Harvard Medical School professor Conor L. Evans has developed a transparent liquid bandage that does not need to be removed to check oxygen levels. Its phosphors glow red when a wound isn’t getting enough oxygen, and green when it is. The glowing effect is triggered by a light source that can be captured with a smartphone camera. The bandage can also map oxygen supply across a wound.

Diabetics with chronic wounds, burn patients, and those with tissue transplants can immediately benefit from the technology.