Compact and Low-Cost Optical Fiber Respiratory Monitoring Sensor Based on Intensity Interrogation

In this paper, a plastic optical fiber sensor for respiratory monitoring purposes is presented. The sensor was integrated into a small, robust, and flexible package to be attached directly on a wide variety of positions on the upper body to monitor the motion induced by breathing. The sensor's operating principle is based on the variation in the intensity of the optical coupling intensity ratio between an input and a set of aligned output optical fibers. The system is demonstrated to be able to track the time-varying breathing signal when the sensor is placed at four different positions of the torso (including diaphragmatic and upper costal). The accuracy of the device is confirmed by a simultaneous comparison of the results with a commercial respiratory monitoring device. Measurement of breathing rate on four different healthy subjects showed excellent agreement with the measurement from the commercial respiratory monitoring device. The proposed fiber optic respiration sensor provides the advantages of being relatively low cost, compact, and simple in construction compared to the conventional existing respiration sensors.