Robot controlled by a king oyster mushroom blends living organisms and machines
The Power of Fungi in Robotics
On September 4th, 2024, a wheeled robot rolls across the floor, controlled by a fungus in an awkward movement. Powered by conventional electricity, either from a plug or battery, these simple robotic creations would be unremarkable. However, what sets these two robots apart is that they are controlled by a living entity: a king oyster mushroom.
By growing the mushroom’s mycelium, or rootlike threads, into the robot’s hardware, a team led by Cornell University researchers has engineered two types of robots that sense and respond to the environment by harnessing electrical signals made by the fungus and its sensitivity to light.
Biohybrid Robotics: Merging Biology and Engineering
The robots are the latest accomplishment of scientists in a field known as biohybrid robotics, which seeks to combine biological, living materials such as plant and animal cells or insects with synthetic components to make partly living and partly engineered entities.
Biohybrid robots have yet to venture beyond the lab, but researchers hope one day robot jellyfish may explore oceans, sperm-powered bots may be able to deliver fertility treatments, and cyborg cockroaches could search for survivors in the wake of an earthquake.
“Mechanisms, including computing, understanding, and action as a response, are done in the biological world and in the artificial world that humans have created, and biology most of the time is better at it than our artificial systems are,” said Robert Shepherd, a senior author of a study detailing the robots published August 28 in *Science Robotics*.
Engineering the Robots
The team began by growing king oyster mushrooms (*Pleurotus eryngii*) in the lab from a simple kit ordered online. The researchers chose this species of mushroom because it grows easily and quickly. They cultivated the mushroom’s threadlike structures or mycelium, which can form networks that, according to the study, can sense, communicate, and transport nutrients, functioning a little like neurons in a brain.
Alas, it’s not strictly accurate to call the creations "shroom bots." The mushroom is the fruit of the fungi; the robots are powered by the rootlike mycelium.
The Electrical Signals of Mycelium
Mycelium produces small electrical signals and can be connected to electrodes. Andrew Adamatzky, a professor of unconventional computing at the University of the West of England in Bristol who builds fungal computers, said it isn’t clear how fungi produce electrical signals.
“No one knows for sure,” said Adamatzky, who wasn’t involved in the research but reviewed it before publication. “Essentially, all living cells produce action potential like spikes, and fungi are no exception.”
The study team found it challenging to engineer a system that could detect and use the small electrical signals from the mycelia to command the robot.
“You have to make sure that your electrode touches in the right position because the mycelia are very thin. There is not a lot of biomass there,” said lead author Anand Mishra, a postdoctoral research associate in Cornell’s Organic Robotics Lab. “Then you culture them, and when the mycelia start growing, they wrap around the electrode.”
The Robot’s Response to Stimuli
Mishra engineered an electrical interface that accurately reads the mycelia’s raw electrical activity, then processes and converts it into digital information that can activate the robot’s actuators or moving parts.
The robots were able to walk and roll as a response to the electrical spikes generated by the mycelia, and when Mishra and his colleagues stimulated the robots with ultraviolet light, they changed their gait and trajectory, showing that they were able to respond to their environment.
“Mushrooms don’t really like light,” Shepherd said. “Based on the difference in the intensities (of the light), you can get different functions of the robot. It will move faster or move away from the light.”
Fungi in Biohybrid Robotics: The Future
It’s exciting to see more work in biohybrid robotics that moves beyond human, animal, and insect tissues, said Victoria Webster Wood, an associate professor at Carnegie Mellon University’s Biohybrid and Organic Robotics Group in Pittsburgh. “Fungi may have advantages over other biohybrid approaches in terms of the conditions required to keep them alive,” said Webster Wood, who wasn’t involved in the research.
“If they are more robust to environmental conditions, this could make them an excellent candidate for biohybrid robots for applications in agriculture and marine monitoring or exploration.”
The study noted that fungi can be cultivated in large quantities and can thrive in many different environments.
The researchers operated the rolling robot without a tether connecting it to the electrical hardware—a feat that Webster Wood called particularly noteworthy.
Truly biohybrid robots are a challenge in the field, and seeing them achieve this with the mycelium system is an exciting development.