Research On Humidity Sensitivity Of Polyiminde Film Based On SPR Technology

The humidity of the environment has an important influence on the fields of industrial and agricultural production, meteorology, environmental protection, national defense, aerospace, so the measurmeant of humidity shows a significant position. In this paper, we combined the SPR technology and humidity sensitivity of polyiminde to invite a kind of new humidity sensor. And using the humidity sensor to test the different humidity environment. Finally, make a conclusion according to the data.Surface Plasmon Resonance is a optical phenomenon which happened on the boundary of metal and electrolyte. When the incident light interact with the interface of metal and electrolyte, the reflected light intensity will change along with the dielectric constant of electrolyte. Therefor, using SPR techno-logy can realize real-time monitoring, the dielectric constant of electrolyte so as to realize the analysis of the concentration of the material. A lot of researchers has been appealed to SPR technology due to its high sensitivity, response time short, strong anti-jamming capability. And SPR technology has been used in many areas, such as life science, food testing, measurement of drug concentration.The selection of metal film is quite important in SPR technology. The film need to be high sensitivity, good adhesion ability, chemical stability. And during the process of preparing the film, the thickness and the surface roughness of the film are making a big difference on the ability of the film. In this paper, we apply high purity gold as the metal material, through the sputtering method to get a thin film,which thickness is around 50 nm. Then heating treatment was carried out on the thin film under different temperatures, in order to change the roughness of the surface. In the result, we found that with the temperature increased the surface became smooth, and the position of SPR resonance peak moved right.Polyiminde(PI) is a kind of organic polymer,which contain imide rings(-CO-NH-CO-) in its main chain. The structure contain a large number of amino and hydroxyl, which interact with the hydrone in the air will change the dielectric constant of the polyimide. According this mechanism, the humidity-dependent sensor which using polyimide as the humidity-sensing material has gotten a wide range of research and attention.The humidity sensor film that we used was consists of PI film and Au film. And the sensor film was tested in different humidity environment. In the result, we found that the resonant peak position of SPR was changed in different humidity. And the resonant peak moved left as the humidity increased. The relation between the position of the resonant angle and the humidity of the environment was linear.