Researchers from the University of Granada and RMIT University in Melbourne have developed personalized and low-cost wearable ultraviolet (UV) sensors that warn users when their exposure to the sun has become dangerous.
The paper-based sensor, which can be worn as a wristband, features happy and sad emoticon faces—drawn in an invisible UV-sensitive ink—that successively light up as you reach 25%, 50%, 75% and finally 100% of your daily recommended UV exposure.
