Detection of nitrogen dioxide using mixed tungsten oxide-based thick film semiconductor sensor

The thick film semiconductor sensor for NO(2) gas detection was fabricated by screen-printing method using a mixed WO(3)-based as sensing material. The sensing characteristics, such as response time, response linearity, sensitivity, working range, cross sensitivity, and long-term stability were further studied by using a WO(3)-based mixed with different metal oxides (SnO(2), TiO(2) and In(2)O(3)) and doped with noble metals (Au, Pd and Pt) as sensing materials was observed. The highest sensitivity for low concentrations (<16 mg l(-1)) was observed using WO(3)-based mixed with In(2)O(3) or TiO(2). The NO(2) gas sensor showing the fastest response and recovery time (both within 2 min), good linearity (Y=0.606X+0.788 R(2)=0.991) for gas concentrations from 3 to 310 mg l(-1), low resistance (3 MOmega), high sensitivity, undesirable cross sensitivity effect and good long-term stability (at least 120 days) using WO(3)-SnO(2)-Au as sensing material.