Room temperature ammonia sensors

Abstract

In this thesis, different materials were used to make ceramic sensors to ammonia, obtained by screen printing, working at room temperature. The main objective is to apply these devices to food chemistry, in order to evaluate quantitatively the alteration products of certain food categories, for example meat, which tends to generate biogenic amines, such as cadaverine, putrescine, histamine and others. Since the ammonia is the simplest amino group, it was decided to characterize ceramic sensors in ammonia atmosphere. The ceramic materials used for the realization of sensors are ZnO, Fe2O3, WO3 and Bi2O3. However, the tests performed have shown that the ceramic oxides were not sufficient to ensure good electrical responses. So, we have functionalized sensors mainly with carboxyl groups, in order to improve the electrical response to ammonia: the best results were obtained by functionalization of glass ceramic with canforquinone (CQ) and benzophenone (BP) via plasma. These sensors give a good response in ammonia atmosphere starting from few ppm