Fatigue Resistant Miniature Piezoceramic Actuators

Abstract

Piezoelectric ceramics are desirable actuator materials for many biomedical applications due to their ability to generate precise, controlled motion with applied voltage. Herein, we report the fabrication of miniature piezoceramic actuators and their subsequent performance testing under high electric fields. Actuators were produced by tape casting sub-micrometer lead zirconate titanate (PZT) powder, followed by electroding, laminating, and dicing to form multilayer devices. The resulting devices consisted of ten active PZT layers, each of which was -50 mm thick. To evaluate the effect of microstructure on performance, the components were heated to seven different temperatures ranging from 1175 to 1325°C and held at each temperature for 24 min. Fatigue resistance was determined by monitoring changes in polarization during continuous cyclic operation. Actuators sintered at lower temperatures possessed smaller grains and exhibited improved fatigue resistance. In these specimens, polarization decreased by <15% compared to more than 50% for devices processed at higher temperatures. These results indicate that sintering control can be effectively used to minimize performance degradation, improve reliability, and promote long-term stability.

Dependence of Piezoelectric Properties on Layer Thickness for Multilayer Actuators

“…From the results reported by Hooker et al [6] it might be expected that the life time performance of CMA's with PG01 will outperform those with PXE55 because of the smaller grain size and the smaller distribution. Another factor which is important for the life time behavior of CMA's is the poling process itself.…”

“…However, the coercive field does not change with particle size. Finally, Hooker et al [6] shows that a decrease of the grain size in actuators improves the fatigue resistance during continuous cyclic operation. This shows that grain size control can be used to minimize performance degradation, improve reliability and promote longterm stability.…”

Understanding microstructural effects on long term electrical fatigue in multilayer PZT actuators

“…We found that the fractional change in P r as a result of cyclic actuation was significantly smaller for samples processed at T S < 1250 °C, indicating a higher fatigue resistance in this temperature range. However, a nearly constant level of fatigue (≈50 % of P init ) is found for T S > 1250_°C (more detailed results of electrical polarization-fatigue measurements can be found elsewhere [9]). In the following, these electrical results will be explained by the observed changes in microstructure.…”

Modeling and optimization of bistable composite laminates for piezoelectric actuation

“…The piezoelectric layers modeled in this work have a working range of -500V to 1500V. However, frequent use at these high voltage levels can lead to degradation of the piezoelectric and a reduced lifespan (Pritchard, Bowen and Lowrie, 2001;Hooker et al, 2007). Furthermore the use of drive voltages in excess of 1000V may limit application of the technology due to safety concerns or the need to rectify local power sources.…”