RingBP: Towards Continuous, Comfortable, and Generalized Blood Pressure Monitoring Using a Smart Ring

The utilization of wearable devices with integrated photoplethysmography (PPG) sensors for continuous and comfortable Arterial Blood Pressure (ABP) monitoring has gained popularity. However, our analysis on a large-scale self-collected dataset reveals a significant challenge: approximately 56.7% of individuals experience the absence of the dicrotic notch (a vital morphology feature) in wrist-PPG data, while 23.8% face the same issue in finger-PPG data, which poses a big obstacle to generalized ABP monitoring. To address this challenge, we propose a morphology-independent ABP estimation algorithm based on the Frank-Starling law. We also devise techniques to address calibration and PPG data drift issues commonly faced in continuous ABP monitoring. Further, a system called RingBP is developed towards continuous, comfortable, and generalized ABP monitoring using a smart ring. We design and implement a smart ring prototype and conduct extensive experiments involving 85 participants, demonstrating its superiority over other solutions.