Biometric Data Acquisition and Monitoring via Light Signal Processing Technologies

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Wearable devices enable continuous monitoring of physiological parameters through non-invasive sensors. This paper presents a biometric data acquisition and monitoring system implemented on the open-source PineTime smartwatch. The system is designed for heart-rate estimation and stress assessment based on photoplethysmography (PPG) signal processing.The proposed system consists of two applications, HRX and Zenify. HRX provides real-time heart-rate monitoring by displaying the photoplethysmographic waveform, the current heart-rate estimate, and the minimum recorded heart rate. Zenify assesses stress through heart-rate variability (HRV) analysis and classifies stress levels as low, moderate, or high.The system architecture relies on the PineTime smartwatch’s built-in optical heart-rate sensor and accelerometer, which are combined with light-signal processing algorithms. The original InfiniTime firmware was replaced with Wasp-OS, an open-source MicroPython-based watch operating system that supports rapid development and testing of biometric applications.The proposed system may be applied in preventive medicine to support early detection of physiological abnormalities, stress monitoring, and personalized health management.