Answer: On their skin.
The ultrathin device monitors a patient’s heart rate and displays it on a screen composed of 384 LEDs integrated into a rubber-like sheet. This sheet is flexible and expandable, able to stretch to almost twice its original size. It sticks directly to a patient’s skin for up to a week without any inflammation or other harmful side effects, according to its developers at University of Tokyo and Dai Nippon Printing.
This electronic skin is also capable of wirelessly transmitting data to the cloud, so a doctor can remotely monitor a patient’s condition. Researchers believe this tech would be highly beneficial to young or elderly patients who are restricted by age from acquiring their medical data themselves.