Mechanically Decoupled Organic Photodetector-Integrated Wearable PPG Sensor Toward Ambulatory Blood Pressure Monitoring

초록

Continuous, non-invasive ambulatory blood pressure monitoring is essential for timely cardiovascular risk assessment, yet conventional wearable photoplethysmography sensors suffer from severe motion artifacts caused by physical instability at the sensor-skin interface. Although hardware miniaturization can suppress these inertial artifacts, reducing sensor dimensions inherently degrades the signal-to-noise ratio. Herein, we report a motion-robust wearable photoplethysmography platform that overcomes this trade-off by integrating a high-gain organic photodetector with a mechanically decoupled architecture. The developed ZnO/P3HT:PCBM bulk-heterojunction organic photodetector exhibits an external quantum efficiency of 9532 % at −2 V under photoconductive operation, ensuring high-fidelity photoplethysmography acquisition even under light and miniaturized hardware conditions. By separating the lightweight optical module (<25 g) from the primary electronic instrumentation, we fundamentally minimized mechanical loading at the measurement site. Comprehensive Monte Carlo optical simulations and kinematic vibration analyses optimized the interface design to secure a stable skin-coupling mechanism under dynamic acceleration. Leveraging an artificial intelligence framework, a CatBoost-based model trained on 55 multidimensional features successfully tracks continuous blood pressure variations during high-intensity indoor cycling. The model satisfies international medical instrumentation standards for error criteria and achieves top-tier performance grades under the evaluated conditions, demonstrating significant potential for next-generation personalized digital healthcare platforms. © 2001-2012 IEEE.

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