Impedance-Based Temperature Sensing With Piezoceramic Devices

This paper deals with the temperature dependence of the electrical impedance of piezoceramic transducers. The behavior under thermal loads is investigated for bulk ceramics and composite structures where the piezoceramics are integrated into passive materials. According to these identified dependencies, temperature sensing through the piezoceramics impedance is realized using a polynomial fitting method. A creep operator and a lead filter are introduced to consider the time-dependent behavior of the electrical impedance. The presented approach is applied to a commercially available air ultrasound transducer. The accuracy of the measurement method is investigated for an arbitrary temperature profile yielding +/- 4.5 degrees C. The presented method can be utilized for additionally sensing temperature in devices with integrated piezoceramic transducers, especially ultrasound transducers or in structural health-monitoring applications.