Patent ID: 8168053

Claim:
A gas sensing member to be exposed to a measured gas, comprising: A unit structure having a first surface area and a second surface area and having a gas inlet, at which the measured gas enters, on the first surface area; and A porous protective layer, which removes poison from the measured gas before the measured gas enters at the gas inlet of the unit structure, disposed on the first surface area of the unit structure, The unit structure comprising: A solid electrolyte body, through which oxygen ions are transmittable, which has both surfaces opposite to each other along a lamination direction; A porous diffused resistor layer through which the measured gas entering at the gas inlet is transmitted; A gas measurement electrode which is disposed on one surface of the solid electrolyte body and is exposed to the measured gas after the measured gas enters at the gas inlet and is transmitted through the porous diffused resistor layer; A reference gas electrode which is disposed on the other surface of the solid electrolyte body and is exposed to a reference gas; A heater which is disposed on or close to the solid electrolyte body so as to face one of the surfaces of the solid electrolyte body and has a heater substrate and a heating element disposed in or on the heater substrate, the heating element heating the solid electrolyte body; A chamber forming layer disposed between the solid electrolyte body and the heater so as to form a reference gas chamber between the solid electrolyte body and the chamber forming layer, and Wherein the heater substrate of the heater has a side corner area which is disposed at a side corner of the unit structure in a width direction of the unit structure, the width direction being substantially perpendicular to the lamination direction, and the side corner area extends along a longitudinal direction of the unit structure, the longitudinal direction being substantially perpendicular to both the lamination and width directions, so as to be adjacent to the heating element along the width direction, Wherein the porous protective layer is not disposed on the second surface area of the unit structure, and at least a portion of the side corner area of the heater substrate is disposed in the second surface area of the unit structure, Wherein a first distance D 1 along the lamination direction from the side corner area of the heater substrate to the porous protective layer and a second distance D 2 along the lamination direction from the side corner area of the heater substrate to a surface of the unit structure opposite to the heater with respect to the solid electrolyte body are set to satisfy a relation of D 1 /D 2 equal to or larger than 0.05 and equal to or smaller than 0.7, Wherein the porous protective layer is disposed on at least a portion of the chamber forming layer, and Wherein the side corner area is chamfered.