Figure 1. A CTO gas sensor device.

The figure shows the construction of a gas sensor device. The gas sensitive material (in this case CTO) is printed on top of gold electrodes on an alumina chip. The reverse side has a platinum heater track on it. The gold electrodes and platinum heater track are attached to the plastic sensor housing by micro-welding 50 micron platinum wire between the housing posts and the alumina chip. The complete device will also have a cover which is ommited here for clarity.