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How the Apple Watch Series 8 might measure temperature

Apple Watch Series 7 being worn on a wrist

Apple will unveil the Apple Watch Series 8 during the iPhone 14 event in a few weeks. The new wearable series isn’t exactly a secret, as we have plenty of reports detailing the new smartwatches. Most agree that Apple will introduce a new sensor this year, allowing the Apple Watch Series 8 to take temperature measurements.

This is just a rumor, but Apple has already patented technology explaining how it plans to read temperature using a wearable like the Apple Watch. Moreover, Apple could apply the tech to other Apple gadgets for different purposes.

How the Samsung Galaxy Watch 5 measures temperature

Samsung currently makes the best Apple Watch alternative, and the Korean giant just unveiled the Galaxy Watch 5 series. The new watch series comes in three sizes, including a Pro version. Apple’s Series 8 should also feature three sizes, including a new Pro version.

Also, the Galaxy Watch 5 models come with a temperature sensor. Samsung explained during the press conference that it uses a new infrared sensor pointing at the skin to measure temperature. It’s unclear whether the sensor will deliver actual temperature readings or whether it’ll only be able to tell the difference between a regular temperature and a possible fever.

Samsung did say the infrared sensor can provide accurate readings, even if the temperature of the wearer’s surroundings changes.

The Galaxy Watch 5's new infrared sensor measures the wearer's temperature.
The Galaxy Watch 5’s new infrared sensor measures the wearer’s temperature. Image source: Samsung

Apple Watch Series 8 temperature sensor rumors

Various insiders with accurate track records have said that Apple plans to add a temperature sensor to the Series 8. But the Apple Watch might not necessarily take the precise body temperature. Instead, the device might be able to tell if you might have a fever.

Moreover, the temperature sensor might improve algorithms for sleep monitoring. Another potential technology implementation involves fertility planning, allowing women to monitor their ovulation cycle better.

Apple will only confirm the Apple Watch temperature sensor’s capabilities during the launch event. But we don’t have to wait for the iPhone 14 and Apple Watch Series 8 announcement to know with certainty that Apple wants to add temperature sensors to its devices.

From the patent “the wearable electronic device 100 may […] leverage a temperature sensing system […] to detect an absolute temperature of a back crystal 108 that contacts the user's skin.”
From the patent: “the wearable electronic device 100 may […] leverage a temperature sensing system […] to detect an absolute temperature of a back crystal 108 that contacts the user’s skin.” Image source: Apple via USPTO

A new patent hints at sophisticated features

Apple just won a patent titled Temperature gradient sensing in portable electronic devices. Found by MyHealthyApple, the document was filed with the USPTO in mid-July 2022. The agency awarded the patent to Apple on August 9th.

The patent describes the hardware technology that will allow an electronic device like the Apple Watch Series 8 to measure temperature.

Unlike Samsung, Apple’s patent doesn’t use infrared to register temperature readings. Instead, it uses a temperature sensor and a differential temperature probe. Apple can implement the system efficiently without taking up too much space inside the device. And without increasing manufacturing costs.

A smartwatch device (200) includes a housing (202) that might contain a back crystal (204) that comes in touch with a user’s skin. A differential temperature probe (208) comes in contact with the crystal.
A smartwatch device (200) includes a housing (202) that might contain a back crystal (204) that comes in touch with a user’s skin. A differential temperature probe (208) comes in contact with the crystal. Image source: Apple via USPTO

The way this works is relatively simple.

The differential temperature probe may sit on a flexible thin-film substrate. One of its ends would be routed through the watch to a component that comes in contact with the user’s skin. Like the back crystal of a smartwatch. The other end would connect to the temperature sensor:

As a result of this constructions, the wearable electronic device can obtain a highly accurate and highly precise measurement of the user’s skin temperature which, in turn, can be leveraged for: health or fitness recommendations; health or fitness tracking; biometric identification; wearable device fit evaluation; and so on. It may be appreciated that these foregoing examples are not exhaustive. Instead, a person of skill in the art may readily appreciate that any suitable biometric purpose related to or informed by temperature can be achieved by leveraging systems as described herein.

Applications beyond the Apple Watch Series 8

The documentation also details other uses for the temperature sensing technology. For example, Apple might use the differential temperature probe to measure air temperature. It can also use multiple probes connected to a single sensor to perform temperature readings of a device’s internal components.

Apple’s patent says it can use the same type of temperature sensor inside wireless headphones or earbuds. They would be able to detect the temperature of the wearer. Similarly, Apple might incorporate such sensors inside the Apple Pencil to determine whether the user is grasping the stylus.

Differential temperature probe (300) includes a substrate (302) that can be flexible and two electrodes (304, 306). A voltage corresponding to temperature differentials can be measured between the electrodes.
Differential temperature probe (300) includes a substrate (302) that can be flexible and two electrodes (304, 306). A voltage corresponding to temperature differentials can be measured between the electrodes. Image source: Apple via USPTO

All these claims indicate that Apple wants to have its devices make accurate temperature readings. But the sophisticated tech in the patent suggests more advanced tech than what the Apple Watch Series 8 might offer initially in terms of temperature monitoring.

Moreover, the patent seems to describe only the hardware Apple needs to make a temperature sensor happen on the Apple Watch. Software algorithms will interpret the readings in a broader context.

Also, let’s not forget that companies like Apple constantly patent new innovations they’re working on. But those inventions do not always make it into commercial products.


More Apple Watch coverage: For more Apple Watch news, visit our Apple Watch Series 8 guide.

Chris Smith has been covering consumer electronics ever since the iPhone revolutionized the industry in 2008. When he’s not writing about the most recent tech news for BGR, he closely follows the events in Marvel’s Cinematic Universe and other blockbuster franchises. Outside of work, you’ll catch him streaming almost every new movie and TV show release as soon as it's available.