Japanese engineers have developed a dexterous cyborg by integrating living muscle tissue into robots, according to a study published in the journal Science Robotics.

Researchers at The University of Tokyo Institute of Industrial Science developed a new method that could turn individual muscle precursor cells to muscle-cell-filled sheets, and then to fully functioning skeletal muscle tissues.

They incorporated these muscles into a biohybrid robot as antagonistic pairs mimicking those in the body to achieve remarkable robot movement and continued muscle function for over a week, according to the study.

The team, led by Shoji Takeuchi, the paper's corresponding author, first constructed a robot skeleton on which to install the pair of functioning muscles.

It included a rotatable joint, anchors where the muscles could attach, and electrodes to provide the stimulus to induce muscle contraction.

They used hydrogel sheets containing muscle precursor cells called myoblasts, holes to attach these sheets to the robot skeleton anchors, and stripes to encourage the muscle fibers to form in an aligned manner.

"Once we had built the muscles, we successfully used them as antagonistic pairs in the robot, with one contracting and the other expanding, just like in the body," said Takeuchi.

The team also tested the robots in different applications, including having one pick up and place a ring, and having two robots work in unison to pick up a square frame.

The results showed that the robots could perform these tasks well, with activation of the muscles leading to flexing of a finger-like protuberance at the end of the robot by around 90 degrees.

"Our findings show that, using this antagonistic arrangement of muscles, these robots can mimic the actions of a human finger," the paper's lead author Yuya Morimoto said. "If we can combine more of these muscles into a single device, we should be able to reproduce the complex muscular interplay that allow hands, arms, and other parts of the body to function."