Two Dimensional And Highly Integrated High Field Asymmetric Wave Lon Mobility Spectrometry

High field asymmetric wave ion mobility spectrometry (FAIMS), also called Differential Ion Mobility Spectrometry (DMS), is a technique for quick detection of gas ion under atmosphere pressure. This technology has acquired significant development according to several breakthroughs:fundamental research in the late 1980s by Soviet Union, ionic focusing research in FAIMS by introducing cylinder drift tube in the mid 1990s, plate ion drift tube research in FAIMS by introducing MEMS processing technology in the early 21st century. It has demonstrated broad application prospect at isomers separation and base removal in mass spectrometry, security detection, pollution detection and industrial gas monitoring.Under higher electric field there is a nonlinear dependence of ion mobility, which is a physical property of gas ion. According to this, ion can be separated and detected for the difference between their mobility in gases at high and low electric fields by applying an asymmetric field.As a field detection method, FAIMS has the advantages of high sensitivity, rapid detection, lower manufacturing costs due to MEMS manufacturing. However, this technology has two bottom problems in its application.The first problem is the techniques of integration of FAIMS. Thought the ion drift tube of FAIMS is small and can be fabricated by MEMS, lots of service devices like carrier gas interface, sample injector, ion source and temperature control device are still not integrated, which make it difficult in air tightness, precision of temperature control, miniaturization and power control.The second problem is the resolution of FAIMS. The FAIMS technology has high sensitivity in trace detection, while its highest resolution is just 50 until now. The nonlinear part of ion mobility is quiet small and cannot be described by current theory, so the small drift of FAIMS spectral peak position is hard to be removed, which cause the obvious error in nonlinear coefficient calculation. Therefore, the resolution of FAIMS is still low.In view of these two problems, the main works of this dissertation have been divided into two parts:the design and fabrication of highly integrated ion drift tube and the acquirement of high resolution in characterizing.A ion drift tube which integrated carrier gas interface, sample injector, ion source and temperature control device had been fabricated by thick film technology, and its volume is only 95mm X 75mm X 2mm. This ion drift tube has the advantages of good air tightness, high precision of temperature control, miniaturization, low power control and good mechanical properties. Based on this, a FAIMS device was self set up, with which enough FAIMS spectra were obtained successfully. This part research provided the basis for FAIMS miniaturization.A two-dimensional characterizing method based on FAIMS spectra had been proposed and tested. The FAIMS spectra imply lots of information like gas flow rate, temperature, pressure, structure of ion drift tube, diffusion coefficient and ion mobility in low field, while these parameters are hard to be obtained for the lack of FAIMS spectral profile theory. In this dissertation, a novel method has been proposed to build a universal and effective model of FAIMS spectral peak profile by introducing ion trajectory. The dispersion voltages and carrier gas flow rate on the FAIMS spectral peak characteristics like Full Width at Half Maximum (FWHM) and peak height is analyzed and discussed, and the model agrees well with the experimental data. With this model and the FAIMS spectra, the ion mobilities of about ten materials, such as benzene, acetone, chlorobenzene, and so on had been obtained with error less than 0.2cm2V-1s-1. This method provides a new dimensional of FAIMS detection without the need for any other device.The study of this dissertation also included:a strict calculation method on nonlinear ion mobility had been proposed for more accurate coefficients; a simple and effective device for the effective evaluation of PID lamp had been produced, which provide a safety, stable and rapid contaminant detection without the need for expensive apparatus.In view of the two bottom problems of FAIMS, a highly integrated ion drift tube had been fabricated by thick film and a two-dimensional characterizing method had been proposed by building a novel model of FAIMS spectral profile. The experimental results proved the validity of them. This work provides the basis for the application of FAIMS in field detection.