| With the growing demand for home health monitoring equipment,respiratory gas measurement has become a popular topic in disease research.The measurement of NO gas exhaled by the human body is a non-invasive method for evaluating asthma that can be used to determine a patient’s "asthma control" and aid in treatment.Currently,the detection equipment for NO gas exhaled by the human body is only available in a handful of hospitals,as it is too expensive to meet the monitoring requirements of families daily,and the measured value is affected by numerous variables,including inflammation,diet,smoking,etc.Continuous dynamic measurement is scientifically superior.Studying a health monitoring device that can record the exhaled NO level of the human body daily to control airway inflammation is,therefore,of great application value and practical significance.NO exhaled by the human organism is typically represented by Fe NO(Fractional exhaled Nitric Oxide),a trace gas with a concentration of ppb that is difficult to monitor.In this paper,the electrochemical method of artificial olfactory technology is used to achieve rapid detection of exhaled NO gas.By analyzing the primary methods of exhaled gas detection,sensor types,bionic structure,and the development status of the data compensation algorithm,and by analyzing the influence of the gas flow field on the trace gas detection system and electrochemical sensor,a circulating tuyere-designed active pumping detection system is constructed to improve the system’s response time.To enhance the sensitivity of the detection system,a double-chambered structure of bionic canine ethmoidal bone was designed,and the sensor was placed in the "olfactory recess" position.A new algorithm,MRGA-BP,is used to compensate the flow rate for the large response error of active pumping systems to trace gas,thereby enhancing the system’s detection precision.This paper focuses on the detection mechanism of exhaled NO artificial sense of smell,the construction of exhaled NO detection system,the structure of the canine bionic chamber,and the pumped flow compensation algorithm.The investigation of the detection mechanism of exhaled NO synthetic sense of smell.The quantitative relationship between asthma and endogenous NO gas in the human body was analyzed in this paper.Simultaneously,the mode of the human sense of smell and the key factors affecting the performance of the human sense of smell were studied.The detection mechanism of artificial odor was subsequently analyzed,and technical means of enhancing the performance of a trace gas detection system were identified.The sensor is the central component of artificial olfactory detection,and its detection performance is the most influential factor in determining the system’s detection level.Analyses of the detection principle of an electrochemical sensor and the chemical properties of exhaled NO gas to be detected.Considering the gas flow field pattern,the ANSYS software was used to analyze the gas flow field within the electrochemical sensor at various flow rates.A detection platform was constructed,and the influence of gas flow rate on the sensitivity,response time,detection limit,and repeatability of the NO electrochemical sensor was examined.There is a linear relationship between the gas flow rate,sensitivity,and response time of the electrochemical sensor.Constructed exhaled gas NO detection system.On the basis of research on the detection mechanism of exhaled NO artificial sense of smell,a basic model of active pumped exhaled NO detection is proposed to improve the response time of the system and reduce the detection error resulting from NO oxidation.In the trace gas detection system,the mode of gas diffusion in the system and the mutual angle between the gas flow and electrochemical sensor will impact the gas concentration near the sensor.In order to optimize the fundamental model of the detection system,AIRPAK software was used to simulate the gas flow field of two distinct gas chamber structures,and the detection parameters of electrochemical sensors were tested under different gas flow angles.In accordance with simulation and experimental findings,an electrochemical artificial olfactory detection system with active pumped and opposite circulating tuyere was constructed,and the gas collection chamber was placed perpendicular to the sensor so that the angle between the gas flow and the sensor surface is 90°.The structure of the canine bionic chamber was investigated.On the basis of the construction of the exhaled NO detection system,the gas collection chamber,an essential component of the detection system,was refined.The structure of the chamber determines the airflow pattern traversing the sensor surface and influences the system’s detection performance.On the basis of an in-depth analysis of the structure of the nasal cavity and the pattern of nasal airflow in dogs with an acute sense of smell,the basic configuration of bionic double-chamber structure in dogs was proposed.Through ANSYS gas flow field analysis,the chamber’s structure was gradually optimized.On the basis of the chamber structure of the canine bionic nasal septum,a double-chamber structure of the canine bionic ethmoid bone was designed,and the sensor is positioned in the "olfactory recess" with a high eddy current intensity.A bionic chamber’s length,inner diameter,sieve plate,and the number of holes were determined by an orthogonal experiment.In the constructed exhaled NO detection system,three-chamber structures are utilized for gas detection experiments.The results indicate that the detection system with the double-chamber structure of the canine bionic ethmoid nose has the highest stability and the lowest error.The NO gas exhaled by 18 volunteers was measured,and the detection system’s efficacy is validated.The investigation of flow compensation algorithm.In the active pumped detection system,various pumped flow rates were used to detect the standard sample NO with concentrations ranging from 5 ppb to 200 ppb.The variance analysis of the system response results reveal that the pumped flow rate has a significant impact on the electrochemical artificial olfactory system for trace gas detection and that there is a normal relationship between the pumped flow rate and the system accuracy.Using the flow compensation algorithm,the system’s error rate and detection precision can be decreased and enhanced,respectively.On the basis of the linear MR algorithm and the nonlinear GA-BP algorithm,a new flow compensation algorithm based on the prediction error discrimination and optimized by MR-GA-BP was proposed.The NO gas test of the standard sample improves the system’s detection accuracy from17.8 %FS before compensation to 6.8 %FS.In conclusion,the research findings indicate that artificial olfactory detection with active pumped electrochemical bionic chamber structure and flow compensation algorithm can detect exhaled NO at the ppb level.This study provides a theoretical foundation for the practical development of daily NO monitoring equipment. |
