Researchers build microscopic biohybrid robots powered by muscles, nerves

Researchers have developed soft robotic devices driven by neuromuscular tissue that are triggered when stimulated by light, bringing mechanical engineering closer to the development of autonomous biobots.

In 2014, teams of researchers led by Taher Saif, professor of mechanical sciences and engineering, and Rashid Bashir, professor of bioengineering at the University of Illinois, collaborated on the development of the first self-propelled biobots for swimming and walking by biohybrid, fed by cardiac muscle cells deriving from rats.

"Our first study of swimmers successfully demonstrated that sperm-like robots could actually swim," Saif said. "This generation of individual-tailed robots used heart tissue that beats alone, but it could not detect the environment or make a decision."

In a new study published in the Proceedings of the National Academy of Sciences and led by Saif, researchers are demonstrating a new generation of two-tailed robots powered by skeletal muscle tissue stimulated by integrated motor neurons. Neurons have optogenetic properties: when exposed to light, neurons activate to activate the muscles.

"We applied an optogenetic neural cell culture, derived from mouse stem cells, adjacent to muscle tissue," Saif said. "The neurons advanced to the muscle and formed neuromuscular junctions, and the swimmer assembled alone."

After confirming that the neuromuscular tissue was compatible with synthetic biobot skeletons, the team worked to optimize the swimmer's abilities.

"We used computer models, led by Mattia Gazzola, professor of mechanical sciences and engineering, to determine the physical attributes that would lead to the fastest and most efficient swim," said Saif. "For example, we examined variations in the number of tails and their lengths for a more efficient design of the biohybrid swimmer."

"Since biological actuators, or biobots, are not as mature as other technologies, they are unable to produce large forces, making their movement difficult to control," Gazzola said. "It is very important to design the scaffolding on which biobots develop and interact with each other to make the most of technology and perform locomotive functions." The computer simulations we run play a crucial role in this task. because we can cover a number of possible designs, and select only the most promising ones for real-life testing. "

"The ability to drive muscle activity with neurons paves the way for further integration of neural units into biohybrid systems," Saif said. "Given our understanding of neuronal control in animals, it may be possible to move forward with biohybrid neuromuscular design using a hierarchical organization of neural networks."

Saif stated that he and his team were considering this breakthrough for the development of multi-celled, life-saving systems capable of intelligently responding to environmental signals for applications in bioengineering, medicine and self-healing materials. healing.

However, the team recognizes that, like living organisms, no biohybrid machine will develop in exactly the same way.

"Just as twins are not really identical, two machines designed to perform the same function will not be the same," Saif said. "One can move faster or heal differently than the other, unique attribute of living machines."