New Self-Healing Materials Detect When They're Damaged and Fix Themselves

A Thermal Image Shows the Shape-Memory System in Action
Where infrared laser light – that is, heat – is applied, the material toughens and regains its original shape, strengthening cracks or tears in the material.Image courtesy of American Institute of Physics

Call it science imitating art imitating life. Arizona State researchers are working up a self-diagnosing, self-healing material that can sense the presence of damage and regenerate itself -- just like the Terminator. Like a biological structure, this "autonomous adaptive structure" could be used to develop useable composites that are self-healing, halting the progression of cracks or damage and regenerating material wherever needed to re-strengthen the structure.

The material employs "shape-memory" polymers, or materials that return to a pre-defined shape when heated to a certain temperature (for a very straightforward demonstration of how this works, see the video below). The polymers are embedded with a fiber-optic network that serves as both damage sensor and heat delivery system.

When the material sustains damage, such as a tear, an infrared laser transmits light through the fiber-optic network, delivering thermal energy to the trouble-spot. That triggers the shape-memory polymers, which are programmed to toughen up to 11 times. The shape-memory effect can also close up a crack or tear, regaining an unheard of 96 percent of the material's original strength. Moreover, the material can self-heal while it is in operation – whatever that operation may be.

Those autonomous adaptive structures could be further advanced with some interesting shape-memory polymer research coming out of MIT this week as well. Scientists there have for the first time mathematically modeled shape-memory polymers in detail, which should make it a lot easier to design them for new applications like implantable medical devices or space materials that can be compacted into tiny packages and then automatically expanded into complex structures once they're aloft. Or robot assassins.