How much sunlight is too much?
According to the American Cancer Society, an estimated 5.4 basal (bottom layer) and squamous (flattened layer) cell skin cancers are identified every year. Though the sun contributes vitamin D, which is vital for bone health, how can we tell when we’ve had enough sun exposure?
Associate Professor Andrea M. Armani and doctoral candidate Michele E. Lee, both in the Mork Family Department of Chemical Engineering and Materials Science at the USC Viterbi School of Engineering, have created a color-changing wearable that can alert users when they’ve reached their recommended UV exposure for the day, allowing them to obtain a balance between sufficient sunlight and overexposure.
The user wears a clear, plastic 0.5 by 0.5 millimeter flexible strip (similar to a patch) that alerts the wearer of their total amount of UV exposure by changing colors. Since the sensor patch is so small, it’s very flexible. The design is ideal for athletes and exercise enthusiasts, and unlike an iPhone or Samsung watch, it doesn’t need a power source. In addition to being self-sustaining, the patch is still operational when it gets wet, and can adjust its responses when sunscreen is applied.
The sensors are comprised of a material patented by Armani and Lee, and are made of FDA-approved non-toxic polymers, suitable for human use and food contact. According to researchers Armani and Lee, the sensor addresses the exceptional challenges of trying to gauge sun exposure in the face of the differing geographical and environmental influences, as well as the bio-chemical make-up of individual users.
In the future, the researchers can change sensor performance and optimize the sensors for different skin types through the use of extra coatings and tailoring of the color-changing layer.