| The outbreak of the new crown epidemic in late 2019 and the gradual increase in the incidence of cardiovascular diseases among urban and rural residents in recent years,China’s gradual entry into a deeply aging society and the constant food safety outbreaks have forced modern people to pay more and more attention to their health status.During the Spring and Autumn period,the magpie met with Duke Cai Huan,revealing that health protection should focus on "treating the disease before it happens",so it is necessary to test several vital signs of the human body at home in order to prevent and avoid the occurrence of major diseases.In view of the fact that most of the medical electronic devices on the market at this stage have the defects of single measurement index,cumbersome measurement process or trauma caused by the measurement process,this paper designs a home vital signs parameter detection system,which can non-invasively measure pulse rate,oxygen saturation,perfusion index,blood pressure,temperature and cardiac output to help daily health testing.In this paper,we start with the photoplethysmography(PPG)signal for in-depth analysis and experimental discussion.We explain the measurement method,morphological characteristics and significance of the waveform,study the noise composition and experiment with three filtering methods,and select the appropriate filter after comprehensive analysis.The principles of blood oxygen and pulse rate measurement are explained.The third-order PPG derivative is introduced to assist in solving the pulse wave conduction time,and the measurement model is optimized to calculate the systolic blood pressure,diastolic blood pressure and cardiac output respectively by combining the PPG signals.The main wave crest extraction and perfusion index measurement model based on the time-domain PPG signal are introduced and improved.The robustness of the algorithms for pulse wave conduction time,perfusion index,and PPG waveform feature extraction is improved.In this paper,a prototype vital sign parameter measurement machine is designed based on embedded Linux technology,and the hardware is divided into two parts,in which the finger-clip front-end signal structure part contains non-contact temperature measurement circuit,microcontroller module,dual light source light-emitting tube driver circuit,photoreceiver tube signal acquisition circuit and signal processing circuit.The main control and display part contains the main control S5PV210 module,storage module,display and function interaction module,power management and soft start circuit,SD card circuit,USB to TTL circuit,test port module and LED status display circuit.Write drivers for hardware circuits,design function codes,write interaction and display interface programs,and complete the software and hardware design of the instrument.Develop the experimental program,compare this system with different commercial instruments and do statistical analysis.The experimental results show that the system has a high correlation and consistency with commercial instruments in measuring several vital sign parameters,and achieves accurate measurement of several vital sign parameters. |
