Quartz Crystal Microbalance Gas Sensor Array Measurement System

QCM (Quartz Crystal Microbalance-QCM) gas sensor is a nanogram masssensor, which has good selectivity, high sensitivity, ease of automation, etc, and theinstrument is simple and easy to operate. The study found that when the quartz crystaladsorption of other substances, the natural frequency will change, Using this featureof the quartz body, measured in quartz surface layer of gas-sensitive film topcoat,selective gas adsorption test gas sensitive film, crystal frequency will change. Inferthe type and concentration of toxic gases by measuring the change of QCM crystalfrequency. Based on the above principles, QCM gas sensor gas can be used to analyzethe chemical composition and concentration.Studies have shown that the existing single-channel QCM its limitedfunctionality and is gradually being phased out. The single gas-sensitive sensormaterial has not been found. Single sensor to different gas-sensitive response mayvary, but do not have the automatic identification of the type and quantity of gascapacity. Multi-channel QCM gas sensor array can solve the above problem.Frequency signal acquisition mainly uses USB, PCI, Ethernet three transmissionmethods. Relative to the USB, PCI transmission, Ethernet transmission has highstability, low cost, fast transmission, transmission distance and other characteristics.This design uses protocol quartz crystal microbalance (QCM) measurementsystem based on a32-channel Ethernet transmission. The system consists of an arrayof QCM gas sensor module start-up and high-precision frequency acquisition card.Start-up module includes a quartz crystal oscillator circuit and32quartz crystaloscillator module generates32from the quartz crystal frequency signal; Precisionfrequency capture cards include FPGA module, EPCS module, SDRAM modules,FLASH module, Fast Ethernet modules. Precision frequency capture card numberdirectly samples frequency signal via FPGA internal counter, and the frequency of thesignal data is encapsulated into UDP data package, Via Ethernet speed transmission tothe host computer for data storage, processing and waveform display.This article uses the Verilog language to complete the internal counter and timerlogic FPGA preparation; using C language to complete Ethernet Fast Ethernettransmission protocols and controls in the NIOS II IDE in; using Visual C#enablesPC interface display program for the entire measurement application development system.The test results show that the system can achieve real-time, multi-channel,high-speed, high-precision data acquisition and send. Based on the above features, thesystem can be used in the fields of scientific research measurement, data acquisitionindoor toxic gases and so on.