Abstract
This paper describes a geometrical method of discriminating and quantifying gases using an electronic system composed of an integrated sensor and a microprocessor.
The integrated sensor with three different elements on an alumina substrate was fabricated by using thick film techniques. The elements are kept at around 400°C by a Pt heater mounted on the back of the substrate. Since these elements were made from different semiconductor oxides, they possess different sensitivities to methane as the principal component of the city gas, carbon monoxide generated by imperfect combustion, and ethanol and hydrogen as interference gases. Then the integrated sensor can develop specific patterns corresponding to each gas in terms of histograms of conductance ratios for each element.
The microprocessor discriminates target gases for identification on the basis of similarities calculated by comparing standard patterns stored in the memory and a sample pattern developed by the integrated sensor. The gases are then quantified by using the sensor element with the highest sensitivity to the identified gas.
The experimental results show that methane and carbon monoxide in mixture with ethanol can be identified and quantified without any trouble according by the proposed method.
