Design And Implementation Of Quartz Crystal Microbalance Sensor Array For Harmful Gas Detection System

In daily production and life,it is indispensable for the related work of environmental monitoring.More and more production safety problems have aroused people’s attention to the detection of gas composition and concentration.In recent years,many dangerous gases carrying malignant diseases have been reported,such as formaldehyde,benzene,xylene,nitrobenzene and other nitroaromatic compounds.Many harmful gases themselves smell very light or even tasteless,and human sensory organs alone cannot respond in time.In order to improve the sensitivity and selectivity of gas sensors,doping technology or new micro-trace detection methods can be developed.Therefore,the quartz crystal microbalance（QCM）sensor can well meet the above requirements.QCM gas sensor is a micro-mass sensor with high sensitivity and high precision for sustainable measurement.It has the advantages of small size,light weight and low power consumption.It can convert the measured gas concentration into electrical signals and output them to computers or other devices for data processing through supporting sensing systems.It has the advantages of environmental sensitivity and has been widely used in biomedicine,environmental inspection and monitoring,material science and other fields.This topic is about the design and implementation of a quartz crystal microbalance sensor array detection system for high-precision detection of harmful gases.The main contents are as follows:（1）From an innovative point of view,a gas sensing material for QCM detection of harmful gases,Eu-doped Zn-MOFs powder（Zn（Eu）-MOFs）and its derivative film Zn（Eu）-MOFs@PAN NFMs were prepared.The fluorescence properties of the MOFs material were used to detect different concentrations of nitrobenzene（NB）,4-nitrophenol（4-NP）,benzaldehyde（BA）and Fe³⁺solution.It was found that there were different degrees of quenching effect.The detection limits were 0.861 ppm^-1,0.631ppm^-1,0.981 ppm^-1and 3.418 ppm^-1,respectively.（2）In-depth exploration of the mechanism of gas sensitive material adsorption.Through the sensing mechanism of Zn（Eu）-MOFs to nitrobenzene,the adsorption isotherm was obtained by the method of variable temperature experiment to extract the adsorption enthalpy of nitrobenzene gas molecules.Furthermore,the basic principle of QCM,Sauerbrey equation and Langmuir adsorption theorem,are combined and theoretically calculated to simulate the frequency change trend of CO₂,nitrobenzene and formaldehyde gas.（3）Design and implement the development and construction of QCM sensor array detection system.According to the application requirements of QCM,the whole system mainly includes detection module,frequency measurement module and data processing module.The most important high-precision frequency acquisition module is directly collected by the FPGA internal counter.This sensor detection system realizes the array detection of nitrobenzene gas by the developed new sensitive material,and can display the detection results in real time through the host computer.