When Muscles Meet Machines

AsianScientist (Jun. 13, 2018) – A research group in Japan has created a robot that is part muscle and part machine. Their biohybrid robot, described in a study published in Science Robotics, had living muscle cells that survived and functioned for over a week.

The new field of biohybrid robotics involves the use of living tissue within robots, rather than just metal and plastic. Muscle is one potential key component of such robots, providing the driving force for movement and function.

However, in efforts to integrate living muscle into these machines, there have been problems with the force these muscles can exert and the duration before which they start to shrink and lose their function.

In this study, researchers at the Institute of Industrial Science of the University of Tokyo, Japan, have incorporated muscles into a biohybrid robot as antagonistic pairs mimicking those in the human body. The team first constructed a robot skeleton on which pairs of functioning muscles could be installed. This included a rotatable joint, anchors where the muscles could be attached and electrodes to provide the stimulus to induce muscle contraction.

For the living muscle part of the robot, rather than extract and use a muscle that had fully formed in the body, the team built one from scratch. For this, they used hydrogel sheets containing muscle precursor cells called myoblasts. These sheets contained holes which allowed them to be attached 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 Professor Shoji Takeuchi who is the corresponding author of the study. “The fact that they were exerting opposing forces on each other stopped them from shrinking and deteriorating as they did in previous studies.”

The team also tested the robots in different applications, including having them 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—when the muscles were stimulated, the robot could flex a finger-like protuberance by approximately 90°.

“Our findings show that, using this antagonistic arrangement of muscles, these robots can mimic the actions of a human finger,” said lead author Dr. Yuya Morimoto of the University of Tokyo. “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.”

The article can be found at: Morimoto et al. (2018) Biohybrid Robot Powered by an Antagonistic Pair of Skeletal Muscle Tissues.

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Source: University of Tokyo; Photo: Shoji Takeuchi/Institute of Industrial Science.
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