A resistive gas sensor with elimination and utilization of parasitic electric fields

Resistive gas sensors on silicon substrates consist of a stack of several thin layers. Therefore, high electric fields result between the buried heater and the near sensitive layer and its contacts. These fields pervade the thin sensitive layer and affect the sensor response. This paper presents a special sensor substrate which was developed to control this cross effect. Electric fields across the sensing layer can be avoided and, furthermore, they can be homogeneously applied. The experimental results of a tin oxide gas sensor show, that the sensitivity towards nitrogen oxide can be improved by external electric fields. In conclusion, suggestions are made to implement this feature for innovative gas sensors with micro-hot plates.