Optical Fiber Microvibration Sensor Design for Wearable Multi-Point Breathing Monitoring

Breathing is an important physiological indicator of human health. In this paper, a wearable compact single mode-no core-single mode fiber (SNCS) optical microvibration sensor based breathing monitoring system is proposed. Firstly, piezoelectric vibration experiments were conducted, focusing on low-frequency signals to verify the feasibility of optical fiber microvibration sensor for breathing monitoring, and measured frequencies reached to 0.1Hz. The piezoelectric vibration frequency is fitted to the measured frequency with a slope of 0.99772 and correlation of 0.99879. Multi-point wearable breathing monitoring experiments on the nose and abdomen were conducted. It is demonstrated that breathing states could be identified by details such as respiratory rate, exhale and inhale time between three normal and four irregular breathing states. Real-time and precise breath detection are ensured by the quick response time (0.11s) and recovery time (0.14s) of the sensor. The proposed sensor is repeatable, responsive, comfortable to wear, recognises different breathing states, and can be used for prediction of obstructive sleep apnea (OSA) syndrome and post-treatment rehabilitation monitoring, which has a promising medical application.