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Imagine a cyber-fungus on the move, the soft sinuous flesh merged with synthetic parts, a kind of creeping chimera.
Recently, a team of scientists cobbled together two such hybrids: Powered by the fungi’s bioelectrical signaling, one walked and the other rode on wheels. Their findings were published in Science Robotics.
The work is part of a growing field called biohybrid robotics, which aims to make robots more lifelike by fusing them with living tissue. “Mammalian tissue is hard to work with, but mushrooms are easy,” says Robert Shepherd, a mechanical and aerospace engineer at Cornell University and one of the authors of the paper.
Shepherd and his team experimented with king oyster mushrooms, which they cultivated themselves. The group started with the fruiting bodies—the mushroom caps we see above the soil—as the living material, but they soon learned that these caps decompose too quickly. So they turned to mycelia, the root-like structure of a fungus consisting of a mass of branching filaments.
Mammalian tissue is hard to work with, but mushrooms are easy.
Mycelia have evolved to sense their environment, communicate over large distances, and transport nutrients. They are also naturally sensitive to light. It turns out this sensitivity can be used to power movement. The team created an electrical interface that interpreted the mycelia’s activity and translated it into information to move the robot parts. When stimulated by ultraviolet light, the robot fungi fled from the light.
Unlike animal cells, fungi can be easily cultured in large quantities, and it is relatively simple to keep them alive: They tend to last for about a month before they start to decompose, says Shepherd. Some can also thrive in extreme environments, such as the Arctic and Antarctic, nuclear radiation sites, and highly acidic and saline conditions, which makes them great for robot hybrids that would operate in hazardous conditions.
Working with living tissues gives a bit of an existential flair to robotics. “Even though they are very durable, they do start to die,” says Shepherd. “Anyone working in biohybrid systems has to deal with the life cycle: robots get older, and their signals slowly get weaker.”
When stimulated by ultraviolet light, the robot fungi fled from the light.
Robert Katzschmann, a roboticist in the Soft Robotics Lab at ETH Zürich in Switzerland says the idea of using fungi to control a robot is innovative—though it comes with some challenges. “I’m not sure how far we can take fungi for more complex roles in robotics,” he says. But their sensitivity to environmental stimuli could make them very useful as sensors, he says, or in structural materials. “It’ll be fascinating to see where this research leads,” he says.
Shepherd thinks the applications fall in two broad categories: One is using mycelia to create a kind of circulatory system inside robots, one that would transmit energy from one component to another—“like a venous network…inside a machine.”
The other application is using these robots out in the world. Since mycelia are so adept at sensing the chemical and biology signals in their environment, for example, they could measure soil properties to help farmers determine the optimal amount of phosphorus, fertilizer, or pesticides needed to manage crops. Shepherd says mycelia have an advantage over existing technologies used to measure soil properties in that they are more sensitive to a wider range of biological and chemical threats and rewards and they are inexpensive to develop.
Working so closely with fungi has made Shepherd think about webs of connection—not unlike the massive webs of fungal filaments lying quietly below the surface of the Earth. “I am thinking more about how life is interconnected with everything,” he says—even robots. 
Lead image: Room27 / Shutterstock
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