To enable the development of wearable devices that possess advanced ultraviolet (UV) detection functions, scientists from NTU Singapore have created a new type of light sensor that is both flexible and highly sensitive.While invisible to the human eye, UV rays surround us in our environment, and excessive exposure can cause health issues including skin cancer and premature skin aging. The intensity of UV rays is typically reported through an index during weather reports. A wearable device, such as a T-shirt or watch that monitors the actual personal UV exposure throughout the day, would be a useful and more accurate guide for people seeking to avoid sun damage.