A team of scientists at Northwestern's McCormick School of Engineering have developed the world's smallest battery-free wearable device. The device, which is thinner than a credit card and as small as an M&M, can measure the wearer's light exposure across multiple wavelengths. Applications include tracking UV light exposure, optimized treatment of neonatal jaundice and seasonal affective disorder.
“From the standpoint of the user, it couldn’t be easier to use – it’s always on yet never needs to be recharged,” said John Rogers, the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering in the McCormick School of Engineering and a professor of neurological surgery at Northwestern University Feinberg School of Medicine. “It weighs as much as a raindrop, has a diameter smaller than that of an M&M and the thickness of a credit card. You can mount it on your hat or glue it to your sunglasses or watch. There are no switches or interfaces to wear out, and it is completely sealed in a thin layer of transparent plastic. It interacts wirelessly with your phone. We think it will last forever.”
From the Northwestern University article: "When the solar-powered, virtually indestructible device was mounted on human study participants, it recorded multiple forms of light exposure during outdoor activities, even in the water. The device monitored therapeutic UV light in clinical phototherapy booths for psoriasis and atopic dermatitis as well as blue light phototherapy for newborns with jaundice in the neonatal intensive care unit. It also demonstrated the ability to measure white light exposure for seasonal affective disorder. As such, it enables precision phototherapy for these health conditions, and it can monitor, separately and accurately, UVB and UVA exposure for people at high risk for melanoma, a deadly form of skin cancer. For recreational users, the sensor can help warn of impending sunburn."
Read more about the wearable UV exposure warning device at Northwestern University.