It’s a dilemma anyone who has worn a bandage has faced: How can you tell if a wound is healing without taking off the dressing and potentially damaging delicate new skin? A different kind of ‘smart’ ...

It used to be so simple. You were a kid. You fell down, and skinned your knee. You cried. Mom came to the rescue, washed off your wound and applied hydrogen peroxide or mercurochrome. You cried again.

So Mom now is faced with store shelves jam-packed with products: liquid and spray-on bandages, ionized-silver bandages or waterproof or moist-environment-promoting or easy-to-remove bandages. Or ...