Development of new capacitive strain sensors based on thick film polymer and cermet technologies

In this work, the strain sensing characteristics of new thick film capacitive sensors are presented. New cermet and polymer dielectric pastes based on lead-zirconate-titanate (PZT) and polyvinylidene fluoride (PVDF) have been developed. The screen printing technique has been used to fabricate the sensors on 96% alumina substrates. Various strain gauge characteristics have been studied, including the electrical properties of both the cermet and polymeric films. Both the cermet and polymer sensors exhibit good dielectric properties with gauge factors comparable to piezoresistive strain sensors. An application circuit based on integrated bipolar arrays incorporating the new capacitive strain sensors was designed and tested. The output from this circuit is a frequency that is proportional to the applied strain. (C) 2000 Elsevier Science S.A. All rights reserved.