the research paper, established the Unconventional Computing Lab.

Previous studies have shown that fungi can conduct electricity and communicate with each other through electrical signals transmitted via their root-like structures called mycelium. The underground mycelium network connects an entire forest, allowing trees to communicate (see: The chitter-chatter of forest fungi), send messages, and share nutrients.

The UWE Bristol group's study shows that mushrooms exhibit properties similar to those of the three basic elements of an electronic circuit: resistor, capacitor, and inductor. The researchers experimented with five species of fresh mushrooms. They measured the alternating current of various frequencies passing through pieces of fungi, tracking how the resistance value changed with the frequencies of the electrical signal. The mycelium and the mushrooms also store charges as capacitors in an electronic circuit. Additionally, fungi exhibit sensing abilities. Researchers explored fresh and dried mushrooms to understand how they responded to different ecosystems.

"We've taken different samples of fungi, some being… the mushroom you're familiar with. And then we've looked at what happens when you put different signals through at different frequencies, and how those change, and what you find is the characteristics of the material," says Phillips.

The study infers that fungal bodies may help make analogue computers. For example, living mycelium may be used for sensing, combining sensory data, and pre-processing information in oscillator-based computing and edge computing. Combining silicon parts with networks of mycelium, especially dried mycelium, could create new possibilities for future computers. "In our pursuit to create computing devices based on fungi, it is imperative to understand how mycelium networks transfer and process information," says Adamatzky.

For over 20 years, Adamatzky has been working on creating unconventional computing methods using living organisms such as fungi and slime moulds, as well as biodegradable materials with mycelium (known as mycelium-bound composites). In 2022, Adamatzky, who is a Professor in the Faculty of Environment and Technology at UWE, and his colleague Nic Roberts created experimental prototypes for multi-information processing using oyster fungi (bit.ly/logic-fng). In electronics, different logic gates perform this task. The two researchers figured out the possible logic gates for fungi-based machines. They placed many pairs of electrodes into the mycelium. Two electrodes were active, while the others recorded electrical activity. They sent binary strings such as 01, 10, and 11, where 1 meant a spike and 0 meant no spike. They then analysed the responses from the recording electrodes to find the corresponding logic gates.

"We found that mycelium-bound composites can perform a range of functions, including very complex ones," says Adamatzky. "These results are important for unconventional computing, showing that fungi can be used for practical computing and creating intelligent materials with mycelium-bound composites," he told Shaastra in an e-mail interview.

In its modelling and lab experiments, the UWE Bristol group showed that fungi could create a variety of logic gate circuits. While fungi are slower than conventional computers, they have several advantages: mycelium is inexhaustible; the growth of mycelium networks can be guided using repellents and attractants; fungi can evolve like all living things; and fungi can operate on minimal energy, like that from rotting trees.

The work reveals that the electrical properties of fungi can shed light on ecosystem interactions. Future research may link electrical recordings with environmental factors such as soil pH, temperature, and moisture. This could improve agricultural practices, such as mushroom cultivation, and soil health. The findings highlight the need for combining electronics, ecology, and mycology – the study of fungi – to fully explore fungal electronics.