Measurement of Motion Activity during Ambulatory Using Pulse Oximeter and Triaxial Accelerometer

An ambulatory pulse oximeter system based on wireless sensor network is designed and integrated to the wearable sensor node. The system is developed to measure motion activities using pulse oximeter and triaxial accelerometer sensor during in motion. The input signals are pulse oximeter and triaxial acceleration signals which are acquired from a finger. However, motion artifact is originated a result in a distorted PPG signal which may cause between the skin and sensor during physical activity. Therefore, motion artifacts prevent their broad in wearable, ambulatory pulse oximeter system. The measurement of those signals, such as the PPG and the electrocardiogram (ECG) requires being still tight during the measurement in order to get the accurate result preventing noises caused by the casual movement. In this paper, we calibrate the distorted PPG signal with the motion activities by measuring PPG and motion signals by using triaxial accelerometer as a reference signal. The system allows PPG signals to be transmitted in wireless sensor network from the pulse oximeter to a base-station connected to server PC via IEEE 802.15.4. The experiments were performed by using wearable ECG, accelerometer sensor and ambulatory pulse oximeter for measuring in different scenarios such as resting, swing, walking, etc.