The technology of the planar probe probably corresponds to the working method in electronics. Also other components are produced at a reasonable price in some sort of layer technology. However, much more important is the fact that the measuring cell becomes smaller and lighter and can be heated faster. Also the power consumption of the lambda oxygen sensor is important. In addition, a certain construction equality is established with the broadband probe, produced in larger quantities.
How it works
In principle, this lambda oxygen sensor works like the finger sensor. Through several layers of foils and conducting paths a hollow cavity opens to the right. Surrounding air penetrates into the opening. The heating is completely integrated. It is installed as a conducting path (green) on the floor of the hollow cavity with an isolation layer on top and below. Upwards the surrounding air first hits the inside electrode (red) which is connected - like with the finger sensor - with the control unit. Without electrons the oxygen flows through the sensor foil to the outside electrode (blue) which is connected with the case (ground) of the lambda oxygen sensor. The sensor foil fulfils the same task as the ZrO2 with the finger sensor. And also here it is protected by a porous protective coating and a metal cover with corresponding openings.
The area of the hollow cavity which is lined by a conductive foil (inside electrode) is called measuring cell.