New Wristband Provides Personalized and Real-Time Tracking of UV Exposure

A paper-based sensor, which can be worn as a wristband, features happy and sad emoticon faces drawn in an invisible UV-sensitive ink. They successively light up as you reach 25%, 50%, 75%, and finally 100% of your daily recommended UV exposure. The research team also created six versions of the color-changing wristbands, each of which is personalized for a specific skin tone — an important characteristic given that darker people need more sun exposure to produce vitamin D, which is essential for healthy bones, teeth, and muscles.