OPSensing: Embracing Real-Time PPG Monitoring with Intraoral Wearables

Photoplethysmography (PPG) is a widely used non-invasive optical technique for monitoring physiological parameters such as Pulse Rate (PR) and Blood Oxygen Saturation (SpO2). However, traditional wearables, which typically measure PPG from the wrist or fingertip, encounter shortcomings in motion artifacts, environmental noise, and discomfort during prolonged use. To address these challenges, we propose OPSensing, an intraOral PPG Sensing system designed for real-time physiological monitoring. By exploiting the stable and shielded oral environment, OPSensing achieves high-quality signal acquisition and analysis. The system integrates modest signal processing algorithms and a multi-wavelength PPG approach to ensure real-time and accurate PR and SpO2 estimation. We collected data from 10 participants and used a commercial pulse oximeter (Masimo MightySat) as the ground-truth reference. Experimental results show that OPSensing achieves a Root Mean Square Error (RMSE) of 1.88 beats per minute (bpm) for PR and 2.99% for SpO2, meeting the RMSE values recommended by U.S. Food and Drug Administration (FDA). In addition, sleep studies validate its capabilities to provide continuous monitoring over seven hours. This work demonstrates the potential of intraoral wearables for noninvasive, continuous physiological monitoring.