Laminating two-layer thick films structure tin oxide-based butane gas sensor operating at low temperature

Laminating two-layer sensing thick films sensors for the application to a portable gas alarm device was fabricated by screen-printing technique. For miniaturization, a sensor's construction of two-side substrate was adopted. The first layer was SnO2-based film covered directly with alumina-supported Pd catalyst as second layer promoting the selectivity and stability of C4H10 gas determination and at low operation temperature. The maximum sensitivity was obtained using 15-20 mum thickness of the first layer and the second layer for C4H10. The sensor cross-sensitivity effect (selectivity) and the humidity effect were effectively restrained using laminating two-layer thick films at low operation temperature (250degreesC). The sensor is composed of 15-20 mum thickness first layer and 30-40 mum thickness second layer was chosen as the optimal sensor structure for testing the basic sensor characteristics. The sensor had fast response (less 30 s), good repeatability, good linearity (Y = -0.513X + 5.05R(2) = 0.9990) for C4H10 gas with concentrations from 50 to 1000 ppm and good long-term stability (at least 78 days) at operation temperature of 250 degreesC. (C) 2003 Elsevier B.V. All rights reserved.