The Fabriction And Gas Sensirng Performance Of VOC Gas Sensor

Most of the VOCs(volatile organic compounds) existing in every corner of the environment gases are harmful to human beings and the natural environment, they are the mainly component of the atmosphere pollutants, therefore the detection of the VOCs gases is very important, and the research of VOCs gas sensors has become a hot topic in the field of gas sensors in recent years. At the moment, many methods such as Electrochemistry method, catalytic combustion method, optical interferometer sensor, gas chromatography method, semiconductor method and gas sensor based on polymer are chosen to detect VOCs gases. As gas sensors based on polymer have such advantages as low cost, working at room temperature and a lot of sensitive polymer, more attention has been attracted to the research of this type of gas sensors. VOCs gas sensors using the polymer/ carbon nanotubes films as the sensitive materials and the interdigital electrodes as the basic structure are prepared and characterized. The mainly work is as follows:1. A PECH/MWCNTs(Multi-walled carbon nanotubes) gas sensor is fabricated, and different thickness on the properties of the sensors has been studied. Meanwhile, in order to check the difference of the films, SEM(scanning electron microscope) was used to characterize the surface of the films. Results showed that the composite structure PECH/MWNTs gas sensors own a greater response than bilayer film gas sensor, and the thicker composite film has a better response than its counterpart. SEM pictures showed that the composite films are rougher than the bilayer film. In addition, the sensitive properties of the sensors to different VOCs like ethanol, methanol, acetone, isopropyl alcohol showed that the PECH/MWNTs composite film has a good selectivity to ethanol vapor. And the PECH/MWNTs gas sensor has a good repeatability to the ethanol. In addition, in order to observe the stability of the sensor, the response of the same gas sensor was tested to same organic vapor two months later. Results showed that the resistance of the film decreased seriously, but the response of the sensor maintained.2. The effect of TiO2 nano-particle on the sensing properties of P2VP/ MWNTs film gas sesnors was studied. The gas sensor is prepared by air-brush method on the interdigital electrode. The response of the gas sensor to ethanol vapor showed that the P2VP/MWNTs composite film doped with TiO2 nano particle had a better response to ethanol than its counterpart without TiO2. And the response of the sensor doped with TiO2 nano particle is twice of the latter, but the noise of the former is worse than the latter. The effect of different solvent on the response of the composite films was also studied, and the result showed that it has a better response when the solvent is same to the vapor been tested.