What are living bots?

The Xenobots are living robots made up of skin cells and heart muscle cells derived from stem cells harvested from the early stages of frog embryos. The Xenobots are named after the African clawed frog (Xenopus laevis) from which they take their stem cells; the machines are less than a millimeter wide -- small enough to travel inside human bodies. Xenobiotics are called “living robots” as computers specifically design them to perform some desired function and are built by combining different biological tissues.  Xenobiotics come in different basic shapes and can scoot themselves in linear or circular directions, join up to act collectively, and move small objects by harnessing their cellular energy for a maximum of 10 days. They heal and repair themselves and can survive without food for more than 7 days.

The new creatures were designed on a supercomputer and then assembled and tested by biologists at Tufts University. As the Tufts scientists worked, their colleagues at the University of Vermont (UVM) used an evolutionary algorithm running on a supercomputer to simulate how different Xenobot shapes would behave. Researchers from Tufts and the University of Vermont have now developed a second iteration, Xenobots 2.0, if you will, which can “self-assemble a body from single cells, do not require muscle cells to move, and even demonstrate the capability of recordable memory.

Performing those jobs would be a hell of a lot easier with the ability to retain and access memory for guiding their actions — something the original Xenobots lacked. This time around, the researchers gave them the ability to hold on to one piece of information.

The researchers injected the frog stem cells with mRNA carrying the instructions for a protein called EosFP. This protein normally glows green, but it turns red when exposed to a specific wavelength (at 390nm wavelength) of light.

Armed with their little running light, the Xenobots could now keep a record of being exposed to certain wavelengths of blue light in their environment. Further work could potentially allow them to keep track of multiple variables or even alter their behaviors accordingly.

When bringing in more capabilities to the bots, it can use the computer simulations to design them with more complex behaviors and carry out more elaborate tasks. It could potentially be designed to report conditions in their environment and modify and repair conditions in their environment.

Applications of Xenobots that have been speculated

• They could be used to clean our polluted oceans by collecting microplastics.
• Similarly, they may be used to enter confined or dangerous areas to scavenge toxins or radioactive materials.
• Xenobiotics designed with carefully shaped “pouches” might be able to carry drugs into human bodies.
• Future versions may be built from a patient’s own cells to repair tissue or target cancers. Being biodegradable, xenobiotics would have an edge on technologies made of plastic or metal.
• Further development of biological “robots” could accelerate our understanding of living and robotic systems. Life is incredibly complex, so manipulating living things could reveal some of life’s mysteries — and improve our use of AI.