Penn State and Max Planck Institute scientists have created a new squid ring teeth protein-inspired, self-healing and biodegradable material for soft robot actuators.
Squid ring teeth are circular predatory appendages located on the suction cups of squid used to grasp prey. If the teeth are broken, they can heal themselves.
The soft parts in the proteins is what helps the broken proteins to fuse back together in water, while the hard parts help to reinforce the structure and keep it strong.
Taking a cue from this, the Penn State and Max Planck team has developed a new biosynthetic polymer to help repair materials that come under continual repetitive movement such as robotic machines, prosthetics, ventilators and hazmat suits.
The study was funded by the U.S. Army Combat Capabilities Development Command’s (CCDC) Army Research Laboratory (ARL).
“Materials that undergo continual repetitive motion often develop tiny tears and cracks that can expand, leading to catastrophic failure,” says ARL biochemistry program manager Dr. Stephanie McElhinny.
“With a self-healing bio-based synthetic material, any sites of damage that emerge can be repaired, extending the lifetime of the system or device.”
Current strategies for material self-healing have significant limitations, including requirements for potentially hazardous chemicals, loss in functionality of the healed material relative to the original state, and long healing times, often greater than 24 hours.
“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 lead author and Max Planck postdoc Abdon Pena-Francelsch.
“In nature, self-healing takes a long time. In this sense, our technology outsmarts nature.”
The self-healing polymer heals with the application of water and heat, but it can also be programmed to heal with light.
Moreover, it is 100% biodegradable and 100% recyclable – courtesy of an acid like vinegar – into the same, original polymer.
This is in stark contrast to petroleum-based polymers that can be recycled only into something different but never the same.
For example, polyester t-shirts can be recycled into bottles but not into polyester fibers again.
Image and content: Abdon Pena-Francesch-Max Planck Institute/CCDC ARL