A recent breakthrough from Stanford engineers, have successfully developed a Health sensor that resembles a sticker, can measure physiological signals emanating from the skin and sends these readings to a receiver attached to the person's clothing.
source: nature electronics
The technology works as an array of sensor networks called " BodyNet" that can be placed onto different body parts, will be used to monitor patients that suffer from heart conditions and sleep disorders. Dr. Zhenan Bao, the chemical engineering professor says that her lab is also developing new stickers to sense sweat and other skin secretions to hopefully track body temperature and stress. "The ultimate goal is make the BodyNet work wirelessly that can track multiple types of physiological data without interfering with the person's normal behavior."
The sticker sensors are strechable which makes them more comfortable to wear without the need of batteries or rigid circuitry, the stricker works similarly to an RFID ID card, it has small antenna that stretches as well, although to make it's signal stable the researchers made a new RFID system that generates accurate signals to the receiver even if the antenna is bent or stretched. then uses bluetooth to upload the proccessed data from the sticker to a smartphone, computer. But to make this technology consumer friendly they need to keep the receiver and the sensors close to each other, the researchers stick the receiver to the clothing above each sensor.