The capabilities of soft robots have increased massively in the last ten years, but have often come with an unfortunate trade-off. While the ability of the robots to mimic natural organisms with their flexibility is impressive, such dexterity involves a reduction of strength in the materials used. However, researchers have now created origami-inspired artificial muscles that allow soft robots to lift objects that are up to 1000 times their own weight.
“We were very surprised by how strong the actuators [aka, “muscles”] were. We expected they’d have a higher maximum functional weight than ordinary soft robots, but we didn’t expect a thousand-fold increase. It’s like giving these robots superpowers,” said Dr Daniela Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT and one of the senior authors of a paper on the artificial muscles.
“Artificial muscle-like actuators are one of the most important grand challenges in all of engineering,” added Dr Rob Wood, corresponding author of the paper and Founding Core Faculty member of the Wyss Institute. “Now that we have created actuators with properties similar to natural muscle, we can imagine building almost any robot for almost any task.”
Developed by researchers at the Wyss Institute at Harvard University and MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), the new muscles use just water or air pressure to achieve their results.
They consist of an inner ‘skeleton’ that can be made of various materials, surrounded by air or fluid and sealed inside a plastic or textile bag that serves as the ‘skin’. By applying a vacuum to the inside of the bag, movement is initiated as the skin collapses onto the skeleton and the created tension drives motion.
“One of the key aspects of these muscles is that they’re programmable, in the sense that designing how the skeleton folds defines how the whole structure moves. You essentially get that motion for free, without the need for a control system,” said first author Dr Shuguang Li, a Postdoctoral Fellow at the Wyss Institute and MIT CSAIL.
Removing the need for a control system means that the muscles can be both very compact and simple, thus making them more appropriate for use in mobile or body-mounted systems that cannot accommodate large or heavy machinery.
Moreover, they can not only generate about six times more force per unit area than mammalian skeletal muscle, but a single muscle can be constructed within ten minutes from materials costing less than a $1.
By powering the muscles with a vacuum, it allows them to be far safer than most other kinds of artificial muscle being tested as they have a lower risk of rupture, failure, and damage.
The muscles are also highly scalable and can even be built out of the water-soluble polymer PVA, meaning they could be used with minimal environmental impact or even as part of ingestible robots for targeted drug release.
Soft robots may soon be able to do far more than just mimic nature.