The principle of pressure measurement in mi band is photoelectric transmission measurement. In principle, the sensor that contacts the bracelet with the skin will emit a beam of light to irradiate the skin and measure the reflected/transmitted light.
Because blood absorbs light with a specific wavelength, every time the heart pumps blood, that wavelength will be absorbed in large quantities. Blood is red, reflecting red light and absorbing green light, so that the heartbeat can be determined. Mi band combines green LED light with photosensitive photodiode to detect the blood circulation at the wrist at a specific time, thus obtaining the heart rate information.
Conceptual analysis
Pressure value detection is probably to judge the working state of your heart according to the stability and abnormal performance of the pulse, and finally give the pressure value to help you quantify your physical condition.
Mi band has added the stress testing function for the first time, which can check our stress situation through various data. If we can cooperate with APP to give a reasonable way to reduce blood pressure, it will be of great help to our physical and mental health, and also make the smart bracelet have a qualitative leap in human health monitoring.