In comparison with robots, human bodies are flexible, able to high-quality movements, and may convert energy efficiently into movement. Drawing inspiration from human gait, researchers from Japan crafted a two-legged biohybrid robot by combining muscle tissues and artificial materials. Publishing on January 26 within the journal Matter, this method allows the robot to walk and pivot.
“Research on biohybrid robots, that are a fusion of biology and mechanics, is recently attracting attention as a brand new field of robotics featuring biological function,” says corresponding creator Shoji Takeuchi of the University of Tokyo, Japan. “Using muscle as actuators allows us to construct a compact robot and achieve efficient, silent movements with a soft touch.”
The research team’s two-legged robot, an progressive bipedal design, builds on the legacy of biohybrid robots that benefit from muscles. Muscle tissues have driven biohybrid robots to crawl and swim clear-cut and make turns — but not sharp ones. Yet, with the ability to pivot and make sharp turns is a vital feature for robots to avoid obstacles.
To construct a nimbler robot with high-quality and delicate movements, the researchers designed a biohybrid robot that mimics human gait and operates in water. The robot has a foam buoy top and weighted legs to assist it stand straight underwater. The skeleton of the robot is especially constituted of silicone rubber that may bend and flex to evolve to muscle movements. The researchers then attached strips of lab-grown skeletal muscle tissues to the silicone rubber and every leg.
When the researchers zapped the muscle tissue with electricity, the muscle contracted, lifting the leg up. The heel of the leg then landed forward when the electricity dissipated. By alternating the electrical stimulation between the left and right leg every 5 seconds, the biohybrid robot successfully “walked” on the speed of 5.4 mm/min (0.002 mph). To show, researchers repeatedly zapped the best leg every 5 seconds while the left leg served as an anchor. The robot made a 90-degree left turn in 62 seconds. The findings showed that the muscle-driven bipedal robot can walk, stop, and make fine-tuned turning motions.
“Currently, we’re manually moving a pair of electrodes to use an electrical field individually to the legs, which takes time,” says Takeuchi. “In the longer term, by integrating the electrodes into the robot, we expect to extend the speed more efficiently.”
The team also plans to provide joints and thicker muscle tissues to the bipedal robot to enable more sophisticated and powerful movements. But before upgrading the robot with more biological components, Takeuchi says the team can have to integrate a nutrient supply system to sustain the living tissues and device structures that allow the robot to operate within the air.
“A cheer broke out during our regular lab meeting after we saw the robot successfully walk on the video,” says Takeuchi. “Though they could seem to be small steps, they’re, the truth is, giant leaps forward for the biohybrid robots.”
This work was supported by JST-Mirai Program, JST Fusion Oriented Research for disruptive Science and Technology, and the Japan Society for the Promotion of Science.
