Patent ID: 6554983
Filing Date: 2003-04-29
Classification: G01N

Abstract:
A gas sensing element comprising:first and second chambers into which an objective gas to be measured is introduced; a first diffusion resistive passage connecting said first chamber to an outside of said gas sensing element; a second diffusion resistive passage connecting said first chamber to said second chamber; a pump cell provided on a surface defining said first chamber for pumping oxygen in accordance with an applied voltage; a first monitor cell provided on a surface defining said first chamber for generating an electromotive force representing an oxygen concentration in said first chamber; a second monitor cell provided on a surface defining said second chamber for generating an electromotive force representing an oxygen concentration in said second chamber; and a sensor cell provided on a surface defining said second chamber and responsive to application of a predetermined voltage for generating a sensor current representing a specific gas concentration in said objective gas, wherein said voltage applied to said pump cell is controlled based on a difference between the electromotive forces obtained from said first and second monitor cells.