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

The thick film semiconductor sensor for NO2 gas detection was fabricated by screen-printing method using a mixed WO3-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 WO3-based mixed with different metal oxides (SnO2, TiO2 and In2O3) 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 WO3-based mixed with In2O3 or TiO2. The NO2 gas sensor showing the fastest response and recovery time (both within 2 min), good linearity (Y=0.606X+0.788 R2=0.991) for gas concentrations from 3 to 310 mg l−1, low resistance (3 MΩ), high sensitivity, undesirable cross sensitivity effect and good long-term stability (at least 120 days) using WO3–SnO2–Au as sensing material.