Characteristics of the TiO2/SnO2 thick film semiconductor gas sensor to determine fish freshness

This study is to investigate the use of TiO2, Pd, Pt, In, Ru, and Rh in a gas sensor material, which greatly improves the sensitivity of detecting trimethylamine gas. The metal-SnO2 thick films are prepared by screen-printing method onto Al2O3 substrates with platinum electrode. The sensing characteristics are investigated by measuring the electrical resistance of each sensor in a test box as a function of gas concentration. This is then used to detect trimethylamine, dimethylamine and ammonia gases within a concentration range of 100–1000 ppm. The gas sensing properties of metal-SnO2 thick films depend on the kind and the amount of metal added. The sensor material of SnO2 containing 1 wt.% Pd and 10 wt.% TiO2 shows the best sensitivity to TMA gas and good selectivity to dimethylamine and ammonia gases with respect to TMA gas at 250 °C.