A novel way of reducing drift problems of the electrode potential of metal oxide pH sensors is presented. The method employs a FET-structure that uses the conducting metal oxide electrode as a gate contact. From the threshold voltage of this structure a signal can be derived which is independent of the electrode potential and can be used to compensate for the drift of it. In addition to the reduced drift, the compensation leads to an almost ideal nernstian response. First a theoretical explanation is given, which is then confirmed by measurement results.
- Iridium oxide
- pH sensor