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Xenobots- What’s the Hype?

Updated: Jul 5, 2022

We all must have heard or read about Xenobots since their discovery in 2020 by the researchers of the University of Vermont (UVM), Tufts University, and Wyss Institute for Biologically Inspired Engineering. Developed by Douglas Blackiston and Josh Bongard based on the AI-generated blueprints by Sam Kriegman, Xenobots are named after Xenopus laevis, the African Clawed frog. However, they are not a very new concept; it turns out the inspiration for Xenobots dates back to 1994 when a computer graphics artist, Karl Sims, brought-to-light some of the world’s first known virtual creatures. He designed them to be in a simulation that resembled real-world physics and gave them simple tasks to perform, such as battling with another digital creature. They can be seen as programmable lifeforms designed by computers with medicine and environmental rehabilitation applications.

AI-designed (C-shaped) organisms push loose stem cells (white) into piles as they move through their environment. Credit: Douglas Blackiston and Sam Kriegman

Less than a millimetre wide, these small “biological robots” are composed of only two things; heart muscle cells and skin cells, both derived from the stem cells of the early blastula stages of Xenopus embryos. It is interesting to see how scientists developed such creatures without manipulating genes and by simply isolating frog embryo cells and leaving them to incubate. Stem cells are unspecialized cells that encompass the ability to develop into different cell types. The initial Xenobots were sphere-shaped and were made up of roughly 3000 cells. [2]

Acting like small motors, the heart cells propel the Xenobot forward by contracting and expanding, while the skin cells provide rigid support. By trial and error in the simulations conducted, these living robots are designed to push pellets, walk, carry small objects, and collect debris along the surface of a dish. In addition, they can go on for weeks without food and have the ability to self-heal. Another interesting characteristic of these microscopic robots is their ability to grow cilia which, instead of the heart muscle, act like tiny oars and enable movement. However, this locomotion is less controllable than cardiac muscle-driven locomotion.

Scientists at Tufts University developed physical organisms from stem cells. Alongside this, computer simulations were developed and run by the scientists at UVM to check if the bots exhibit different behaviours when in groups and as single entities. A dedicated team of researchers simulated the biological robots under thousands of randomly created environmental conditions using an evolutionary algorithm and the Deep Green Supercomputer cluster at UVM’s Vermont Advanced Computing Core. The algorithm mimics the process of natural selection by generating potential solutions and then randomly selecting and mutating the most promising ones. The evolutionary algorithm starts with random swarms and then evolves them with increasing self-replicative ability on the basis of random selection. Each round of replication requires a week to determine suitable conditions for self-replication. This algorithm was combined with a physics simulator to check the developed conditions and select those which were likely to increase the yield of these microscopic robots. [1, 4]

What is interesting is their recently discovered ability to reproduce – in a self-discovered way of their own and demonstrating recordable memory. Gathering loose cells such that they can form new Xenobots is not a big task for these self-replicating creatures. Up until now, they were only believed to replicate in certain particular circumstances. The pattern of replication they follow is known as ‘Kinetic Replication,’ a process observed only at the molecular level [5, 6]. Thanks to the versatile tool of Artificial Intelligence, researchers could test billions of shapes that facilitated this method of replication. The most effective shape turned out to be a C-shape, resembling the classic game character Pac-Man. [1]

Xenobots, being a newly developed technology, have limited applications as of now; most of them are in the fields of medicine and environmental conservation. An exciting application, especially for all the personalized medicine enthusiasts, is the potential use of Xenobots in the field of drug delivery. They are the perfect candidate since they are biodegradable and pose a significantly low threat to the patient [3]. Detection and treatment of cancer via Xenobots is also a topic of hot debate. The current technology in cancer treatment involves inserting foreign bodies into the patient’s body, but since Xenobots can be programmed to mimic the cells of the host, there are low chances of the body rejecting them. This could prove to be a huge breakthrough. Good news for the environmentalists out there, Xenobots can also be used to break down microplastics and detect detrimental radioactive contaminants in the environment in the future.

An AI-designed “parent” organism (C shape; red) beside stem cells that have been compressed into a ball (“offspring”; green). Credit: Douglas Blackiston and Sam Kriegman

Like all biological and technological advancements, Xenobots too are subject to ethical concerns. These concerns are not prominent until this first crop of Xenobots is further developed. With future versions expected to be developed in association with nervous systems, sensory cells, and rudimentary abilities to perceive and react to their environment, the only dilemma remaining would be as to whether these AI-designed organisms should be treated as machines or living creatures!


[1] Kriegman, S., Blackiston, D., Levin, M. and Bongard, J., 2021. Kinematic self-replication in reconfigurable organisms. Proceedings of the National Academy of Sciences, 118 (49), p.e2112672118.

[2] Scientists Create the Next Generation of Living Robots. (2021b, March 31). TuftsNow. Retrieved December 9, 2021, from

[3] Balfour, H. (2020, January 16). NEWS First living robots, called ‘xenobots’, could be used in drug delivery. European Pharmaceutical Review. Retrieved December 9, 2021, from

[4] Douglas Heaven, W. (2020, January 14). These “xenobots” are living machines designed by an evolutionary algorithm. MIT Technology Review. Retrieved December 9, 2021, from

[5] Sanders, L. (2021, December 3). Tiny living machines called xenobots can create copies of themselves. ScienceNews. Retrieved December 9, 2021, from

[6] Brown, J. (2021, November 29). Team builds first living robots—that can reproduce. Wyss Institute. Retrieved December 9, 2021, from

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