Abstract: Disclosed is a gas sensor comprising inner pumping electrodes arranged on upper and lower surfaces and both side surfaces in a first chamber so that O.sub.2 contained in a measurement gas introduced through a first diffusion rate-determining section is effectively removed by the aid of a pumping voltage applied between the inner pumping electrodes and an outer pumping electrode. After the removal of O.sub.2, the measurement gas is introduced into a second chamber through a second diffusion rate-determining section so that oxides contained in the measurement gas are decomposed by the aid of a detecting electrode, or O.sub.2 is bound to inflammable gases contained in the measurement gas. An amount of oxygen moved or transported in accordance therewith is measured to determine the concentration of the oxides or the inflammable gases. Accordingly, the oxygen contained in the measurement gas can be effectively controlled, making it possible to highly accurately measure the oxides or the inflammable gases.

Abstract: A method and a sensing device of measuring a concentration of a gas component of a measurement gas, which method includes the steps of: introducing the measurement gas containing the gas component, from an external measurement-gas space into a first internal space, under a diffusion resistance; controlling an amount of oxygen in the measurement gas within the first internal space, so as to produce an atmosphere which does not substantially affect measurement of the gas component and which does not convert the gas component; introducing the atmosphere from the first internal space into a second internal space, under a diffusion resistance; and measuring the concentration of the gas component present in the atmosphere in the second internal space.

Abstract: A method and a sensing device of measuring a concentration of a gas component of a measurement gas, which method includes the steps of: introducing the measurement gas containing the gas component, from an external measurement-gas space into a first internal space, under a diffusion resistance; controlling an amount of oxygen in the measurement gas within the first internal space, so as to produce an atmosphere which does not substantially affect measurement of the gas component and which does not convert the gas component; introducing the atmosphere from the first internal space into a second internal space, under a diffusion resistance; and measuring the concentration of the gas component present in the atmosphere in the second internal space.