A Multi-Wavelength Photoplethysmography-Based Patch Physiological Monitoring System: Design and Functional Validation

Photoplethysmography (PPG) is a non-invasive optical technique that provides valuable physiological information, including heart rate (HR), pulse wave (PW), and blood oxygen saturation (SpO2). However, wearable devices often have variable signal quality, lacking monitoring capabilities or precision in daily use. To address these limitations, we propose a multi-wavelength PPG-based patch physiological monitoring system. The system utilizes three PPG wavelengths of enhanced signal quality, leading to improved accuracy and potentially extracting a wider range of physiological information compared to standard devices. We evaluated the system's performance by extracting PPG signals from three locations on the human body and analyzing their quality. The results demonstrate that the system successfully extracts high-quality PW, enabling accurate estimation of HR, SpO2, and even blood pressure (BP). The BP estimation model, particularly with personalized adaptation, exhibits good performance. The system offers the potential for continuous, non-invasive measurement of a wider range of physiological parameters compared to traditional wearable devices, and its portability and ease of use make it a compelling solution for user-friendly daily healthcare monitoring.