Skin patches and contact lenses that change colour when exposed to UV light could provide us with a visual alert to apply sunscreen or seek some shade
Source:
https://www.newscientist.com/article/2232082-contact-lens-senses-uv-light-to-tell-you-when-its-time-for-sunscreen/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home