A newly discovered Apple patent, which was only published today, describes a method of calculating blood pressure. Based on Apple’s wording on its patent application, the feature might become available for the Apple Watch in the future.

The patent filing was first discovered by Patently Apple early Thursday after it was published by the U.S. Patent and Trademark Office. It was filed by Apple some time during the first quarter of 2017. Apple’s patent mentions “wrist-worn devices” multiple times which is a direct reference to the Apple Watch. The patent describes a new method on how blood pressure is calculated using the built-in accelerometer and a photo-plethysmogram (PPG).

The idea behind this method is the wrist-worn device will be able to detect the wearer’s heartbeat and then detect the pulse created by it on the user’s wrist. Users will then have to time how long the pulse travels from their heart to their wrist. This is called pulse transmit time (PTT), and that is what is being used to calculate a user’s blood pressure, as explained by 9To5Mac.

Apple said on its patent that users will have to put their wrist-word device against their chest. The accelerometer and the PPG in the device will then be able to detect the user’s heartbeat. The heart-rate sensor on the device will then be used to detect the user’s pulse to calculate the PTT. The patent states that this method should be able to generate one or more blood pressure values for the user based on the PTT.

The Apple patent also delved deep into what users can do with their blood pressure data. Users will be able to use an authentication process to secure their private information without using a password. This likely refers to Apple’s Touch ID fingerprint sensor or the new Face ID facial recognition system that’s on the iPhone X.

The patent states the user’s health information and or biometric data can be used to provide them with feedback about their fitness and heath levels. Apple is taking users’ privacy seriously too by stating that collectors of this personal data should have user’s permission and consent, and cannot be sole outside “reasonable uses.” Users can also block, disable or selectively prevent others from accessing their blood pressure and other health related data.

There’s no information on when this new blood pressure tracking method will be applied to the Apple Watch. Seeing that this is just a patent for now, it might take some time. Another thing to consider here is that Apple files a lot of patents, and most of them don’t even actually end up becoming real. However, Apple CEO Tim Cook did say they have some plans for its health services.

“There’s much more in the health area. There’s a lot of stuff that I can’t tell you about that we’re working on, some of which it’s clear there’s a commercial business there. And some of it it’s clear there’s not. And some of it it‘s not clear. I do think it’s a big area for Apple’s future,” Cook told Fortune last month.

Apple Watch Apple patent hints at new method that allows an Apple Watch to measure blood pressure. Photo: REUTERS/Jason Reed