The Xiaomi Mi 11 is able to measure heart rate with as much precision as a connected watch. In any case, this is what our colleagues from the Chinese site MyDrivers say.
At the end of December 2020, Xiaomi officially unveiled the Mi 11, a high-end smartphone for the moment intended for the Chinese market. Among its main assets, we note the integration of a 2K 120 Hz screen, the latest Qualcomm Snapdragon 888 processor, the OS MIUI 12.5 and a triple photo sensor on the back.
He won’t be alone since it has been confirmed that Xiaomi is also working on a 5G compatible Xiaomi Mi Lite, as well as a Xiaomi Mi 11 Pro, presumably equipped with a curved screen. And if the Mi 11 displays solid technical characteristics, it also does not forget to bring new features, such as the possibility of measuring heart rate.
The Mi 11 as precise as a professional pulse oximeter
According to Xiaomi CEO Lei Jun, the Mi 11 is able to offer much more precise heart rate measurements than those offered by a connected bracelet. According to diagrams relayed by the Chinese site MyDrivers, the heart rate is measured via the fingerprint scanner located under the screen, without adding an additional sensor.
As a reminder, a connected bracelet measures the heart rate using a simple optical technique called PGG or photoplethysmography. To summarize, the principle is to send green light to the heart of the capillaries. Depending on the level of reflected light, the sensor will be able to determine the blood flow and by extension the heart rate.
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However, the Mi 11’s heart rate measurement function is well thought out, since it uses the AMOLED screen as a light source and the fingerprint scanner as information reception. When the user wants to know his heart rate, all he has to do is put his finger on the sensor.
The light from the screen passes through the finger, while the scanner detects variations in brightness. Thanks to the integration of a dedicated algorithm, the sensors measure the time intervals between the different variations in light intensity. You have your heart rate.
To ensure high measurement accuracy, the Mi 11 screen emits green light when the function is activated. Blood absorbs this light particularly well and it is therefore easier for the optical sensor to detect changes in light. According to the results of tests carried out by the SGS laboratory and relayed by MyDrivers, the difference in performance between the measurement function of the Mi 11 and a professional pulse oximeter is 2.11 beats per minute. In the case of the vast majority of bracelets and smartwatches, this difference is 3 beats per minute.