A stick-on patch that can take an ultrasound scan of a person’s insides as they go about daily life is a revolution in medical imaging. The wearable patch, only the size of a postage stamp, can image blood vessels, digestive system and internal organs for up to 48 hours, and can give doctors a detailed picture of a patient’s health. Professor Xuanhe Zhao at Massachusetts Institute of Technology, who led the team, envisions people buying boxes of these patches over the counter and using them along with their mobile phones. With it, they can monitor their heart, lungs and digestive systems for early signs of disease or infection, or even their muscles during rehabilitation or physical training. At the moment, the patch needs to be connected to an instrument that turns the reflections into images, but the researchers are developing a wireless patch to work with mobile software. Even without this, however, the patches can make an immediate difference in hospitals.