Theoretical analysis of a blocking-electrode oxygen sensor for combustion-gas streams

The currently employed oxygen sensor for internal combustion engines, which is used to control the intake air-to-fuel ratio (A/F), performs well near the stoichiometric A/F, but cannot provide precise control during fuel-lean or fuel-rich operation. We propose an alternate oxygen-sensor design, which is based on an established concept of a blocking electrode, and mathematically simulate the sensor response to a typical engine exhaust regime. Mathematical modeling of this device is particularly helpful since (i) the experiments required for the device characterization are difficult and (ii) the differential equations governing the device operation apply to electron, hole, and gas transport, all of which are well understood.