Research ArticleBiosensors

Wireless, battery-free, flexible, miniaturized dosimeters monitor exposure to solar radiation and to light for phototherapy

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Science Translational Medicine  05 Dec 2018:
Vol. 10, Issue 470, eaau1643
DOI: 10.1126/scitranslmed.aau1643

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Safer sun exposure

Almost all skin cancers are caused by excessive ultraviolet (UV) irradiation from the sun. Sunscreens can reflect or absorb UV light to protect skin from damage but do not provide a measure of UV exposure. Heo et al. developed flexible, wireless, battery-free dosimeters to monitor light exposure. Body-worn sensors on human participants recorded UVA exposure during recreational outdoor activities, including swimming. Sensors could be fabricated in different shapes and sizes, could capture UVA and UVB exposure for clinical phototherapy, and could measure blue light exposure on infants with jaundice during bilirubin phototherapy. This wireless sensor platform technology enables high precision tracking of instantaneous and cumulative light exposure.

Abstract

Exposure to electromagnetic radiation can have a profound impact on human health. Ultraviolet (UV) radiation from the sun causes skin cancer. Blue light affects the body’s circadian melatonin rhythm. At the same time, electromagnetic radiation in controlled quantities has beneficial use. UV light treats various inflammatory skin conditions, and blue light phototherapy is the standard of care for neonatal jaundice. Although quantitative measurements of exposure in these contexts are important, current systems have limited applicability outside of laboratories because of an unfavorable set of factors in bulk, weight, cost, and accuracy. We present optical metrology approaches, optoelectronic designs, and wireless modes of operation that serve as the basis for miniature, low-cost, and battery-free devices for precise dosimetry at multiple wavelengths. These platforms use a system on a chip with near-field communication functionality, a radio frequency antenna, photodiodes, supercapacitors, and a transistor to exploit a continuous accumulation mechanism for measurement. Experimental and computational studies of the individual components, the collective systems, and the performance parameters highlight the operating principles and design considerations. Evaluations on human participants monitored solar UV exposure during outdoor activities, captured instantaneous and cumulative exposure during blue light phototherapy in neonatal intensive care units, and tracked light illumination for seasonal affective disorder phototherapy. Versatile applications of this dosimetry platform provide means for consumers and medical providers to modulate light exposure across the electromagnetic spectrum in a way that can both reduce risks in the context of excessive exposure and optimize benefits in the context of phototherapy.

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