| Abstract | Ammonia is one of the major chemicals used in many industries. For example, ammonia is heavily applied in the pulp and paper, fertilizer and refrigerant industries. These industries are known to release significant levels of ammonia gas into the workplace atmosphere and into the environment. Prolonged exposure to ammonia can lead to serious health issues and even death. Most ammonia sensors today are derived from metal-oxide technology and are costly to manufacture, operate and maintain. Polymer-based sensors available for low parts-per-million (ppm) sensing applications, on the other hand, are showing promise, however they are still in the research phase. An ammonia sensor with high sensitivity, selectivity and low cost is required for environmental real time monitoring. In this work, the development, fabrication and testing of an ammonia sensor based on polythiophene polymer thin films is demonstrated. Using an organic field effect transistor electronic (OFET) component layer, the polythiophene (P3HT) is spin-coated to give the thin sensing element. Spin coating techniques were investigated to obtain optimal layer thickness and quality. The OFET consisted of six layers developed during this research: 1. aluminum gate; 2. polymethylmethacrylate (PMMA) dielectric layer; 3. the gold electrode; 4. Tween80™ surfactant; and 5 & 6. two layers of P3HT sensing material. Anisole solvent provided the best vehicle for good adhesion of PMMA to the gate layer made of aluminum. This work represents the fabrication steps, simulation and preliminary testing in the process of developing the operational ammonia gas sensing elements. |