Investigation of corrosion phenomena on chemical microsensors

Compared to normally sized sensors, chemical microsensors are exposed to a higher corrosion risk. Corrosive damage can be caused by both the direct attack of the measuring medium on the chemically sensitive layer and the corrosion of the substrate materials or the electrical contacts due to absorption or penetration of moisture through the encapsulating material. Corrosion phenomena on chemical sensors have been investigated by using electrochemical methods like the measurement of electrode potentials and sensor output signals or the measurement of the electrochemical noise, by resistance and impedance measurements as well as by gravimetric methods and by microscopic or REM observation of the specimen under test. In the paper, results of corrosion measurements on pH glass electrodes, ISFET pH sensors, semiconductor-based miniaturised oxygen sensors and zirconia-based potentiometric gas sensors by utilising the above listed methods are presented and discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.