Samsung says it has figured out a blood pressure monitoring application for a smartwatch, and the solution will start shipping on the Galaxy Watch Active2, a Tizen watch that launched last year. Samsung says the app "has been cleared by the South Koreas Ministry of Food and Drug Safety (MFDS), as a Software as a Medical Device (SaMD), making it a government-cleared, over-the-counter and cuffless blood pressure monitoring application."
The only sensors on the back of a Galaxy Watch Active2 are a photoplethysmography (PPG) heart rate sensor and an electrode for electrocardiograms, but the company says that's enough to obtain a blood pressure rating. The trick is that you'll first need to calibrate the sensors with a real blood pressure cuff. The setup process has you wear the watch while taking a blood pressure reading with a cuff, then you enter the cuff reading into Samsung's software. From there, the software can supposedly take further readings with just the watch hardware.
Traditional automated blood pressure cuffs inflate to restrict blood flow in your arm, and, as the cuff releases the pressure, arterial pulsations are measured with a pressure sensor. There already is a smartwatch with an inflating band that is basically a tiny blood pressure cuff—the Omron HeartGuide—but Samsung's watch doesn't work like that. Instead, the company says, "the device measures blood pressure through pulse wave analysis, which is tracked with the Heart Rate Monitoring sensors. The program then analyzes the relationship between the calibration value and the blood pressure Read More – Source