Development of a Wearable In-Ear PPG System for Continuous Monitoring

In this paper, a wearable electronic platform for in-ear photoplethysmography is presented. The system is specifically designed with a miniaturized form factor in order to enable the potential monitoring of athletes during physical activity, as well as professionals wearing earbuds or headphones during their normal duties. Measurements have been collected to address the main factors affecting the signal quality. As a result, the fine tuning of the configuration parameters allowed the extension of the battery lifetime of the system to over 3 days of continuous operation. Moreover, an investigation of the best body measurement location has been carried out. Two different algorithms have been developed: the former is a lightweight procedure for heart rate (HR) estimation suitable for embedded implementation whereas the latter features a motion mitigation adaptive filter to compensate the effect of motion artifacts (MAs).