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 1(-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 R-2 = 0.991) for gas concentrations from 3 to 310 mg 1(-1) low resistance (3 MOmega), high sensitivity, undesirable cross sensitivity effect and good long-term stability (at least 120 days) using WO3-SnO2-Au as sensing material. (C) 2002 Elsevier Science B.V. All rights reserved.