Samsung Galaxy S5 can measure your heart rate

The newly unveiled Samsung Galaxy S5 smartphone can measure your heart rate. It is one of the special features of Samsung's flagship product, and is part of Samsung's S Health portfolio which integrates its activity tracking app, fitness band (Gear Fit), smartwatch (Galaxy Gear 2), and cloud health data services (S Health app). How does the Galaxy S5 measure heart rate?

It takes advantage of the same principle as the Xbox One:

"Basically, the Xbox One uses technology developed at MIT Media Labs that measures the light from your face (using the camera) and decomposes it into the red, green and blue signals (RGB). Typically, one or more of these signals will show a periodicity that is related to your heart rate. For example, your face may become more or less red depending on the phase of the heart beat. This periodic rhythm can be quantitated by calculating the power spectrum of the signal and identifying the frequency with the highest peak (power) in a certain frequency range appropriate for your heart rate (45 - 240 beats per minute)."

As shown in Figure 1, the S5 uses its camera LED flash to shine light on your finger (which you place over the flash), and then a sensor next to the LED can measure the light signal from the finger (instead of the face as in the Xbox One). It is a clever idea, although somewhat awkward.

Some suspect that the iWatch will also possess a heart rate monitor. A band is probably a more convenient form-factor for measuring heart rate since it is on the wrist and can conceivable track your heart rate (by shining light on your wrist) continuously while you go about your activities (although battery life is a concern). I am more optimistic that the iWatch will have the heart rate monitor than a blood glucose monitor.

Figure 1. Measuring heart rate with a Samsung Galaxy S5.