An Optical Micro/Nano Fiber Sensor for Monitoring Respiration

In the field of clinical medicine, the real-time monitoring of carbon dioxide (CO2) gas exhaled by the human body is of great significance. At present, the detection devices on the market mainly work by sucking a small amount of gas from the nasal cavity into the detection device, and they present some problems such as overly long sampling tubes, easy blockage or distortion, and an abnormal gas dispersion. In this paper, a micro/nano optical fiber sensor that can directly detect respiration is proposed and is characterized by the relative change in CO2 concentration. The measurement is achieved by using the principle of high evanescent field absorption, and the operating band is 2.004 mu m. The sensing effects of micro/nano fibers with different diameters are compared, and the experiment proves that a micro/nano fiber with a diameter of 1 mu m can be measured. The light intensity change over 30 s was measured, and the breathing rate was 10-11 times/min. The sensor can achieve a rapid real-time response to CO2 gas detection and is small in size, low-cost, and easy to replace. It has a great application potential in clinical scenarios such as in gastrointestinal endoscopes that require real-time monitoring of human respiration.