JPS6478149A - Oxygen sensor - Google Patents

Abstract

PURPOSE:To obtain a stable sensor which is simple and whose power consumption is small by constituting a zirconia solid-state electrolyte substrate of a porous substrate, and using it as a diffusion controlled speed means. CONSTITUTION:On both faces of a zirconia solid-state electrolyte substrate 21, porous electrode layers 22, 23 are formed, and the electrode 23 is isolated and closed up hermetically from an external atmosphere by a spacer 25 and a sealing plate 26. In this state, first of all, the substrate 1 is heated, and subsequently, between the electrodes 22, 23, a DC constant-voltage is applied. As a result, oxygen being at the electrode 23 side is ionized, moves in the substrate 21, and an oxygen ion which has reached the electrode 22 is oxidized and blown off as gas oxide. Therefore, since oxygen partial pressure of the electrode 23 side drops, oxygen flows in from an external atmosphere through a pore of the substrate 21. In this case, since the substrate 21 functions as a diffusion controlled speed layer, oxygen diffused to the electrode 23 side is brought to controlled speed, and the oxygen partial pressure of the electrode 23 side is balanced to the oxygen partial pressure of an external atmosphere with some difference. In this case, between the electrodes 22, 23, a threshold current being in a steady state which does not depend on the applied voltage flows, and by measuring this current value, oxygen concentration of the external atmosphere can be determined.