Fitbit is considering the use of photoplethysmography (PPG) for pulse wave analysis via wearable tech, as suggested by a newly filed patent. This innovative approach might allow for a non-invasive measure of arterial stiffness, which is a key indicator of cardiovascular risk. It could also pave the way for blood pressure measurements from the wrist.
Arterial stiffness, which occurs as a result of vascular ageing, diseases, and specific diets, is an indicator of cardiovascular dysfunction. It has traditionally required professional medical equipment and skill to measure. Pulse wave analysis (PWA) of blood pressure data is the most common method. Fitbit is looking to make this process more accessible by allowing users to estimate artery stiffness conveniently and non-invasively from the wrist.
Fitbit patent for measuring arterial stiffness
According to patent number 11684281 filed with the USPTO a couple of days ago, the company’s suggested wearable biometric monitoring device contains a wearable fixing structure, an inertial sensor, a PPG sensor, along with one or more CPUs. The gadget is intended to be worn by the user while participating in various activities, with sensors capturing inertial and PPG data.
This data is then processed by the device, which filters the PPG sensor data using the inertial data information. The filtered data can then be utilised to identify morphological aspects of a pulse waveform that correspond to arterial stiffness.
By the looks of it, this will be built into the company’s smartwatch range. Most likely Versa and Sense and possibly the Google Pixel Watch.
Fitbit’s unique technology contains innovative features that may appeal to a diverse variety of users. Because the device’s CPU can identify precise settings for data collecting based on the user’s behaviour or location, it becomes more practical and adaptable. For example, it can detect when a user is doing resistance training, aerobic exercise, endurance training, sitting, working, or sleeping. It modifies the operation of the PPG sensor based on the user’s activity or device orientation.
Furthermore, the gadget could integrate additional sensors. For example, temperature sensors, strain sensors, or pressure sensors could help enhance the analysis. The data from these sensors might be utilised to conduct wave normalisation on the pulse waveform, improving measurement accuracy.
The big picture
Because arterial stiffness is a well-established indicator of cardiovascular risk, the real-world consequences of this filing could be far-reaching. If the patent reaches real-world application, it will help to widen access to crucial health information by making arterial stiffness measurement convenient and non-invasive. This will empower individuals to take proactive actions towards better heart health.
Mind you, there is technology out there that will allow you to take these type of measurements from the comfort of your home. But it is few and far between. Withings is a name that springs to mind. It has scales that are capable of capturing pulse wave velocity information.
This isn’t the first time Fitbit has submitted a patent for gauging arterial stiffness using wrist-based devices. In fact, a similar proposal surfaced back in 2021. It’s interesting to note that this method could potentially allow for ongoing blood pressure measurements without a cuff. Let’s see what happens next.
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