Study On The Multi-component Detection System For Human Exhaled Gas

With the development of modern medicine,the corresponding relationship between human exhaled gas and disease has become a research hotspot.How to accurately and quantitatively measure and analyze the concentration of exhaled gas is imminent,and it has broad application prospects in the fields of disease diagnosis and prevention.Based on the previous research results,this paper designs a set of human exhaled gas multi-component detection system using electrochemical sensors as the core sensing unit.Human exhaled gas carries unique metabolic information,such as nitric oxide,ammonia,and acetone in human exhalation,which are markers of asthma,kidney disease,and diabetes,respectively.Because of its advantages of painless,non-invasive,and simple operation,human breath detection has been widely used in the prevention and diagnosis of diseases,enabling early realization,early diagnosis and early treatment of diseases,reducing treatment costs and mortality.This article describes the pathogenesis between human exhalation and asthma,diabetes,and kidney disease,and analyzes the detection methods of human exhaled gases.A multi-component detection system for human exhaled gas was designed to detect the exhaled nitric oxide,ammonia,acetone,and carbon monoxide gas.In practice,the nitric oxide gas detection system was preferentially realized according to the demand.This paper introduces the system design ideas,functional technical indicators,hardware and software design.The data filtering,system calibration,human-computer interaction system,STM32F103ZET6 minimum system unit,data storage,communication and other hardware system modules are furtherly introduced.The system hardware design environment is Altium Designer14.,The modular schematic is drawn in Altium Designer14 after comparing and analyzing the functions and power consumption of the components involved in the system hardware design,and following the system design schemes and principles and technical indicators.And then each component is packaged,and the PCB layout and drawing are completed according to the circuit schematic of the hardware design.The specific design of the hardware is based on the selection of core controllers,core sensor selection,minimum system design and module circuit design,data storage module,IIC circuit design,communication module and human-computer interaction module circuit.Meet the initial design needs.At the same time,an expandable interface is reserved,which is convenient for the expansion of functions and the updating of technology.In this paper,the software design includes the design of the lower machine and the upper machine.The software design should be simple,modular,portable,easy to operate and easy to learn.The software structure of the lower machine includes system initialization,signal acquisition and processing,digital filtering,data storage and reading,liquid crystal display,touch screen key input and serial communication.The PC software design is in LABVIEW(lab virtual instrument integration environment).Designing,communicating with the lower machine through the serial port,uploading the processed result of the lower machine to the upper machine for buffering and waveform display.At the same time,the data in the buffer area can be downloaded and data inqueried,and the detected data can be saved.The upper machine forms a friendly user interface,which is convenient for users to operate inspection and observation,and download the test results into Excel,TXT and image formats.In this paper,the system hardware circuit and software system are debugged separately to ensure that there is no connection error in the hardware.The circuit and voltage of each module reach the ideal condition;the upper machine and the lower machine software run without error,and can follow the design scheme to do the corresponding operations.After the system debugging is completed,the nitric oxide gas detection experiment is carried out.First,the system is calibrated by introducing a standard gas.After calibration,multi-concentration standard gases are respectively introduced for detection,and the error of the detection result is 0.865% full scale(FS).Then,the nitric oxide gas with a concentration of 50 part per billion(ppb)and 99 ppb was introduced to simulate the exhaled nitric oxide gas from patient.The average value of multiple detections reached 47.62 ppb and 92.27 ppb,respectively.The detection errors were-0.238% FS and-0.673% FS,respectively.The detected exhaled nitric oxide gas concentration from volunteer is 16ppb(the normal healthy human exhaled nitric oxide concentration is 10~25ppb).The experimental results show that the human exhaled gas detection system can meet the system's functional indicators and technical indicators.