Research On Fetal Heart Rate Monitoring Based On Fetal Heart Sound And Fetal Electrocardiogram

With the opening of the two-child policy in recent years,which accompanied with the increasing of older women,besides physical condition of the fetus had become the focus of attention in perinatal period,and regular fetal heart monitoring was an important means to understand the health status of the fetus.One of the most frequently used monitoring methods was Doppler baby's heart instrument,and FDA in the United States clearly pointed out the risk of long-time use of this device in 2018.It was a necessary measure that fetal heart monitoring in perinatal period,which could effectively reduce the occurrence of fetal distress.Therefore,it was particularly important to acquaintance the physical health of the perinatal infant constantly.Because Doppler baby's heart instrument was not suitable for long-term use and inconvenient operation,this article used two completely passive methods of the fetal heart rate monitoring to design a device that simultaneously collected fetal heart sound signals and fetal heart electrical signals.The electrical signals and the acoustic signals in the abdomen separated out the heart sound signals and the electrocardiographic signals of the fetus,to realize the real-time monitoring of the fetal heart rate and the requirement of long-term wear.The main contents of this paper were as follows:(1)Through consulting the literature to understand the existing fetal heart monitoring methods,we could study and analyze the advantages and disadvantages of invasive and non-invasive collection methods,and what's more fully considering the interference factors in the collection process.This article proposed for the first time to combine the noninvasive fetal ECG acquisition method and the noninvasive fetal heart sound acquisition method,and considering the acquisition requirements of these two methods at the same time,which aimed to design a device that could monitor fetal heart rate for a long time.(2)Through the design of the collection probe structure and the electrode patch,and the selection of the sensor chip,a device that used purely passive collection of fetal heart data was finally designed.This device collected the mixed fetal heart sound signal and fetal heart electrical signal on the pregnant woman's abdomen,transfering the data to the Raspberry Pi via Bluetooth 4.2,where could achieve simply data processing and storage in the Raspberry Pi.(3)The fetal heart rate(FHR)was calculated separately by using the data of fetal heart sounds and fetal electrocardiograms,and the two FHR results were fitted linearly to get the final FHR results.In this paper,a similar algorithm was used to process fetal heart sounds and fetal ECG.The algorithm was divided into five steps.First,the original signal was processed by 50 HZ notch wave,baseline drift and so on,and then the signal used empirical mode decomposition to refactoring into 3 Signals,further filtering out clutter;then using independent component analysis and singular value decomposition algorithm to cancel the maternal signal;finally using independent component analysis again to extract the fetal signal.(4)This article analyzed the algorithm by using the fetal heart sound data and fetal electrocardiogram data provided by the standard database,which could verify the usefulness and reliability of the algorithm,and analyze the actual collected data.The results were processed by fitting,and then which compared with the results of Doppler fetal heart rate instrument synchronous acquisition to clarify the feasibility of synchronous acquisition of this system prototype.It could be seen from the experimental results of the heart rate that this system met the technical requirements and actual demands,and this system provided a reference for the design and development of non-invasive fetal heart monitoring equipment.