Application Research of Photoplethysmography technology in Wearable Device Blood Pressure Detection

Photoplethysmography (PPG) is the measurement of changes in reflected or transmitted light intensity by illuminating the skin with light. When the heart contracts, the blood flow increases, absorbing more light and causing fluctuations in the light signal, thus forming a pulse wave. PPG signal contains rich information on human blood flow dynamics. By detecting changes in blood volume, it can effectively extract physiological and pathological features of the cardiovascular system. The elasticity of blood vessels in the human body affects the velocity of pulse waves, so the characteristic parameter of pulse wave propagation velocity (PWV) has a strong correlation with blood pressure. When blood pressure increases, the blood vessel wall becomes harder and the propagation velocity of pulse waves accelerates. So measuring PWV can estimate blood pressure and has important applications in wearable medical devices used for blood pressure measurement. Starting from the measurement principle of PPG, this paper delves into the main methods of non-invasive blood pressure measurement in wearable medical devices, explores and analyzes the traceability technology of blood pressure values, and lays a solid technical foundation for standardizing the wearable medical device market and promoting industry upgrading and progress.