Analysis of Heart Rate Variability with an In-Ear Micro-Optic Sensor in View of Motion Artifacts

The variability of the heart rate has emerged to a popular marker for the overall condition of the circulatory system. In this paper, a novel approach for determining the heart rate by pulseoxymetric measurements inside the ear (IN-MONIT) is presented. Pulse signals from the auditory canal are mainly influenced by jaw motions. This influence can complicate the precise determination of the pulse rate and may yield lacks in the derivated tachograms. Therefore, the correlation properties of heart beat intervals and the influence of possible lacks in the tachograms on the outcome of the analysis are studied. It is shown that the usage of advanced methods of statistical time series analysis (e.g. Lomb-periodograms) is suitable in order to analyse signals without further complex filter designs. Together with this mathematical approach, the IN-MONIT system offers the opportunity to perform a 24/7 monitoring without disturbing the normal life of the monitored subject.