A METHOD FOR CALIBRATING A BLOOD PRESSURE MONITOR, AND A WEARABLE DEVICE THEREOF

Methods and related devices 100 for obtaining the blood pressure of a person in two different ways. The first way comprising steps of providing a light source 101, and an optical sensor 103 configured to detect light from the light source 101 which has propagated through the wrist of a wearer of such a device 100. The amount of light propagating through the wrist depends on the amount of blood in the wrist. Blood pressure is then observed by monitoring the difference in the amplitude of blood pulsation within the wrist when the wrist is lifted above heart level, and when the wrist is lowered below heart level. The second way comprising mathematically analysing light transmission signals though a body part of the same person. Blood pressure readings obtained by the first way are used to calibrate blood pressure readings by the second way.