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A wheeled robot rolls across the floor. A soft-bodied robot star flexes its five legs and moves in an awkward shuffling motion.
These simple robotic creations wouldn’t be anything special if they ran on conventional electricity via a plug or battery, but what sets these two robots apart is that they’re controlled by a living creature: a king oyster mushroom.
By growing the mushroom’s mycelium, or root-like threads, inside the robot’s hardware, a team led by researchers from Cornell University has created two types of robots that sense and respond to their environment by harnessing the fungus’ electrical signals and sensitivity to light.
The robots are the latest achievement by scientists in the field of biohybrid robotics, which seeks to combine biological, living materials, such as plant and animal cells or insects, with synthetic components to create partly living, partly engineered entities.
Biohybrid robots haven’t yet made it beyond the lab, but researchers hope that in the future, robot jellyfish could explore the ocean, robots that run on sperm could perform fertility treatments, and cyborg cockroaches could search for survivors after an earthquake.
“Mechanisms including computation, understanding, and action in response are carried out in the biological world and in the artificial world that humans have created, and biology is usually better at that than our artificial systems,” said Robert Shepherd, a lead author of a study describing the robots published Aug. 28 in the journal Science Robotics.
“Biohybridization is an attempt to find components in the biological world that we can harness, understand and control to make our artificial systems work better,” added Shepherd, a professor of mechanical and aerospace engineering at Cornell University who directs the institution’s Organic Robotics Lab.
Part mold, part machine
The team began by growing king oyster mushrooms (Pleurotus eryngii) in the lab using a simple kit ordered online. The researchers chose this species of mushroom because it is easy and fast to grow.
They grew the mushroom’s threadlike structures, or mycelium, which can form networks that can sense, communicate and transport nutrients, the study says — sort of like neurons in a brain. (Unfortunately, calling the creations shroombots isn’t quite right. The mushroom is the fruit of the fungi — the robots are controlled by the root-like mycelium.)
Mycelium produces small electrical signals and can be connected to electrodes.
Andrew Adamatzky, professor of unconventional computing at the University of the West of England in Bristol, builds fungal computers. He says it is not clear how fungi produce electrical signals.
“Nobody knows for sure,” said Adamatzky, who was not involved in the study but reviewed it for publication.
“In essence, all living cells produce spikes that resemble action potentials, and fungi are no exception.”
The research team found it challenging to design a system that could detect the tiny electrical signals from the mycelia and use them to control the robot.
“You have to make sure that your electrode is hitting the right position, because the mycelia are very thin. There’s not a lot of biomass,” said lead author Anand Mishra, a postdoctoral research associate in Cornell’s Organic Robotics Lab. “Then you culture them, and as the mycelia start to grow, they wrap around the electrode.”
Mishra designed an electrical interface that can accurately measure, process and convert the electrical activity of the mycelium into digital information that can be used to activate the robot’s actuators or moving parts.
The robots were able to walk and roll in response to the electrical surges generated by the fungal filaments. When Mishra and his colleagues stimulated the robots with ultraviolet light, they changed their gait and trajectory, demonstrating that they could respond to their environment.
“Mushrooms don’t really like light,” Shepherd said. “Based on the difference in intensity (of the light) you can get different functions from the robot. It will move faster or move away from the light.”
‘Exciting’ work
“It’s exciting to see more research being done in biohybrid robotics, going beyond human, animal and insect tissue,” said Victoria Webster-Wood, an associate professor in the Biohybrid and Organic Robotics Group at Carnegie Mellon University in Pittsburgh.
“Fungi may have advantages over other biohybrid approaches in terms of the conditions needed to keep them alive,” said Webster-Wood, who was not involved in the study.
“If they are more resistant to environmental conditions, this could make them an excellent candidate for biohybrid robots for applications in agriculture and marine monitoring or exploration.”
The research shows that fungi can be grown in large quantities and thrive in many different environments.
The researchers operated the rolling robot without a cable connecting it to the electrical hardware. Webster-Wood called this achievement particularly remarkable.
“Truly cable-free biohybrid robots pose a challenge in the field,” she said via email, “and it is quite exciting to see how they achieve this with the mycelium system.”
Biohybrid robotics in the real world
According to Shepherd, technology that regulates fungi could also be applied to agriculture.
“In this case we used light as an input, but in the future it will be chemical. The potential for future robots could be to sense soil chemistry in row crops and decide when to add more fertilizer, for example to mitigate downstream effects of agriculture, such as harmful algal blooms,” he told the Cornell Chronicle.
According to Adamatzky, fungus-controlled robots, and fungus computers in general, have enormous potential.
He said his lab has produced more than 30 sensor and computing devices using living fungi, including growing self-healing skin for robots that can respond to light and touch.
“With an adequate drivetrain (transmission system) in place, the robot could, for example, monitor the health of ecological systems. The fungus controller would respond to changes, such as air pollution, and steer the robot accordingly,” Adamatzky said via email.
“The emergence of yet another fungal device – a robotic controller – excitingly demonstrates the remarkable potential of fungi.”
Rafael Mestre, a lecturer at the University of Southampton’s School of Electronics and Computer Science in the United Kingdom who researches the social, ethical and policy implications of emerging technologies, said that if biohybrid robots become more advanced and are deployed in the ocean or other ecosystem, it could disrupt the habitat and challenge the traditional distinction between life and machine.
“You’re putting these things into the trophic chain of an ecosystem where they don’t belong,” said Mestre, who was not involved in the new study. “If you release them in large numbers, it could be disruptive. I don’t see at this point that this particular study has strong ethical concerns … but as it continues to develop, I think it’s really important to consider what happens if we release this publicly.”
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