A COMPUTER ADD-ON CARD AS A GAS-SENSING ANALYZER

A PC add-on card was designed for fast multi-channel data acquisition and analysis of the surface resistances of a gas sensor array to detec t the components of a gas mixture. Commercial data acquisition systems such as Lab View from National Instruments, HP VEE for windows and Ke ithley data acquisition system are costly and require long development time to configure for a specified application. They usually require e xternal power sources and other instruments, in addition to external s ignal conditioning circuitry. Moreover, they have limited sampling rat e and precision. In the present system, apart from data acquisition, d ata processing and analysis were carried out using FFT techniques, mul tivariate regression and artificial intelligent techniques such as neu ral network and fuzzy logic to detect the components H-2 and CO in a g as mixture quantitatively. The initial resistances, final steady state resistances, dynamic responses, relative humidity, and temperature ar e used to predict quantitatively the gas concentration of a gas mixtur e.