Fabrication Of Multilayer Structure And Its Property In Gas Sensors

In the past decades, a rapid and efficient detection of various components of air or a special gas mixture is becoming much more important, because air pollution has been more and more serious. 1DPCs multilayer film, composed of vapor-responsive materials, could work as a gas sensor. When exposed to gases, multilayer films will absorb the gas, and the refractive index difference between two layers and the thickness of the vapor- responsive layer are increased, leading to the reflection peak position shift and color change.In this article, based on the requirements of the vapor response, as well as cost factors, polyvinyl alcohol (PVA, water-vapor -responsive) and polyvinylpyrrolidone (PVP, water-vapor-responsive and ethanol-vapor- responsive) are chosen as the responsive layers. The multilayer films are fabricated by spin-coating alternately, which is low-cost and high-efficient. Although the refractive index difference between the two layers is not very big, we could still get a good response signal. Our work are listed as follows:(1) PVA/mr-NIL6000 multilayer films are fabricated by spin coating alternately(mr-NIL6000 layers work as inert and high reflective layers), which has a unique response for water vapor. This provides an alternative to detect water vapor in a gas mixture.(2) PVP/PVA/mr-NIL6000 multilayer films are fabricated by spin coating alternately, which have better response signals for water vapor than PVA/mr-NIL6000 multilayer films (but not unique, because PVP also has response for other organic vapors). (3) PVP/PVA/mr-NIL6000 multilayer films have also response for ethanol vapor and other organic vapors according to the dissolving property of PVP, so this kind of multilayer films could work as sensors for ethanol vapor and other organic vapors.In conclusion, a few kinds of vapor-responsive multilayer films are fabricated, and we also compare the difference between single layer film and multilayer film in gas sensing. This work may provide an approach for the preparation of more efficient, more reliable, and more sensitive gas sensors.