Frog Stem Cells Used To Build First Living Robots

“These are entirely new lifeforms. They have never before existed on Earth,” said Michael Levin, the director of the Allen Discovery Center at Tufts University in Medford, Massachusetts. “They are living, programmable organisms.”

Rather than using metal and plastics Levin and colleagues see the benefits in making robotics from biological tissues, such as living robot being able to heal their wounds, and once a task is complete they will fall apart just as natural organisms decay after dying. 

An evolutionary algorithm that runs on a super computer was used to create thousands of random designs to stimulate passive skin cells and heart cells to contract, the best design performers were used to spawn new designs. This algorithm also asks the designs to achieve tasks assigned by the scientists such as walking in any one direction; the most promising designs have been built from living cells scraped from frog embryos. 

Hundreds of generations were created before the scientists picked a handful of designs to build in the lab using tweezers and cauterising tools to sculpt early stage skin and heart cells from the stem cells scraped from the frog embryos.

As published in the Proceedings of the National Academy of Sciences these xenobots are less than 1mm long, and because heart cells spontaneously contract/relax they behave like engines to drive the robots until their energy reserves deplete within a week to ten days. 

In the future their unique feature may enable robotic versions that may be deployed to clean up microplastics from the ocean, locate and digest toxic materials, or deliver drugs in a human body as well as remove plaque from artery walls. 

“It’s impossible to know what the applications will be for any new technology, so we can really only guess,” said Joshua Bongard, a senior researcher on the team at the University of Vermont.

“These are very small, but ultimately the plan is to make them to scale,” said Levin. Xenobots might be built with blood vessels, nervous systems and sensory cells, to form rudimentary eyes. By building them out of mammalian cells, they could live on dry land.

This work does raise some ethical issues, especially since future variants may have nervous systems and be selected for cognitive capability that will make them more active participants in the world: 

“What’s important to me is that this is public, so we can have a discussion as a society and policymakers can decide what is the best course of action,” says Sam Kriegman, PhD student at the UofV. “If you watch the video, it’s hard to fear that these things are taking over any time soon,” he said. “The aim is to understand the software of life,” Levin adds. “If you think about birth defects, cancer, age-related diseases, all of these things could be solved if we knew how to make biological structures, to have ultimate control over growth and form.”

“There are interesting ethical questions about the moral status of these xenobots. At what point would they become beings with interests that ought to be protected? I think they’d acquire moral significance only if they included neural tissue that enabled some kind of mental life, such as the ability to experience pain. But some are more liberal about moral status. They think that all living creatures have interests that should be given some moral consideration. For these people, difficult questions could arise about whether these xenobots should be classified as living creatures or machines,” says Thomas Douglas, a senior research fellow at the Oxford Uehiro Centre for Practical Ethics.

This work is being funded by the US Defense Advanced Research Projects Agency’s lifelong learning machines programme, which has the goal of creating biological learning processes in machines. 

“Just because you can doesn't mean you should.” ~ Sherrilyn Kenyon.