A limiting current type sensor for hydrocarbons

A hydrocarbon (HC) sensor, composed of yttria-stabilized zirconia (YSZ) as a solid electrolyte and catalytically active and passive material for HC as electrodes, is proposed. The active and passive electrodes were attached to the same side of a YSZ disk as cathodes. A Pt electrode was applied to the other side of YSZ as anode. The diffusion of gas to the cathodes was limited by a pinhole of a cover attached to YSZ and the sensor showed a limiting current behavior by applying voltage. The difference between the limiting current, ΔI, of two cathodes increased linearly with the concentration of HC such as methane and isobutane, which suggests that HC concentration can be obtained by measuring ΔI.