Research On Micro-vibration Sensing Technology Based On Multi-mode Fiber Specklegram

As people become more aware of their own health,the health monitoring industry is increasingly in demand.In the human health monitoring,the human heartbeat signal is an important index.If a professional electrocardiograph is used to monitor the heartbeat signal of the human body,multiple electrodes need to be worn and the operation can only be carried out by professionals,which gives the monitored person a bad experience and is expensive.In this paper,on the premise of ensuring high accuracy and low cost,a fiber optic micro-vibration sensor for measuring human heartbeat signal is proposed and verified by experiments.Perturbation on the outside of the fiber will cause different speckle images to be received at the end of the fiber,so as to measure the human heartbeat signal.It is found that the effects of vibration sensing system with different core diameters of fiber are very different,and this phenomenon is studied experimentally.In the study,suitable optical fibers were screened out from common materials and common core diameters to build a micro-vibration sensing system.Since the selected fiber is dependent on the current speckle statistics method,the speckle statistics methods and the fiber core diameters are jointly optimized to achieve better vibration sensing effect.Finally,the system with good sensing effect is used to measure the human pulse signal to get heartbeat information,and the collected speckle image is processed to get a clear heartbeat signal curve,which shows the potential application value in health monitoring.Compared with other schemes for measuring heartbeat signals,this system has the advantages of anti-electromagnetic interference,good sensing effect,low cost and non-contact.