Now a team of scientists at Rice University have come up with a new twist. It's a Self-Adaptive Composite (SAC) that is not only self healing, but also has reversible self-stiffening properties that allow it to spring back into shape like a sponge.

Until now, self-healing materials have tended to be fairly rigid substances laced with microchannels or capsules filled with resins that squirt out and harden around damaged areas after they've been cracked or punctured. The problem is that this rigidity limits their applications as well as their ability to self-repair. Seeking something that was more a biocompatible material for tissue engineering or that can act as a lightweight, defect-tolerant structural component, the Rice team hit on the idea of a new material based on the structure of living tissue.