Discrimination and quantification of flammable gases with a SnO2 sniffing sensor

Abstract

Sample gases (methane, ethane, propane, CO, and ethylene) can be quantitatively and qualitatively distinguished using an artificial ‘sniffing’ system based on the nonlinear dynamic response of a SnO₂ semiconductor gas sensor. In this system, the sample gas is periodically blown onto the sensor using an electric fan, and the resulting output conductance of the sensor is analyzed by complex fast Fourier transformation (FFT). The higher harmonics of the complex FFT characterize the time-dependent nonlinear properties of the response depending on the gas species. The nonlinear dynamic response using this ‘sniffing’ system is discussed in terms of the kinetics of the gas species at the sensor surface.