Vital Signs Monitoring System For Patients With Respiratory Diseases

Respiratory diseases include both non-communicable diseases such as chronic obstructive pulmonary disease and asthma,as well as infectious diseases such as viral pneumonia and tuberculosis.In particular,this year the novel coronavirus is rampant in the world,and people pay more and more attention to respiratory diseases,so it is particularly important to design a vital signs monitoring system for respiratory diseases.Considering the high price of the existing monitor,the thesis designed an ultra-low-cost monitor for pulse rate,blood oxygen saturation,respiration rate and body temperature,which are closely related to respiratory diseases.The monitor can be connected to the vital signs monitoring server through wireless network.The thesis first introduces the measurement scheme of four physiological parameters.Through analysis and comparison,the measurement scheme adopted in this design has been determined,and its detection principles are introduced in detail.Photoplethysmography is adopted to analyze and obtain the pulse rate and blood oxygen saturation through the reflective PPG signal at the fingertip of the human body.Respiratory rate is measured by using a thin film pressure sensor,which is fixed on the chest or abdomen of the human body by elastic chest band.Infrared temperature measurement technology is used to measure body temperature.The hardware design of the monitor is mainly divided into three parts: blood oxygen saturation probe circuit,chest band and control board.The blood oxygen saturation probe circuit is responsible for collecting and filtering the PPG signal,and then sends the PPG signal to the control board through the RS-232 protocol.The pressure sensor is fixed on the chest band,which is responsible for the collection of respiratory wave,and connected to the control board through cable.The microcontroller selected on the control board is ESP32,which has Wi-Fi module and can be connected to the wireless network.In the software part,this thesis studies how to process the PPG signal and respiratory wave to extract the relevant physiological parameters,and how to write driver for each module.This thesis also designed a monitoring server to record physiological data and remind medical staff automatically when patients' condition deteriorates.Through the preliminary experiments,we verified the feasibility of the design and achieved the expected results,providing a reference for subsequent improvement.