Metal robot arms can help us assemble cars and make cocktails, but they don’t yet have the flexibility of human arms, hands, and fingers. Advances in “biohybrid” robotics, which combine biological elements with mechanical ones, are paving the way for machines that will move a lot more like humans one day.
Robotics researchers at the University of Tokyo’s Institute of Industrial Science, for example, have managed to graft living muscle onto an artificial fingerbone, allowing a robotic finger to pick up and drop a ring—a task that looks easy but is actually a complicated dance of joint movements, muscle control, and neural signals. Their research, published in Science Robotics on Wednesday (May 30), detailed the process, which involved growing muscles from primitive muscle cells.
The lab-grown muscles had the ability to contract, and allowed the rotation of a robotic joint in two directions. The biohybrid robot could pick up the ring thanks to its antagonistic muscle pairs (think triceps and biceps, when one relaxes, the other contracts, to make a movement), which allowed them to work in opposition to one another.
Electric currents contracted the muscles on one side of the robotic finger to allow it to pick up and carry the ring, while stimulation of the muscle on the other side of the finger allowed it to put it down. Two biohybrid robots also worked together to pick up a square frame, demonstrating a 90° joint rotation, a similar range of motion to that of living skeleton muscle, noted the study.
The structure they created resembles the muscles in a human being’s forearm, said Shoji Takeuchi, an author of the report and a mechanical engineer at the University of Tokyo. Takeuchi also noted that the muscles they created in this experiment were able to be used for up to a week, while in earlier experiments, cultivated muscles shrank quickly and were no longer usable. For now, the muscles can only survive in water, but electrically stimulating the muscles produces bubbles that degrade the tissues. The researchers hope to solve the problem by building motor neurons into the muscles.
A future application of their work might be to help scientists test drugs on lab-grown muscles instead of living animals, Takeuchi said. Another ambitious future application would be building a real biohybrid robot.
“The first primary motivation to make a biohybrid robot is kind of the scientific fiction,” Takeuchi said, adding that the dream is to “make a real robot… behave like a real living body.”