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Self-Powered Sun Exposure Chip, App Developed

UV sensor chip

Sensor chip measuring UV rays worn on thumbnail (Northwestern University)

6 Dec. 2018. A tiny wireless sensor chip measuring exposure to ultraviolet or UV rays from the sun, developed by a university lab, is now offered by a cosmetics company with an accompanying smartphone app. The solar radiation sensor is a creation of an international team led by engineers at Northwestern University and described in yesterday’s issue of the journal Science Translational Medicine (paid subscription required).

Researchers from the lab of Northwestern engineering and materials science professor John Rogers in Evanston, Illinois are seeking more convenient ways for individuals to monitor their exposure to sunlight, which is a mixed blessing for many people. While controlled exposure to UV rays and blue light therapy can treat some skin conditions and jaundice in newborn infants, overexposure to UV rays are a leading cause of skin cancer, including basal cell and squamous cell carcinoma, and the more malignant cancer melanoma. American Cancer Society expects more than 91,000 people in the U.S. will be diagnosed with melanoma in 2018, leading to some 9,300 deaths.

Yet, up to now, simple and easy-to-use devices to measure UV exposure that withstand the rigors of active outdoor lifestyles are not yet available. Wearable devices on the market today for measuring UV exposure, like badges, patches, or wristbands, tend to be bulky and require an external power source or need recharging. Rogers — with colleagues from Northwestern, other universities in the U.S. and Korea, and the French cosmetics company L’Oréal — developed a simpler, self-contained device for measuring UV rays.

The Northwestern UV device measures 8 millimeters in diameter and 1 millimeter in thickness. The chip contains a UV photodiode sensor, temperature sensor, and a radio-frequency antenna to transmit in near-field communications mode to nearby mobile devices. Plus, the device is solar powered, thus relieving the need for a battery or external power source. In addition, it has no switches and is sealed in a thin layer of plastic.

“From the standpoint of the user, it couldn’t be easier to use,” says Rogers in a university statement. “It’s always on yet never needs to be recharged. 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.”

The researchers tested their device for technical performance in the lab, including measurement of infrared as well as UV rays, and for ruggedness under real-life conditions, such as boiling in water and a simulated washing machine. The team field tested 20 devices with 9 volunteers in Brazil, who took part in rooftop activities, wearing the chip on thumb and fingernails. The volunteers then wore the devices during swimming, showering, and use of soaps and skin creams. During all of these activities for 4 days, 14 of the 20 chips remained adhered. The researchers also tested the device to measure UV exposure during phototherapy for  seasonal affective disorder and blue light treatments for jaundice in newborns.

L’Oréal is already commercializing the UV device, through its La Roche-Posay skin care brand. The cosmetics company offers My Skin Track UV as a wearable device measuring 12 by 6 millimeters. My Skin Track UV sends data to a smartphone app, available on both Apple and Android phones, indicating safe UV-A and B ray exposure, as well as pollen, pollution, temperature, and humidity.The device sells for $59.95 from or at Apple stores.

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