Dense diffusion barrier limiting current oxygen sensors

A new type of miniature amperometric oxygen sensor has been developed. The sensors are high temperature micro-electrochemical devices that use a dense diffusion barrier of a metal oxide that readily transports oxygen and conduct electrons. The diffusion barrier is deposited in thin film form on top of a zirconia-based electrochemical pump. When a voltage is applied to the pump, oxygen is depleted from one side of the diffusion barrier and the ionic current is proportional to the flux of oxygen across the thin film layer. If the pumping voltage reaches a high enough value, the transport of oxygen across the membrane and hence the device's output current, will be limited by the external, oxygen concentration and the transport characteristics of the diffusion barrier. The sensors can be manufactured in a planar design that offers a faster time response, much simpler design and potentially lower cost than existing limiting current oxygen sensors. (C) 1998 Elsevier Science S.A. All rights reserved.