Research On Phthalocyanine Surface Acoustic Wave Gas Sensor And Doping Carbon Nanotubes

The researched work of surface acoustic wave(SAW) gas sensor had gradually developed before 20 years ago, now we could use it to detect NO2, H2S, NH3, SO2, and other gases, the SAW sensor could directly output the digital signals, which could not be compared with other types of sensors, Moreover, it also had the particular of small size, light quality, high anti-interference ability, high sensitivity, good linearity and the effective detection range, high accuracy and so on.Phthalocyanine was a synthetic compound, has a large conjugated system structure of 18 electronic, the hole structure of it could adsorbed gas well and it also had a good chemical properties and stability. Metal phthalocyanine caused conductivity and quality changes of the SAW devices when it adsorbed the gases, through the frequency change of the SAW devices we could detect the different concentrations of gas.A SAW gas sensor featuring ZnPc as the sensitive component for NO2 detecting at room temperature was presented. The film of ZnPc was synthesized through a simple physical route by mixing ZnPc in N-N dimethylamide solution. After some studied we found that the ZnPc film of SAW devices had shown a detection limit of lppm for NO2 at room temperature. It also had a very good response and recovery.Carbon nanotubes not only had good mechanical properties, electrical conductivity, thermal conductivity, but also it had other aspects properties of optical performance and so on, it had a large surface area and a rich hole structure, we kuew it was a ideal material for gas adsorption. We could use the structure of it to improve the sensitivity of other materials properties. We found that because of the doping MWCNTs, the sensitivity of the ZnPc film has been greatly improved. By comparing the scanning electro microscopy (SEM) graph of the doping MWCNTs before and after. In order to detect the choice and stability of our device, at first at room temperature we detected lOppm SO2, H2S, NO2 etc gases, at the same time we compared the detect result of them; Secondly, the stability of the device was tested by three-month, as a result we found that at room temperature the ZnPc/MWCNTs film had a good selectivity and stability.