Thin coat temperature compensated resistance oxide gas sensor

Claim 1

In a method of forming a temperature compensated electrical oxygen sensing element having an insulating ceramic support with a first, second and third electrode disposed in spaced relation on the surface of the ceramic support that is to be exposed to the exhaust gas, the improvement comprising: (a) applying a template or the like so as to mask a first part of said surface, said first part including the third electrode and a portion of the second electrode, such that a second part of said surface including the first electrode and the other portion of the second electrode remains unmasked; (b) applying to said second part of the surface by a hot thin-layer technique a layer of a first resistive ceramic oxide material, the resistance of said material varying only as a function of temperature; (c) removing said template so that both the first and second parts of said surface are unmasked; and (d) applying to said first and second parts of said surface a layer of a second resistive ceramic material, the resistance of said material varying as a function of temperature and the partial pressure of oxygen in the gas to which it is exposed.