Oxygen sensor

Claim 1

An oxygen sensor for detecting oxygen density of an oxygen-containing gas in a region of pulsating pressure, said oxygen sensor comprising: a body formed of a solid electrolyte material that is capable of conducting oxygen ions; a wall enclosing a portion of the surface of the solid electrolyte body, the wall and the solid electrolyte body forming a hollow structure, the interior of which forms a diffusion chamber; and a plurality of electrodes mounted on the structure, the electrodes being adapted to be connected to a voltage source to provide a sensor cell and a pumping cell, wherein the structure, when placed in said region of pulsating pressure, is permeable to gas molecules only through at least one pin-hole opening formed in the structure and through a porous portion of the structure not including the pin-hole opening, the total flow area of the at least one pin-hole opening is selected to be small enough to control the rate of diffusion of oxygen molecules from the region of pulsating pressure into the diffusion chamber, and the flow area of each pin-hole opening is selected to be large enough to control the diffusion rate primarily by causing multiple collisions between the gas molecules passing through the pin-hole rather than primarily by multiple collisions between the gas molecules and the inner surface of the pin-hole opening, and the size of each pore in the porous portion is much smaller than the size of the pin-hole and the total pore area of all the pores in the porous portion is substantially smaller than the flow area of the pin-hole opening but is sufficient to permit pulsative changes in the pulsating pressure region to be transmitted to the diffusion chamber.