Apple wants to use its smartwatch to help users measure whether they are sufficiently protected by sunscreen, according to a patent application published by the U.S. Patent & Trademark Office and reported by Patently Apple.
The patent is another signal of Apple's work turning its smartwatch into a medical device.
The sunscreen detector is called a UV-IR spectrometer and is designed for either the watch or the watch band to identify the degree of sunscreen coverage in exposed areas of the skin. The detector will search for parts of the skin where sunscreen is missing or inadequate and could help notify users when to reapply sunscreen or whether they may be in the early stages of sunburn.
The detector may involve a visible light source that guides users to scan a skin region to check for sun protection. The spectrometer might then display a visual on the watch's face or trigger a sound based on the amount of UV light the skin has absorbed or reflected.
Apple's patent application was published July 19 and was originally filed December 2017.