Patent reveals highly-accurate temperature sensor for Apple Watch ahead of expected Series 8 launch

Apple Watch Series 7
(Image credit: Stephen Warwick / iMore)

One of the most anticipated features of the Apple Watch Series 8 is the long-rumored temperature sensor. While initially tipped for the Series 7 Watch, multiple sources have now explained they expect the new feature to appear in the new Series 8, set to be released later this year. 

Mark Gurman has revealed that the sensor may be used to detect changes in temperature from normal measurements, which could indicate illness. More specifically, he mentions a potential feature around fertility planning, taking measurements during a woman’s menstrual cycle.

Now, we’ve seen the first hard evidence of the potential feature with a patent filed by Apple.

Rumors of an Apple Watch temperature sensor are heating up 

Apple Watch temperature patent

(Image credit: USPTO)

The recent patent Apple filed with the USPTO details temperature gradient sensing in electronic devices. Spotted by MyHealthyApple, the patent explains how the temperature tech will work, and demonstrates it on the Apple Watch in diagrams. While the patent is for a general sensor, the diagrams suggest Apple will be using it for the Apple Watch.

The temperature sensing system uses a temperature sensor to detect the ambient temperature, and a flexible probe to record the body temperature. The system will then calculate the difference in temperature between the two numbers. This can produce a reading for each and also a differential temperature measurement, which is used in other health-tracking devices (such as the Oura ring).

Essentially, the probe uses a small voltage to find the temperature gradient between the two ends of the probe. The probe can measure the temperature of both internal and external surfaces, making it ideal for body temperature measurements. 

Apple’s patent claims the system can be used to measure the “absolute temperature” of the surface, implying that the tech is extremely accurate. In further details, Apple specifically mentions a potential application in the “back crystal of a smartwatch", and demonstrates a number of variations of the system.


While a patent alone doesn’t mean the technology will ever see the light of day, the number of rumors around the Apple Watch’s temperature sensor makes it highly likely. Considering Apple considers the Watch-specific use in the patent, we know that’s certainly an intention. There also aren’t many other devices that could suitably house a temperature sensor. A thermometer sensing pad on the back of your iPhone? No, thanks. While the feature is not confirmed for the Apple Watch Series 8, that is the most likely contender. And even if we don’t see it this year, we can be fairly confident that a future Apple Watch will be able to keep an eye on our temperature, and could be one of the best Apple Watch features added in recent years.

Connor Jewiss

Connor is a technology writer and editor, with a byline on multiple platforms. He has been writing for around seven years now across the web and in print too. Connor has experience on most major platforms, though does hold a place in his heart for macOS, iOS/iPadOS, electric vehicles, and smartphone tech.