| Gas chromatograph plays an important role in national security,environmental health,health monitoring,food industry and other fields due to its advantages of high sensitivity,good selectivity and high analysis speed.However,traditional chromatographic instruments still have some obvious shortcomings,such as large size,the need to be used with hydrogen generators and other facilities.These problems greatly limit their portability and make them difficult to achieve real-time and on-site analysis.Nowadays,the miniaturization of instruments has become an important research direction in the development of instrument science.The exploitation of portable analysis system with small size,light weight and high integration is of great significance to promote scientific research and propel the development of instrument industry.In this thesis,a series of gas chromatography analysis systems were developed based on the micro gas sensor——thin film bulk acoustic wave resonator(FBAR),and the feasibility of FBAR as gas chromatography detector was verified.The main topics of this thesis are listed as follows:1.A gas chromatography detector based on FBAR was developed.The temperature compensated FBAR sensor was designed and fabricated by microelectromechanical system(MEMS)technology,and its sensing performance at different temperatures was examined.The gas detection results of the FBAR sensor were compared with that of the traditional gas chromatography detector——flame ionization detector(FID).The feasibility and stability of FBAR sensor as gas chromatography detector were verified under different chromatographic conditions(injection volume,flow rate,column temperature,and detector temperature).2.An encapsulation method of FBAR detector with commercial chromatography system was developed,and the FBAR sensor was connected in series with chromatography separation system and FID.The detection sensitivity of FBAR to gases was improved by modification of polymer films on the surface of device.The FBAR sensor array was prepared by using the interface modification of different polymer films.With this method,the orthogonal-selectivity detection of the target analytes was realized,and the secondary specific recognition of the system was achieved by combining the algorithm of principal component analysis,solving the problem of the overlapping peaks,which is difficult to be solved by traditional gas chromatography,and improving the resolution of the system.3.In order to solve the problems of dead volume of microsensor in gas chromatography detection system,an encapsulation method of FBAR detector based on gas microchannel structure with chromatography system was developed.The influence of different dimensions of microfluidic channel configurations on gas flow rate above the FBAR sensor was investigated through finite element simulation.The FBAR structure of microchannel was designed and fabricated.And the noise,detection limit and sensitivity of the new detection structure were analyzed in sequence.A two-dimensional gas chromatography system based on FBAR detector was realized by changing the tandem sequence of microchannel FBAR sensor,chromatography separation column and FID.This system can be employed to directly detect the concentration profile of gas on the solid surface as well as in the mobile phase by FBAR sensor with FID at the same time by only one injection,and the response ratio of both detectors was analyte-specific and proved to be independent of the injection mass.4.Based on the above research results,a novel gas chromatography analysis system was constructed by combining the microchannel FBAR detector with the micro chromatography column fabricated by MEMS technology.The test results showed that the system can detect the target chemical warfare agent simulants with high sensitivity and specificity. |
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