While sunburn is the main cause of skin cancer, any type of sun exposure can damage the skin and increase the risk of developing skin cancer and premature signs of aging. To help people monitor their sun exposure, J. Justin Gooding and a group of colleagues at The University of New South Wales in Australia created a disposable sunburn sensor. To do so, they inkjet printed titanium dioxide and a food dye on paper. The titanium dioxide acts as a photocatalyst and gradually degrades the food dye. The combination will change color when enough UV radiation hits the paper, providing a warning for people to get out of the sun or apply more sunscreen. The researchers also adjusted the sensor for various skintones and sunscreen use by adding UV neutral density filters that can sped up or slow down the discoloration time of the sensor. Currently, most UV sensor technologies involve integration of the sensing material into other devices (such as smart phones) or other high-technology wearable sensors. This easy-to-use innovation makes sun safety and awareness easy for anyone.