A flexible tonoarteriography-based body sensor network for cuffless measurement of arterial blood pressure

Recent advances in unobtrusive sensing technology, especially those in flexible, stretchable, and printable sensing, have given rise to various novel signal acquisition modalities, such as stretchable epidermal electrocardiography (ECG), organic photoplethysmography (PPG), and flexible tonoarteriography (TAG) which is the cuffless and continuous recording of arterial blood pressure (BP). With the fast development of wearable computing and wireless communication technologies, all these modalities can be integrated into a body sensor network (BSN) for remote physiological multi-parameter monitoring. In this paper, we propose a TAG-based BSN for unobtrusive BP measurement with possible automatic cuffless BP calibration, and our efforts focus on the effect of posture change on the various pulse transit time (PTT) calculated from different BSN nodes consisting of TAG, ECG, and PPG sensors. Specifically, correlations of different PTTs with reference continuous BP at different postures are examined. The results of this study demonstrate that the PTT from ECG and TAG sensors has higher correlation with the reference BP as compared to that from ECG and PPG sensors, which suggests that flexible TAG sensor may potentially be utilized not only for cuffless calibration, but also as an alternative node in the BSN for continuous, cuffless BP measurement with better accuracy.