Quote: Human skin is a special material: It needs to be flexible, so that it doesn’t crack every time a user clenches his fist. It needs to be sensitive to stimuli like touch and pressure — which are measured as electrical signals, so it needs to conduct electricity. Crucially, if it’s to survive the wear and tear it’s put through every day, it needs to be able to repair itself. Now, researchers in California may have designed a synthetic version — a flexible, electrically conductive, self-healing polymer.
The result is part of a decadelong miniboom in “epidermal electronics” — the production of circuits thin and flexible enough to be attached to skin (for use as wearable heart rate monitors, for example) or to provide skinlike touch sensitivity to prosthetic limbs. The problem is that silicon, the base material of the electronics industry, is brittle. So various research groups have investigated different ways to produce flexible electronic sensors.
Chemists, meanwhile, have become increasingly interested in “self-healing” polymers. This sounds like science fiction, but several research groups have produced plastics that can join their cut edges together when scientists heat them, shine a light on them, or even just hold the cut edges together. In 2008, researchers at ESPCI ParisTech showed that a specially designed rubber compound could recover its mechanical properties after being broken and healed repeatedly. | 
