Effect of condensing environments on characteristics of piezoresistive ceramic pressure sensors

A humid atmosphere with water drops is among the most problematic environments for pressure sensors. In general the sensors are protected against harmful effects of media with conformal coatings which, however, in some way affect the characteristics of the sensor. LTCC technology enables manufacturing of the sensing structures that may operate in harsh environments without additional protection. Independently of the implemented protection we should be aware of the changes in the sensor response to the occasional contact with water drops, which result from the changed thermal conditions in the sensing structure. Our experiments demonstrated the influence of the protective coating on the response of the sensor exposed to a humid environment or immersed in the water as well as the effects of the changes in the response due to the water drops applied on the sensor without protection. Appropriate measures taken on the basis of forecasting sensor operation in condensing environments are a part of proactive system maintenance.