Wearable body sensor network towards continuous cuff-less blood pressure monitoring

We present a wearable IEEE 802.15.4-based Body Sensor Network (BSN) that enables continuous cuff-less blood pressure monitoring, opening up new perspectives for hypertension diagnosis and treatment, cardio-vascular event detection, and stress monitoring. Arterial blood pressure is estimated based on the Pulse Arrival Time (PAT), which is measured using a single lead electrocardiogram (ECG) patch on the chest and a photoplethysmogram (PPG) sensor at the finger or ear. Measurement context information—user posture and activity level—is extracted using a 3-D acceleration sensor. Since precise PAT measurements require the synchronization of the BSN devices’ clocks, the Flooding Time Synchronization Protocol (FTSP) was implemented. The acquired data are stored and displayed on a PDA or a wristwatch. Our BSN can currently operate for up to eight hours and perform PAT measurements under moderate activity conditions. Future work includes higher motion tolerance, posture-corrected blood pressure estimation and on-sensor data processing and storage.