SpO2 and heart rate measurement with wearable watch based on PPG

This paper is based on the Photoplethysmography technology to measure the arterial blood oxygen saturation (SpO2) and Heart rate which are people´s vital sign. In the system we design a non-invasive continuous and portable wearable watch to measure human SpO2 and Heart rate. The wearable watch uses the micro-optoelectronic sensors to get PPG signal and utilizes wireless Bluetooth 4.0 to communicate with PC or mobile phone. The principle of Photoplethysmography is that reflection or transmission light changes with blood volume in the microvascular of tissue. So the PPG signal contains much valuable information about cardiovascular system such as SpO2, heart rate, blood pressure, and respiratory rate. The most advantages of PPG is non-invasive and low-cost, however the transmitting and receiving channel of PPG is easily disturbed by outside light and motion. In this Paper, to minimize the PPG channel noise and motion artifacts, we build the PPG signal channel model and use sensor to measure the outside light to cancel the distance disturbance between micro-optoelectronic sensors and skin. Because of the motion noises falls within the same frequency band as the physiological signal, we use MEMS approach to measure the motion information and cancel the disturbance. Disease about cardiovascular will be monitored and predicted in future work.