Study Of The Prepatation Of The Field Ionization Gas Sensor Based On The One Dimension Materials And Its Gas Sensitivity

Progress of the research in field ionization gas sensor was investigated and there are still some disadvantages: high working voltage, bad selectivity and stability. In this work, dark discharge current of gas ionization sensor and the character of the pulse current after breakdown were studied other than the decrease of breakdown voltage and breakdown current value, which were main methods for previous research. The traditional detecting method is based on the strong gas ionization current, which will destroy the nano structure of the electrode. Furthermore, the type and concentrate of the detecting gas can not be obtained only using the value of the breakdown voltage and breakdown current. A new gas detecting method based on the dark discharge current and the character of the pulse current after breakdown was proposed in this paper. Systematic research was carried out in mechanism, theory and influencing effects and this method was applied in the detection of the hazard gases and humidity. A kind of field ionization gas sensor was designed and fabricated, the corresponding test equipment for current and voltage measurement was established.Chapter 1 is mainly focused on the review of the progress of the research on the gas sensors, the methods of gas detection, the classification of the gas sensors, the type of the gas ionization, gas ionization sensors and the nano material's effect on the gas ionization. The disadvantage of the traditional field ionization gas sensor is bad selectivity and stability. To improve this, the method based on the dark discharge current and the character of the pulse current after breakdown was studied and acetic acid, ammonia etc. were used as detected gases.One dimensional materials and nano arrays were fabricated. In-situ synthesis of the polymer, chemical vapor deposition, and screen print was carried out to synthesize carbon nanotube film and solvent therm was used for the fabrication of zinc oxide arrays. The morphology and structures of them were characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Raman spectra apparatus.In chapter 3, the fabrication of the field ionization gas sensor was discussed. The testing equipment for the measurement of the dark discharge current and breakdown voltage was established and the effects of different anode nano materials on gas ionization were compared. A new gas detecting method based on dark discharge current was put out and the response mechanism was deeply discussed that the relation between the dark discharge current and the concentration of detected gas was theoretically established and studied. In experiment, the gas sensoring of the field...