Microscopic 'living robots' created from frog embryo stem cells have memories


A microscopic ‘living robot’ made from frog embryo stem cells have been designed with self-healing powers and the ability to keep memories.

The innovation pulls from previous work released last year, called Xenobots, but has been upgraded to move more efficiently and perform more complex tasks.

Dubbed Xenobots 2.0, the machines are able to self-propel using hair-like ‘legs’ of cilia, while its predecessor relied on a muscle to move, allowing it to travel faster along surfaces.

However, the greatest advancement is the ability to recall things such as radioactive contamination, chemical pollutants or a disease condition in the body that can be reported back to researchers for further analyses.

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A microscopic 'living robot' made from frog embryo stem cells have been designed with self-healing powers and the ability to keep memories. The innovation pulls from previous work released last year, called Xenobots, but has been upgraded to move more efficiently and perform more complex tasks

A microscopic ‘living robot’ made from frog embryo stem cells have been designed with self-healing powers and the ability to keep memories. The innovation pulls from previous work released last year, called Xenobots, but has been upgraded to move more efficiently and perform more complex tasks

Both machines were developed by biologists and computer scientists from Tufts University and the University of Vermont (UVM), which used the name ‘Xenobots’ after the African frog Xenopus Laevis that were used to gather cells.

The initial bots were programmed to perform a range of tasks, specifically delivering medicine directly to a point in the body.

However, the 2.0 versions have been upgraded to move faster, navigate different environments and have longer lifespans, but still possess the ability to work together in groups and heal themselves if damaged.

While the Tufts scientists created the physical organisms, scientists at UVM were busy running computer simulations that modeled different shapes of the Xenobots to see if they might exhibit different behaviors, both individually and in groups.

The robots were created from stem cells collected from African frog Xenopus Laevis embryos 24 hours after they are formed

The robots were created from stem cells collected from African frog Xenopus Laevis embryos 24 hours after they are formed

They team placed the embryos under a microscope to harvest the cell tissue

They team placed the embryos under a microscope to harvest the cell tissue

Josh Bongard with UVM said: ‘When we bring in more capabilities to the bots, we can use the computer simulations to design them with more complex behaviors and the ability to carry out more elaborate tasks.

‘We could potentially design them not only to report conditions in their environment but also to modify and repair conditions in their environment.’

Following the simulations, the team determined that the new Xenobots are much faster and more skilled at tasks such as collecting microplastics in water or containments – and it did so much quicker than the first version.

‘We know the task, but it’s not at all obvious — for people — what a successful design should look like. That’s where the supercomputer comes in and searches over the space of all possible Xenobot swarms to find the swarm that does the job best,’ said Bongard.

The tissue then formed into the shape of the living robots, allowing scientists to then program them with specials skills

The tissue then formed into the shape of the living robots, allowing scientists to then program them with specials skills 

‘We want Xenobots to do useful work. Right now we’re giving them simple tasks, but ultimately we’re aiming for a new kind of living tool that could, for example, clean up microplastics in the ocean or contaminants in soil.’

The key to a successful robot is its ability to record memory, which it uses to modify its behavior and abilities.

With that in mind, the Tufts scientists engineered the Xenobots with a read and write capability to record one bit of information, using a fluorescent reporter protein called EosFP, which normally glows green. 

However, when exposed to light at 390nm wavelength, the protein emits red light instead.

The cells of the frog embryos were injected with messenger RNA coding for the EosFP protein before stem cells were excised to create the Xenobots. 

The mature Xenobots now have a built-in fluorescent switch which can record exposure to blue light around 390nm. The researchers tested the memory function by allowing 10 Xenobots to swim around a surface on which one spot is illuminated with a beam of 390nm light. 

Dubbed Xenobots 2.0, the machines are able to self-propel using hair-like 'legs' of cilia, while its predecessor relied on a muscle to move, allowing it to travel faster along surfaces

Dubbed Xenobots 2.0, the machines are able to self-propel using hair-like ‘legs’ of cilia, while its predecessor relied on a muscle to move, allowing it to travel faster along surfaces

The greatest advancement is the ability to recall things such as radioactive contamination, chemical pollutants or a disease condition in the body that can be reported back to researchers for further analyses. The illumination shows they are recording information

The greatest advancement is the ability to recall things such as radioactive contamination, chemical pollutants or a disease condition in the body that can be reported back to researchers for further analyses. The illumination shows they are recording information

After two hours, they found that three bots emitted red light. The rest remained their original green, effectively recording the ‘travel experience’ of the bots.

This proof of principle of molecular memory could be extended in the future to detect and record not only light but also the presence of radioactive contamination, chemical pollutants, drugs, or a disease condition. 

Further engineering of the memory function could enable the recording of multiple stimuli (more bits of information) or allow the bots to release compounds or change behavior upon sensation of stimuli.

‘The ultimate goal for the Tufts and UVM researchers is not only to explore the full scope of biological robots they can make, but tos also to understand the relationship between the ‘hardware’ of the genome and the ‘software’ of cellular communications that go into creating organized tissues, organs and limbs, the team shared in a statement.’

‘Then we can gain greater control of that morphogenesis for regenerative medicine, and the treatment of cancer and diseases of aging.’

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