| Oxygen is an indispensable part of respiration and metabolism to the body,the normal activities of the body cells depends on the continuous supply of oxygen,and the appropriate oxygen supply determines the coordination of the heart,the lung and the blood system function,the monitoring of FiO2,EtO2,FiCO2 and EtCO2 in the respiratory system can reflect the functional states of the whole respiratory and circulatory system,especially in surgical applications,oxygen and carbon dioxide concentration monitoring can help physicians to judge the patient's physiological state and the normal use of equipment primarily,and to play a guiding role in the doctor's operation.These can effectively improve the safety of surgery,and ensure the normal and orderly operation,so the oxygen and carbon dioxide gas concentration monitoring has a very important significance.At present,the technology of monitoring oxygen concentration and carbon dioxide concentration is very scarce,especially in the aspect of paramagnetic oxygen concentration monitoring technology.Therefore,this paper proposed the development of a paramagnetic oxygen measurement technology,and combined with side-stream carbon dioxide concentration measurement module to form a synchronous system of oxygen and carbon dioxide measurement.In this paper,a survey based on the domestic and foreign development and application of oxygen and carbon dioxide concentration monitoring technology is completed and compared the advantages and disadvantages of each method.In addition,this paper first introduced the significance of oxygen concentration monitoring and the existing methods at the same time also introduced the development of domestic and international situation and the mainstream products on the market,The following described the oxygen monitoring methods in detail,presented the principles and implementation methods of paramagnetic oxygen concentration monitoring,Then,the design scheme of the whole monitoring system is put forward,which includes four aspects: system mechanical design,system hardware design,module software design and PC evaluation software design.The mechanical design of the system includes the design of the gas chamber of the whole measurement module and the design of the internal pipeline of the gas chamber.The hardware design includes the selection and customization of key components in the whole module,also includes power module,sensor signal amplifying and filtering module,signal acquisition module and digital circuit,the signal acquisition module is used in external 24 bit high precision ADC,the main CPU digital circuit for STMicroelectronics the STM32F103 Series MCU.The design of the module software includes the driving of the electromagnetic coil and the control of the external high-precision AD.The function of PC evaluation software is to display the working state of the module and the value of each parameter,which can respond to the command of the lower computer software or send the command to the lower computer software.In the part of the algorithm,the calculation of oxygen concentration value and how to realize the calibration are introduced in detail,and the calculation of the compensation algorithm is done because the temperature will affect the measurement results.The validation of oxygen and carbon dioxide concentration measurement module is divided into two main parts.First,the relevant requirements of the basic safety and the main performance requirements of the national medical electrical equipment respiratory gas monitor is validated.Then,the performance of the main parameters is compared with the market Of Mature products.The results of two tests show that the measurement system developed in this paper has good stability and accuracy,in which the measurement range of oxygen is 0-100%,the measurement accuracy is ± 1% in order to meet the relevant standards.At the end of this paper,we summarize the current research progress of the subject module,and also put forward the shortcomings and future direction of improvement. |
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