Planning on some fun in the sun this summer? If so, a new device can help you avoid a sunburn. Cosmetics company L’Oréal recently partnered with scientists to create UV Sense, a sensor that can be temporarily stuck to your fingernail or glasses. Using a smartphone, you can program the device with information like your skin type and sunscreen use. Then it alerts you if your skin receives too much ultraviolet (UV) radiation from the sun. “We designed the technology to be solar-powered and waterproof so you can keep it on all day,” says John Rogers, an engineer at Northwestern University in Illinois who worked on the device.