Skin, the human body's largest organ, is an amazing mass of tissues with its resilience, flexibility, sensitive, and ability to heal. Finding an artificial material with those same properties is not easy as some of these properties do not occur together or require special conditions that make them impractical. Researchers at the Stanford School of Engineering however have successfully created a material that not only has these properties, but surprised them as to their extent.
Making a self-healing material is tricky and many of those that do exist now either require high temperatures to heal or are only able to heal once. The researchers fixed that by picking a polymer with long chains of molecules joined by hydrogen bonds. This type of bond is a weak attraction between the positive and negative charges of neighboring molecules. This weakness is actually a strength though as the bonds are readily remade. In fact, after cutting the material apart, the researchers only had to hold the two pieces together for a few seconds for it to regain 75% of its strength.
To make the material sensitive the researchers added nickel nanoparticles that allow a charge to flow through the polymer, by jumping from one nanoparticle to the next. When pressure is applied to the material, the placement of the nanoparticles is disturbed, which then changes the conductivity of the material in a detectable way. The researchers see this sensitivity potentially being used on prosthetics to sense touch, or even to create self-healing electrical cables, as when the strength of the material returns, so too does its conductivity.