A field effect transistor type gas sensor based on polyaniline

The researched sensor at this paper is based on gas sensitive conducting polymer. Some types of conducting polymer have gas sensitivity at room temperature (Matsuguchi et al., 2002). These conducting polymers have several shortages such as low sensitivity. The transistor type gas sensor has been studied for several decades. These sensors are based on metal oxide ceramics such as tin dioxide (Wollenstein et al., 2000 and Popova et al., 1991). We researched a polymer FET gas sensor. The sensor structure is similar to thin film transistor (TFT) one. This sensor can detect very low concentration of ammonia gas. The synthesized polyaniline has the resistance change for ammonia gas. Normally IDT electrode resistor sensor can detect several decade ppm or more ammonia gas. The FET type sensor which has the same polyaniline film can detect 5 ppm of ammonia.