Tests show a smartphone camera can give you a vital health metric
Google has been working on a system that tracks your health using your front-facing camera.
There are a number of ways to get a heart rate reading. Most smartwatches from companies like Apple, Samsung, Google, etc. will give you an actual-time beats-per-minute count. You can also try a pulse oximeter – squeeze the hinge, put your finger in and let it close. A smart watch you hit a button and seconds later you have your number. A good resting heart rate is 60-100 BPM, but 50-70 BPM points to better cardiovascular fitness .
The old school non-tech way? Place the tips of your index and middle fingers on your wrist, just below your thumb. Count to fifteen and multiply by four. And your maximum bpm is 220 minus your age.
How smartphones can save more lives than smartwatches
Google on Saturday released findings from a health study suggesting that resting heart rate (RHR) is an important indicator of cardiovascular health and long-term risk. High or increasing RHR has been linked to all-cause mortality and major adverse cardiovascular events. In simpler terms, a higher resting heart rate is associated with heart problems and a shorter life.
Google wrote: "Smartphones present a unique opportunity to expand access to health tracking – today, around five billion people have a device with powerful sensors that can track their health. In 2022, Google demonstrated how you could hold a finger over your phone’s camera to measure your heart rate on demand. That concept has become a smartphone system that passively monitors heart rate.
How Google’s system operates
This system, called Passive Heart Rate Monitoring (PHRM), uses the front-facing selfie camera to sense tiny changes in your skin as blood pulses through your body. These changes are not visible to the naked eye, but video taken in the first few seconds after face unlock can pick them up. This is a true Passive heart rate monitoring smartphone approach – you don't need to start anything.
A neural network is used to estimate heart rate from 8 second clips of facial video through deep learning. These predictions are summed over a day. With PHRM, HR and RHR can be computed in the background during normal phone usage. That’s the beauty of a Passive heart rate monitoring smartphone – it just works as you go about your normal business on your device.
Testing & Accuracy
Google trained the system on more than 350,000 video clips from nearly 700 participants with a wide variety of skin tones, as darker skin can make it more difficult to read blood flow via camera. In real-world testing, participants wore ECG equipment and a Fitbit tracker, and used their own phones for a week. The system apparently performed well.
But there is still work to do. While the readings are correct for dark skin tones, it has been hard to get those readings. Errors also occurred when subjects were talking or moving their heads. So Passive heart rate monitoring smartphone concept is promising, but not perfect yet.
The broader picture
Once Google irons out the bugs, smartphones could become a ubiquitous health tool. Because there are many more smartphone owners than smartwatch owners, this Passive heart rate monitoring smartphone approach could help billions of people track their heart health. Facial recognition biometrics could assure privacy. There is a future worth waiting for, and every Passive heart rate monitoring smartphone has the potential to save lives.