Squid-inspired robotic muscles heal themselves in a second
Materials that can heal themselves after becoming damaged have opened up some interesting new possibilities over the past decade or so, pointing to a future of scratch-resistant car paints and space ships that can plug their own holes. A newly developed squid-inspired self-healing material is claimed to act faster than most, with the ability to repair itself in just a second.
The material was developed by scientists at Penn State University and the Max Planck Institute for Intelligent Systems, and partly funded by the US Army Research Office (ARO), in an effort to find more durable and reliable solutions for soft robotic actuators. These moving parts are subject to repetitive stress that can wear them down over time so, like many others in the field of robotics, the researchers set out to develop an innovative solution that could handle some of the repairs itself.
This led them to the ring teeth that squids use to latch onto their prey, which feature proteins with a mix of soft and hard components that enable the teeth to heal themselves when broken. The soft parts facilitate the fusion of the busted proteins, while the hard parts offer the structural integrity to keep the teeth strong.
Playing around with the repetitive sequences that make up these special proteins, the team was able to create a synthetic version with repeating sets of amino acids in a bacterial bioreactor. Like the squid teeth it is modeled on, the polymer is able to heal itself with the application of water and heat, and in just a fraction of the time of comparable materials.
"We were able to reduce a typical 24-hour healing period to one second so our protein-based soft robots can now repair themselves immediately," says Penn State’s Abdon Pena-Francesch, lead author of the paper. "In nature, self-healing takes a long time. In this sense, our technology outsmarts nature."
Even when the material is cut in half, it can heal and regain 100 percent of its original strength, according to the team. Additionally, it is entirely biodegradable and can also be recycled into the same original polymer, unlike many petroleum-based polymers that need to be recycled into something else entirely.
"Sooner or later we will run out of petroleum and it is also polluting and causing global warming,” says Melik Demirel, who led the research. “We can't compete with the really inexpensive plastics. The only way to compete is to supply something the petroleum-based polymers can't deliver and self-healing provides the performance needed."
In addition to soft robotics, the researchers imagine the material finding uses in other areas, such as protective equipment like hazmat suits where damage needs to be quickly repaired, or even ventilators.
“The rapid and high-strength self-healing of these synthetic proteins demonstrates the potential of this approach to deliver novel materials for future Army applications, such as personal protective equipment or flexible robots that could maneuver in confined spaces,” says Stephanie McElhinny, biochemistry program manager in the Army Research Office.
You can see the material heal itself in the video below, while the research was published in the journal Nature Materials.