High-Precision Strain Sensing System Based on Optoelectronic Oscillator for Human Pulse Monitoring

Traditional wearable fiber-optic sensors based on intensity demodulation are prone to interference and offer limited detection capabilities, whereas those utilizing wavelength demodulation provide better stability but at a higher cost. In this article, we present a high-precision strain sensing system based on an optoelectronic oscillator (OEO) for human pulse monitoring, which employs frequency demodulation to achieve exceptional accuracy while reducing system costs. The sensor head consists of a fiber optic Fabry-Pérot (FP) cavity, offering notable advantages, such as the ease of fabrication, affordability, and high robustness. Experimental results indicate that our proposed strain sensing system achieves a high resolution of $0.021~\mu \varepsilon $ and the frequencies of detecting signals as low as 40 kHz, with excellent system stability demonstrated by a frequency drift of only 300 Hz over 15 min. The system’s performance was validated through pulse monitoring experiments, effectively addressing the challenges posed by the low-frequency and noise susceptibility of pulse signals. Some cardiovascular metrics, such as pulse wave velocity (PWV) and stiffness index (SI), were successfully extracted, demonstrating the potential of this system for high-precision health monitoring and offering a promising technological solution for future advancements in precise human pulse monitoring.