Materials scientists at the University of California Riverside and the University of Colorado have come up with a self-healing, stretchable material that’s being hailed as the first synthetic ionic conductor.
Crediting the Marvel superhero Wolverine and his self-regenerating powers served in part for the inspiration, the researchers say the new material may someday be used in electronic devices, including the construction of self-repairing, flexible and soft robots.
“Creating a material with all these properties has been a puzzle for years,” says study co-author Chao Wang, material chemist at the UC Riverside and self-confessed lifelong fan of the Wolverine comics. “We did that and now are just beginning to explore the applications.”
The material came about as the product of mixing together a high ionic strength salt with a stretchable polar polymer, the result being an electrically conductive material within which the molecules exhibit an electrostatic attraction such that when separated (through tearing or cutting) they have the ability to recombine, essentially “healing” the wound in the process.
“Nature has perfected mechanisms of self-healing through evolution into a preeminent survival feature of biological systems,” say the study’s authors, whose work is published in the journal Advanced Materials. “Similarly, man-made materials with self-healing capabilities are highly desirable for areas of application spanning from weather resistant surfaces to robust electronics.”
The material is both inexpensive and highly stretchable -up to 50 times its original length- and able to heal itself within 24 hours of being cut when left at room temperature. Potential applications include the creation of longer-life lithium ion batteries for electric cars and, as shown in the study, soft robotics: the researchers created an artificial muscle prototype made from two layers of the new material with a transparent membrane in between, thus showing the material’s prospects for creating more human-like, soft and flexible robots.
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Co-author Christophy Keplinger of the University of Colorado spoke of the product as helping science to advance past the traditional idea of the robot as a metallic, clumsy piece of hardware. “Now imagine a new class of robots that are based on soft, elastic materials, being powered by stretchable electronic circuits and thus much more closely resemble the elegant design of biology,” says Dr. Keplinger. “This is the type of robot that will soon help us out in the household or help us care for elderly people.”
Self-healing materials have been a recent fixation of material engineers, from the release of a prototype for self-mending fabrics coasted in yeast and bacteria and able to sew themselves back together to the creation of self-repairing silicon electrodes and sensors.
In 2015, Dutch researchers at the Delft University of Technology came out with a self-healing type of concrete, one which they say will help make the ubiquity of concrete structures around the world more durable and long-lasting. As reported in the Toronto Star, the material’s developers say the self-healing concrete could be used to save the dilapidated Gardiner Expressway in downtown Toronto (recently approved for repair and redevelopment by Toronto City Council).
“We think every road like that could benefit from our bio-concrete,” said Dr. Henk Jonkers, co-developer of the self-healing concrete. “We’ve already had requests from all over the world, including Australia, Russia and South America —but none from Canada yet.”