Human beings, unlike robots, are flexible, capable of precise movements, and can efficiently transform energy into movement. Drawing inspiration from human movement, Japanese researchers created a two-legged biohybrid robot by mixing muscle tissues with synthetic components. This technology, published on January 26 in the journal Matter, enables the robot to walk and turn.
“Research on biohybrid robots, which are a fusion of biology and mechanics, is recently attracting attention as a new field of robotics featuring biological function,” explains corresponding author Shoji Takeuchi of the University of Tokyo, Japan. “Using muscle as actuators allows us to build a compact robot and achieve efficient, silent movements with a soft touch.”
The research team’s two-legged robot, an innovative bipedal design, builds on the legacy of biohybrid robots that take advantage of muscles. Muscle tissues have driven biohybrid robots to crawl and swim straight forward and make turns — but not sharp ones. Yet, being able to pivot and make sharp turns is an essential feature for robots to avoid obstacles.
Research on biohybrid robots, which are a fusion of biology and mechanics, is recently attracting attention as a new field of robotics featuring biological function. Using muscle as actuators allows us to build a compact robot and achieve efficient, silent movements with a soft touch.
Shoji Takeuchi
To create a more agile robot with fine and delicate movements, the researchers created a biohybrid robot that resembles human stride and operates in water. The robot features a foam buoy top and weighted legs that allow it to stand upright underwater. The robot’s skeleton is primarily comprised of silicone rubber, which bends and flexes to accommodate muscle motions. The researchers then affixed strips of lab-grown skeletal muscle tissue to the silicone rubber and each 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 electric stimulation between the left and right leg every 5 seconds, the biohybrid robot successfully “walked” at the speed of 5.4 mm/min (0.002 mph).
To turn, researchers repeatedly zapped the right 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 are manually moving a pair of electrodes to apply an electric field individually to the legs, which takes time,” says Takeuchi. “In the future, by integrating the electrodes into the robot, we expect to increase the speed more efficiently.”
The team also intends to provide the bipedal robot more joints and larger muscle tissues, allowing for more complex and powerful movements. However, before adding more biological components to the robot, Takeuchi says the team will need to combine a food delivery system to support the living tissues and device structures that allow the robot to work in the air.
“A cheer broke out during our regular lab meeting when we saw the robot successfully walk on the video,” Takeuchi said in a statement. “Though they might seem like small steps, they are, in fact, giant leaps forward for the biohybrid robots.”
