Low group delay signal conditioning for wearable central blood pressure monitoring device

Pulse transit time (ptt) is a widely researched approach for wearable, unobtrusive, blood pressure monitoring. The estimation of ptt, being a delay measurement, may be affected by the group delay introduced by the signal conditioning chain. In this work a previously reported method for estimating central (aortic) blood pressure from ptt at aortic domain, using ECG R wave and BCG J wave detection, is considered. A simple design approach for the signal conditioning chain, which is suitable for a wearable device and that takes care of minimizing the impact of eventually introduced spurious delays is presented. The design provides less than 2ms group-delay. The design of a wearable device prototype for ECG, BCG and ptt acquisition and experimental results of its application are reported, showing the effectiveness of the proposed approach.