Limiting electric current type oxygen sensor

摘要

A limiting electric current type oxygen sensor comprising a first electrode of a gas-permeable film, a thin solid electrolyte film which is crystallized along one direction to decrease resistance and which has a thickness falling in the range between 0.1 mu m and 30 mu m, and a second electrode of a gas-permeable film sequentially formed on an electrically insulating substrate. This limiting electric current type oxygen sensor is also provided with a porous coating layer or a dense coating layer. The porous coating layer made of Al2O3, SiO2, spinnel, SiC, Si3N4 and etc., has a porosity of not more than 30% and a thickness of not less than 1 mu m, and serves as a gas diffusion flow rate-determining portion. The dense coating layer serves to control a gas permeation path such that either the first electrode or the substrate is used as the gas diffusion flow rate-determining portion.