The gas sensor fabricated in such a way was fixed at a container
of 1 L capacity and treated for stabilization for 12 h at the same
temperature as measuring temperature in order to remove the
electrons inside the thick film device. To supply the heat
corresponding to the operating temperature to the semi-conductor
sensor, a constant voltage was supplied to the device using DC
power supply (HC2330AD). The measurement of temperature and
resistance of the sensor substrate was implemented using the
digital thermometers (MS-1280, Metex), respectively. As for the
sensor gas, a 500 ppm of mixed gas was fabricated in a make-toorder
by mixing 250 ppm of trimethylamine and 250 ppm of
ammonia charged at 100 kg/cm2. Using MFC (M3 030 V, Line-Tech)
and MFC controller (FM30VE, Line-Tech), the sensor gas for each
density of the mixed gas was injected into the container.