Research On Vital Signs Sensor Based On Dual Biconical Structure Mach-Zehnder Fiber Interferometer

Vital signs monitoring have attracted wide attention with the continuous progress of biosensing technology and Internet of things.There are several techniques for heart rate monitoring,including invasion and non-invasion.Traditional devices for vital signs monitoring are not suitable for long-term monitoring in usual due to the disadvantages of heavy weight and electromagnetic interference.Therefore,optical fiber sensors applied in vital signs monitoring shows great prospect due to the advantages such as compact size,light weight and immunity to electromagnetic.In this paper,a dual biconical fiber based on Mach-Zenhder interferometer is proposed and experimentally demonstrated.The dual biconical fiber sensor is fabricated by a CO₂ laser splicer.The sensor is packed by the environmentally friendly silica gel.And we studied the interference spectrum characteristics of this interferometer through experiments.We used the dual biconical structure Mach-Zehnder fiber interferometer vital sign sensor to measure the vital signs parameters,and studied the intensity modulation principle and the amplitude modulation principle.The vital signs monitoring experiments of the proposed sensor was carried out in nine volunteers.The experiment results have shown that the error of this device in the heart rate detection is less than 3bpm,and the error in the respiratory rate detection is less than 2 bpm.Both the errors of the two parameters meet the requirements of applications.Due to the advantages of easy fabrication and lower cost,our sensor shows potential application prospects in vital signs monitoring.