Apple patent application reveals sophisticated way for Apple Watch to measure blood pressure

“Today the US Patent & Trademark Office published a patent application from Apple titled ‘Wrist Worn Accelerometer for Pulse Transmit Time (PTT) Measurements of Blood Pressure’ that relates to the Apple Watch being used to measure blood pressure in a very sophisticated manner,” Jack Purcher reports for Patently Apple.

“In describing their invention, Apple notes in their patent filing that ‘Wrist-worn devices and related methods measure a pulse transit time non-invasively and calculate a blood pressure value using the pulse transit time. A wrist-worn device includes an accelerometer, a photo-plethysmogram (PPG) or a pulse pressure sensor, and a controller. The PPG or the pulse pressure sensor coupled to the wrist-worn device for detecting an arrival of a blood pressure pulse at the user’s wrist. The controller is configured to process output signals from the accelerometer to detect when the blood pressure pulse is propagated from the left ventricle of the user’s heart, process a signal from the PPG or the pulse pressure sensor to detect when the blood pressure pulse arrives at the wrist, calculate a pulse transit time (PTT) for propagation of the blood pressure pulse from the left ventricle to the wrist, and generate one or more blood pressure values for the user based on the PTT,'” Purcher reports.

Purcher reports, “Towards the end of the patent filing Apple notes that ‘It will be appreciated that personal information data may be utilized in a number of ways to provide benefits to a user of a device. For example, personal information such as health or biometric data may be utilized for convenient authentication and/or access to the device without the need of a user having to enter a password.'”

Read more in the full article here.

MacDailyNews Take: Coupled with the announcement last month that Apple is among those selected by the U.S. FDA to participate in a new digital health software precertification pilot program shows that there is much, much more Apple Watch can do in terms of monitoring users’ health and vital signs. Apple Watch has already extended and saved lives, it could soon be extending and saving untold numbers more!

U.S. FDA selects participants, including Apple, for new digital health software precertification pilot program – September 26, 2017
Apple Watch sales could soar with new U.S. FDA plan – June 19, 2017
A personal story: Apple Watch may have saved my life – February 8, 2017
How my Apple Watch saved my life – July 25, 2016
A real lifesaver: Apple Watch saves lives – March 28, 2016
Man credits Apple Watch with saving his life – March 15, 2016
Apple Watch saves teenager’s life; Tim Cook offers thankful teen an internship – October 2, 2015


  1. Monitoring blood pressure during physical activities is a huge deal for a lot of people and that is not currently possible or practical. I hope Apple will be able to pull it off.

    1. Absolutely. An accurate wrist-worn blood pressure monitor would be tremendous. A large percentage of the population has BP issues to some degree, and having a steady long-term history would be a breakthrough.
      If/when they can get this working it will be huge.

  2. There is always a huge gulf between a patent application and shipping a working product and many patent applications fail to end up in products, so obviously we shouldn’t read too much into this, but at the same time, it’s a very exciting possibility and if Apple develops a quick and reliable way of measuring blood pressure in this manner, it’s going to be life changing product for millions of people.

    As one with high blood pressure, this discussion is very close to my heart ( sorry for that ! ) and as I am always interested in discovering how things work, I examined the patent application and note that the image of how it works shows the watch around the wrist, but with the forearm held against the chest.

    I was initially intrigued how the Pulse Transit Time could be measured by a wrist worn device with such small dimensions and then realised that it appears to need the wrist held against the chest in order to measure the time taken between the heart beating and that pulse reaching the wrist.

    It doesn’t appear to offer continuous monitoring as I initially imagined, but does offer on rapid, on demand near-instantaneous measurements with minimal effort.

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