Robots with real muscles: ETH video shows mini actuators that jump and grasp

Researchers at ETH Zurich's Soft Robotics Lab have developed muscle actuators that let small biohybrid robots jump, swim, walk and grasp. The roughly 1.5-centimetre components combine living skeletal muscle tissue, grown from mouse muscle cells, with a soft hydrogel scaffold. What is new is that both parts were designed together on a computer for the first time: an algorithm searched for the configuration in which muscle contraction produces the largest movement of the whole component. The scaffolds are printed with light using xolography, about one minute each. The study appeared in Nature Communications.

According to ETH, the range of motion is up to eleven times greater than in earlier systems with a comparable amount of muscle. "With previous systems, you sometimes had to look under a microscope to see the flexing," says co-lead author Aiste Balciunaite. With a single contraction, the actuator lifts itself about five millimetres off the bottom of the dish, a third of its body length. A walking version covers 6.2 millimetres per second – faster relative to its body length than any walking biohybrid robot reported so far. The ETH video shows the movements.

A robot for long-term use is still a long way off: the robots need a nutrient solution to keep the muscle tissue alive. Larger systems would require a kind of artificial blood supply, explains lab head Robert Katzschmann. Cultured tissue also does not always behave the same way. "We're just beginning to build robots in a more natural way," Katzschmann says.