In-Fiber Breathing Monitoring Sensor by Micro-Tapered Long-Period Grating Structure

A simple in-fiber breathing monitoring sensor based on amicro-tapered long-period fiber grating (MT-LPFG) structure was proposed and demonstrated. The MT-LPFG structure was manufactured through the periodical tapering of an optical fiber utilizing a CO2 laser fusion splicer. Without the use of a humidity sensitive film, the MT-LPFG structure can directly and dynamically monitoring relative humidity with a fast response, based on which, the breathing process can be monitored in real time through the monitoring of its transmission affected by the humidity. Experiments show that breathing rate and breathing status during respiration were successfullymonitored by placing the sensor structure nearby the nose in a breathing mask. A rise time of 0.237 s and a fall time of 0.299 s were realized in the breathing process monitoring. For its advantages of simple fabrication, miniature size, and fast response, the proposed sensor may found applications in visual observation of the patient's breathing condition.

Automated summary

A simple in-fiber breathing monitoring sensor based on a micro-tapered long-period fiber grating structure is proposed and demonstrated. The structure is manufactured through the periodical tapering of an optical fiber utilizing a CO2 laser fusion splicer. The sensor can directly and dynamically monitor relative humidity with a fast response, and thus monitor the breathing process in real time. Experimental results show that the sensor successfully monitors breathing rate and status during respiration when placed nearby the nose in a breathing mask. The proposed sensor has advantages of simple fabrication, miniature size, and fast response, which makes it potentially useful in visual observation of patients' breathing condition.