Electrochemical gas sensor cells using three dimensional sensing

Abstract

An electrochemical gas sensor cell is provided, the use of which permits quantitative measurement of volatile gas contaminants in an atmosphere being monitored. The cell comprises at least a first sensor electrode and a second counter electrode, on either side of an ion conductive electrolyte which may be immobilized in a matrix. The electrolyte may also be a solid electrolyte or a polymer electrolyte. The sensing electrode has a high surface area catalyst dispersed on a porous substrate, and is mounted in such a manner as to be exposed to the atmosphere which is to be sensed for gaseous contaminants, with the counter electrode being isolated from any exposure to that atmosphere. Generally, the electrodes are mounted in electrically conductive frames, sandwiching a third non-conductive frame member in which the ion conductive electrolyte is substantially located. The conductive frames may comprise electronically conductive materials such as conductive polymers, ceramics, nitrides, oxides and graphites. In an alternative embodiment, a further reference electrode may be mounted so as to be exposed to the electrolyte. The porous electrode may comprise a porous substrate or a base layer, a catalytically active metal, alloy, or metal oxide (usually a noble metal) dispersed in a high surface area form, carbon, and a polymeric hydrophobic binder.