Accelerometer-assisted PPG Measurement During Physical Exercise Using the LAVIMO Sensor System

Abstract

A method is presented for long-term monitoring of vital signs tested during physical exercise. The system is based on reflective photoplethysmography (PPG), whose main component is a micro-optoelectronic sensor. The sensor is sealed within a biocompatible otoplastic housing so that it can be placed in the external auditory canal. The electronic device has a Bluetooth connection which enables to record/visualize the PPG signal on a personal computer or SmartPhone. This technology was tested indoors with a subject running on a treadmill at different speeds. The PPG signal was recorded together with an ECG used as a reference, and with an accelerometer to monitor and record motor activity. Theaccelerometer data were later used to reduce motion artifacts in the PPG signal. The results show that the system has potential to monitor cardiac activity at moderate speed (up to 4 km/h), but with increasing speed (i.e. running) the motion artifacts dominate the PPG. Therefore, additional studies on signal processing are needed to actively reduce motion artifacts, including the accelerometer data.