Stereo-BP: Non-Invasive Blood Pressure Sensing with Earables
23 January 2023
Frequent blood pressure monitoring with earables has been increasingly explored owing to its importance in diagnosing cardiac health. While previous solutions for blood pressure estimation in earables are uncomfortable and less accurate, the objective of this study is to achieve non-invasive, accurate and cuff-less blood pressure monitoring with PPG sensors integrated into earphones. To this end, we investigated photoplethysmograph (PPG) signals from the left and right ears and found that blood arrives earlier in the left ear due to the closer distance from the heart. Based on our findings, we propose Stereo-BP --- an earable system leveraging the pulse time difference measured between PPG signals from our left and right ear-worn prototypes to estimate blood pressure. Our preliminary evaluation with 20 participants shows the feasibility of measuring systolic and diastolic blood pressure from the ears, with mean absolute errors of 3.85 mmHg and 3.56 mmHg, respectively, against ground truth blood pressure measurements from a clinical-grade cuff-based device. Our investigation shows the feasibility of Stereo-BP in providing frequent blood pressure estimation with future earables.
