Compared to robots, the human body is flexible, capable of fine movements and can efficiently convert energy into movement. Taking inspiration from human locomotion, researchers in Japan have created a two-legged biohybrid robot by combining muscle tissue and artificial materials. The journal is being published Jan. 26 matterThis method allows the robot to walk and pivot.
Research on biohybrid robots, which combine biology and mechanics, has recently been attracting attention as a new field of robotics with biological functions. Using muscles as actuators allows us to build a compact robot and achieve efficient, silent movements with a soft touch.”
Shoji Takeuchi is a corresponding author at the University of Tokyo, Japan
The research team’s two-legged robot, an innovative bipedal design, builds on a legacy of biohybrid robots that take advantage of muscles. The muscle tissue enabled the biohybrid robots to crawl and swim straight ahead and make turns—but not sharp ones. Nevertheless, being able to pivot and make sharp turns is an essential feature for robots to avoid obstacles.
To create a nimbler robot with fine and delicate movements, the researchers designed a biohybrid robot that mimics human stiffness and works in water. The robot has a foam buoy top and weighted legs so it can stand upright underwater. The skeleton of the robot is mainly made of silicone rubber which can bend and flex according to the muscle movements. The researchers then attached strips of silicone rubber and lab-grown skeletal muscle tissue to each leg.
When the researchers zap the muscle tissue with electricity, the muscle contracts, lifting the leg up. When the power goes out, the heel drops forward. By alternating electrical stimulation between the left and right legs every 5 seconds, the biohybrid robot successfully “walked” at a speed of 5.4 mm/min (0.002 mi). To turn around, the researchers zap the right leg repeatedly every 5 seconds while the left leg acts as an anchor. The robot makes a 90-degree left turn in 62 seconds. Research has shown that muscle-powered bipedal robots can walk, stop and make fine-tuned turning motions.
“Currently, we are manually moving a pair of electrodes to apply an electric field to the legs individually, which takes time,” said Takeuchi. “In the future, by integrating electrodes into robots, we hope to increase speed more efficiently.”
The team plans to give the bipedal robot joints and thicker muscle tissue to enable more sophisticated and powerful movements. But before the robot can be upgraded with more biological components, Takeuchi says the team needs to integrate a nutrient supply system to maintain living tissues and device structures that allow the robot to operate in air.
“During our regular lab meeting there was a cheer when we saw the robot walking successfully on video,” says Takeuchi. “While they may seem like small steps, they are, in fact, giant leaps forward for biohybrid robots.”
This work was supported by the JST-Mirai Program, JST Fusion Oriented Research for Disruptive Science and Technology, and the Japan Society for the Promotion of Science.
Kinzo, R., etc. (2024). Biohybrid bipedal robots powered by skeletal muscle tissue. matter. doi.org/10.1016/j.matt.2023.12.035.