Wrinkling of elastomeric coatings by an electric field is reported. The associated changes in the coating's optical properties yield switchable mirrors and windows. The field Ec needed to induce wrinkling is a factor of 4.4 lower than the theoretically predicted value, which is attributed to space-charge injection.
Structured lead zirconium titanate (PZT)-epoxy composites are prepared by dielectrophoresis. The piezoelectric and dielectric properties of the composites as a function of PZT volume fraction are investigated and compared with the corresponding unstructured composites. The effect of poling voltage on piezoelectric properties of the composites is studied for various volume fractions of PZT composites. The experimentally observed piezoelectric and dielectric properties have been compared with theoretical models. Dielectrophoretically structured composites exhibit higher piezoelectric voltage coefficients compared to 0-3 composites. Structured composites with 0.1 volume fraction of PZT have the highest piezoelectric voltage coefficient. The flexural strength and bending modulus of the structured and random composites were analyzed using three-point bending tests.
Biomimetic movement and low operating voltage have made ionic electroactive polymer actuators (iEAPs) interesting for applications where interactions with living organisms occur, such as haptic devices operating mainly in air or minimally invasive or chronically implanted medical devices operating in biological fluids. However, not all materials that are typically used in the fabrication of iEAPs are biofriendly, nor are the biological environments with various electrolyte compositions safe or optimal for the actuator. This paper presents a comprehensive overview of materials and methods that have been previously used to encapsulate ionic electroactive polymer actuators. Recently, increasing emphasis has been given to the miniaturization of actuators for the biomedical field, and therefore in the detailed overview we have focused on automated, tunable and industrially applicable coating methods, together with promising biocompatible encapsulant materials. In the final section, we introduce a carbon-based actuator that has been dip-coated with polydimethylsiloxane elastomer that shows extended lifetime during actuation in water.
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