Sometimes nature provides the best blueprints for building efficient robots. It can also provide the best material. Billions of years of natural selection have produced some pretty impressive machines, so you can’t really blame the engineers for borrowing a little inspiration from the world around them. In particular, the field of soft robotics — with its flexible and compatible components — owes much to animal biology.
While these systems have soft forms, however, many of their components are still rigid like their more traditional counterparts. Researchers are working to bring flexible components to create movement for these soft robots. As MIT succinctly puts it, “our muscles are nature’s perfect actuators.”
However, the team goes beyond simple muscle mimicry here. Researchers at school they use living muscle tissue combined with synthetic robot parts for a classification of robots known as ‘biohybrids’.
MIT Engineering Professor Ritu Raman confirmed the process with TechCrunch, noting, “We build the muscle tissues from mouse cells, and then we put the muscle tissues into the skeleton of our robot. The muscles then act as actuators for the robot — every time the muscle contracts, the robot moves.”
Muscle fibers are connected by a spring-like device called a “flexure,” which serves as a kind of skeletal structure for the system. Biological muscle tissue can be difficult to work with and generally unpredictable. Left in a Petri dish, the tissue will expand and contract as hoped, but not in a controlled manner.
To be developed into robotic systems, they must be reliable, predictable and repeatable. In this case, this requires the use of structures that are compatible in one direction and resistant in the other. Raman’s team found a solution in Professor Martin Culpepper’s MIT fabrication lab.
The bends still had to be adjusted to the robot’s specifications, eventually choosing structures with 1/100u the stiffness of the muscle tissue. “When the muscle contracts, all the force is converted into movement in that direction,” Raman said notes. It’s a huge increase.”
The muscle fiber/bending system can be applied to different kinds of robots in different sizes, but Raman says the team is focused on creating ultra-small robots that could one day work inside the body to perform minimally invasive procedures.
