Semi-conductor type sensor especially based on $SnO_2$ has been widely commerciallized because of its merits such as low cost, high sensitivity, easy maintenance and simple circuit to operate. But it also has demerits to overcome for more extensive application. Among them most serious problem is lack of selectivity.
In this study, the possibility of selectivity improvment for $SnO_2$ base semi-conductor type hydrocarbon sensor has been looked over using compensating device. The sensor was fabricated through thick film process and two sensing materials were screen-printed on one device. The main sensing material is composed of $SnO_2$, $Sb_2O_5$ and Pt to detect hydrocarbon and the compensating material is of $SnO_2$, $Sb_2O_5$ and Pd to detect ethanol as interfering gas. The ratio of resistance change of each sensing material is different according to gases and the selectivity improvement was confirmed utilizing this characteristics.
