Methanol and ammonia sensing characteristics of sol–gel derived thin film gas sensor

SnO2 thin film gas sensors have been prepared by sol–gel technique. The tin alkoxide precursor was synthesized by chemical reactions involving tin tetrachloride and sodium ethoxide. The gas sensing characteristics have been studied using a flow injection analysis and liquid samples of alcohol and ammonia. The experimental results revealed that the film thickness strongly affected gas sensitivity of the SnO2 films. The SnO2 gas sensors gave linear relationship between logarithm of gas sensitivity and logarithm of sample concentration in the range of 0.26–10% by volume for alcohol and 0.05–10% by volume for ammonia with the operation temperature of 350°C.